WO1995029369A1 - Systemes et procedes destines a reduire au minimum la decomposition d'un additif de transfert thermique dans un generateur de compresseur frigorifique a absorption - Google Patents

Systemes et procedes destines a reduire au minimum la decomposition d'un additif de transfert thermique dans un generateur de compresseur frigorifique a absorption Download PDF

Info

Publication number
WO1995029369A1
WO1995029369A1 PCT/US1995/004835 US9504835W WO9529369A1 WO 1995029369 A1 WO1995029369 A1 WO 1995029369A1 US 9504835 W US9504835 W US 9504835W WO 9529369 A1 WO9529369 A1 WO 9529369A1
Authority
WO
WIPO (PCT)
Prior art keywords
fluid
heat
transfer additive
generator
refrigerant
Prior art date
Application number
PCT/US1995/004835
Other languages
English (en)
Inventor
Wendell J. Biermann
Original Assignee
York International Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by York International Corporation filed Critical York International Corporation
Priority to AU23587/95A priority Critical patent/AU2358795A/en
Publication of WO1995029369A1 publication Critical patent/WO1995029369A1/fr

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B15/00—Sorption machines, plants or systems, operating continuously, e.g. absorption type
    • F25B15/02—Sorption machines, plants or systems, operating continuously, e.g. absorption type without inert gas
    • F25B15/06—Sorption machines, plants or systems, operating continuously, e.g. absorption type without inert gas the refrigerant being water vapour evaporated from a salt solution, e.g. lithium bromide
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K5/00—Heat-transfer, heat-exchange or heat-storage materials, e.g. refrigerants; Materials for the production of heat or cold by chemical reactions other than by combustion
    • C09K5/02—Materials undergoing a change of physical state when used
    • C09K5/04—Materials undergoing a change of physical state when used the change of state being from liquid to vapour or vice versa
    • C09K5/047—Materials undergoing a change of physical state when used the change of state being from liquid to vapour or vice versa for absorption-type refrigeration systems
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B15/00—Sorption machines, plants or systems, operating continuously, e.g. absorption type
    • F25B15/008—Sorption machines, plants or systems, operating continuously, e.g. absorption type with multi-stage operation
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A30/00—Adapting or protecting infrastructure or their operation
    • Y02A30/27—Relating to heating, ventilation or air conditioning [HVAC] technologies
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B30/00—Energy efficient heating, ventilation or air conditioning [HVAC]
    • Y02B30/62—Absorption based systems
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/10—Process efficiency

