WO2003070356A2 - Energy efficient liquid desiccent regeneration - Google Patents

Energy efficient liquid desiccent regeneration Download PDF

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Publication number
WO2003070356A2
WO2003070356A2 PCT/IN2003/000028 IN0300028W WO03070356A2 WO 2003070356 A2 WO2003070356 A2 WO 2003070356A2 IN 0300028 W IN0300028 W IN 0300028W WO 03070356 A2 WO03070356 A2 WO 03070356A2
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WO
WIPO (PCT)
Prior art keywords
regenerator
ltr
absorber
ocd
icd
Prior art date
Application number
PCT/IN2003/000028
Other languages
French (fr)
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WO2003070356A9 (en
WO2003070356A3 (en
Inventor
M. V. Rane
S. V. Reddy
J. S. Bajaj
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The Indian Institute Of Technology, Bombay
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Publication date
Application filed by The Indian Institute Of Technology, Bombay filed Critical The Indian Institute Of Technology, Bombay
Priority to AU2003223102A priority Critical patent/AU2003223102A1/en
Priority to EP03719073A priority patent/EP1478450A2/en
Publication of WO2003070356A2 publication Critical patent/WO2003070356A2/en
Publication of WO2003070356A3 publication Critical patent/WO2003070356A3/en
Publication of WO2003070356A9 publication Critical patent/WO2003070356A9/en

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F3/00—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems
    • F24F3/12—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems characterised by the treatment of the air otherwise than by heating and cooling
    • F24F3/14—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems characterised by the treatment of the air otherwise than by heating and cooling by humidification; by dehumidification
    • F24F3/1411—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems characterised by the treatment of the air otherwise than by heating and cooling by humidification; by dehumidification by absorbing or adsorbing water, e.g. using an hygroscopic desiccant
    • F24F3/1417—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems characterised by the treatment of the air otherwise than by heating and cooling by humidification; by dehumidification by absorbing or adsorbing water, e.g. using an hygroscopic desiccant with liquid hygroscopic desiccants
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/26—Drying gases or vapours
    • B01D53/263—Drying gases or vapours by absorption
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F3/00—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems
    • F24F3/12—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems characterised by the treatment of the air otherwise than by heating and cooling
    • F24F3/14—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems characterised by the treatment of the air otherwise than by heating and cooling by humidification; by dehumidification
    • F24F2003/144—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems characterised by the treatment of the air otherwise than by heating and cooling by humidification; by dehumidification by dehumidification only
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F2203/00—Devices or apparatus used for air treatment
    • F24F2203/10—Rotary wheel
    • F24F2203/1016—Rotary wheel combined with another type of cooling principle, e.g. compression cycle
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F2203/00—Devices or apparatus used for air treatment
    • F24F2203/10—Rotary wheel
    • F24F2203/1032—Desiccant wheel
    • F24F2203/1036—Details
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F2203/00—Devices or apparatus used for air treatment
    • F24F2203/10—Rotary wheel
    • F24F2203/1068—Rotary wheel comprising one rotor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F2203/00—Devices or apparatus used for air treatment
    • F24F2203/10—Rotary wheel
    • F24F2203/1084—Rotary wheel comprising two flow rotor segments

