Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
  • F24F12/00—Use of energy recovery systems in air conditioning, ventilation or screening
  • F24F12/001—Use of energy recovery systems in air conditioning, ventilation or screening with heat-exchange between supplied and exhausted air
  • F24F12/002—Use of energy recovery systems in air conditioning, ventilation or screening with heat-exchange between supplied and exhausted air using an intermediate heat-transfer fluid
  • F24F12/003—Use of energy recovery systems in air conditioning, ventilation or screening with heat-exchange between supplied and exhausted air using an intermediate heat-transfer fluid using a heat pump
• • 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
  • F24F3/1423—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 a moving bed of solid desiccants, e.g. a rotary wheel supporting solid desiccants
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
  • F24F12/00—Use of energy recovery systems in air conditioning, ventilation or screening
  • F24F12/001—Use of energy recovery systems in air conditioning, ventilation or screening with heat-exchange between supplied and exhausted air
  • F24F2012/007—Use of energy recovery systems in air conditioning, ventilation or screening with heat-exchange between supplied and exhausted air using a by-pass for bypassing the heat-exchanger
• • 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
• • 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
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
  • F28D19/00—Regenerative heat-exchange apparatus in which the intermediate heat-transfer medium or body is moved successively into contact with each heat-exchange medium
  • F28D19/04—Regenerative heat-exchange apparatus in which the intermediate heat-transfer medium or body is moved successively into contact with each heat-exchange medium using rigid bodies, e.g. mounted on a movable carrier
• • 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]
• • 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]
  • Y02B30/12—Hot water central heating systems using heat pumps
• • 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]
  • Y02B30/52—Heat recovery pumps, i.e. heat pump based systems or units able to transfer the thermal energy from one area of the premises or part of the facilities to a different one, improving the overall efficiency
• • 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]
  • Y02B30/56—Heat recovery units

Definitions

• the present invention relates to air conditioning and dehumidification equipment, and more particularly to an air conditioning method and apparatus using desiccant dehumidification technology.
• ASHRAE standard 62-1989 Due to their inefficiency ASHRAE standard 62-1989 has precluded the use of reheat devices in air conditioning systems unless the heat is recovered from the site. In addition, ASHRAE standard 62-1989 requires that systems with larger air flows must use some form of exhaust energy recovery to minimize the amount of energy used to condition outside air being introduced to the space. [0005] A number of commercially available systems have been developed that combine energy recovery, pre-treatment, with cooling coil dehumidification and site recovered reheat. One such system is shown in Figure 1 wherein an energy recovery ventilator with a packaged DX cooling and condenser reheat system is illustrated. An energy recovery ventilator generally consists of an enthalpy wheel of known construction which transfers both heat and sensible energy between two air streams.
• Enthalpy wheels are commonly used to transfer outgoing temperature and humidity (energy) to incoming ambient air. These energy exchangers are generally made of porous materials to increase surface area which aids in energy transfer. Other forms of energy transfer systems, such as heat pipes, can also be used.
• a fresh or outdoor supply of air (ambient air) is passed through a segment of the energy recovery device (in this case an enthalpy wheel) to reduce the supply air's humidity and temperature.
• the supply air is then passed through an evaporator/cooling coil of a conventional refrigeration system to reduce its humidity and temperature further.
• the dehumidified and cooled air is then passed through the condenser coil of the refrigeration system to raise the supply air temperature.
• the thus dehumidified and warm air is then supplied through a duct system directly to the desired space.
• exhaust air is drawn from the space with a fan or blower (not shown) and passed through a separate segment of the enthalpy wheel energy recovery device.
• Figure 2 is a psychrometric diagram of the system in Figure 1 and provides the psychrometric analysis of the effects of each component of the system on the supply air.
• the ambient or outside air has a humidity ratio of about 100 gr/lb and a temperature of about 94 0 F; after leaving the energy recovery wheel it has a humidity ratio of about 80 gr/lb and a temperature of about 83°F; after passing through the evaporator coil it has a humidity ratio of about 59 gr/lb and temperature of about 53 0 F and, after leaving the condenser coil has the same humidity ratio, about 59 gr/lb and a temperature of about 72°F.