Definitions

  • the present invention relates to devices employing an absorption cycle, such as absorption-type chillers.
  • the present invention relates to absorption-type chillers using a refrigerant, an absorbent, and a heat-transfer additive.
  • Absorption-type chillers typically include an absorber, one or more pumps, one or more generators, a condenser, an evaporator, and necessary piping and controls. Their operation can be briefly explained in reference to an absorption cycle using a single generator.
  • a fluid called a "weak fluid” because it is relatively weak in absorbent, is contained in the absorber. The pressure of the weak fluid is raised to the generator pressure by a pump.
  • refrigerant vapor is driven out of the weak fluid.
  • the refrigerant is then condensed in the condenser and passes to the evaporator.
  • the chilling effect is realized in the evaporator where ambient heat is absorbed by vaporizing the refrigerant.
  • Another fluid called the "strong fluid” in the sense that it is relatively strong in absorbent, is returned from the generator to the absorber.
  • Refrigerant vapor leaving the evaporator is exposed in the absorber to the strong fluid from the generator. By the removal of heat, the refrigerant is absorbed by the strong fluid, transferring heat to the coolant, and producing a liquid stronger in the refrigerant.
  • a "weak fluid” contains approximately 56-60 weight percent lithium bromide and a "strong fluid” contains approximately 59-65 weight percent lithium bromide, the exact values depending upon operating temperatures and the design of the cycle.
  • additives results in improved performance of absorption-type chillers.
  • addition of octyl alcohol (2- ethyl 1-hexanol) to an aqueous lithium bromide fluid improves the performance of absorption-type chillers using such a fluid.
  • heat-transfer additives The major beneficial effect of the additive is realized in the absorber where it improves the rate of heat-transfer.
  • heat-transfer additives also have a beneficial effect in the condenser where the heat exchange is also improved.
  • the operating temperature of the generator may be above the thermal degradation temperature of the heat-transfer additive. Accordingly, there is interest in removing heat- transfer additives from a fluid before they enter the generator.
  • U.S. Patent No. 4,315,411 describes a separator for separating a part of the heat-transfer additive from the fluid.
  • the separator is disclosed as being at a point where the weak fluid exits the absorber.
  • the disclosed separator operates on gravity separation. It is described as including a vessel large enough for slowing down the flow velocity of the fluid.
  • the vessel is described as including an inlet at its lower part and an outlet at its upper part. A small part of the fluid, substantially enriched in heat-transfer additive, flows out of the outlet at its upper part while the bulk of the fluid, weak in heat- transfer additive, flows out of the outlet at its lower part.
  • the present invention provides improved systems and methods for selectively removing a heat- transfer additive from a fluid in an absorption-type chiller.
  • the methods and systems of the present invention can be employed in-line and operate quickly to allow them to perform at their rated capacity.
  • the methods and systems of the present invention can be configured to ensure that heat- transfer additive is removed before it reaches portions of the cycle having operating temperatures above its temperature of thermal decomposition.
  • a heat-transfer additive is used in combination with an absorbent and a refrigerant.
  • the heat-transfer additive has a specific gravity differing from that of the absorbent and the refrigerant.
  • Such an absorption-type chiller comprises an absorber in which a fluid containing absorbent and heat-transfer additive absorbs refrigerant vapor to form a fluid containing absorbent, refrigerant and heat-transfer additive.
  • a centrifugal separator is placed in fluid communication with the absorber and is capable of separating the weak fluid into a heat-transfer additive depleted fluid and a heat-transfer additive enriched fluid.
  • Means are provided for feeding the heat-transfer additive enriched fluid to the absorber and for feeding the heat-transfer additive depleted fluid to one or more generators.
  • the one or more generators are capable of evaporating the refrigerant from the heat-transfer additive depleted fluid to form a strong fluid and condensing the evaporated refrigerant to form a refrigerant liquid.
  • An evaporator is provided in fluid communication with at least one condenser within a generator for placing a coolant in a heat exchange relationship with the refrigerant liquid to cool the coolant and form refrigerant vapor.
  • the evaporator is in vapor communication with the absorber.
  • the absorption-type chiller of the present invention may also include a pump for increasing the pressure of the weak fluid to generator pressure.
  • the absorption-type chiller of the present invention may also include at least one dual channel heat exchanger positioned between the centrifugal separator and the one or more generators whereby the heat-transfer additive depleted fluid flows through one channel of the heat exchanger and is heated by the strong fluid from at least one of the one or more generators flowing through the other channel to the heat exchange means.
  • the one or more generators would likely include one or more high-temperature generators having an operating temperature above the thermal decomposition temperature of the heat-transfer additive.
  • the centrifugal separator separating the weak fluid into a heat-transfer additive depleted fluid and a heat-transfer additive enriched fluid is preferably located at least before the weak fluid enters the one or more high-temperature generators.
  • FIGURE 1 is a schematic view, not according to scale, of a single-effect absorption-type chiller in accordance with the present invention.
  • FIGURE 2 is a schematic view, not according to scale, of a triple effect absorption-type chiller in accordance with the present invention.
  • An absorption-type chiller in accordance with the present invention includes an absorber, such as absorber 10 shown in Figs. 1 and 2, in which a fluid containing absorbent and heat-transfer additive absorbs refrigerant vapor to form a weak fluid containing absorbent, refrigerant and heat- transfer additive.
  • the refrigerant used in an absorption-type chiller in accordance with the present invention is water and the absorbent is lithium bromide solution.
  • the heat-transfer additive used in the absorption-type chiller in accordance with the present invention is octyl alcohol (2-ethyl 1-hexanol) , in particular where the refrigerant is water and the absorbent is lithium bromide solution.
  • the octyl alcohol and the water-lithium bromide solution form a mixture or suspension.
  • the invention can be applied to systems and methods utilizing other types of absorbents, refrigerants, and heat- transfer additives.
  • heat-transfer additives to the fluid including refrigerant and absorbent results in improved performance of absorption-type chillers.