Definitions

  • the present invention relates to a novel energy efficient multi-stage regeneration process, for regenerating liquid desiccant (LD), and further relates to the application of rotating contacting disks to provide intimate contact between LD and vapour/gas to enhance the interfacial area between them for increased heat and/or mass transfer, without/problems of carryover of liquid in to the vapour/gas stream or flooding having the provision to heat/cool the liquid based on the application.
  • the invention further finds applications in Hybrid Cooling Systems (HCS), in which air temperature and humidity are simultaneously controlled using a contacting device, which meets the needs of dehumidification, decrease in temperature and significant reduction in electrical power consumption with increase in cooling and/or dehumidification capacity for a given refrigeration compressor.
  • HCS Hybrid Cooling Systems
  • Equipment often employed for regeneration process of LD are packed bed regenerators, spray towers with finned tube heat exchangers, solar regenerator, simple boiler and multiple effect boiler. Processes requiring mass transfer between two contacting fluids often employ equipment such as spray towers, packed towers and tray towers.
  • spray towers and spray chambers the liquid is generally sprayed into a gas stream by some means to disperse the liquid into fine spray of drops.
  • the flow may be counter current and co-current as in vertical towers, or parallel as in horizontal spray chambers.
  • Packed tower is used for regeneration process of LD (Martin, V. and Goswamy D. Y., Heat and Mass Transfer in Packed Bed Liquid Desiccant Regenerators - An Experimental
  • the desiccant is distributed over the packing by spray heads and the process air was blown through the packing for regeneration of LD.
  • the process air picks up the water from the LD because of the partial pressure difference of water in the process air and LD.
  • the main problem associated in this regeneration process is carryover of LD along with air stream. Requirement of minimum irrigation rate and limitations of flooding in packed towers complicates the design or reduces the efficacy of the regeneration process. Also large power is required to circulate air/gas through packed bed.
  • Spray chamber with finned tube heat exchanger is the practical equipment for regeneration process of LD (Peng, C. S. P. and Howell R J., The Performance of Various Types of Regenerators for Liquid Desiccants, Journal of Solar Energy Engineering, Transactions of the ASME, Vol 106, pp 133-141 , USA, 1984).
  • Finned tube heat exchangers are stacked horizontally with a column with hot water flowing in the tube side.
  • LD was sprayed on the heat exchanger and drips down.
  • a blower was used to circulate process air through the regenerator counter current to the falling LD.
  • the advantage of the system is lower pressure drop for the air/gas side.
  • there is a relatively high pumping cost for spraying the LD The tendency for carry over of liquid by the air/gas is considerable in the spray towers and mist eliminators will almost always be necessary leading to increase the air/gas side pressure drop. Even with mist eliminators 100% elimination of carryover is not ensured.
  • Regeneration of LD can be done using solar energy.
  • Solar regenerator consists of inclined surface with transparent glazing as a covering where weak LD that is to be regenerated flows down the sloping surface as a falling film and is heated by the absorbed solar radiation (Peng, C. S. P. and Howell R J., The Performance of Various Types of Regenerators for Liquid Desiccants, Journal of Solar Energy Engineering, Transactions of the ASME, Vol 106, pp 133- 141 , USA, 1984).
  • the water vapour that is evaporated from the solution surface is removed by blowing air through the slot formed between the glazing and the film surface.
  • the disadvantage of the regeneration process is that the system is not operative during non-solar hours. There must be backup heat source for the regeneration of LD during non-solar hours.
  • the regeneration process of LD in a simple boiler can be achieved by heating the LD to boiling temperature (Lowenstein, A. I. and Dean, M. H., The Effect of Regenerator Performance on A Liquid Desiccant Air-Conditioner, ASHRAE Transactions: Symposia, Vol. 98, No.1 , pp 704- 711 , USA, 1992).
  • This regeneration process increases the energy required to preheat the weak desiccant that enters the regenerator.
  • the regeneration process in a simple boiler is not energy efficient since the latent heat of the vapour generated is not recycled. Regeneration at sub atmospheric pressure can reduce the higher temperature of the simple desiccant boiler. Adding a vapour condenser to the boiler can do this.
  • a non-condensable pump is required to maintain the vacuum in the regenerator. This increases the electrical power consumption.
  • vapour from high-pressure boiler has a saturation temperature that is sufficient to provide required thermal input to lower pressure boiler.
  • Low-pressure boiler is operating under vacuum.
  • a non-condensable pump is required to maintain vacuum (Lowenstein, A. I. and Dean, M. H., The Effect of Regenerator Performance on A Liquid Desiccant Air-Conditioner, ASHRAE Transactions: Symposia, Vol. 98, No.1 , pp 704-711, USA, 1992).
  • Latent heat of vapour from high-pressure boiler is utilised in low-pressure boiler.
  • maintaining vacuum in low-pressure boiler increases the electrical power consumption. Costly components are required for high-pressure boilers and an issue of safety becomes more complex.
  • US Patent No. 5,213,154 discloses a single stage regeneration system for use in air conditioning system.
  • the system comprises of a direct- fired natural circulation boiler for regenerating LD.
  • a falling film heat exchanger is used for transferring heat from concentrated desiccant to dilute desiccant. It is single stage regeneration process, the latent heat from the vapour leaving from the boiler is not recycled/reutilised. The single stage regeneration process is exergetically less efficient.
  • US Patent No. 5, 097, 668, "Energy Reuse Regenerator for Liquid Desiccant Air Conditioners” discloses the regeneration process of LD in air-conditioners, which uses LD for dehumidification of air.
  • the regeneration of LD is achieved in a desiccant boiler and a desiccant evaporator/condenser in combination with heat exchangers.
  • the evaporator /condenser receive the vapour produced by the boiler to provide a reuse of heat for regeneration.
  • Certain quantity of LD from air-conditioner is flowing to evaporator /condenser, where it is sprayed over the surface through which vapour from boiler is flowing.
  • Certain quantity of LD from air-conditioner is directly flowing to boiler for regeneration. As the LD is sprayed in presence of air in the evaporator/condenser carryover of LD with the air stream is inevitable. Additional electrical power is required for spraying LD in the evaporator/ condenser.
  • US Patent No. 4,189,848 "Energy Efficient Regenerative Liquid Desiccant Drying Process” discloses a method and apparatus for the drying of harvested crops by utilising desiccants with a closed loop drying loop and open drying loop.
  • the closed drying loop cycle the drying air brought in to contact with a desiccant in a packed tower after it exits from a crop- drying bin.
  • the open loop drying cycle the used desiccant is heated and regenerated at high temperature driving water vapour from the desiccant.
  • the water vapour condensed was used to pre heat the dilute desiccant before heat is added from the external source in the regenerator.
  • the carryover of LD in to the air stream is inevitable. Large electrical power is required to circulate the air through packed towers.
  • US Patent No. 4,941 ,324, "Hybrid Vapour Compression/Liquid Desiccant Air Conditioner” discloses a hybrid air-conditioning system consisting of a compressor, evaporator, condenser and refrigerant. LD and refrigerant are simultaneously circulated between evaporator and condenser for cooling and dehumidifying air forced therein. The regeneration of the LD is achieved by spraying the LD on the condenser of vapour compression refrigeration system. A blower is provided to circulate the outdoor air to regenerate the LD. The main problem with such arrangement is corrosion of the condenser coil. Moreover as the LD is sprayed, carryover and loss of LD to indoor and out door air streams is inevitable.
  • Packing in packed towers provide large interfacial surface between liquid and air/gas.
  • the key requirements of the packing are large surface area per unit volume and must permit large volume flow of fluids through small tower cross section with lower pressure drop for the air/gas.
  • Packings in the form of Collinsing rings, Lessing ring, Partition ring, Berl saddle and Pall rings are commonly used in packed columns (Robert, E. Treybal, Mass - Transfer Operations, pp 187-191 , Mcgraw-Hill Book Company, 1981).
  • Random packings offer large specific surface but suffer from larger air/gas side pressure drop.
  • Regular or stacked packings like Collinsing rings, Double spiral ring, Wood grids offer lower pressure drop than random packings for the air/gas side.
  • US Patent No. 4333894 loses mass transfer column consisting of one or more contact zones.
  • the contact zones are exclusively provided with packings placed in prearranged locations.
  • optimal operating conditions for the packing are created over the entire height of the contact zones in order to achieve a minimal pressure loss at a concomitant high separating efficiency. This is done by a suitable gradated adaptability of the packing to vapour and liquid loads varying over the height of the contact zones. It was claimed uniform flow of liquid through the bed. However, this patent does not address the issue of carry over of liquid along with air/gas.
  • Second packing zone is an annulus adjacent at an upper part of the tower wall. Rest of the tower acts as the second zone. First packing pieces are smaller than the second plurality of packing pieces. Surface area of the packing is 119 m 2 /m 3 with 2 x 2 x 4 inch ceramic saddles in the first zone. In the second zone the packing is also ceramic saddled of size 3 x 3 x 6 inch which were giving a surface area of 93 m 2 /m 3 . In this patent too the carryover of liquid along with air/gas stream is not addressed.
  • vapour absorption heat pump In the development of vapour absorption heat pump, contacting discs have also been used in mixed alkali hydroxides to absorb water vapour (Shallow, F. E. and Smith, I. E., "Vapour Absorption Into Liquid Film on Rotating Discs” Proceeding of the Work Shop on Absorption Heat Pumps, London, pp 373-381 , 1988). Copper discs of 110 mm diameter were rotated at the speed of 200 rpm in vacuum chamber. There is no specific teaching about spacing between the discs and wetting of the surface of the discs with liquid.
  • Desiccants are a subset of a group of materials called sorbents. Desiccants in particular have high affinity for water and their absorption capacity varies with the structural characteristics of the material. For example, nylon can absorb up to 6 percent of its weight of water, wood can absorb 23 percent of its weight, whereas a commercially available desiccant can hold about 1100 percent of its weight of water. Some examples of such desiccants are Lithium chloride, Lithium bromide, etc. (ASHRAE, "Fundamentals Handbook", American Society for Heating Refrigeration and Air-conditioning Engineers, pp 21.1-21.5, Atlanta, USA, 1997). The desiccant affinity to absorb the moisture can be regenerated repeatedly by applying heat to the desiccant material to drive off collected moisture.
  • Low-grade heat can be obtained from a variety of sources such as solar collector, radiator hot water, engine exhaust, condenser heat recovery from refrigeration machines, burning bio mass, etc.
  • the temperature for this process is generally in the range of 50°C to 260°C depending on the material.
  • Desiccant cooling systems are energy efficient and environmentally safe. In recent years, DCS have received considerable attention due to their inherent ability to use low- grade thermal energy and reduce the latent cooling load significantly. Desiccant dehumidification can reduce total electricity demand by as much as 25% in humid regions. These systems provide a drier, more comfortable and cleaner indoor environment with lower consumption of electric power.
  • liquid desiccant (LD) dehumidification systems air is dehumidified when exposed to hygroscopic solutions. At a given temperature the desiccant has a lower vapour pressure than pure water, and hence moisture transfer takes place from air to solution.
  • desiccants such as Triethylene glycol, Lithium chloride, Lithium bromide, Calcium chloride etc. are extensively in use. Some desiccants also have the ability of simultaneously controlling microbiological contaminants from air streams to improve the quality of air (ASHRAE, "Fundamentals Handbook", American Society for Heating Refrigeration and Air-conditioning Engineers, pp 21.1-21.5, Atlanta, USA, 1997).
  • the LD is sprayed on the evaporator of the vapour compression refrigeration system for cooling and dehumidification of air.
  • the regeneration of the LD is achieved by spraying the LD on the condenser of vapour compression refrigeration system.
  • Two blowers were provided to circulate the indoor air over the cooling coil and out door air to regenerate the LD.
  • An adiabatic humidifier is provided in the cycle.
  • the main problem with such arrangement is corrosion of the condenser and evaporator coils.
  • carryover of LD to indoor and out door air streams is inevitable.
  • US Patent No. 5,022,241 discloses a residential type hybrid air conditioning system, having a conventional absorption refrigeration subsystem to handle the sensible heat loads and a LD subsystem to handle the system latent load. This system incorporates an evaporative cooler for cooling and re-humidification of the process air. In this case too the carry over of LD with the process air is unavoidable as the desiccant is sprayed in the system.
  • US Patent No. 4,180,985 discloses an air-conditioning system with a regeneratable desiccant bed. This arrangement employs a desiccant pad of any suitable material that can be disposed and supported within the feed duct to allow the moist feed air to flow through the pad and contact the LD material. Materials such as fiber glass pads, wire screens, packed steel shavings have been used. In this patent problems due to the carryover of LD with air stream are not addressed
  • the LD regeneration process/system ideally should exhibit the following attributes:
  • the main object of the present invention is to provide a novel energy efficient multi-stage regeneration process, for regenerating liquid desiccant (LD), with application of rotating contacting disks to provide intimate contact between LD and vapour/gas to enhance the interfacial area between them for increased heat and/or mass transfer, without problems of carryover of liquid in to the vapour/gas stream or flooding having the provision to heat/cool the liquid based on the application. Further it is an object of the invention to explore applications in Hybrid Cooling Systems (HCS), in which air temperature and humidity are simultaneously controlled using a contacting device, which meets the needs of dehumidification, decrease in temperature and significant reduction in electrical power consumption with increase in cooling and/or dehumidification capacity for a given refrigeration compressor.
  • HCS Hybrid Cooling Systems
  • One of the objects of the invention is to regenerate the LD with higher specific water removal rates.
  • Another object of the invention is to develop HTR with no carryover of LD in to the steam, in which water rich LD boil to remove water in the form of steam, while performing the operation of regeneration of LD.
  • Another object of the invention is to develop HTR, which operates at atmospheric pressure.
  • Another object of the invention is to pass the partially regenerated LD from HTR to LTR for further regeneration or pass the partially regenerated LD from LTR to HTR for further regeneration or split the flow of LD into two streams and pass them to HTR and LTR
  • Another object of the invention is to provide intimate contact between LD and air to enhance the interfacial area between the vapour/gas stream and LD using large heat and mass transfer area, which ensures no carryover of LD in to the outdoor air stream, while, regenerating' LD.
  • Another object of the present invention is to develop regenerator that has no limit on liquid throughput leading to high efficacy of the process (by reducing recirculation losses at lower liquid throughputs).
  • Another object of the invention is to provide a contacting device that operates with low power consumption.
  • Yet another object of the invention is to deliver the latent heat of the vapour generated in HTR to LD in LTR for regeneration. Yet another object of the invention is to use alternate materials to reduce the weight and cost, while eliminating corrosion problems.
  • Yet another object of the invention is to develop a multi-stage regenerator comprising of Intermediate Temperature Regenerator/s (ITRs) to operate in conjunction with the HTR and LTR.
  • Another object of the invention is to provide a contacting device that incorporates surface density in the rage of 450 to 600 m 2 /m 3, which is far superior to conventional polypropylene Rauschert Hiflow rings of size 2.54 cm having surface density of 210 m 2 /m 3 .
  • Another object of the present invention is to provide a contact device that has no limit on liquid throughput leading to high efficacy of the selective applications.
  • Yet another object of the invention is to provide a contacting device having the provision to heat / cool the liquid, vapour/gas, based on the application.
  • Another object of the invention is to provide design for HCS with significantly higher cooling capacity, than that of the VCRS using similar compressor.
  • Yet another object of the invention is to provide design for a HCS with significantly lower compressor displacement requirement as compared to that of a VCRS for a required cooling capacity
  • Yet another object of the invention is to develop an ICD a non-adiabatic or adiabatic absorber that ensures no carryover of LD to the indoor air stream, while performing operations of dehumidification and/or cooling of the indoor air stream.
  • Yet another object of the present invention is to develop an regenerator/outdoor contacting device (OCD), a non-adiabatic or an adiabatic regenerator, that ensures no carryover of LD in to the outdoor air stream, while, performing the operation of regeneration of LD.
  • OCD regenerator/outdoor contacting device
  • Yet another object of the invention is to use alternate materials to reduce the weight and cost, while eliminating corrosion problems.
  • Yet another object of the invention is to use the liquid-liquid heat exchanger to increase the cooling capacity and COP of the HCS.
  • a single stage regeneration process comprises of:
  • LTR which incorporates large surface density contacting device, having provision to heat the LD, with the hot fluid passing through passages, which are in thermal contact with a container such as a the containing the LTR
  • Optional arrangement such as a hood with chimney to aid the flow of ambient air through LTR to pickup the moisture from LD.
  • the single stage regeneration process may be extended to a two-stage regeneration process in a system comprising:
  • LTR incorporating large surface density contacting device, having provision to heat the LD, with vapour generated in HTR condensing in passages which are in thermal contact with a container such as a trough containing the LTR •
  • Optional arrangement such as a hood with chimney to aid the flow of ambient air through LTR to pickup the moisture from LD.
  • the two-stage regeneration process may be extended to a multi-stage regeneration process in a system comprising:
  • HTR operating at highest pressure in the system boiling the weak LD absorbing heat from an external source, having insulation on exposed surface to avoid heat loss from LD to surroundings and giving off vapour to next relatively low temperature ITR, in which the latent heat of vapour generated in HTR is used to boil the LD.
  • a LTR operating at atmospheric pressure, incorporating large surface density contacting device, having provision to heat the LD, with vapour generated in immediate higher temperature HTR/ITR condensing in the passages, in thermal contact with a container such as a the containing the LTR •
  • Optional arrangement such as a hood with chimney to aid the flow of ambient air through LTR to pickup the moisture from LD.
  • HTRHE Optional heat exchangers HTRHE, ITRHE and LTRHE used to recycle heat to enhance the energy efficiency of the process • Pressure reducing devices such as throttle valve
  • the number of stages in regeneration process may be increased by appropriately adding ITRs, liquid-liquid heat exchangers and pressure reducing devices between HTR and LTR.
  • the contacting device providing intimate contact between fluids to enhance the interfacial area between them comprises of:
  • the Hybrid Cooling System in accordance with the inventioncomprises: • An absorber/ Indoor Contacting Device (ICD), for dehumidifying air by bringing it in contact with the LD while being cooled by evaporating refrigerant in the integrated evaporator
  • ICD absorber/ Indoor Contacting Device
  • a regenerator/ Out Door Contacting Device for regenerating LD by bringing it in contact with air, while LD being heated by condensing refrigerant in the integrated condenser .
  • a refrigerant compressor to compress the refrigerant vapour coming from absorber/ICD after absorbing heat from LD and send the high pressure refrigerant vapour to regenerator/OCD for delivering heat to the LD
  • a throttling device for throttling liquid refrigerant moving from regenerator/OCD to absorber/ICD •
  • Optional liquid-liquid heat exchanger to recycle heat from the hot regenerated strong LD flowing from the regenerator/OCD into the weak LD pumped out of the absorber/ICD
  • SCD Spiral Contacting Device
  • FIG.1a is a contacting mesh
  • FIG.1b a single stage low temperature regenerator with fan and chimney
  • FIG.2 is a schematic of absorber/ICD or regenerator/OCD with spiral contacting device (SCD)
  • FIG.3a is a a series flow two-stage regenerator with weak LD entering HTR
  • FIG.3b is a series flow two-stage regenerator with weak LD entering LTR
  • FIG.3c is a parallel flow two-stage regenerator
  • FIG.4a is a series flow three-stage regenerator with weak LD entering HTR
  • FIG.4b is a series flow three-stage regenerator with weak LD entering LTR
  • FIG.4c is a parallel flow three-stage regenerator
  • FIG.5 is a schematic of the hybrid cooling system
  • FIG.6 shows a comparison of VCRS, DCS and HCS on psychrometric chart
  • FIG.1a shows the contacting mesh for the mass transfer.
  • Dimples, 114 are provided to give the required gap between the discs, when they are assembled on the shaft.
  • Dimples on the mesh are providing the self-spacing between the discs. This leads to reduction in time required to assemble the discs on the shaft.
  • the depth and diameter of the dimple can be varied.
  • the spacers of required thickness on the shaft can provide spacing between the discs. This eliminates the dimples on the circumference of the disc A lip, 115 on the circumference of the contacting disc provides enough rigidity to the contacting surface.
  • Inner surface of the disc is 116.
  • a square hole at the centre is 117.
  • the discs can be thermally bonded with the shaft. Thermally bonded discs can be acting as fins and help in heat transfer between fluid in the trough and fluid flowing through the shaft.
  • FIG.1b shows a single stage Low Temperature Regenerator.
  • the disc, 1 provides the contacting surface between the LD and air.
  • the contacting surface is the mesh, or roughened surface, which holds the liquid on the surface for mass transfer.
  • the disc, in plurality are mounted on a square hallow or solid shaft 2.
  • a trough, 3 contains the LD. Material of construction of the trough can be a metallic, non-metallic or any other suitable, which is compatible with the LD and vapour/gas.
  • the LD to be regenerated flows in to the trough 3 through inlet conduit 6.
  • the regenerated LD flows out from the trough 3 through outlet conduit 7.
  • Passages, 9 in plurality are in thermal contact with the trough.
  • the passages can be metallic or non metallic or any other suitable material, which is compatible with fluid flowing through it.
  • a hood, 14 is provided to ensure to vapour/gas passes in closed contact with contacting discs 1.
  • a chimney 15 or a fan 16 is provided to circulate the air/gas through the contacting device.
  • the heat transfer fluid is supplied through conduit 10 to the passages 9 wherein it exchanges heat with the LD in the trough and leaves through conduit 12.
  • a device 5 is provided to rotate the contacting disc assembly and is supported on support 4. The surface of the contacting disc can hold large quantity of the liquid. Rotating contacting surface partially dipped in a liquid eliminates the need for a pump to irrigate the contacting device. Thereby making the irrigation mechanism simpler. Carryover is eliminated if low vapour/gas velocities are maintained.
  • Fluid flowing through the passages, which are in thermal contact with the trough can be a hot or cold fluid.
  • the hot fluid can be steam, compressed air, exhaust gases from the engine or any hot fluids from suitable hot source.
  • the cold fluid can be a cold refrigerant from heat pump, water from the cooling tower.
  • the contacting disc may be a mesh, plain, roughened surface, and porous material.
  • the contacting device is preferably circular.
  • the contacting disc may be octagonal, hexagonal or any other shape based on the application.
  • the contacting device is of metal.
  • the contacting may non-metallic or of any suitable material that is compatible with the fluids.
  • the central hole in the contacting device preferably a non-circular cross section to ensure that the discs move along with the shaft.
  • the hole in the contacting can be circular.
  • the contacting disc may optionally have dimples/projections on the circumference to provide self-spacing when the discs are assembled on a shaft. In other embodiments, the contacting discs do not have dimples, but spacing between the discs is provided with spacers.
  • the spacers may be metallic or non metallic or any other suitable, which is compatible with liquid and vapour/gas.
  • One of the preferred embodiments is a square shaft that could be passed through the square hole in the contacting disc.
  • the shaft may be a hollow or solid as per the application.
  • the shaft is metallic.
  • the shaft may be non-metallic or any other suitable material, which is compatible with the fluids.
  • the trough holding the liquid may have the discs that are partially submerged.
  • material of construction of the trough may be a metallic, non- metallic or of any suitable material, which is compatible with the fluids.
  • the heat exchanging passages on the trough is a coil, or multiplicity of tubes of any material in thermal contact with the inner or outer surface of the trough or integrated into the trough.
  • the material of the passages may be metallic, non-metallic, or any other suitable material, which is compatible with the fluid flowing through it.
  • a cover with chimney is provided to circulate the vapour/gas through the device.
  • the material of construction of enclosure to guide the flow of vapour/gas may be metallic or non metallic which is compatible with the fluids.
  • a low speed drive may be used to rotate the contacting disc assembly.
  • FIG.2 shows one of the preferred embodiments of the absorber/ICD or regenerator/ OCD with spiral contacting device (SCD).
  • a trough 347 is the housing to contain the LD 348.
  • the contacting spiral mesh is wound on a housing 350.
  • the spiral-contacting device is 349.
  • the SCD 351 at the centre of the SCD is connected to an electric motor 352.
  • the SCD is rotated by a motor at low rpm in the LD, preferably at around 3 to 5 rpm or oscillated to angle greater than
  • a fan 353 is provided to circulate indoor air in case of absorber/ICD and outdoor air in case of regenerator/OCD. In an embodiment the fan may be a forced/induced draft fan.
  • a support 354 is provided to the trough.
  • the heat exchanger in the trough of absorber/ICD or regenerator/OCD is 355. Refrigerant passes to the heat exchanger through the conduit 356 to cool the LD in case of absorber/ICD and to heat the LD in case of regenerator/OCD.
  • the outlet of refrigerant from the absorber/ICD or regenerator/OCD is 357.
  • FIG. 3a shows a series flow two-stage regenerator with weak LD entering HTR.
  • the weak LD from the source passes to the pump 75 through inlet conduit 74 and is pumped to LTRHE
  • HTRHE High Temperature Regenerator Heat exchanger
  • Partially regenerated LD from HTR 32 exits through conduit 34 and then passes through HTRHE 41 where it gets sub cooled and passes to LTR 18 through conduit 6. After complete regeneration of LD in LTR it exits through conduit 7 and then passes through LTRHE 21 where it gets sub-cooled and the regenerated LD leaves through conduit 24.
  • the vapour generated in HTR flows to HTRHE, 41 through conduit 36 and gets desuperheated and the desuper heated vapour flows to the LTR 18 through conduit 10 and is condensed in passages thermally in contact with LTR 18 and the condensate from LTR flows to
  • LTRHE 21 through conduit 12 and then subcooled in LTRHE and comes out through conduit 73.
  • FIG. 3b shows a series flow two-stage regenerator with weak LD entering LTR.
  • LD from the source passes to the pump 75 through inlet conduit 74 and is pumped to LTRHE
  • Partially regenerated LD from LTR flows through the conduit 7 to the suction of the pump 64 and pumped through HTRHE 41 where it is preheated and then flows to HTR 32 through conduit 34.
  • the LD level in the HTR is 37 and the insulation to HTR is 38.
  • the LD is fully regenerated by absorbing heat from the heat source 39.
  • the fully regenerated LD from HTR flows to HTRHE 41 through conduit 33 and then subcooled in HTRHE and flows to LTRHE 21 through conduit 43, where it is subcooled further before being returned to the source through conduit 24.
  • the vapour generated in HTR flows to HTRHE, 41 through conduit 36 and gets desuperheated and the desuper heated vapour flows to the LTR 18 through conduit 10 and is condensed in passages thermally in contact with LTR 18 and the condensate from LTR flows to LTRHE 21 through conduit 12 and then subcooled in LTRHE and comes out through conduit 73.
  • FIG.3c shows a parallel flow two-stage regenerator.
  • the weak LD from the source passes to the pump 75 through inlet conduit 74 and is pumped to LTRHE 21, through conduit 29 and where it is heated and passes through conduit 30, and part of the LD flow is throttled into the LTR in throttling device 25 and fully regenerated and the other part of the LD flow is preheated through HTRHE, 41 on its way to HTR.
  • the LD level in the HTR is 37 and the insulation to HTR is 38. In the HTR the LD is fully regenerated by absorbing heat from the heat source 39.
  • FIG.4a shows a series flow three-stage regenerator with three pumps and two throttle valves.
  • the weak LD from the source passes to the pump 75 through inlet conduit 74 and is pumped to LTRHE 21, through conduit 29 and then is heated, further it passes through conduit 30 and gets heated in Intermediate Temperature Regenerator Heat exchanger (ITRHE) 61, further it passes through conduit 42 which leads it High Temperature Regenerator Heat exchanger (HTRHE) 41 where it gets heated further and then through conduit 33 it is introduced into HTR 32. Vapour is generated from the solution at high temperature ' and pressure due to the addition of heat 39.
  • ITRHE Intermediate Temperature Regenerator Heat exchanger
  • HTRHE High Temperature Regenerator Heat exchanger
  • This vapour passes through conduit 36 and gets sensibly cooled in HTRHE 41, further it passes through conduit 45 and condenses in heat exchanger 60 and further condensate passes through ITRHE 61 where it gets subcooled and it passes through throttle valve 66 and is led through conduit 10 after mixing with vapour coming from ITR 51 through conduit 67.
  • This condensate vapour mixture condenses completely in passages of LTR 18 and then passes through conduit 12 and further passes through Low Temperature Regenerator Heat Exchanger (LTRHE) 21 where it gets sub cooled further.
  • LTRHE Low Temperature Regenerator Heat Exchanger
  • Partially regenerated LD from HTR 32 is led through conduit 34 into HTRHE 41 where it gets sub cooled before it is throttled in throttling device 46 and led through conduit 52 into ITR 51.
  • Vapour is generated in ITR 51 at intermediate temperature and pressure due to heat delivered through heat exchanger 60. This vapour passes through conduit 55 which is desuperheated in ITRHE 61 and further it passes through conduit 67 leading to conduit 10.
  • Partially regenerated LD from ITR 51 which operates under vacuum passes through conduit 54 which leads into LD pump 64 which increases the pressure of the LD from ITR to atmospheric pressure which is then led in to trough of LTR 18.
  • FIG.4b shows a series flow three-stage regenerator with weak LD entering LTR.
  • the weak LD from the source passes to the pump 75 through inlet conduit 74 and is pumped to LTRHE 21, through conduit 29 and then is heated and further passes to LTR 18 through conduit 6 and partially regenerated in the LTR then pumped to ITRHE 61 with pump 64, through conduit 7, where it is preheated before it is regenerated further in ITR 51.
  • the partially regenerated LD is pumped to HTR 32 with pump 64 through the HTRHE 41 where it is preheated through HTRHE and passes to HTR through conduit 33 and regenerated further in HTR thereafter the fully regenerated LD flows to HTRHE wherein it is subcooled, and passes to ITRHE through conduit 43 and further flows to LTRHE 21 through conduit 23 and then pumped back to the source through conduit 24
  • the vapour generated in HTR flows to HTRHE 41 through conduit 36 and gets desuperheated and the desuperheated vapour flows to the ITR 51 and gets condensed and further subcooled in ITRHE 61 and throttled in throttling device 66 and mix with the vapour generated in ITR.
  • This liquid vapour stream is then condensed in "passages" thermally in contact with LTR, 18 and the condensate from LTR passes to LTRHE 21 through conduit 12 and subcooled in LTRHE before being pumped out through conduit 73.
  • FIG.4c shows the parallel flow three stage regenerator.
  • the weak LD from the source passes to the pump 75 through inlet conduit 74 and is pumped to LTRHE 21 through conduit 29 and then it is heated and a portion of the LD further passes to LTR 18 through conduit 6 through throttling device 25 and conduit 6.
  • Another portion of weak LD passes through conduit 30 to ITRHE 61.
  • This stream of LD passes from ITRHE 61 to ITR 51 through conduit 68 and portion of this stream is taken into ITR 51 through throttling device 49 and conduit 52. The remaining portion of this stream flows through throttle valve 48 and conduit 42 to HTRHE 41 and flows through conduit 33 to HTR.
  • the partially regenerated LD from LTR 18 passes through pump 64 through conduit 63 to ITRHE 61 and flows to HTR 32 through HTRHE.
  • the vapour generated in HTR flows to HTRHE 41 through conduit 36 and gets desuperheated and the desuperheated vapour flows to the ITR 51 through conduit 45 and gets condensed in the heat exchanger 60 in ITR and flows to the ITRHE through conduit 57 and further subcooled in ITRHE 61 and throttled in throttling device 66 and mix with the vapour generated in ITR.
  • This liquid vapour stream is then condensed in "passages" thermally in contact with LTR, 18 and the condensate from LTR passes to LTRHE 21 through conduit 12 and subcooled in LTRHE before being pumped out through conduit 73.
  • the number of stages in regeneration process may be increased by adding ITRs, liquid- liquid heat exchangers and pressure reducing devices between HTR and LTR.
  • the heat source to the HTR is electric heater, solar collector, burning of biomass or biogas.
  • the heat source to the HTR may be waste heat source from the engine exhaust or any other waste heat source.
  • the HTR may be a metallic or non-metallic, which is compatible with LD.
  • the shape of the HTR may be a cylindrical, rectangular, square or any other suitable shape for integration with the heat source.
  • the HTR may be placed horizontally, vertically or any position suitable for integration with the heat source.
  • the HTR is covered with insulating material to avoid heat transfer between LD and ambient.
  • a solution heat exchanger is incorporated to preheat the weak
  • additional solution heat exchangers may be incorporated to internally recycle heat from hot to cold LD.
  • the material of construction of heat exchanger may be a plastic or any other suitable material compatible with LD.
  • HTR entire flow of the LD, after regeneration in HTR is flowing through LTR.
  • HTR and LTR are operating in series.
  • certain flow of LD after regeneration in HTR may be bypassed.
  • HTR and LTR are operating in parallel.
  • partially regenerated LD passes from the HTR to LTR for further regeneration or the partially regenerated LD may pass from LTR to HTR for further regeneration or the flow of LD is split into two streams and then passed to HTR and LTR
  • the LTR incorporates rotating disks as the contacting media between LD and vapour/gas.
  • the condensation of vapour takes place in the passages, which are in thermal contact with the LTR.
  • the passages, through which vapour condenses may be in thermal contact while being inside or outside or integrated with LTR.
  • an arrangement such as a hood with chimney is provided to aid the ambient air through the LTR over the contacting media, which is wet with LD.
  • the HTR is at a higher elevation than the LTR, and one LD pump is used to pump the weak LD to HTR.
  • two pumps are used, one pump to LTR and the other to HTR.
  • one pump to pump LD to LTR and LD from LTR flows due to gravity.
  • the heat source to the ITR may be the vapour generated in HTR.
  • the ITR may be a metallic or non-metallic, which is compatible with LD.
  • the shape of the ITR may be a cylindrical, rectangular, square or any other suitable shape for integration with the heat source from ITR/HTR operating at next higher pressure level.
  • FIG.5 shows a schematic diagram of the novel HCS.
  • the system comprises of an absorber/ICD 318, which incorporates large surface density contacting discs 1, in plurality mounted on a shaft 2.
  • the disc-assembly placed in a trough 3, containing the LD.
  • the trough is made of any material that is compatible with the LD and air.
  • a fan, 16 circulates the indoor air through the absorber/ICD, which gets dehumidified and cooled as it passes through the absorber. In an embodiment the fan may be a forced/induced draft fan.
  • a hood, 14 guides the indoor air over the contacting disc assembly. Concentrated LD enters the absorber/ICD through conduit 306. Weak LD leaves the absorber/ICD through conduit 307.
  • the contacting discs are partially submerged in the LD, in the absorber/ ICD.
  • the disc assembly is rotated by a drive at low rpm in the LD, preferably at around 3 to 5 rpm or oscillated to an angle greater than 30° in either direction.
  • the refrigerant of VCRS is expanded in the throttle valve, 321 and the low temperature refrigerant flows in through conduit 311 to the passages 9, that are in thermal contact with the outer lower surface or inner surface or integrated with the trough wall of the absorber/ ICD.
  • the LD in the absorber/ICD is cooled as the refrigerant evaporates in the passages 9.
  • the cooled desiccant in the absorber has high affinity to absorb the moisture from the indoor air.
  • weak LD flows through conduit 307 and led to the pump 330, to the regenerator/OCD, 18 through a liquid-liquid heat exchanger 331.
  • This heat exchanger is provided to heat the LD from the absorber/ICD and cool the desiccant stream as it flows from regenerator/OCD 18, which flows in to the absorber/ ICD.
  • Refrigerant after compression passes through conduit 10 to the passages 9 of regenerator/OCD, 18 which are in thermal contact with the outer lower surface or inner surface or integrated with the trough wall of the regenerator/OCD.
  • the weak LD from absorber/ICD after liquid-liquid heat exchanger flows to the regenerator/OCD.
  • the weak LD enters the regenerator /OCD through conduit 6.
  • the heat required for the regeneration is supplied by the refrigerant condensing in the passages 9. After condensation of the refrigerant in regenerator/ OCD, it moves through conduit 12 which led to throttling device 321.
  • the regenerated, strong LD flows out from the regenerator/OCD through conduit 7 and pumped with LD pump 332 to the absorber/ ICD through the liquid-liquid heat exchanger, 331.
  • a hood 14 is provided to guide the outdoor air through the regenerator/OCD.
  • a fan 16 is provided to circulate the outdoor air through the regenerator/OCD.
  • the contacting disc assembly is partially submerged in the LD in the regenerator/OCD.
  • the ambient air pickups the moisture from the hot desiccant, in the trough of regenerator/OCD.
  • the disc assembly is rotated by a motor at low rpm in the LD, preferably at around 3 to 5 rpm or oscillated to an angle greater than 30° in either direction.
  • FIG.6 shows the ideal state points on psychrometric chart that the conditioned air experiences in VCRS, DCS and HCS.
  • the air-conditioning process is represented by locus of 334-335-336-337, on psychrometric chart.
  • DCS the process is represented by locus 334- 338- 339- 340- 337.
  • HCS the process is represented by locus 334- 338- 337 and 334- 337.
  • HCS eliminates the process of cooling the air below its dew point temperature and reheating as in VCRS.
  • HCS also eliminate the processes of deep dehumidification and re-humidification, which occurs in the DCS.
  • an absorber/ICD is coupled with an evaporator of conventional VCRS.
  • the absorber/ICD is an adiabatic contacting device with a separate heat exchanger to cool the LD.
  • the evaporation of the refrigerant takes place in the passages, which are in thermal contact with the trough containing the LD.
  • the passages may be in thermal contact by being placed inside or outside the trough or integral with trough.
  • an absorber/ICD and/or regenerator/OCD incorporates large surface density rotating contacting disc assembly as the contacting media between air and LD.
  • the rotating contact disc assembly in the absorber/ICD and/or regenerator/OCD is a mesh, plain /roughened surface or porous material and their like constructed of materials such as a plastic or any other suitable material, which is compatible with LD and air.
  • the contacting disc assembly absorber/ICD and regenerator/OCD is rotated at low rpm in the LD, preferably at around 3 to 5 rpm or oscillated to an angle greater than 30° in either direction.
  • the contacting disc assembly in the absorber/ICD and/or regenerator/OCD is mounted in a trough or any suitable container constructed of non conducting material with wall thickness of ⁇ 0.2 mm and to withstand the pressure of the heat transfer fluid.
  • the absorber/ICD and/or regenerator/OCD optionally incorporates Spiral Contacting Device (SCD) as the contacting media between the LD and air.
  • SCD Spiral Contacting Device
  • SCD in the absorber/ICD and/or regenerator/OCD is rotated at low rpm in the LD, preferably at around 3 to 5 rpm or oscillated to an angle greater than 30° in either direction.
  • SCD in the absorber/ICD and/or regenerator/OCD is mounted in a trough or any suitable container without passages.
  • the trough to mount the SCD is constructed of conducting /non conducting material without limitation of wall thickness
  • a liquid-liquid heat exchanger selected from any suitable material compatible with the LD may be incorporated in the system to recycle heat from the hot regenerated strong LD coming from the regenerator/OCD into the weak LD coming out of the absorber/ICD.
  • a regenerator/OCD is coupled with a condenser of conventional VCRS.
  • the regenerator/OCD is an adiabatic contacting device with a separate heat exchanger to heat the LD.
  • the condensation of the refrigerant takes place in the passages, which are in thermal contact with the inner or outer or integrated into the trough of regenerator/OCD.
  • the evaporation of the refrigerant takes place in the passages, which are in thermal contact with the inner or outer or integrated into the trough of absorber/ICD.
  • two LD pumps are used to pump the LD, one from the absorber/ICD to regenerator/OCD and the other from the absorber/ICD to regenerator/OCD.
  • the regenerator/OCD may be placed at higher elevation than the absorber/ICD in which case the LD flows by gravity from the regenerator/OCD to absorber/ICD
  • one LD pump is used to pump the LD from the absorber/ICD to regenerator/OCD.
  • absorber/ICD may be placed at higher elevation than the regenerator/OCD in which case the LD flows by gravity from the absorber/ICD to regenerator/OCD.
  • one LD pump is used to pump the LD from the regenerator/OCD to absorber/ICD
  • the said VCRS is replaced by Vapour Absorption/Adsorption System.
  • a preferred embodiment of the Energy efficient regeneration process is illustrated with a non- limiting example.
  • a two-stage regenerator device was fabricated and tested for regeneration of calcium chloride LD. It consists of a HTR made of aluminium rectangular channel in which electrical heaters are incorporated as heat source. LTR incorporates the aluminium disks are of 150 mm diameter, with circumferential lip and dimples as the contacting device between LD and ambient air. The disks are mounted on an aluminium shaft of diameter 9.5 mm. The disks are placed in a semi hexagonal aluminium trough 500 mm (length) x 200 mm (width) x 210 mm (height). It incorporates 337 m 2 /m 3 surface density, when maintaining 5mm gap between the disks using plastic spacers.
  • Contacting device is covered with a hood and a chimney of diameter 100 mm, length 1.5 m. Airflow through the contacting device is due to natural convection induced by the chimney effect.
  • the disks are made to rotate at 5 rpm using an electric motor. Inlet and out let of LD to the trough is through 9.5 mm diameter aluminium tubes.
  • Table 1 shows that the regenerator is capable of removing 2.6 kg/kW-h water from calcium chloride LD. It is observed that there is no carry over of LD with air stream and along the condensate collected from LTR.
  • the contacting device was fabricated and tested for humidification of ambient air. It consists of discs made of aluminium mesh. The discs are of 150 mm diameter, with circumferential lip and dimples. The discs are mounted on an aluminium shaft of diameter 9.5 mm. The discs are placed in a semi hexagonal aluminium trough 500 mm (length) x 200 mm (width) x 210 mm (height). It incorporates 337m 2 /m 3 surface density, when maintaining 5mm gap between the discs using plastic spacers. Contacting device is covered with a hood and a chimney of diameter 100 mm, length 1.5 m. Airflow through the contacting device is due to natural convection induced by the chimney effect.
  • the discs are made to rotate at 5 rpm using an electric motor. Inlet and out let of water to the trough is through 9.5 mm diameter aluminium tubes.
  • Table 2 shows that the contacting device efficiency for humidification of air is as high as 98% for the ambient conditions are 26.8°C and 48% relative humidity. It is observed that there is no carry over of liquid with air stream.
  • a hybrid cooling system is designed with the following specification:
  • the salient features of the model are as follows: a. The model is developed for the design of a HCS with single stage VCRS b. A liquid-vapour heat exchanger/refrigerant sub-cooler may be incorporated on the refrigerant side to further improve the capacity and COP of the HCS. c. A liquid-liquid heat exchanger/solution heat exchanger is also designed on CaCI 2 solution streamside for energy saving and for enhancing the overall system COP and capacity, h. The relevant simulated results are given in Table 3.
  • volumetric Efficiency 87 92 6 increase The main advantages of the system are the significantly improved energy efficiency, zero carryover of LD into process air streams, increase in cooling capacity for a given compressor in comparison to the conventional HCS using "packed” or “spray type-contacting devices". This is possible with the appropriately designing of the absorber, regenerator, liquid-liquid heat exchanger and other components of HCS. Significant reduction in weight and cost is achieved with the use of alternate materials such as plastics and eliminates any problems due to corrosion of the absorber/regenerator as in conventional systems.
  • the contacting media disclosed in this invention offers high surface densities as high as 600 m 2 /m 3 , which is about 185% greater than conventional packing.
  • the system is compact, lower weight and techno- economically viable for air-conditioning.