  • addition of octyl alcohol to a fluid including lithium bromide and water improves the performance of absorption-type chillers using such a fluid.
  • Other organic heat-transfer additives suitable for use with aqueous lithium bromide, including 1-amino nonane, are known or would be obvious to persons of ordinary skill in the art, once the principles and scope of the invention disclosed herein are understood.
  • heat-transfer additives may be preferred.
  • nitrobenzene may be used as a heat-transfer additive.
  • 1- octanol for example, may be used as a heat-transfer additive.
  • absorbents for fluids in which water is the refrigerant include combinations of sodium and potassium hydroxide or combinations of lithium, zinc and calcium bromides.
  • suitable heat-transfer additives in systems using these fluids would also be desirable.
  • 2-ethyl 1-hexanol operates in combination with these fluids as a heat-transfer additive, but not as well as with an aqueous lithium bromide-containing fluid.
  • the present invention finds application for all combinations of refrigerants, absorbents, and heat-transfer additives, in which the heat-transfer additive does not dissolve in the refrigerant-absorbent solution, but instead is suspended within that solution.
  • a fluid may contain more than two components that make up the refrigerant-absorbent solution.
  • the absorbent added to the water (or other refrigerant) may comprise two or more components.
  • other additives such as corrosion inhibitors, may be present in the fluid.
  • the present invention is applicable to a wide variety of such fluids.
  • the cooling capacity increases. This is because the heat-transfer additive increases the absorber film heat transfer coefficient by a significant factor.
  • the heat transfer coefficient increases from about 70-80 Btu/ ft 2 - o F_ r to about 250 Btu/ft 2 -°F-hr.
  • “subcooling” is a measure of the deviation of actual operating conditions from the desired equilibrium conditions.
  • the fluid containing absorbent, refrigerant and heat-transfer additive passes through the absorber, there is a point at which it has absorbed the maximum amount of refrigerant possible. At that point, the fluid is "at equilibrium” with the refrigerant vapor in the absorber. Under normal operating conditions, however, the fluid does not stay in the absorber long enough for equilibrium to be reached. Accordingly, the degree of cooling that is theoretically possible is not achieved.
  • concentration of the weak fluid leaving the absorber is "stronger” than is calculated from vapor pressure-temperature diagrams.
  • a measure of the failure to reach desirable equilibrium situation is the "subcooling" .
  • Subcooling of 0° would correspond to equilibrium, and larger numbers for subcooling are measures of increasingly deficient absorption which takes place.
  • a large subcooling indicates that the machine capacity will be low. This is because no more refrigerant can be evaporated than can be absorbed.
  • a large subcooling may also indicate that the generator temperature will be increased as the machine attempts to maintain the desired capacity by increasing the concentration of the strong fluid as compensation for the weak fluid leaving the absorber being "stronger" than would be the case if the subcooling were 0°.
  • subcooling in a system employing water as the refrigerant, lithium bromide as the absorbent, and 2-ethyl 1-hexanol as the heat-transfer additive, subcooling may be reduced from a typical 25°F to about 1°F.
  • the quantities of the heat-transfer additive used are comparatively small.
  • a quantity of about 0.5 to 1.0 liters of 2-ethyl 1-hexanol is sufficient.
  • heat-transfer additive results in the agitation of surface films of the lithium bromide fluid on the heat-exchange tubes. Such agitation provides a better heat exchange than steady state films of such fluids on the tubes. Physically, a rather quiescent, glassy film of lithium bromide fluid is present and flowing over absorber tubes when no heat-transfer additive is present. When the heat-transfer additive is present, the film is highly agitated, usually attributable to surface tension gradients. This agitation promotes more rapid mixing, which itself promotes both mass transfer (of vapor into the absorbent fluid) and heat transfer (bringing the surface film, which has been warmed by heat of absorption, to the cold surface of the underlying heat transfer tubes) .
  • the heat-transfer additive may be thought of as analogous to a chemical "catalyst," a substance which speeds up a chemical process without itself being permanently altered.
  • the major beneficial effect of the heat-transfer additive is in the absorber where it improves the rate of heat transfer.
  • the heat-transfer additive also has a beneficial effect in the condenser where the heat exchange is also improved.
  • the heat-transfer additives may decompose. Such very hot portions exist typically in multiple effect absorption-type chillers where one or more of the generators have operating temperatures higher than the thermal decomposition temperature of the heat-transfer additive.
  • the heat-transfer additive preferably has a specific gravity differing from that of the solution of the absorbent and the refrigerant. Most preferably, the difference in specific gravities of the absorbent and refrigerant solution on the one hand and the heat-transfer additive on the other hand should be sufficient to ensure the adequate separation of the heat-transfer additive in a system or method in accordance with the present invention.
  • the specific gravity of a lithium bromide and water solution is typically 1.5 to 1.6, whereas
  • 2-ethyl 1-hexanol has a specific gravity of about 0.8.
  • the heat transfer additive used in the present invention is insoluble in the fluid containing the refrigerant and the absorbent. In this way, the heat transfer additive forms a second phase with recognizable geometric boundaries between it and the fluid containing the refrigerant and the absorbent.
  • a fluid including absorbent and heat-transfer additive absorbs refrigerant vapor to form a weak fluid containing absorbent, refrigerant and heat-transfer additive.
  • Heat transfer additive may be applied to absorber 10 through, for example, service valves, which are well known in the art.
  • service valves are generally provided for evacuation of absorber 10, withdrawing purge gases, sampling, and adding liquids.
  • service valves are located at or in the vicinity of an outlet 12, at the suction side of a pump 16.
  • Absorber 10 includes an outlet 12 located substantially at its bottom, through which the resultant weak fluid can exit.
  • a pump is preferably provided for increasing the pressure of the weak fluid 21 exiting from the absorber.
  • outlet 12 is in fluid communication through pipe 14 to pump 16.
  • Pump 16 is driven by conventional means, for example, by an electric motor 17 operating through a shaft 19, to increase the pressure of the weak fluid 21 that includes the heat-transfer additive.
  • a centrifugal separator is provided to separate the weak fluid into a heat-transfer additive depleted fluid and a heat- transfer additive enriched fluid.