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Abstract

The present invention relates to a novel energy efficient liquid desiccant regeneration, and further relates to the application of rotating contacting discs to provide intimate contact between LID and vapour/gas without problems of carryover of LID in to the vapour/gas stream or flooding and suitable for low liquid throughputs, with significant change in concentration. The main advantages of energy efficient multi-stage regeneration of LID are no carryover problem, no orifices or nozzles to wear or clog, modular system that can be installed with flexibility, silent operation without splashing or spraying sounds and low auxiliary electrical power consumption. The present invention also relates to a novel contacting device to provide intimate contact between fluids to enhance the interfacial area between them for increased heat and/or mass transfer, without problems of carryover of liquid in to the vapour/gas stream or flooding, having the provision to heat/cool the liquid based on the application. The novel contacting device in combination with appropriate devices is capable of being used for applications involving dehumidification, humidification, cooling towers, air-conditioning. Further this can be used for applications involving separation of gases from the liquid, regeneration of liquid desiccants, distillation columns, rectification columns, absorption refrigeration systems, multiphase-multi component adiabatic/non-adiabatic chemical/bio reactors, and cold/heat storage applications. The present invention further relates to a Hybrid Cooling System (HCS), in which air temperature and humidity are simultaneously controlled using a contacting device, which meets the needs of dehumidification, decrease in temperature and significant reduction in electrical power consumption with increase in cooling and/or dehumidification capacity for a given refrigeration compressor. The main advantages of the system are the significantly improved energy efficiency, elimination of carryover of LID into process air streams, increase in cooling capacity for a given compressor in comparison to the conventional HCS using 'packed' or 'spray type-contacting devices'. The pressure ratio across the compressor is reduced up to 36%. The cooling effect produced is increased up to 60% and COP increased up to 45% as compared to VCRS for air conditioning and refrigeration applications involving cooling and/or dehumidification/drying.

Description

ENERGY EFFICIENT LIQUID DESICCENT REGENERATION Field of the Invention
The present invention relates to a novel energy efficient multi-stage regeneration process, for regenerating liquid desiccant (LD), and further relates to the application of rotating contacting disks to provide intimate contact between LD and vapour/gas to enhance the interfacial area between them for increased heat and/or mass transfer, without/problems of carryover of liquid in to the vapour/gas stream or flooding having the provision to heat/cool the liquid based on the application. The invention further finds applications in Hybrid Cooling Systems (HCS), in which air temperature and humidity are simultaneously controlled using a contacting device, which meets the needs of dehumidification, decrease in temperature and significant reduction in electrical power consumption with increase in cooling and/or dehumidification capacity for a given refrigeration compressor.
Background Art
Equipment often employed for regeneration process of LD are packed bed regenerators, spray towers with finned tube heat exchangers, solar regenerator, simple boiler and multiple effect boiler. Processes requiring mass transfer between two contacting fluids often employ equipment such as spray towers, packed towers and tray towers. In spray towers and spray chambers the liquid is generally sprayed into a gas stream by some means to disperse the liquid into fine spray of drops. The flow may be counter current and co-current as in vertical towers, or parallel as in horizontal spray chambers. These devices have the advantage of low- pressure drop of the gas but may suffer from relatively high pumping cost for the liquid in spray. The tendency for carry over of liquid by the air/gas is considerable in the spray towers and mist eliminators will almost always be necessary leading to increase the air/gas side pressure drop. In conventional vapour compression refrigeration, system (VCRS) air is cooled below its dew point to reduce the moisture content, followed by reheating of the air to the desired temperatures prior to its introduction in the conditioned space. As the evaporator operates at lower temperature, the COP of the conventional VCRS is low.
Prior Art
We now review the prior art relevant to the invention. Prior art related to liquid desiccant regeneration systems
Packed tower is used for regeneration process of LD (Martin, V. and Goswamy D. Y., Heat and Mass Transfer in Packed Bed Liquid Desiccant Regenerators - An Experimental
Investigation, Journal of Solar Energy Engineering, Transactions of the ASME, Vol 121 , pp163- W
169, USA, 1999). In this case the desiccant is distributed over the packing by spray heads and the process air was blown through the packing for regeneration of LD. The process air picks up the water from the LD because of the partial pressure difference of water in the process air and LD. The main problem associated in this regeneration process is carryover of LD along with air stream. Requirement of minimum irrigation rate and limitations of flooding in packed towers complicates the design or reduces the efficacy of the regeneration process. Also large power is required to circulate air/gas through packed bed.
Spray chamber with finned tube heat exchanger is the practical equipment for regeneration process of LD (Peng, C. S. P. and Howell R J., The Performance of Various Types of Regenerators for Liquid Desiccants, Journal of Solar Energy Engineering, Transactions of the ASME, Vol 106, pp 133-141 , USA, 1984). Finned tube heat exchangers are stacked horizontally with a column with hot water flowing in the tube side. LD was sprayed on the heat exchanger and drips down. A blower was used to circulate process air through the regenerator counter current to the falling LD. The advantage of the system is lower pressure drop for the air/gas side. However, there is a relatively high pumping cost for spraying the LD. The tendency for carry over of liquid by the air/gas is considerable in the spray towers and mist eliminators will almost always be necessary leading to increase the air/gas side pressure drop. Even with mist eliminators 100% elimination of carryover is not ensured.
Regeneration of LD can be done using solar energy. Solar regenerator consists of inclined surface with transparent glazing as a covering where weak LD that is to be regenerated flows down the sloping surface as a falling film and is heated by the absorbed solar radiation (Peng, C. S. P. and Howell R J., The Performance of Various Types of Regenerators for Liquid Desiccants, Journal of Solar Energy Engineering, Transactions of the ASME, Vol 106, pp 133- 141 , USA, 1984). The water vapour that is evaporated from the solution surface is removed by blowing air through the slot formed between the glazing and the film surface. The disadvantage of the regeneration process is that the system is not operative during non-solar hours. There must be backup heat source for the regeneration of LD during non-solar hours.
The regeneration process of LD in a simple boiler can be achieved by heating the LD to boiling temperature (Lowenstein, A. I. and Dean, M. H., The Effect of Regenerator Performance on A Liquid Desiccant Air-Conditioner, ASHRAE Transactions: Symposia, Vol. 98, No.1 , pp 704- 711 , USA, 1992). This regeneration process increases the energy required to preheat the weak desiccant that enters the regenerator. The higher the regeneration temperature higher is the regenerator corrosion rate. The regeneration process in a simple boiler is not energy efficient since the latent heat of the vapour generated is not recycled. Regeneration at sub atmospheric pressure can reduce the higher temperature of the simple desiccant boiler. Adding a vapour condenser to the boiler can do this. A non-condensable pump is required to maintain the vacuum in the regenerator. This increases the electrical power consumption.
In a double effect boiler, vapour from high-pressure boiler has a saturation temperature that is sufficient to provide required thermal input to lower pressure boiler. Low-pressure boiler is operating under vacuum. A non-condensable pump is required to maintain vacuum (Lowenstein, A. I. and Dean, M. H., The Effect of Regenerator Performance on A Liquid Desiccant Air-Conditioner, ASHRAE Transactions: Symposia, Vol. 98, No.1 , pp 704-711, USA, 1992). Latent heat of vapour from high-pressure boiler is utilised in low-pressure boiler. However, maintaining vacuum in low-pressure boiler increases the electrical power consumption. Costly components are required for high-pressure boilers and an issue of safety becomes more complex.
US Patent No. 5,213,154, "Liquid Desiccant Regeneration System", discloses a single stage regeneration system for use in air conditioning system. The system comprises of a direct- fired natural circulation boiler for regenerating LD. A falling film heat exchanger is used for transferring heat from concentrated desiccant to dilute desiccant. It is single stage regeneration process, the latent heat from the vapour leaving from the boiler is not recycled/reutilised. The single stage regeneration process is exergetically less efficient.
US Patent No. 4,939,906, "Multi-Stage Boiler/Regenerator for Liquid Desiccant Dehumidifier", describe a regeneration process with a gas fired desiccant boiler and a combined desiccant regenerator/interchange heat exchanger for use in air-conditioning system. The regeneration process accomplished by diverting portion of LD flowing through a desiccant conditioner and heating the desiccant in an interchange heat exchanger, an air desiccant regenerator, a second interchange heat exchanger and a boiler. The latent heat of vapour generated in the boiler is delivered to the air in a heat exchanger. The weak desiccant is preheated in another heat exchanger using heated air, before entering the boiler. Two heat exchangers are used to deliver the latent heat of vapour to pre heat the LD, which is not energy efficient.
US Patent No. 5, 097, 668, "Energy Reuse Regenerator for Liquid Desiccant Air Conditioners", discloses the regeneration process of LD in air-conditioners, which uses LD for dehumidification of air. The regeneration of LD is achieved in a desiccant boiler and a desiccant evaporator/condenser in combination with heat exchangers. The evaporator /condenser receive the vapour produced by the boiler to provide a reuse of heat for regeneration. Certain quantity of LD from air-conditioner is flowing to evaporator /condenser, where it is sprayed over the surface through which vapour from boiler is flowing. Certain quantity of LD from air-conditioner is directly flowing to boiler for regeneration. As the LD is sprayed in presence of air in the evaporator/condenser carryover of LD with the air stream is inevitable. Additional electrical power is required for spraying LD in the evaporator/ condenser.
US Patent No. 4,189,848 "Energy Efficient Regenerative Liquid Desiccant Drying Process", discloses a method and apparatus for the drying of harvested crops by utilising desiccants with a closed loop drying loop and open drying loop. In the closed drying loop cycle the drying air brought in to contact with a desiccant in a packed tower after it exits from a crop- drying bin. During the open loop drying cycle the used desiccant is heated and regenerated at high temperature driving water vapour from the desiccant. The water vapour condensed was used to pre heat the dilute desiccant before heat is added from the external source in the regenerator. As the regeneration and absorption processes are taking place in the packed towers the carryover of LD in to the air stream is inevitable. Large electrical power is required to circulate the air through packed towers.
US Patent No. 4,941 ,324, "Hybrid Vapour Compression/Liquid Desiccant Air Conditioner", discloses a hybrid air-conditioning system consisting of a compressor, evaporator, condenser and refrigerant. LD and refrigerant are simultaneously circulated between evaporator and condenser for cooling and dehumidifying air forced therein. The regeneration of the LD is achieved by spraying the LD on the condenser of vapour compression refrigeration system. A blower is provided to circulate the outdoor air to regenerate the LD. The main problem with such arrangement is corrosion of the condenser coil. Moreover as the LD is sprayed, carryover and loss of LD to indoor and out door air streams is inevitable.
US Patent No. 4,180,985, "Air-conditioning System with Regeneratable Desiccant Bed" discloses the regeneration process using a desiccant pad material such as fibreglass pads, wire screens and packed steel shavings. The desiccant pad is disposed and supported within the feed duct. Condenser coil of vapour compression refrigeration system is disposed within the regenerator duct. The air is directed across the condenser coil by mean a fan. Liquid desiccant is sprayed in presence of hot air stream across the desiccant pad, which provides large surface area between desiccant and air. In this process carryover of LD to air stream is inevitable. In spite of use of mist eliminators carryover of LD is inevitable.
US Patent No. 4,259,849, "Chemical Dehumidification System Which Utilises A Refrigeration Unit for Supplying Energy to the System", discloses a sorbent type air-conditioning system which employs refrigeration unit, including a compressor, evaporator, condenser and refrigerant. The regeneration of LD is achieved in a packed tower with spray nozzles. Corrugated sheet material impregnated with a thermosetting resin is the packing material, through which LD trickles by gravity. Large pressure drops across the packing material. Carryover of LD with air stream is not addressed. Prior Art related to Contacting Devices
Packing in packed towers provide large interfacial surface between liquid and air/gas. The key requirements of the packing are large surface area per unit volume and must permit large volume flow of fluids through small tower cross section with lower pressure drop for the air/gas. Packings in the form of Ranching rings, Lessing ring, Partition ring, Berl saddle and Pall rings are commonly used in packed columns (Robert, E. Treybal, Mass - Transfer Operations, pp 187-191 , Mcgraw-Hill Book Company, 1981). Random packings offer large specific surface but suffer from larger air/gas side pressure drop. Regular or stacked packings like Ranching rings, Double spiral ring, Wood grids offer lower pressure drop than random packings for the air/gas side. Generally absorbers with regular packings are designed for air/gas side pressure drop of 200 to 400 Pa per m of packed depth (Robert, E. Treybal, Mass - Transfer Operations, pp 187-191 , Mcgraw-Hill Book Company, 1981). Regular packings are costlier than random packings, polypropylene Rauschert Hiflow rings of size 2.54 cm offer a surface density of about 210 m2/m3 (Oberg, V. and Goswamy D. Y., Experimental study of the heat and mass transfer in a packed bed liquid desiccant air dehumidifier, Journal of Solar Energy Engineering, Transactions, of the ASME, Vol 120, pp 289-297, USA, 1998). Such equipments need well- designed tower shells, packing supports, liquid distributors, packing restrainers, entrainment eliminators etc., which make them fairly expensive. Minimum irrigation rate and flooding in packed towers complicates the design or reduces the efficacy of the process. Large power is required to circulate air/gas through packed bed.
The long felt need in this field has been to innovate contacting devices that are techno- economically viable and provide for the essential functional features so as to: a. incorporate large heat and mass transfer area between vapour/gas stream and liquid b. ensure no carryover of liquid in to the vapour/gas stream c. have the provision to heat/ cool the liquid depending on the application d. extending the limits on the minimum irrigation rate and flooding
US Patent No. 4333894, loses mass transfer column consisting of one or more contact zones. The contact zones are exclusively provided with packings placed in prearranged locations. In the contact zones, optimal operating conditions for the packing are created over the entire height of the contact zones in order to achieve a minimal pressure loss at a concomitant high separating efficiency. This is done by a suitable gradated adaptability of the packing to vapour and liquid loads varying over the height of the contact zones. It was claimed uniform flow of liquid through the bed. However, this patent does not address the issue of carry over of liquid along with air/gas. US Patent No. 5679290, describes an improved packed tower for effecting the adsorption of a gas into a liquid, comprising a cylindrical tower wall defining a packing zone; a plurality of packing pieces contained within a packing zone; a liquid distributor above the packing zone for distributing liquid on to the packing pieces; a gas feeding inlet below the packing pieces for feeding gas through the packing zone. The improvement claimed in this patent is in the plurality of packing pieces and the packing of different sizes in two zones. First packing zone is an annulus adjacent at an upper part of the tower wall. Rest of the tower acts as the second zone. First packing pieces are smaller than the second plurality of packing pieces. Surface area of the packing is 119 m2/m3 with 2 x 2 x 4 inch ceramic saddles in the first zone. In the second zone the packing is also ceramic saddled of size 3 x 3 x 6 inch which were giving a surface area of 93 m2/m3. In this patent too the carryover of liquid along with air/gas stream is not addressed.
In US Patent No. 5882772 and 6007915, packing materials to increase the surface area, in packed bed towers are reported but do not comprehensively resolve all the issues as required. Contacting discs have been used in evaporatively cooled condenser for vapour compression refrigeration system (Yunho, Hwang, Reinhard Radermacher and William Kopko, "An Experimetal Evaluation of A Residential Sized Evaporatively Cooled Condenser", International Journal of Refrigeration, 24, pp 238-249, 2001). Plastic discs of 2 feet diameter are used as contacting device between ambient air and water used for condensing the refrigerant. However, the prior art does not teach any of the aspects of the wetting of the discs by water, their optimal sizes, etc.
In the development of vapour absorption heat pump, contacting discs have also been used in mixed alkali hydroxides to absorb water vapour (Shallow, F. E. and Smith, I. E., "Vapour Absorption Into Liquid Film on Rotating Discs" Proceeding of the Work Shop on Absorption Heat Pumps, London, pp 373-381 , 1988). Copper discs of 110 mm diameter were rotated at the speed of 200 rpm in vacuum chamber. There is no specific teaching about spacing between the discs and wetting of the surface of the discs with liquid.
The rotary evaporative cooler with rotary vertical wheel shaped saturating pads 127 mm thick and 660mm to 1370 mm diameter, composed of spirally wound layers of alternatively flat or crimped bronze screen wires have been losed in the article by (John, R. Watt, Evaporative Air Conditioning hand Book, pp 115-161, Chapman and Hall, New York, 1986). This device does address the issue of proper wetting of the pad without splashing or blowing, at rotating speeds of around 2 rpm, but the cost of the rotor is high. Prior Art related to Hybrid Cooling Systems
Desiccants are a subset of a group of materials called sorbents. Desiccants in particular have high affinity for water and their absorption capacity varies with the structural characteristics of the material. For example, nylon can absorb up to 6 percent of its weight of water, wood can absorb 23 percent of its weight, whereas a commercially available desiccant can hold about 1100 percent of its weight of water. Some examples of such desiccants are Lithium chloride, Lithium bromide, etc. (ASHRAE, "Fundamentals Handbook", American Society for Heating Refrigeration and Air-conditioning Engineers, pp 21.1-21.5, Atlanta, USA, 1997). The desiccant affinity to absorb the moisture can be regenerated repeatedly by applying heat to the desiccant material to drive off collected moisture. Low-grade heat can be obtained from a variety of sources such as solar collector, radiator hot water, engine exhaust, condenser heat recovery from refrigeration machines, burning bio mass, etc. The temperature for this process is generally in the range of 50°C to 260°C depending on the material. Desiccant cooling systems (DCS) are energy efficient and environmentally safe. In recent years, DCS have received considerable attention due to their inherent ability to use low- grade thermal energy and reduce the latent cooling load significantly. Desiccant dehumidification can reduce total electricity demand by as much as 25% in humid regions. These systems provide a drier, more comfortable and cleaner indoor environment with lower consumption of electric power.
In liquid desiccant (LD) dehumidification systems air is dehumidified when exposed to hygroscopic solutions. At a given temperature the desiccant has a lower vapour pressure than pure water, and hence moisture transfer takes place from air to solution. Several desiccants such as Triethylene glycol, Lithium chloride, Lithium bromide, Calcium chloride etc. are extensively in use. Some desiccants also have the ability of simultaneously controlling microbiological contaminants from air streams to improve the quality of air (ASHRAE, "Fundamentals Handbook", American Society for Heating Refrigeration and Air-conditioning Engineers, pp 21.1-21.5, Atlanta, USA, 1997). It may also be noted that as the process air is not allowed to reach the saturation condition at any point in the desiccant cycle it prohibits the growth of moulds, fungi, or other microbial organisms in air conditioners (Lowenstein, A. I. and Dean, M. H., "The Effect of Regenerator Performance on A Liquid Desiccant Air-Conditioner", ASHRAE Transactions: Symposia, Vol. 98, No.1 , pp 704-711 , USA. 1992).
Similar to conventional DCS, most of HCS have two air streams, one is the processed air delivered to conditioned space, the other stream is used to regenerate liquid desiccant. Howell and Peterson, 1986 have studied a hybrid system combining liquid desiccant dehumidification with VCRS (Howell, J. R. and Peterson, J. C, "Preliminary Performance Evaluation of A Hybrid Vapour Compression/Liquid Desiccant Air-Conditioning System", ASME, paper 86- WA/sol.9, Anaheim, California, USA., December 1986). It was found that the hybrid system reduces area of evaporation and condensation by 34%, and power consumption by 25%, compared with VCRS alone. Study on a gas fired air conditioning system combining vapour compression machine with solid desiccant dehumidifier, it is reported that cooling capacity of hybrid system increased by 50% and the COP increased by 40%. However, the initial cost increased to US$ 140 per kW cooling capacity (Parson, B. K., Pesaran, A. A., Bharathan, D. and Shelpuk, B. "Improving Gas Fired Heat Pump Capacity and Performance by Adding A Desiccant Dehumidification Subsystem", ASHRAE Transactions, Vol 95, pp 835-844, USA. 1989). Hybrid vapour compression/liquid desiccant air conditioner has been described in US
Patent No. 4,941,324. In this approach, the LD is sprayed on the evaporator of the vapour compression refrigeration system for cooling and dehumidification of air. The regeneration of the LD is achieved by spraying the LD on the condenser of vapour compression refrigeration system. Two blowers were provided to circulate the indoor air over the cooling coil and out door air to regenerate the LD. An adiabatic humidifier is provided in the cycle. The main problem with such arrangement is corrosion of the condenser and evaporator coils. Moreover as the LD is sprayed, carryover of LD to indoor and out door air streams is inevitable.
US Patent No. 5,022,241 discloses a residential type hybrid air conditioning system, having a conventional absorption refrigeration subsystem to handle the sensible heat loads and a LD subsystem to handle the system latent load. This system incorporates an evaporative cooler for cooling and re-humidification of the process air. In this case too the carry over of LD with the process air is unavoidable as the desiccant is sprayed in the system.
US Patent No. 4,180,985 discloses an air-conditioning system with a regeneratable desiccant bed. This arrangement employs a desiccant pad of any suitable material that can be disposed and supported within the feed duct to allow the moist feed air to flow through the pad and contact the LD material. Materials such as fiber glass pads, wire screens, packed steel shavings have been used. In this patent problems due to the carryover of LD with air stream are not addressed