  • a pipe 18 is provided to place the weak fluid, including the heat-transfer additive, in fluid communication from pump 16 to a centrifugal separator 20.
  • the centrifugal separator is of the spinning disc type, such as, for example, those disclosed in U.S. Patent No. 4,521,313 or U.S. Patent No. 5,084,189.
  • the present invention is not limited, however, to any particular type of centrifugal separator.
  • any type of centrifugal separator or other type of mechanical separator capable of separating heat-transfer additive from a weak fluid as described herein is suitable.
  • Centrifugal separator 20 may be driven, for example, by a motor 22 connected to it through a shaft 24.
  • the centrifugal separator 20 is preferably positioned on the pressure side of the pump 16 because, in the preferred system, such positioning reduces the volume of fluid that must be separated by the centrifugal separator 20.
  • only a portion of the fluid output by pump 16 is supplied to a generator and, thus, only that portion of the fluid requires additive separation.
  • the remaining fluid which is not supplied to a generator, does not require additive separation.
  • a portion of the remaining fluid is supplied to the absorber 10 to wet tube bundle 52.
  • a pipe 15 is provided to place the weak fluid in fluid communication from pump 16 to pipe 34 and spray header 54. Another portion of the remaining fluid actuates a purge system for removing non-condensable gases from absorber 10.
  • a pipe 23 is provided to place the weak fluid in fluid communication from pump 16 to a conventional purge system 25.
  • Exemplary purge systems are shown in U.S. Patent No. 3,138,005 and U.S. Patent No. 3,367,134, the disclosures of which are incorporated herein by reference.
  • the centrifugal separator 20 accepts the weak fluid including refrigerant, absorbent and heat-transfer additive and separates that fluid into two departing streams: a heat-transfer additive enriched fluid that exits into pipe 26 and a heat-transfer additive depleted fluid that exits into pipe 30.
  • the high-pressure fluid is introduced into the separator 20 at a pressure of at least about 1 psia.
  • a first flow path is provided for returning the heat-transfer additive enriched fluid to the absorber.
  • the flow path may be embodied as pipes 26 and 34 and spray header 54.
  • pipe 26 through which the heat-transfer additive enriched fluid passes, intersects pipe 34, through which absorbent, such as lithium bromide solution, passes.
  • absorbent such as lithium bromide solution
  • the heat-transfer additive enriched fluid passing through pipe 26 (referred to herein also as "separated additive”) will likely be suspended in an amount of a weak lithium bromide-containing fluid.
  • the separated additive is injected into pipe 34, through which the strong fluid passes, and then to spray header 54 in absorber 10. In this way, the volume of fluid flowing through spray header 54 can be increased, enabling complete wetting of tube bundle 52 to take place.
  • the separated heat-transfer additive flowing through pipe 26 may be fed directly into a common enclosure 58 which contains, inter alia, absorber 10, using a separate entry point without actually intersecting pipe 34. This may be done, for example, through pipe 26', shown in dashed line, which terminates in a spray header 27 above the tube bundle 52 without interconnecting with the strong fluid flow contained in pipe 34.
  • the separated heat transfer additive could be fed to any part of the absorber 10, and the systems and methods of the present invention would still remain functional. Routing the additive through spray headers 54 or 27 is presently preferred, however, because they place the additive directly onto the tube bundle 52 where it performs its function.
  • a second flow path is provided for feeding the heat-transfer additive depleted fluid to one or more generators. It should be understood that the present invention is applicable to systems using one generator (a single effect system) or to systems using multiple generators (multiple effect systems) .
  • FIG. 1 A single effect system is shown in Fig. 1 and described in reference to that figure.
  • FIG. 2 A multiple effect system, specifically a triple effect system, is shown in Fig. 2 and described in reference to that figure.
  • Fig. 1 shows a single effect system employing a single generator 28.
  • generator 28 external heat is supplied to separate refrigerant from absorbent. This separation is accomplished by heating the fluid containing refrigerant and absorbent sufficiently to evaporate the refrigerant.
  • the means for feeding the heat-transfer additive depleted fluid to generator 28 may be embodied as a pipe 30 which enters, then exits, heat exchanger 32 (the purpose of which is explained below) and then enters generator 28.
  • a heat exchanger 32 is included between centrifugal separator 20 and 'generator 28.
  • the heat-transfer additive depleted fluid passing through pipe 30 is placed in heat exchange relationship with a strong fluid fed from generator 28 to absorber 10 through heat exchanger 32.
  • the strong fluid preferably flows through a pipe 34 that enters and exits the heat exchanger 32.
  • the heat-transfer additive depleted fluid is pre-heated prior to entering generator 28. Less heat needs to be added to the weak fluid (the heat-transfer additive depleted fluid) in generator 28, therefore, to evaporate the refrigerant.
  • refrigerant is evaporated from the weak fluid and then condensed to form a refrigerant liquid.
  • the evaporation of refrigerant is accomplished when the weak fluid is sufficiently heated by heat exchanger coil 36.
  • a burner 37 which operates, for example, on a hydrocarbon fuel such as natural gas or oil, is used to provide a stream of hot fluid which is in a heat exchange relationship through heat exchanger coil 36 with the weak fluid that has been conveyed into the housing of generator 28.
  • the heat exchanger coil 36 could be heated by a direct fire in the coil, which is conventional in the art, or by other means known to a person skilled in the art.
  • the external heating of the refrigerant-containing fluid in generator 28 is sufficient to effect the evaporation (or boiling-off) of the refrigerant from the absorbent liquid to concentrate the absorbent in a base portion or bottom of generator 28.
  • a further heat exchanger 38 is provided, preferably in the upper portion of generator 28, to condense the evaporated refrigerant into a condenser receptacle 40 to form a refrigerant liquid.
  • Heat exchanger 38 and heat exchanger coil 52 are preferably interconnected to each other and to a source of cooling liquid, for example, a cooling tower 63.
  • the preferred cooling liquid is non- scaling, noncorrosive water below 95°F. While water from a pond, river, well or ocean may be used as a cooling liquid, water from a cooling tower is preferred due to better control of temperature and quality of the cooling liquid.
  • refrigerant liquid from the condenser receptacle 40 passes through pipe 42 to an eductor 44 and then through a header 47 in an evaporator 46.
  • the pressure of the refrigerant liquid in condenser receptacle 40 is not high enough to properly spray the refrigerant liquid through nozzle 47.