US Patent No. 4,887,438 describes a desiccant assisted air conditioning system with silica gel. Regeneration temperature was around 98°C. It is reported that energy saving can be 10 to 15% and reheating after refrigeration is eliminated. As the regeneration temperature is high, the coefficient of performance (COP) of this VCRS is low. Problems in Prior Art
The LD regeneration process/system ideally should exhibit the following attributes:
• Energy efficient multi effect regenerator in which latent heat of vapour from the boiler is recycled
• Elimination of carryover of LD in the process air as well as regeneration air, by elimination of spraying of LD
• High area density for mass transfer equipment to make the system compact
• Elimination of regeneration air blower In the field of regeneration of LD, the challenges have been to make the process techno- economically viable by designing features to meet the needs of regeneration and achieve with significant reduction in the consumption of electrical power. It is desirable to increase the specific water removal rate from the LD. The specific water removal rate is the water removed from the LD in kg/ kWh of heat input. It is desirable to increase this value in order to make the regeneration process efficient.
In the field of hybrid cooling systems the challenges have been to make them techno- economically viable by designing features to meet the needs of dehumidification, decrease in temperature, eliminating carryover of LD in to air streams and operate with significant reduction in electrical power consumption.
Summary of the invention
The main object of the present invention is to provide a novel energy efficient multi-stage regeneration process, for regenerating liquid desiccant (LD), with application of rotating contacting disks to provide intimate contact between LD and vapour/gas to enhance the interfacial area between them for increased heat and/or mass transfer, without problems of carryover of liquid in to the vapour/gas stream or flooding having the provision to heat/cool the liquid based on the application. Further it is an object of the invention to explore applications in Hybrid Cooling Systems (HCS), in which air temperature and humidity are simultaneously controlled using a contacting device, which meets the needs of dehumidification, decrease in temperature and significant reduction in electrical power consumption with increase in cooling and/or dehumidification capacity for a given refrigeration compressor.
One of the objects of the invention is to regenerate the LD with higher specific water removal rates. Another object of the invention is to develop HTR with no carryover of LD in to the steam, in which water rich LD boil to remove water in the form of steam, while performing the operation of regeneration of LD.
Another object of the invention is to develop HTR, which operates at atmospheric pressure.
Another object of the invention is to pass the partially regenerated LD from HTR to LTR for further regeneration or pass the partially regenerated LD from LTR to HTR for further regeneration or split the flow of LD into two streams and pass them to HTR and LTR
Another object of the invention is to provide intimate contact between LD and air to enhance the interfacial area between the vapour/gas stream and LD using large heat and mass transfer area, which ensures no carryover of LD in to the outdoor air stream, while, regenerating' LD.
Another object of the present invention is to develop regenerator that has no limit on liquid throughput leading to high efficacy of the process (by reducing recirculation losses at lower liquid throughputs).
Another object of the invention is to provide a contacting device that operates with low power consumption.
Yet another object of the invention is to deliver the latent heat of the vapour generated in HTR to LD in LTR for regeneration. Yet another object of the invention is to use alternate materials to reduce the weight and cost, while eliminating corrosion problems.
Yet another object of the invention is to develop a multi-stage regenerator comprising of Intermediate Temperature Regenerator/s (ITRs) to operate in conjunction with the HTR and LTR. Another object of the invention is to provide a contacting device that incorporates surface density in the rage of 450 to 600 m2/m3, which is far superior to conventional polypropylene Rauschert Hiflow rings of size 2.54 cm having surface density of 210 m2/m3.
Yet another object of the invention is to provide a contacting device that does not have any carryover of liquid with the vapour/gas stream. Yet another object of the invention is to provide a contacting device to operate with pressure drop across the contacting device as low as 5 Pa.
Another object of the present invention is to provide a contact device that has no limit on liquid throughput leading to high efficacy of the selective applications.
Another object of the invention is to provide a contacting device that operates with low power consumption. Another object of the invention is to provide an easy to assemble contact device and yet providing sufficient rigidity to the contacting surface.
Yet another object of the invention is to provide a contacting device having the provision to heat / cool the liquid, vapour/gas, based on the application. Another object of the invention is to provide design for HCS with significantly higher cooling capacity, than that of the VCRS using similar compressor.
Yet another object of the invention is to provide design for a HCS with significantly lower compressor displacement requirement as compared to that of a VCRS for a required cooling capacity Yet another object of the invention is to develop an ICD a non-adiabatic or adiabatic absorber that ensures no carryover of LD to the indoor air stream, while performing operations of dehumidification and/or cooling of the indoor air stream.
Yet another object of the present invention is to develop an regenerator/outdoor contacting device (OCD), a non-adiabatic or an adiabatic regenerator, that ensures no carryover of LD in to the outdoor air stream, while, performing the operation of regeneration of LD.
Yet another object of the invention is to use alternate materials to reduce the weight and cost, while eliminating corrosion problems.
Yet another object of the invention is to use the liquid-liquid heat exchanger to increase the cooling capacity and COP of the HCS.
Thus in accordance with the invention for example a single stage regeneration process comprises of:
• LTR, which incorporates large surface density contacting device, having provision to heat the LD, with the hot fluid passing through passages, which are in thermal contact with a container such as a the containing the LTR
• Optional arrangement such as a hood with chimney to aid the flow of ambient air through LTR to pickup the moisture from LD.
• A device to rotate/oscillate the contacting disc assembly in the LTR
Further in accordance with the invention the single stage regeneration process may be extended to a two-stage regeneration process in a system comprising:
• HTR, in which weak LD boils absorbing heat from an external source, having insulation on exposed surface to avoid heat loss from LD to surroundings
• LTR, incorporating large surface density contacting device, having provision to heat the LD, with vapour generated in HTR condensing in passages which are in thermal contact with a container such as a trough containing the LTR • Optional arrangement such as a hood with chimney to aid the flow of ambient air through LTR to pickup the moisture from LD.
• A device to rotate/oscillate the contacting discs assembly in the LTR
• Optional heat exchanger used to recycle heat to enhance the energy efficiency of the process
• Liquid desiccant pump
Further in accordance with the invention the two-stage regeneration process may be extended to a multi-stage regeneration process in a system comprising:
• HTR operating at highest pressure in the system boiling the weak LD absorbing heat from an external source, having insulation on exposed surface to avoid heat loss from LD to surroundings and giving off vapour to next relatively low temperature ITR, in which the latent heat of vapour generated in HTR is used to boil the LD.
• ITR operating at a particular pressure heated using the vapour generated in the ITR/HTR operating at next higher-pressure level wherein the vapour generated in the ITR is passed on to the next ITR/LTR operating at next lower pressure level.
• A LTR, operating at atmospheric pressure, incorporating large surface density contacting device, having provision to heat the LD, with vapour generated in immediate higher temperature HTR/ITR condensing in the passages, in thermal contact with a container such as a the containing the LTR • Optional arrangement such as a hood with chimney to aid the flow of ambient air through LTR to pickup the moisture from LD.
• A device to rotate/oscillate the contacting discs assembly in the LTR
• Optional heat exchangers HTRHE, ITRHE and LTRHE used to recycle heat to enhance the energy efficiency of the process • Pressure reducing devices such as throttle valve
• Liquid desiccant pump(s)
The number of stages in regeneration process may be increased by appropriately adding ITRs, liquid-liquid heat exchangers and pressure reducing devices between HTR and LTR.
The contacting device providing intimate contact between fluids to enhance the interfacial area between them comprises of:
• assembly of contacting discs
• shaft for mounting the contacting discs for increased heat and /or mass transfer
• device for rotating/oscillating the contacting discs assembly • trough to hold fluids in which the disc assembly is partially or fully submerged • passages in thermal contact with a trough
• optional device to induce vapour/gas flow
• optional enclosure with arrangement to guide the flow of vapour/gas
The Hybrid Cooling System ( HCS) in accordance with the inventioncomprises: • An absorber/ Indoor Contacting Device (ICD), for dehumidifying air by bringing it in contact with the LD while being cooled by evaporating refrigerant in the integrated evaporator
• A regenerator/ Out Door Contacting Device (OCD) for regenerating LD by bringing it in contact with air, while LD being heated by condensing refrigerant in the integrated condenser . • A refrigerant compressor, to compress the refrigerant vapour coming from absorber/ICD after absorbing heat from LD and send the high pressure refrigerant vapour to regenerator/OCD for delivering heat to the LD
• A throttling device, for throttling liquid refrigerant moving from regenerator/OCD to absorber/ICD • Optional liquid-liquid heat exchanger to recycle heat from the hot regenerated strong LD flowing from the regenerator/OCD into the weak LD pumped out of the absorber/ICD
• Two optional LD pumps to pump the LD, one from the absorber/ICD to regenerator/OCD and the other from the regenerator/OCD to absorber/ICD
• Optional refrigerant liquid to vapour heat exchanger to sub cool the liquid refrigerant coming out of the condenser using the cooling effect of refrigerant vapour coming out of the evaporator
• Optional Spiral Contacting Device (SCD) incorporated by the absorber/ICD and regenerator/OCD
• Optional external refrigerant evaporator/LD cooler instead of integrated evaporator with absorber/ICD
• Optional external refrigerant condenser/LD heater instead of integrated condenser with regenerator/OCD
• Optional device to circulate the indoor air through the absorber/ICD and outdoor air through regenerator/OCD • Optional duct mounting of absorber/ICD and regenerator/OCD Detailed Description of the Invention
Other features and advantages of this invention will become apparent in the following detailed description of the preferred embodiments of this invention with reference to the accompanying drawings, in which: FIG.1a is a contacting mesh
FIG.1b a single stage low temperature regenerator with fan and chimney
FIG.2 is a schematic of absorber/ICD or regenerator/OCD with spiral contacting device (SCD)
FIG.3a is a a series flow two-stage regenerator with weak LD entering HTR
FIG.3b is a series flow two-stage regenerator with weak LD entering LTR FIG.3c is a parallel flow two-stage regenerator
FIG.4a is a series flow three-stage regenerator with weak LD entering HTR FIG.4b is a series flow three-stage regenerator with weak LD entering LTR FIG.4c is a parallel flow three-stage regenerator FIG.5 is a schematic of the hybrid cooling system FIG.6 shows a comparison of VCRS, DCS and HCS on psychrometric chart
FIG.1a shows the contacting mesh for the mass transfer. Dimples, 114 are provided to give the required gap between the discs, when they are assembled on the shaft. Dimples on the mesh are providing the self-spacing between the discs. This leads to reduction in time required to assemble the discs on the shaft. The depth and diameter of the dimple can be varied. The spacers of required thickness on the shaft can provide spacing between the discs. This eliminates the dimples on the circumference of the disc A lip, 115 on the circumference of the contacting disc provides enough rigidity to the contacting surface. Inner surface of the disc is 116. A square hole at the centre is 117. The discs can be thermally bonded with the shaft. Thermally bonded discs can be acting as fins and help in heat transfer between fluid in the trough and fluid flowing through the shaft.
FIG.1b shows a single stage Low Temperature Regenerator. The disc, 1 provides the contacting surface between the LD and air. The contacting surface is the mesh, or roughened surface, which holds the liquid on the surface for mass transfer. The disc, in plurality are mounted on a square hallow or solid shaft 2. A trough, 3 contains the LD. Material of construction of the trough can be a metallic, non-metallic or any other suitable, which is compatible with the LD and vapour/gas. The LD to be regenerated flows in to the trough 3 through inlet conduit 6. The regenerated LD flows out from the trough 3 through outlet conduit 7. Passages, 9 in plurality are in thermal contact with the trough. They can be inside/outside or integrated with the wall of the trough and be used for heat transfer to the LD in the trough. The passages can be metallic or non metallic or any other suitable material, which is compatible with fluid flowing through it. A hood, 14 is provided to ensure to vapour/gas passes in closed contact with contacting discs 1. Optionally a chimney 15 or a fan 16 is provided to circulate the air/gas through the contacting device. The heat transfer fluid is supplied through conduit 10 to the passages 9 wherein it exchanges heat with the LD in the trough and leaves through conduit 12. A device 5 is provided to rotate the contacting disc assembly and is supported on support 4. The surface of the contacting disc can hold large quantity of the liquid. Rotating contacting surface partially dipped in a liquid eliminates the need for a pump to irrigate the contacting device. Thereby making the irrigation mechanism simpler. Carryover is eliminated if low vapour/gas velocities are maintained.
Fluid flowing through the passages, which are in thermal contact with the trough, can be a hot or cold fluid. The hot fluid can be steam, compressed air, exhaust gases from the engine or any hot fluids from suitable hot source. The cold fluid can be a cold refrigerant from heat pump, water from the cooling tower.
There are several variants of the contacting that may be designed as per the application.
In one of the embodiments the contacting disc may be a mesh, plain, roughened surface, and porous material.
Another embodiments the contacting device is preferably circular.
In other embodiments the contacting disc may be octagonal, hexagonal or any other shape based on the application.
In a specific embodiment the contacting device is of metal. In other embodiments, the contacting may non-metallic or of any suitable material that is compatible with the fluids.
In one embodiment, the central hole in the contacting device preferably a non-circular cross section to ensure that the discs move along with the shaft. In yet another embodiment the hole in the contacting can be circular. In one of the embodiments, the contacting disc may optionally have dimples/projections on the circumference to provide self-spacing when the discs are assembled on a shaft. In other embodiments, the contacting discs do not have dimples, but spacing between the discs is provided with spacers.
In the other embodiments the spacers may be metallic or non metallic or any other suitable, which is compatible with liquid and vapour/gas.
One of the preferred embodiments is a square shaft that could be passed through the square hole in the contacting disc.
In an embodiment of the contacting disc assembly the shaft may be a hollow or solid as per the application. In an embodiment of the contacting disc assembly the shaft is metallic. In other embodiments, the shaft may be non-metallic or any other suitable material, which is compatible with the fluids.
In one of the embodiments, the trough holding the liquid may have the discs that are partially submerged. In the other embodiments, material of construction of the trough may be a metallic, non- metallic or of any suitable material, which is compatible with the fluids.
In one of the embodiments, the heat exchanging passages on the trough is a coil, or multiplicity of tubes of any material in thermal contact with the inner or outer surface of the trough or integrated into the trough. In other embodiments, the material of the passages may be metallic, non-metallic, or any other suitable material, which is compatible with the fluid flowing through it.
In one of the embodiments, a cover with chimney is provided to circulate the vapour/gas through the device.
In the other embodiments, the material of construction of enclosure to guide the flow of vapour/gas may be metallic or non metallic which is compatible with the fluids.
In one of the embodiments, a low speed drive may be used to rotate the contacting disc assembly.
FIG.2 shows one of the preferred embodiments of the absorber/ICD or regenerator/ OCD with spiral contacting device (SCD). A trough 347, is the housing to contain the LD 348. The contacting spiral mesh is wound on a housing 350. The spiral-contacting device is 349. A shaft
351 at the centre of the SCD is connected to an electric motor 352. The SCD is rotated by a motor at low rpm in the LD, preferably at around 3 to 5 rpm or oscillated to angle greater than
30° in either direction. A fan 353 is provided to circulate indoor air in case of absorber/ICD and outdoor air in case of regenerator/OCD. In an embodiment the fan may be a forced/induced draft fan. A support 354 is provided to the trough. The heat exchanger in the trough of absorber/ICD or regenerator/OCD is 355. Refrigerant passes to the heat exchanger through the conduit 356 to cool the LD in case of absorber/ICD and to heat the LD in case of regenerator/OCD. The outlet of refrigerant from the absorber/ICD or regenerator/OCD is 357.
FIG. 3a shows a series flow two-stage regenerator with weak LD entering HTR. The weak LD from the source passes to the pump 75 through inlet conduit 74 and is pumped to LTRHE
21, through conduit 29 and where it is heated, further it passes through conduit 30 and gets heated in High Temperature Regenerator Heat exchanger (HTRHE) 41 further and then through conduit 33 it is introduced in to HTR 32. Vapour is generated from the LD at high temperature and pressure due to the addition of heat 39. This vapour passes through conduit 36 and gets sensibly cooled in HTRHE 41, further it passes through conduit 10 and flows through the passages of LTR 18 and gets condensed completely in passages of LTR. This condensate then passes through conduit 12 and further passes through Low Temperature Regenerator Heat Exchanger (LTRHE) 21 where it gets sub cooled further. This condensate is collected from the outlet conduit 73.
Partially regenerated LD from HTR 32 exits through conduit 34 and then passes through HTRHE 41 where it gets sub cooled and passes to LTR 18 through conduit 6. After complete regeneration of LD in LTR it exits through conduit 7 and then passes through LTRHE 21 where it gets sub-cooled and the regenerated LD leaves through conduit 24.
The vapour generated in HTR flows to HTRHE, 41 through conduit 36 and gets desuperheated and the desuper heated vapour flows to the LTR 18 through conduit 10 and is condensed in passages thermally in contact with LTR 18 and the condensate from LTR flows to
LTRHE 21 through conduit 12 and then subcooled in LTRHE and comes out through conduit 73.
FIG. 3b shows a series flow two-stage regenerator with weak LD entering LTR. The weak
LD from the source passes to the pump 75 through inlet conduit 74 and is pumped to LTRHE
21, through conduit 29 and where it is heated, further it passes to LTR through conduit 6 then it is partially regenerated in LTR. Partially regenerated LD from LTR flows through the conduit 7 to the suction of the pump 64 and pumped through HTRHE 41 where it is preheated and then flows to HTR 32 through conduit 34. The LD level in the HTR is 37 and the insulation to HTR is 38. In the HTR the LD is fully regenerated by absorbing heat from the heat source 39. The fully regenerated LD from HTR flows to HTRHE 41 through conduit 33 and then subcooled in HTRHE and flows to LTRHE 21 through conduit 43, where it is subcooled further before being returned to the source through conduit 24.
The vapour generated in HTR flows to HTRHE, 41 through conduit 36 and gets desuperheated and the desuper heated vapour flows to the LTR 18 through conduit 10 and is condensed in passages thermally in contact with LTR 18 and the condensate from LTR flows to LTRHE 21 through conduit 12 and then subcooled in LTRHE and comes out through conduit 73.
FIG.3c shows a parallel flow two-stage regenerator. The weak LD from the source passes to the pump 75 through inlet conduit 74 and is pumped to LTRHE 21, through conduit 29 and where it is heated and passes through conduit 30, and part of the LD flow is throttled into the LTR in throttling device 25 and fully regenerated and the other part of the LD flow is preheated through HTRHE, 41 on its way to HTR. The LD level in the HTR is 37 and the insulation to HTR is 38. In the HTR the LD is fully regenerated by absorbing heat from the heat source 39. After regeneration the LD flows to the HTRHE, 41 through conduit 34 where it is subcoled and then further it passes through conduit 43 before being combined with the fully regenerated LD stream from LTR 18 and then flows through conduit 23 and further passes through LTRHE 21 where it is subcooled before being returned to the source through condut 24. The vapour generated in HTR flows to HTRHE 41 through conduit 36 and gets desuperheated and the desuperheated vapour flows to the LTR 18 through conduit 10 and is condensed in passages thermally in contact with LTR 18 and the condensate from LTR flows to LTRHE 21 through conduit 12 and then subcooled in LTRHE and comes out through conduit 73. FIG.4a shows a series flow three-stage regenerator with three pumps and two throttle valves. The weak LD from the source passes to the pump 75 through inlet conduit 74 and is pumped to LTRHE 21, through conduit 29 and then is heated, further it passes through conduit 30 and gets heated in Intermediate Temperature Regenerator Heat exchanger (ITRHE) 61, further it passes through conduit 42 which leads it High Temperature Regenerator Heat exchanger (HTRHE) 41 where it gets heated further and then through conduit 33 it is introduced into HTR 32. Vapour is generated from the solution at high temperature' and pressure due to the addition of heat 39. This vapour passes through conduit 36 and gets sensibly cooled in HTRHE 41, further it passes through conduit 45 and condenses in heat exchanger 60 and further condensate passes through ITRHE 61 where it gets subcooled and it passes through throttle valve 66 and is led through conduit 10 after mixing with vapour coming from ITR 51 through conduit 67. This condensate vapour mixture condenses completely in passages of LTR 18 and then passes through conduit 12 and further passes through Low Temperature Regenerator Heat Exchanger (LTRHE) 21 where it gets sub cooled further. This low-pressure condensate stream is then pumped using pump 72 to atmospheric pressure. The condensate is collected from the outlet conduit 73.
Partially regenerated LD from HTR 32 is led through conduit 34 into HTRHE 41 where it gets sub cooled before it is throttled in throttling device 46 and led through conduit 52 into ITR 51. Vapour is generated in ITR 51 at intermediate temperature and pressure due to heat delivered through heat exchanger 60. This vapour passes through conduit 55 which is desuperheated in ITRHE 61 and further it passes through conduit 67 leading to conduit 10. Partially regenerated LD from ITR 51 which operates under vacuum passes through conduit 54 which leads into LD pump 64 which increases the pressure of the LD from ITR to atmospheric pressure which is then led in to trough of LTR 18.
After complete regeneration of LD in LTR it is led through conduit 7 to LTRHE 21 where it gets sub-cooled further. The regenerated LD flows out through outlet conduit 24.
FIG.4b shows a series flow three-stage regenerator with weak LD entering LTR. The weak LD from the source passes to the pump 75 through inlet conduit 74 and is pumped to LTRHE 21, through conduit 29 and then is heated and further passes to LTR 18 through conduit 6 and partially regenerated in the LTR then pumped to ITRHE 61 with pump 64, through conduit 7, where it is preheated before it is regenerated further in ITR 51. The partially regenerated LD is pumped to HTR 32 with pump 64 through the HTRHE 41 where it is preheated through HTRHE and passes to HTR through conduit 33 and regenerated further in HTR thereafter the fully regenerated LD flows to HTRHE wherein it is subcooled, and passes to ITRHE through conduit 43 and further flows to LTRHE 21 through conduit 23 and then pumped back to the source through conduit 24 The vapour generated in HTR flows to HTRHE 41 through conduit 36 and gets desuperheated and the desuperheated vapour flows to the ITR 51 and gets condensed and further subcooled in ITRHE 61 and throttled in throttling device 66 and mix with the vapour generated in ITR. This liquid vapour stream is then condensed in "passages" thermally in contact with LTR, 18 and the condensate from LTR passes to LTRHE 21 through conduit 12 and subcooled in LTRHE before being pumped out through conduit 73.
FIG.4c shows the parallel flow three stage regenerator. The weak LD from the source passes to the pump 75 through inlet conduit 74 and is pumped to LTRHE 21 through conduit 29 and then it is heated and a portion of the LD further passes to LTR 18 through conduit 6 through throttling device 25 and conduit 6. Another portion of weak LD passes through conduit 30 to ITRHE 61. This stream of LD passes from ITRHE 61 to ITR 51 through conduit 68 and portion of this stream is taken into ITR 51 through throttling device 49 and conduit 52. The remaining portion of this stream flows through throttle valve 48 and conduit 42 to HTRHE 41 and flows through conduit 33 to HTR. The partially regenerated LD from LTR 18 passes through pump 64 through conduit 63 to ITRHE 61 and flows to HTR 32 through HTRHE. The vapour generated in HTR flows to HTRHE 41 through conduit 36 and gets desuperheated and the desuperheated vapour flows to the ITR 51 through conduit 45 and gets condensed in the heat exchanger 60 in ITR and flows to the ITRHE through conduit 57 and further subcooled in ITRHE 61 and throttled in throttling device 66 and mix with the vapour generated in ITR. This liquid vapour stream is then condensed in "passages" thermally in contact with LTR, 18 and the condensate from LTR passes to LTRHE 21 through conduit 12 and subcooled in LTRHE before being pumped out through conduit 73.
The number of stages in regeneration process may be increased by adding ITRs, liquid- liquid heat exchangers and pressure reducing devices between HTR and LTR.
In one of the embodiments, the heat source to the HTR is electric heater, solar collector, burning of biomass or biogas.
In the other embodiment, the heat source to the HTR may be waste heat source from the engine exhaust or any other waste heat source.
In one of the embodiments, the HTR may be a metallic or non-metallic, which is compatible with LD. In the other embodiment, the shape of the HTR may be a cylindrical, rectangular, square or any other suitable shape for integration with the heat source. In the other embodiment the HTR may be placed horizontally, vertically or any position suitable for integration with the heat source.
In one of the embodiments the HTR is covered with insulating material to avoid heat transfer between LD and ambient. ' In one of the embodiments, a solution heat exchanger is incorporated to preheat the weak
LD flowing to HTR, using heat from high temperature LD flowing from HTR.
In one of the embodiment, additional solution heat exchangers may be incorporated to internally recycle heat from hot to cold LD.
In the other embodiment, the material of construction of heat exchanger may be a plastic or any other suitable material compatible with LD.
In one of the embodiments entire flow of the LD, after regeneration in HTR is flowing through LTR. In this case, HTR and LTR are operating in series.
In the other embodiment certain flow of LD after regeneration in HTR may be bypassed. In this case HTR and LTR are operating in parallel. In another embodiment partially regenerated LD passes from the HTR to LTR for further regeneration or the partially regenerated LD may pass from LTR to HTR for further regeneration or the flow of LD is split into two streams and then passed to HTR and LTR
In another embodiment, the LTR incorporates rotating disks as the contacting media between LD and vapour/gas. In one of the embodiments, the condensation of vapour takes place in the passages, which are in thermal contact with the LTR.
In a specific embodiment the passages, through which vapour condenses may be in thermal contact while being inside or outside or integrated with LTR.
In one of the embodiments an arrangement such as a hood with chimney is provided to aid the ambient air through the LTR over the contacting media, which is wet with LD.
In one of the embodiments, the HTR is at a higher elevation than the LTR, and one LD pump is used to pump the weak LD to HTR.
In another embodiment, two pumps are used, one pump to LTR and the other to HTR.
In the other embodiment, one pump to pump LD to LTR and LD from LTR flows due to gravity.
In another embodiment, the heat source to the ITR may be the vapour generated in HTR.
In other embodiments, the ITR may be a metallic or non-metallic, which is compatible with LD.
In the other embodiment the shape of the ITR may be a cylindrical, rectangular, square or any other suitable shape for integration with the heat source from ITR/HTR operating at next higher pressure level. Yet other variants of this invention with more than two-stages of regeneration, which incorporates additional components such as, ITRs, liquid-liquid heat exchangers and pressure reducing devices.
FIG.5 shows a schematic diagram of the novel HCS. The system comprises of an absorber/ICD 318, which incorporates large surface density contacting discs 1, in plurality mounted on a shaft 2. The disc-assembly placed in a trough 3, containing the LD. The trough is made of any material that is compatible with the LD and air. A fan, 16 circulates the indoor air through the absorber/ICD, which gets dehumidified and cooled as it passes through the absorber. In an embodiment the fan may be a forced/induced draft fan. A hood, 14 guides the indoor air over the contacting disc assembly. Concentrated LD enters the absorber/ICD through conduit 306. Weak LD leaves the absorber/ICD through conduit 307. The contacting discs are partially submerged in the LD, in the absorber/ ICD. The disc assembly is rotated by a drive at low rpm in the LD, preferably at around 3 to 5 rpm or oscillated to an angle greater than 30° in either direction. The refrigerant of VCRS is expanded in the throttle valve, 321 and the low temperature refrigerant flows in through conduit 311 to the passages 9, that are in thermal contact with the outer lower surface or inner surface or integrated with the trough wall of the absorber/ ICD. The LD in the absorber/ICD is cooled as the refrigerant evaporates in the passages 9. The cooled desiccant in the absorber has high affinity to absorb the moisture from the indoor air. After absorbing the moisture from the indoor air, weak LD flows through conduit 307 and led to the pump 330, to the regenerator/OCD, 18 through a liquid-liquid heat exchanger 331. This heat exchanger is provided to heat the LD from the absorber/ICD and cool the desiccant stream as it flows from regenerator/OCD 18, which flows in to the absorber/ ICD.
Refrigerant exits from the absorber/ICD through conduit 312 and moves to the compressor 320. Refrigerant after compression passes through conduit 10 to the passages 9 of regenerator/OCD, 18 which are in thermal contact with the outer lower surface or inner surface or integrated with the trough wall of the regenerator/OCD. The weak LD from absorber/ICD after liquid-liquid heat exchanger flows to the regenerator/OCD. The weak LD enters the regenerator /OCD through conduit 6. The heat required for the regeneration is supplied by the refrigerant condensing in the passages 9. After condensation of the refrigerant in regenerator/ OCD, it moves through conduit 12 which led to throttling device 321.
The regenerated, strong LD flows out from the regenerator/OCD through conduit 7 and pumped with LD pump 332 to the absorber/ ICD through the liquid-liquid heat exchanger, 331. A hood 14 is provided to guide the outdoor air through the regenerator/OCD. A fan 16 is provided to circulate the outdoor air through the regenerator/OCD. The contacting disc assembly is partially submerged in the LD in the regenerator/OCD. The ambient air pickups the moisture from the hot desiccant, in the trough of regenerator/OCD. The disc assembly is rotated by a motor at low rpm in the LD, preferably at around 3 to 5 rpm or oscillated to an angle greater than 30° in either direction.
FIG.6 shows the ideal state points on psychrometric chart that the conditioned air experiences in VCRS, DCS and HCS. For VCRS, the air-conditioning process is represented by locus of 334-335-336-337, on psychrometric chart. For DCS, the process is represented by locus 334- 338- 339- 340- 337. For HCS, the process is represented by locus 334- 338- 337 and 334- 337. Compared with the DCS and VCRS, HCS eliminates the process of cooling the air below its dew point temperature and reheating as in VCRS. HCS also eliminate the processes of deep dehumidification and re-humidification, which occurs in the DCS. In one of the embodiments, an absorber/ICD is coupled with an evaporator of conventional VCRS.
In another embodiment, the absorber/ICD is an adiabatic contacting device with a separate heat exchanger to cool the LD.
In one of the embodiments, the evaporation of the refrigerant takes place in the passages, which are in thermal contact with the trough containing the LD.
In a specific embodiment, the passages may be in thermal contact by being placed inside or outside the trough or integral with trough.
In one of the embodiments an absorber/ICD and/or regenerator/OCD incorporates large surface density rotating contacting disc assembly as the contacting media between air and LD. In another embodiment, the rotating contact disc assembly in the absorber/ICD and/or regenerator/OCD is a mesh, plain /roughened surface or porous material and their like constructed of materials such as a plastic or any other suitable material, which is compatible with LD and air.
In one of the embodiments the contacting disc assembly absorber/ICD and regenerator/OCD is rotated at low rpm in the LD, preferably at around 3 to 5 rpm or oscillated to an angle greater than 30° in either direction.
In another embodiment the contacting disc assembly in the absorber/ICD and/or regenerator/OCD is mounted in a trough or any suitable container constructed of non conducting material with wall thickness of < 0.2 mm and to withstand the pressure of the heat transfer fluid.
In one of the embodiments the absorber/ICD and/or regenerator/OCD, optionally incorporates Spiral Contacting Device (SCD) as the contacting media between the LD and air.
In another embodiment SCD in the absorber/ICD and/or regenerator/OCD is rotated at low rpm in the LD, preferably at around 3 to 5 rpm or oscillated to an angle greater than 30° in either direction. In one of the embodiments, SCD in the absorber/ICD and/or regenerator/OCD is mounted in a trough or any suitable container without passages.
In the other embodiment the trough to mount the SCD is constructed of conducting /non conducting material without limitation of wall thickness In one of the embodiments, a liquid-liquid heat exchanger selected from any suitable material compatible with the LD may be incorporated in the system to recycle heat from the hot regenerated strong LD coming from the regenerator/OCD into the weak LD coming out of the absorber/ICD.
In one of the embodiments, a regenerator/OCD is coupled with a condenser of conventional VCRS.
In another embodiment, the regenerator/OCD is an adiabatic contacting device with a separate heat exchanger to heat the LD.
In one of the embodiments the condensation of the refrigerant takes place in the passages, which are in thermal contact with the inner or outer or integrated into the trough of regenerator/OCD.
In one of the embodiments the evaporation of the refrigerant takes place in the passages, which are in thermal contact with the inner or outer or integrated into the trough of absorber/ICD.
In the specific embodiment, where the elevation difference between the regenerator/OCD and the absorber/ICD is not sufficient, two LD pumps are used to pump the LD, one from the absorber/ICD to regenerator/OCD and the other from the absorber/ICD to regenerator/OCD.
In an embodiment the regenerator/OCD may be placed at higher elevation than the absorber/ICD in which case the LD flows by gravity from the regenerator/OCD to absorber/ICD In the specific embodiment, where the regenerator/OCD is at a higher elevation than the absorber/ICD, one LD pump is used to pump the LD from the absorber/ICD to regenerator/OCD.
In one of the embodiments, absorber/ICD may be placed at higher elevation than the regenerator/OCD in which case the LD flows by gravity from the absorber/ICD to regenerator/OCD.
In the specific embodiment, where the absorber/ICD is at a higher elevation than the regenerator/OCD, one LD pump is used to pump the LD from the regenerator/OCD to absorber/ICD
In another set of embodiments the said VCRS is replaced by Vapour Absorption/Adsorption System. W 03
24
Examples
A preferred embodiment of the Energy efficient regeneration process is illustrated with a non- limiting example.
Example 1
A two-stage regenerator device was fabricated and tested for regeneration of calcium chloride LD. It consists of a HTR made of aluminium rectangular channel in which electrical heaters are incorporated as heat source. LTR incorporates the aluminium disks are of 150 mm diameter, with circumferential lip and dimples as the contacting device between LD and ambient air. The disks are mounted on an aluminium shaft of diameter 9.5 mm. The disks are placed in a semi hexagonal aluminium trough 500 mm (length) x 200 mm (width) x 210 mm (height). It incorporates 337 m2/m3 surface density, when maintaining 5mm gap between the disks using plastic spacers. Contacting device is covered with a hood and a chimney of diameter 100 mm, length 1.5 m. Airflow through the contacting device is due to natural convection induced by the chimney effect. The disks are made to rotate at 5 rpm using an electric motor. Inlet and out let of LD to the trough is through 9.5 mm diameter aluminium tubes. The experimental result in Table 1 , shows that the regenerator is capable of removing 2.6 kg/kW-h water from calcium chloride LD. It is observed that there is no carry over of LD with air stream and along the condensate collected from LTR.
Table 1 : Experimental Result for Regeneration of Calcium Chloride Liquid Desiccant with Two-Stage Regenerator
Q Mfw Ambient air Chimney air
DBT WBT kW kg/h RH DBT WBT RH V Remarks
°C °C % °C °C % m/s
21 26.6 19 47 No carry over of LD
60 58 82
Q Electric heat input mfw Total water removed from LD
DBT Dry bulb temperature, WBT Wet bulb temperature
RH Relative humidity V Velocity of air at exit
The other associated advantages of this two stage/multistage regeneration process are, no corrosion, no orifices or nozzles to wear or clog, modular system that can be installed with flexibility, silent operation without splashing or spraying sounds and low electrical power consumption. The invention is now illustrated with a non-limiting example.
Example 2 Humidification of air using contacting device
The contacting device was fabricated and tested for humidification of ambient air. It consists of discs made of aluminium mesh. The discs are of 150 mm diameter, with circumferential lip and dimples. The discs are mounted on an aluminium shaft of diameter 9.5 mm. The discs are placed in a semi hexagonal aluminium trough 500 mm (length) x 200 mm (width) x 210 mm (height). It incorporates 337m2/m3 surface density, when maintaining 5mm gap between the discs using plastic spacers. Contacting device is covered with a hood and a chimney of diameter 100 mm, length 1.5 m. Airflow through the contacting device is due to natural convection induced by the chimney effect. The discs are made to rotate at 5 rpm using an electric motor. Inlet and out let of water to the trough is through 9.5 mm diameter aluminium tubes. The experimental result in Table 2 shows that the contacting device efficiency for humidification of air is as high as 98% for the ambient conditions are 26.8°C and 48% relative humidity. It is observed that there is no carry over of liquid with air stream.
Table 2: Experimental Result for Humidification of Air Using Contacting Device
Ambient air Chimney air
DBT WBT RH DBT WBT RH Remarks
°C °C % °C °C %
No carry over of
26.8 19.5 48 58 57.6 98 liquid with air DBT Dry bulb temperature,
WBT Wet bulb temperature
RH Relative humidity
The other associated advantages of this contacting device are, no corrosion, no pumps, no tubes, no orifices or nozzles to wear or clog, modular system that can be installed with flexibility, silent operation without splashing or spraying sounds and low electrical power consumption. Example 3 Results Of CaCI2 using Hybrid cooling system
A hybrid cooling system is designed with the following specification:
Evaporator duty 3.52 kW (1 TR)
CaCI2 solution temperatures Condenser inlet 45.9°C Condenser outlet 49°C Evaporator inlet 24.1°C Evaporator outlet 20°C c. Evaporator exit superheat 5°C d. Condenser exit sub-cooling 0°C e. Condenser temperature 51°C f. Evaporator temperature 15°C g- Compressor isentropic efficiency 80% h. Hermetic compressor motor efficiency 84% i. Ratio of clearance to swept volume 5%
The salient features of the model are as follows: a. The model is developed for the design of a HCS with single stage VCRS b. A liquid-vapour heat exchanger/refrigerant sub-cooler may be incorporated on the refrigerant side to further improve the capacity and COP of the HCS. c. A liquid-liquid heat exchanger/solution heat exchanger is also designed on CaCI2 solution streamside for energy saving and for enhancing the overall system COP and capacity, h. The relevant simulated results are given in Table 3.
Table 3: Comparison of the Values of the Results between the Novel HCS and a Conventional
VCRS. Parameters VCRS Novel HCS %Change
Pressure ratio 3.66 2.52 31 decrease
Compressor displacement, litre/s 1.13 0.79 30 decrease
Swept Volume, litre/s 1.626 1.01 37.8 decrease
Compressor Work, kW 1.23 0.83 32.5 decrease
Cooling Capacity, TR 1.0 1.6 60 increase
COP 2.85 4.14 45 increase
Volumetric Efficiency 87 92 6 increase The main advantages of the system are the significantly improved energy efficiency, zero carryover of LD into process air streams, increase in cooling capacity for a given compressor in comparison to the conventional HCS using "packed" or "spray type-contacting devices". This is possible with the appropriately designing of the absorber, regenerator, liquid-liquid heat exchanger and other components of HCS. Significant reduction in weight and cost is achieved with the use of alternate materials such as plastics and eliminates any problems due to corrosion of the absorber/regenerator as in conventional systems. The contacting media disclosed in this invention offers high surface densities as high as 600 m2/m3, which is about 185% greater than conventional packing. The system is compact, lower weight and techno- economically viable for air-conditioning.