  • the returning condensate is therefore "pumped", via the eductor 44, by the high pressure, recycled, refrigerant issuing from the refrigerant pump 57. Flashing also assists in distributing the refrigerant over the evaporator coil 48.
  • recirculation via pump 57 is desirable to ensure that the volume of liquid refrigerant is sufficient to wet the surface of evaporator coil 48.
  • the evaporation of the liquid refrigerant sprayed onto evaporator coil 48 cools a coolant fluid passing through it to a temperature of about 3.3 to 8.9°C (38 to 48°F) , depending upon the load requirements.
  • the cooling effect can be extracted from the evaporator by employing a coil in a heat exchange relationship with a suitable work load envisioned for the xefrigeration device as generally indicated by the load 49.
  • the coolant fluid (preferably water or water plus antifreeze) carries heat from the load into the evaporator, where the heat is absorbed by vaporizing refrigerant.
  • chilled coolant fluid (typically 44 to 55°F) is pumped by pump 69 to load 49 where it absorbs heat by increasing its temperature to, typically, 54 to 65°F.
  • the warmed coolant fluid returns to evaporator coil 48 via pipe 67 whereupon it is again chilled by transferring the heat it picked up from the load to the refrigerant, which evaporates in sufficient amount so that the latent heat of vaporization equals the amount of heat transferred from load 49.
  • Any liquid refrigerant that remains in evaporator 46 is preferably directed through an outlet 55 to a pump 57 which can pump the refrigerant through pipe 51 to eductor 44.
  • Pump 57 is preferably driven by a motor 54 through a shaft 56.
  • the liquid refrigerant passes, as described above, from eductor 44 to evaporator 46 where it is directed by a header 47 onto evaporator coil 48. This recirculation of refrigerant liquid within evaporator 46 by pump 57 enhances the evaporation of the refrigerant in evaporator 46.
  • Evaporator 46 and absorber 10 are preferably contained within a common enclosure 58 and separated by a separation wall 60 projecting into enclosure 58.
  • the combined separated additive and absorbent may then be sprayed onto a heat exchanger coil 52 through header 54.
  • Refrigerant vapor in the evaporator 46 flows into the absorber 10 section of the housing 58 through an opening 61 in separation wall 60 which separates the evaporator 46 from the absorber 10.
  • This refrigerant vapor is then absorbed by the concentrated absorbent liquid contained in the absorber 10 so as to dilute or weaken the absorbent fluid.
  • the pressure within the evaporator-absorber shell 58 is the vapor pressure of water at the temperature of the water in evaporator 46, typically about 0.1 psia.
  • the refrigerant vapor is brought into contact with the strong fluid that is sprayed by spray header 54 over the heat exchanger coil 52.
  • the strong fluid preferably is mixed with heat-transfer additive enriched fluid introduced into pipe 34 or sprayed by spray header 27. This strong fluid absorbs refrigerant vapor causing a decrease in lithium bromide concentration and the liberation of heat.
  • the heat-transfer additive greatly speeds up the process of vapor transfer to the strong solution.
  • the liberated heat is transferred to a cool liquid such as, for example, water, provided by a cooling tower 63.
  • the cool liquid is circulated via pipe 65 through the heat exchanger coil 52.
  • Pipe 65 is provided with a suitable circulation pump 69 which is also used to circulate the coolant from the cooling tower 63 through condenser 38.
  • the heat-transfer additive greatly speeds up the process of heat transfer from the fluid to the cool liquid.
  • Typical operating parameters for a single-effect absorption-type chiller in accordance with the present invention have been calculated.
  • the calculated operating parameters that follow are for an absorption-type chiller in which lithium bromide is used as an absorbent, water is used as a refrigerant, and 2-ethyl 1-hexanol is used as a heat- transfer additive.
  • the specific gravity of a lithium bromide-water solution is 1.5 to 1.6, whereas the 2-ethyl 1-hexanol heat- transfer additive has a specific gravity of about 0.8.
  • the weak fluid of refrigerant, absorbent, and heat-transfer additive flows from pump 16 at a mass flow rate of 863 lb/min.
  • Centrifugal separator 20 embodied as described above, may separate most if not all of the heat-transfer additive from the weak fluid.
  • the fluid contains 61.4% lithium bromide, is at 116°F, and has a mass flow rate of 863 lb/min.
  • the mass flow rate of heat-transfer additive through pipe 30 has been calculated as 0.01 lb/min and the mass flow rate of heat- transfer additive in pipe 26 as 0.30 lb/min.
  • the strong fluid flowing from generator 28 through pipe 34 in this example contains 65.4% lithium bromide, exits at a temperature of approximately 214°F, and has a mass flow rate of 815 lb/min.
  • the strong fluid flowing from generator 28 contains substantially no heat-transfer additive.
  • the temperature of the strong fluid in pipe 34 exiting heat exchanger 32 is, in this example, 144°F.
  • water flowing through evaporator coil 48 flows at a volume flow rate of 575 gallons/min.
  • the temperature of the water entering evaporator coil 48 is, in this example, 55°F and the temperature of the chilled water leaving the evaporator coil 48 is 45°F.
  • condensing water flows through the absorber cooling coil 52 at a volume flow rate of 1300 gallons/min. and enters the absorber cooling coil 52 at 85°F. As shown in Fig. 1, the water subsequently flows through condensing heat exchanger 38 where it exits at 97°F.
  • An increase in thermal efficiency or the coefficient of performance (COP) of absorption-type refrigeration systems is provided by multiple effect systems in which two or more generators are coupled to the absorber. Examples of such systems are dual effect systems (including two generators) and triple effect systems (including three generators) .
  • triple effect systems systems using three generators (triple effect systems) be employed. Such systems provide the optimum combination of coefficient of performance and cost of design and manufacture.
  • the embodiments of the present invention described herein should not be interpreted to limit the present invention to single or triple effect systems. Nor should the present invention be limited to the arrangements of the particular triple effect systems described herein.
  • the present invention is particularly applicable to triple effect systems due to the high temperature experienced in the high-temperature generator or generators which may exceed the thermal decomposition temperature of heat-transfer additives. Such high temperatures necessitate the removal of a heat-transfer additive from a fluid prior to its entering a high-temperature generator.
  • FIG. 2 An embodiment of a triple-effect absorption refrigeration system of the present invention is shown generally in Fig. 2. The description of those elements having common reference numerals are the same for the embodiment of Fig. 2 as for Fig. 1 and are incorporated here in the description of the embodiment of Fig. 2.