Claims

CLAIMSWe claim:
1. A novel energy efficient multi-stage regeneration process, for regenerating liquid desiccant (LD), using rotating contacting disks assembly to provide intimate contact between LD and vapour/gas to enhance the interfacial area between them for increased heat and/or mass transfer, without problems of carryover of liquid in to the vapour/gas stream or flooding, having the provision to efficiently heat and/or cool the liquid while cooling and dehumidifying the air using a Hybrid Cooling System (HCS). 2. An energy efficient multi-stage regeneration process (EEMSRP) for regenerating liquid desiccant (LD) as claimed in claim 1 comprising:
Partial or complete regeneration of LD in a Low Temperature Regenerator (LTR) Partial or complete regeneration of LD in a Intermediate Temperature Regenerator (ITR) • Partial or complete regeneration of LD in a High Temperature Regenerator (HTR) desuperheating of vapour generated in HTR in a heat exchanger (HTRHE) while preheating the LD before entering HTR subcooling of LD regenerated in HTR in HTRHE while preheating the LD before entering HTR • condensation of desuperheated vapour from HTRHE in heat exchanger inside
ITR while regenerating LD desuperheating of vapour generated in ITR in a heat exchanger (ITRHE) while preheating the LD before entering ITR and/or HTR subcooling of LD regenerated in ITR in ITRHE while preheating the LD before entering ITR and/or HTR subcooling of condensate from ITR in ITRHE while preheating the LD before entering ITR and/or HTR desuperheating of vapour generated in ITR in a ITRHE while preheating the LD before entering ITR and/or HTR • condensation of desuperheated vapour from ITRHE in "passages" thermally in contact with LTR while regenerating LD flowing of vapour/gas through LTR with the aid of and arrangement such as chimney/fan to pickup the vapours from LD subcooling of LD regenerated in LTR in LTRHE while preheating the LD before entering LTR and/or ITR and/or HTR • subcooling of condensate from LTR in LTRHE while preheating the LD before entering LTR and/or ITR and/or HTR wherein the number of stages in the regeneration process is (2+n) where n is the number of ITR's in the process The EEMSRP claimed in claim 1-2 is a two-stage regeneration process involving a HTR and LTR without involvement of ITRs A two-stage regeneration process claimed in claim 3 comprising:
• partial or complete regeneration of LD in a LTR
• Partial or complete regeneration of LD in a HTR • desuperheating of vapour generated in HTR in HTRHE while preheating the LD before entering HTR
• subcooling of LD regenerated in HTR in HTRHE while preheating the LD before entering HTR
• Condensation of desuperheated vapour from HTRHE in "passages" thermally in contact with LTR while regenerating LD
• Flowing of vapour/gas through LTR with the aid of chimney/fan to pickup the vapours from LD
• subcooling of LD regenerated in LTR is in LTRHE while preheating the LD before entering LTR and/or HTR • subcooling of condensate from LTR is also in LTRHE while preheating the LD before entering LTR and/or HTR A two-stage regeneration process claimed in claim 1-3 wherein weak LD from the source is pumped and preheated through LTRHE then it is further preheated through HTRHE and partially regenerated in HTR thereafter subcooled in HTRHE before being throttled , into LTR where it is fully regenerated and then subcoled in LTRHE and returned to the source A two-stage regeneration process claimed in claim 1-3 wherein weak LD from the source is pumped and preheated through LTRHE then partially regenerated in LTR and pumped through HTRHE where it is preheated before entering HTR where it is fully regenerated and then subcoled in HTRHE and LTRHE before being returned to the source A two-stage regeneration process claimed in claims 1-3 wherein weak LD from the source is pumped and preheated through LTRHE after which part of the LD flow is throttled into the LTR and fully regenerated and the other part of the LD flow is preheated through HTRHE on its way to HTR where it is fully regenerated and then subcoled in HTRHE before being combined with the fully regenerated LD stream from
LTR and then subcooled in LTRHE before being returned to the source
8. A two-stage regeneration process claimed in claims 1-7 wherein vapour generated in HTR is desuperheated in HTRHE and the desuper heated vapour is condensed in "passages" thermally in contact with LTR and the condensate from LTR is then subcooled in LTRHE
9. The EEMSRP claimed in claims 1-2 may be a three-stage regeneration process involving a HTR, LTR and one ITR
10. A three-stage regeneration process claimed in claims 1-2, 9 wherein weak LD from the source is pumped and preheated through LTRHE and ITRHE then it is further preheated through HTRHE and partially regenerated in HTR thereafter it is subcooled in HTRHE and throttled into the ITR where it is regenerated further and them subcooled in ITRHE before being pumped into LTR where it is fully regenerated and then subcoled in LTRHE and returned to the source
11. A three-stage regeneration process claimed in claim 1-2, 9 wherein weak LD from the source is pumped and preheated through LTRHE and partially regenerated in the LTR then pumped through ITRHE where it is preheated before it is regenerated further in
ITRHE then this partially regenerated LD is pumped through the HTRHE where it is preheated through HTRHE and regenerated further in HTR thereafter the fully regenerated LD is subcooled in HTRHE, ITRHE and LTRHE and then pumped back to the source 12. A three-stage regeneration process claimed in claim 1-,2, 9 wherein weak LD from the source is pumped and preheated through LTRHE after which part of the LD flow is throttled into the LTR and fully regenerated and the other part of the LD flow is preheated through ITRHE after which part of the LD flow is throttled into the ITR where it is fully regenerated and the third part of the LD flow is preheated through HTRHE on its way to HTR where it is fully regenerated and then subcoled in HTRHE after which it is combined with the LD flow from the ITR and then subcooled in ITRHE before being combined with the fully regenerated LD stream from LTR and finally it is subcooled in LTRHE before being returned to the source
13. A three-stage regeneration process claimed in claims 1-2, 10-12 wherein vapour generated in HTR is desuperheated in HTRHE and condensed in ITR and further subcooled in ITRHE -before throttling it into the desuperheated vapour generated in ITR this liquid vapour stream is then condensed in "passages" thermally in contact with LTR and the condensate from LTR is then subcooled in LTRHE before being pumped out
14. The energy efficient multi-stage regeneration process (EEMSRP) claimed in claims 1-2 is operated as single stage process wherein there is only a LTR An energy efficient multi-stage regeneration process (EEMSRP) for regenerating liquid desiccant (LD) as claimed in claims 1-2 carried out in a system comprising:
• HTR operating at highest pressure in the system boiling the weak LD absorbing heat from an external source, having insulation on exposed surface to avoid heat loss from LD to surroundings and giving off vapour to next relatively low temperature ITR, in which the latent heat of vapour generated in HTR is used to boil the LD.
• ITR operating at a particular pressure heated using the vapour generated in the ITR/HTR operating at next higher-pressure level wherein the vapour generated in the ITR is passed on to the next ITR/LTR operating at next lower pressure level.
• A LTR, operating at atmospheric pressure, incorporating large surface density contacting device, having provision to heat the LD, with vapour generated in immediate higher temperature HTR/ITR condensing in the passages, in thermal contact with a container such as a the containing the LTR • Optional arrangement such as a hood with chimney to aid the flow of ambient air through LTR to pickup the moisture from LD.
• A device to rotate/oscillate the contacting discs assembly in the LTR
• Optional heat exchangers HTRHE, ITRHE and LTRHE used to recycle heat to enhance the energy efficiency of the process • Pressure reducing devices such as throttle vlave
• Liquid desiccant pump(s) wherein the number of stages in the system for regeneration is (2+n) where n is the number of ITR's in the process A system for energy efficient single stage regeneration process for regenerating liquid desiccant (LD) as claimed in claims 1-2,
15 comprising:
• LTR, incorporating large surface density contacting device, having provision to heat the LD using heat from an external source in passages which are in thermal contact with a container such as a trough containing the LTR
• Optional arrangement such as a hood with chimney to aid the flow of ambient air through LTR to pickup the moisture from LD.
• A device to rotate/oscillate the contacting discs assembly in the LTR
• Optional heat exchanger used to recycle heat to enhance the energy efficiency of the process
• Liquid desiccant pump
16. Novel contacting device providing intimate contact between fluids to enhance the interfacial area between them as claimed in claim 1 comprising:
• assembly of contacting discs
• shaft for mounting the contacting discs for increased heat and /or mass transfer
• device for rotating/oscillating the contacting discs assembly
• trough to hold fluids in which the disc assembly is partially or fully submerged
• passages in thermal contact with a trough
• optional device to induce vapour/gas flow
• optional enclosure with arrangement to guide the flow of vapour/gas
17. Contacting disc claimed in claims 1, 16 is a mesh, plain /roughened surface or porous material and their like
18. Contacting disc claimed in claims 1,16-17 is of any shape preferably circular
19. Contacting disc claimed in claims 1 ,16-18 is of any material including metal, plastic, ceramic, alloys, depending on the end use of the device
20. Contacting disc in the assembly claimed in claims 1 ,16-19 has circular or preferably non- circular hole on the surface for shaft mounting
21. Contacting disc claimed in claims 1 ,16-20 optionally having lipping
22. Assembly of contacting discs of similar or dissimilar types as claimed in claims 16-21 mounted on a solid or hollow shaft of any appropriate material
23. Contacting discs as claimed in claims 1 , 16-22 having dimples/projections atleast on one of its surface functioning as spacers in a disc assembly
24. The shaft claimed in claims 1 , 16 and 20 is a rod, tube with or without internal passages for fluid flow
25. Contacting discs as claimed in claims 1 , 16-22 without dimples/projections mounted with spacers on a shaft
26. Contacting disc assembly as claimed in claims 1, 16, 22-23 fixed or thermally bonded to a shaft
27. Device for rotating/oscillating the contacting discs assembly as claimed in claims 1 , 16, capable of rotating the assembly preferably at 3 to 5 rpm or oscillating it through angles greater than 30° in either direction
28. A trough claimed in claims 16 of any material, shape and size to match the assembly as claimed in claims 1, 16, 22-26
29. Heat exchanging passages claimed in claimsl , 16 is a coil, or multiplicity of tubes of any material in thermal contact with the inner or outer surface of the trough or integrated into the trough
30. Contacting device as claimed in claims 1 ,16-29 without carryover of fluid into the vapour/gas stream or flooding with provision for heating/cooling the liquid depending on the application of the device
31. Contacting device as claimed in claims 1 ,16-30 with surface density in the range of about 450 to about 600 m /m3 operating at pressure drop across the contacting device to as low as about 5 Pa.
32. A contact device as claimed in claims 1 ,16-31 with no limit on liquid throughput leading to high efficiency of the process and operating with low power consumption of around 3 to 10 W per 50 to 100 m3/h volume flow rate of vapour/gas
33. A contact device as claimed in claims 1 , 16-32 in combination with appropriate devices used for applications involving dehumidification, humidification, cooling towers, air- conditioning
34. A contact device as claimed in claims 1 , 16-32 for applications involving separation of gases from the liquid, regeneration of liquid desiccants, distillation columns, rectification columns, absorption refrigeration systems, multiphase-multicomponent adiabatic/non- adiabatic chemical/ bio reactors, and cold/heat storage applications
35. Contacting device as claimed in claims 1 , 16-34 for humidification or cooling and dehumidification with efficiencies up to 98%.
36. A hybrid cooling system, as claimed in claim 1 in which air temperature and humidity are simultaneously controlled, comprising;
• An absorber/ Indoor Contacting Device (ICD), for dehumidifying air by bringing it in contact with the LD while being cooled by evaporating refrigerant in the integrated evaporator
• A regenerator/ Out Door Contacting Device (OCD) for regenerating LD by bringing it in contact with air, while LD being heated by condensing refrigerant in the integrated condenser
• A refrigerant compressor, to compress the refrigerant vapour coming from absorber/ICD after absorbing heat from LD and to send the high pressure refrigerant vapour to regenerator/OCD for delivering heat to the LD • A throttling device, for throttling liquid refrigerant moving from regenerator/OCD to absorber/ICD
• Optional liquid-liquid heat exchanger, to recycle heat from the hot regenerated strong LD flowing from the regenerator/OCD into the weak LD pumped out of the absorber/ICD • Two optional LD pumps to pump the LD, one from the absorber/ICD to regenerator/OCD and the other from the regenerator/OCD to absorber/ICD • Optional refrigerant liquid to vapour heat exchanger to sub cool the liquid refrigerant coming out of the condenser using the cooling effect of refrigerant vapour coming out of the evaporator
• Optional Spiral Contacting Device (SCD) incorporated by the absorber/ICD and regenerator/OCD
• Optional external refrigerant evaporator/LD cooler instead of integrated evaporator with absorber/ICD
• Optional external refrigerant condenser/LD heater instead of integrated condenser with regenerator/OCD • Optional device to circulate the indoor air through the absorber/ICD and outdoor air through regenerator/OCD
• Optional duct mounting of absorber/ICD and regenerator/OCD
37. An absorber/ICD claimed in claims 1 , 36 is coupled with an evaporator of VCRS
38. An absorber/ICD claimed in claims 1 , 36 is an adiabatic contacting device with a separate heat exchanger to cool the LD
39. An absorber/ICD and/or regenerator/OCD claimed in claims 1 , 36 incorporates large surface density rotating contacting disc assembly as the contacting media between air and LD
40. An absorber/ICD and/or regenerator/OCD claimed in claims 1 , 36-39, wherein the rotating disc is a mesh, plain /roughened surface or porous material and their like constructed of materials such as a plastic or any other suitable material, which is compatible with LD and air
41. An absorber/ICD and/or regenerator/OCD claimed in claims 1 , 36-40, wherein the contacting disc assembly is partially submerged in the LD
42. A contacting disc assembly absorber/ICD and regenerator/OCD as claimed in 1 , 39 - 41 is rotated at low rpm in the LD, preferably at around 3 to 5 rpm or oscillated to an angle greater than 30° in either direction
43. A contacting disc assembly in the absorber/ICD and/or regenerator/OCD claimed in claims 1 , 36-42 is mounted in a trough or any suitable container constructed of thermal conducting material
44. A contacting disc assembly in the absorber/ICD and/or regenerator/OCD claimed in claims 1 , 36-42 is mounted in a trough or any suitable container constructed of non conducting material with wall thickness of < 0.2 mm and to withstand the pressure of the heat transfer fluid 45. An absorber/ICD and/or regenerator/OCD claimed in claimsl , 36, optionally incorporates
SCD as the contacting media between the LD and air
46. A SCD in the absorber/ICD and/or regenerator/OCD claimed in claims 1 , 36 and 45, is a mesh, plain /roughened surface or porous material and their like constructed of material such as plastic or any other suitable material which is compatible with LD and air
47. A SCD in the absorber/ICD and/or regenerator/OCD claimed in claims 1 , 45 - 46, is partially submerged in the LD
48. A SCD in the absorber/ICD and/or regenerator/OCD claimed in claims 1 , 45 -47 is rotated at low rpm in the LD, preferably at around 3 to 5 rpm or oscillated to an angle greater than 30° in either direction
49. A SCD in the absorber/ICD and/or regenerator/OCD claimed in claims 1 , 36, 45-48 is mounted in a trough or any suitable container without passages
50. A trough claimed in claims 1 , 49 constructed of conducting /non conducting material without limitation of wall thickness
51. An absorber/ ICD claimed in claims 1 , 36, consists of passages wherein the evaporation of the refrigerant takes place, are in thermal contact with the trough of absorber/ ICD
52. Passages of the absorber/ ICD claimed in claims 1 , 51 are inside or outside or integrated into the trough of absorber/ICD
53. Passages of the absorber/ ICD claimed in claimsl , 51 and 52, wherein the chilled fluid is flowing through the passages instead of evaporating the refrigerant
54. A regenerator/ OCD claimed in claims 1 , 36, consists of the passages wherein the condensation of the refrigerant takes place, are in thermal contact with the trough of the regenerator/ OCD
55. Passages of the regenerator/ OCD claimed in claims 1 , 54 is inside or outside or integrated into the trough of the regenerator/ OCD
56. Passages of the regenerator/ OCD claimed in claims 1 , 54 and 55, where in a hot fluid is flowing through the passages instead of condensing refrigerant
57. The circulating device in the absorber/ICD and/or regenerator as claimed in claims 1 , 36, is forced/induced draft fan
58. The liquid-liquid heat exchanger claimed in claims 1 , 36, is made of alternate material such as plastic or any other suitable material compatible with LD 59. A regenerator/OCD claimed in claims 1 , 36, is coupled with a condenser of conventional
VCRS
60. A regenerator/OCD claimed in claims 1 , 36, is an adiabatic contacting device with a separate heat exchanger to heat the LD
61. The optional device as claimed in claims 1 , 36, to circulate air through the regenerator/OCD is a chimney
62. A hybrid cooling system as claimed in claims 1 , 36, wherein the elevation difference between the regenerator/OCD and the absorber/ICD is not sufficient, two LD pumps are used to pump the LD, one from the absorber/ICD to regenerator/OCD and the other from the regenerator/OCD to absorber/ICD
63. A hybrid cooling system as claimed in claims 1 , 36, wherein the regenerator/OCD is placed at higher elevation than the absorber/ICD with the LD flowing from regenerator/OCD to absorber/ICD by gravity
64. A hybrid cooling system as claimed in claims 1 , 36, wherein the regenerator/OCD is at a higher elevation than the absorber/ICD, one LD pump is used to pump the LD from the absorber/ICD to regenerator/OCD
65. A hybrid cooling system as claimed in claims 1 , 36, wherein the absorber/ICD is placed at higher elevation than the regenerator/OCD with LD flowing from absorber/ICD to regenerator/OCD by gravity
66. A hybrid cooling system as in claims 1 , 36, wherein the absorber/ICD is at a higher elevation than the regenerator/OCD, one LD pump is used to pump the LD from the absorber/ICD to regenerator/OCD
67. A hybrid cooling system as in claims 1 , 36-66, wherein the said VCRS is replaced by Vapour Absorption/Adsorption System
68. Hybrid cooling system as claimed in claims 1 , 36-67, wherein • the pressure ratio across the compressor is reduced up to 36%
• cooling effect produced is increased up to 60%
• COP increased up to 45% as compared to VCRS for air conditioning and refrigeration applications involving cooling and/or dehumidification/drying
PCT/IN2003/000028 2002-02-19 2003-02-19 Energy efficient liquid desiccent regeneration WO2003070356A2 (en)

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EP2502667A1 (en) * 2011-03-23 2012-09-26 Siemens Aktiengesellschaft Hydrogen-cooled generator with continuous gas drying
CN104819526A (en) * 2015-05-27 2015-08-05 青岛大学 Energy-saving type freeze deep dehumidification air processing device
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CN113834303A (en) * 2021-09-18 2021-12-24 湖南芷江正向科技有限公司 High-temperature baking device for electronic components and use method thereof

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Publication number Priority date Publication date Assignee Title
WO2004111557A1 (en) * 2003-06-12 2004-12-23 Rane Milind V Multiutility vapor compression system
EP2502667A1 (en) * 2011-03-23 2012-09-26 Siemens Aktiengesellschaft Hydrogen-cooled generator with continuous gas drying
CN104819526A (en) * 2015-05-27 2015-08-05 青岛大学 Energy-saving type freeze deep dehumidification air processing device
CN104819526B (en) * 2015-05-27 2018-08-17 青岛大学 A kind of energy-saving freezing depth dehumidified air processing unit
CN107170338A (en) * 2017-07-18 2017-09-15 天津商业大学 A kind of salting liquid boiling performance test experimental bed based under vacuum
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WO2020113257A1 (en) * 2018-12-06 2020-06-11 Intex Holdings Pty Ltd An apparatus for removing water from a fluid
EP3891440A4 (en) * 2018-12-06 2022-08-17 Intex Holdings Pty Ltd An apparatus for removing water from a fluid
RU199446U1 (en) * 2020-04-28 2020-09-01 Валерий Михайлович Тарабанов Air conditioning device
CN113834303A (en) * 2021-09-18 2021-12-24 湖南芷江正向科技有限公司 High-temperature baking device for electronic components and use method thereof

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EP1478450A2 (en) 2004-11-24
AU2003223102A1 (en) 2003-09-09
WO2003070356A9 (en) 2004-03-18
WO2003070356A3 (en) 2004-02-12

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