  • a triple effect absorption refrigeration system of the present invention shown Fig. 2 comprises, for example, a high temperature or third generator 70, a medium temperature or second generator 72, and a low temperature or first generator 74 which are coupled to absorber 10 for receiving a stream of a weak fluid therefrom.
  • the weak fluid is discharged from the base of the absorber 10, and the heat- transfer additive depleted fluid from centrifugal separator 20 is circulated through the generators 70, 72, and 74 to provide for the vaporization and removal of the refrigerant from the absorbent and the return of the concentrated absorbent liquid to the absorber 10.
  • the circulation of the weak fluid from absorber 10 may be achieved in many ways, including through a series flow or parallel flow arrangement, with the use of a parallel flow circulating system being preferred in the triple-effect double-condenser coupled absorption refrigeration system of the present invention.
  • FIG. 2 A parallel flow circuit for the distribution of the refrigerant-containing fluid from the absorber 10 to the generators 70, 72, and 74 and the return of the concentrated absorbent liquid from the generator is shown in FIG. 2.
  • This parallel flow circuit comprises a pipe 18 which conveys the refrigerant-containing fluid discharged from the base of absorber 10 through a suitable pump 16 to the centrifugal separator 20 and out through pipe 30.
  • This pipe 30 is intersected at locations between absorber 10 and third generator 70 by pipes 90, 92, and 93 which are respectively coupled to first generator 74, second generator 72, and third generator 70.
  • the concentrated absorbent liquid produced in third, second, and first generators, 70, 72, and 74, respectively, is ultimately returned to absorber 10 through pipe 34 to spray header 54 within absorber 10.
  • Heat exchangers 32, 94, and 96 may be provided so that heat can be transferred from the concentrated absorbent liquid discharged from the generators to the weak fluid entering the generators.
  • weak fluid from separator 20 is heated in heat exchanger 32 by the strong fluid from first generator 74 passing through pipe 34, combined with strong fluid from third generator 70 and second generator 72 passing through pipe 100.
  • the weak fluid is further heated in heat exchanger 94 by the strong fluid from second generator 72 passing through pipe 102, combined with the strong fluid from third generator 70 passing through pipe 100.
  • the weak fluid may be still further heated in heat exchanger 96 by the strong fluid from third generator 70 passing through pipe 100.
  • Heat exchangers 32, 94, and 96 decrease the extent of fluid heating required for the vaporization of the refrigerant in the generators and the extent of cooling of the concentrated absorbent liquid entering absorber 10, thereby increasing the overall thermal efficiency of the system.
  • third generator 70 is shown as including a shell or housing.
  • a burner 37 which operates on a hydrocarbon fuel, such as natural gas or oil, is used to provide a stream of hot fluid which is in heat exchange relationship through heat exchange coils 76 with the weak refrigerant-containing fluid conveyed into the housing of third generator.
  • the heat exchanger coil 36 could be heated by a direct fire in the coil, which is conventional in the art, or by other means known to a person skilled in the art.
  • the external heating of the weak fluid is sufficient to effect the vaporization (or boiling off) of the refrigerant from the absorbent liquid to concentrate the latter in the base portion of third generator 70.
  • the external heating of the refrigerant-containing fluid in third generator 70 considered sufficient is provided by heating the weak fluid to a temperature in the range of about 360°-500°F., with about 425°F. being a typical temperature realized and 500°F. being a preferred temperature.
  • a temperature in the range of about 360°-500°F. with about 425°F. being a typical temperature realized and 500°F. being a preferred temperature.
  • corrosion problems may occur so as to necessitate the use of corrosion resistant materials such as monel in the fabrication of the high temperature components.
  • decomposition of heat-transfer additive may occur at such temperatures (generally above 400°F where 2-ethyl 1-hexanol is employed as the heat- transfer additive) decomposition of heat-transfer additive may occur. In such instances it is necessary to ensure the heat-transfer additive does not reach the third generator 70.
  • a centrifugal separator 20 is employed, as described in reference to Fig. 1, to remove heat-transfer additive at least prior to its
  • centrifugal separator 20 may be located after second generator 72. That is, centrifugal separator 20 may be located along pipe 30 at a point downstream of the point where pipe 92 intersects pipe 30.
  • centrifugal separator 20 may be located after first generator 74. That is, centrifugal separator 20 may be located along pipe 30 at a point downstream of the point where pipe 90 intersects pipe 30, but before the point where pipe 92 intersects pipe 30.
  • the vaporous refrigerant resulting from the vaporization of the weak fluid in the high temperature third generator 70 flows through pipe 82 into a coiled portion of the pipe defining a condenser 78 contained within the housing of second generator 72.
  • the heat of condensation rejected from the condensing refrigerant vapor in condenser 78 is transferred to the weak refrigerant-containing fluid within the second generator 72 for vaporizing the refrigerant contained therein.
  • the hot condensate or liquid refrigerant resulting from the condensation of the refrigerant vapor in the condenser 78 is preferably at a temperature in the range of about 300°-360°F and is conveyed through pipe 84 to a pipe 86.
  • the hot refrigerant vapor from the second generator 72 is passed through pipe 86 into a second condenser 36 which is contained within first generator 74.
  • the weak fluid in the first generator 74 is heated to a temperature in the range of preferably about 180°-210°F which is sufficient to boil-off the refrigerant.
  • the condensed refrigerant from the condenser 36 flows through pipe 88 to pipe 42 where it is combined with the refrigerant liquid from the evaporator container 40 for delivery into the evaporator 46 through the spray header 47.
  • the evaporation of the liquid refrigerant sprayed through spray header 47 into evaporator 46 and onto evaporator coils 48 provides for cooling the refrigerant to a temperature of preferably about 35°-50°F, the cooling effect of which can be extracted from the evaporator by employing an evaporator coil 48 disposed in a heat exchange relationship 'with a suitable work load 49 envisioned for the refrigeration device as generally indicated by the heat exchanger at 49.
  • a pipe 67 and pump 69 circulates the coolant fluid such as water through both the evaporator coil 48 and work load 49.
  • the refrigerant liquid within the evaporator is recirculated through the evaporator 46 by employing a pipe 86 containing a pump 57 and a spray header 47.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Combustion & Propulsion (AREA)
  • Organic Chemistry (AREA)
  • Sorption Type Refrigeration Machines (AREA)

Abstract

Système et procédé destinés à supprimer un additif de transfert thermique d'un absorbant et d'un refrigérant. L'invention comporte un absorbeur (10) dans lequel un fluide contenant l'absorbant et l'additif de transfert thermique absorbe la vapeur du refrigérant, de façon à produire un fluide faible contenant l'absorbant, le refrigérant et l'additif de transfert thermique. Un séparateur centrifuge (20) sépare le fluide faible en un fluide appauvri en additif de transfert thermique et en un fluide enrichi en additif de transfert thermique. Ce dernier est introduit dans l'absorbeur (10) et le premier est introduit dans un ou plusieurs générateurs (28). Ceux-ci (28) effectuent l'évaporation du réfrigérant, de façon à obtenir un fluide fort, ainsi que la condensation du réfrigérant évaporé, de façon à obtenir un liquide réfrigérant. Un évaporateur (46) sert à réchauffer le réfrigérant liquide, afin de refroidir un liquide frigorifique et d'obtenir une vapeur de réfrigérant.
PCT/US1995/004835 1994-04-26 1995-04-25 Systemes et procedes destines a reduire au minimum la decomposition d'un additif de transfert thermique dans un generateur de compresseur frigorifique a absorption WO1995029369A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU23587/95A AU2358795A (en) 1994-04-26 1995-04-25 Systems and methods to minimize heat transfer additive decomposition in an absorption chiller generator

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US23326594A 1994-04-26 1994-04-26
US08/233,265 1994-04-26

Publications (1)

Publication Number Publication Date
WO1995029369A1 true WO1995029369A1 (fr) 1995-11-02

Family

ID=22876568

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1995/004835 WO1995029369A1 (fr) 1994-04-26 1995-04-25 Systemes et procedes destines a reduire au minimum la decomposition d'un additif de transfert thermique dans un generateur de compresseur frigorifique a absorption

Country Status (2)

Country Link
AU (1) AU2358795A (fr)
WO (1) WO1995029369A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110986423A (zh) * 2019-12-23 2020-04-10 泰能天然气有限公司 一种高效冷水机组

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3276217A (en) * 1965-11-09 1966-10-04 Carrier Corp Maintaining the effectiveness of an additive in absorption refrigeration systems
US3977204A (en) * 1975-11-14 1976-08-31 Carrier Corporation Alcohol circulation system
US4521313A (en) * 1982-04-15 1985-06-04 Donaldson Company, Inc. Fluid purification system
US5335515A (en) * 1991-11-27 1994-08-09 Rocky Research Triple effect absorption cycle apparatus

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3276217A (en) * 1965-11-09 1966-10-04 Carrier Corp Maintaining the effectiveness of an additive in absorption refrigeration systems
US3977204A (en) * 1975-11-14 1976-08-31 Carrier Corporation Alcohol circulation system
US4521313A (en) * 1982-04-15 1985-06-04 Donaldson Company, Inc. Fluid purification system
US5335515A (en) * 1991-11-27 1994-08-09 Rocky Research Triple effect absorption cycle apparatus

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
AES, Vol. 31, INTERNATIONAL ABSORPTION HEAT PUMP CONFERENCE, ASME 1993, GROSSMAN, "Modular and Flexible Simulation of Advanced Absorption Systems", pages 345-351. *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110986423A (zh) * 2019-12-23 2020-04-10 泰能天然气有限公司 一种高效冷水机组

Also Published As

Publication number Publication date
AU2358795A (en) 1995-11-16

Similar Documents

Publication Publication Date Title
US5584193A (en) Absorption-type refrigeration systems and methods
US5816070A (en) Enhanced lithium bromide absorption cycle water vapor recompression absorber
JP3414249B2 (ja) 吸収冷凍機
US5946937A (en) Dual loop triple effect absorption chiller utilizing a common evaporator circuit
US4546620A (en) Absorption machine with desorber-resorber
JPH05172437A (ja) 分離した２つの吸収冷却システムによって、流体、特に空気を冷却するための方法及び装置
US3491545A (en) Absorption refrigeration system
US5943868A (en) Absorption refrigerating machine and process for the operation thereof
JPH07139844A (ja) 吸収冷凍機
JP3318222B2 (ja) 吸収式冷凍機
WO1995029369A1 (fr) Systemes et procedes destines a reduire au minimum la decomposition d'un additif de transfert thermique dans un generateur de compresseur frigorifique a absorption
JPH074769A (ja) 一重二重効用吸収冷凍機
US3299667A (en) Solution cooler for an absorption refrigeration system
JP3451237B2 (ja) ２段２重効用吸収冷凍機
JP3281228B2 (ja) 吸収式冷温水ユニット
JP3715157B2 (ja) ２段２重効用吸収冷凍機
US3389570A (en) Refrigerant condensate circuit in multiple-effect absorption refrigeration systems
JPS5816628Y2 (ja) 水−リチウム塩系吸収式冷暖房機
JP3484142B2 (ja) ２段２重効用吸収冷凍機
SU1330419A1 (ru) Абсорбционна гелиохолодильна установка
JPH07248161A (ja) 吸収式冷暖給湯装置
JP2823295B2 (ja) 吸収冷凍機
KR100330542B1 (ko) 흡수식 냉동기
JP3486382B2 (ja) 吸収冷凍機
JPS6040590B2 (ja) 多重効用吸収冷凍機

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AU CA CN DE GB JP KR

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): AT BE CH DE DK ES FR GB GR IE IT LU MC NL PT SE

121 Ep: the epo has been informed by wipo that ep was designated in this application
122 Ep: pct application non-entry in european phase
REG Reference to national code

Ref country code: DE

Ref legal event code: 8642

NENP Non-entry into the national phase

Ref country code: CA