• Another form of condenser regenerated conditioning system is shown in Figure 3 and also in Figure 7 of US Pat. No. 6,557,365 B2.
• That system uses a DX cooling coil to cool and dehumidify ambient/outside air prior to entering a desiccant wheel.
• the air is then dehumidified further and heated with the desiccant wheel before being supplied to the space.
• a separate ambient air stream is used as the regeneration air stream and is first heated utilizing condenser heat from the DX refrigeration cycle; the thus heated air stream is then used to drive moisture off of the desiccant wheel.
• the regeneration air stream collects the moisture and rejects it to the atmosphere.
• Many other desiccant dehumidification systems are commercially available that utilize other sources of heat to regenerate desiccant wheels to provide dehumidification and heating cycles to supply air. The vast majority of these devices require high regeneration temperatures to regenerate the desiccant.
• Figure 4 shows the psychrometric diagram for the system of Figure 3 and shows the effect of the system components on the supply air system.
• the outside air supplied to the evaporator coil has a temperature of about 93 0 F and humidity ratio of about 100 gr/lb.
• the evaporator coil After leaving the evaporator coil it has a temperature of about 62° and humidity ratio about 78 gr/lb.
• the desiccant wheel Upon leaving the desiccant wheel it has a temperature of about 72°F and a humidity ratio of about 58 gr/lb.
• Figure 5 illustrates another prior art air conditioning system which, in this case, uses a condenser regenerated desiccant system with enthalpy recovery pre- treatment of the supply air.
• fresh outdoor ambient supply air is passed through a sector of an enthalpy recovery device, dehumidified and cooled and then passed through the cooling coil of a conventional DX refrigeration system further reducing its humidity and temperature.
• the thus cooled and dried supply air stream is then passed through a desiccant device in which it is dehumidified, heated and thereafter supplied to the space via a duct system.
• Exhaust air is drawn from the space with a fan or blower (not shown) and passed through another section of the enthalpy recovery device in which the exhaust air is heated and humidified and then rejected to the atmosphere.
• a separate air stream from the ambient is heated utilizing the condenser coil from the refrigeration system and is then used as the regeneration air stream.
• FIG. 6 shows the psychrometric diagram of the system of Figure 5 and shows the effects of each component of the system on the supply air.
• the outside supply air initially has a humidity ratio of about 100 gr/lb and temperature of about 93 0 F; after passing through the enthalpy wheel the supply air has a humidity ratio of about 84 gr/lb and a temperature of about 84°F.
• the evaporator coil After passing through the evaporator coil it has a humidity ratio of about 78 gr/lb and a temperature of about 62°F.
• the present invention has significant advantages in treating fresh or outdoor air to supply that air at space temperature and at or below space humidity.
• the most significant advantage is low energy consumption. More specifically, the present invention reduces the required energy input from 30 to 75% as compared to the other techniques available.
• An additional significant benefit of the invention is the ability to provide lower supply air humidity conditions (dew point or gr/lb (absolute humidity ratio)) than some other techniques. More particularly, coil based dehumidif ⁇ er systems have problems with ice forming on the evaporator coils as they provide lower coil temperatures in order to provide lower humidity conditions.
• the present invention on the other hand provides the ability to provide lower supply air humidity conditions (dew point or gr/lb) by utilizing a desiccant based dehumidification cycle after the cooling coil.
• ASHRAE has defined the comfort conditions for a building to be between 73° F and 78° F temperature and about 50% relative humidity or 55 gr/lb of air to 71 gr/lb of air.
• the present invention is particularly suited to treat hot and humid air in the southeastern United States and other hot and humid climates around the world with ambient air conditions ranging from 60°F to 105°F or more and a moisture content of 70 to 180 gr/lb and deliver the treated air to the space temperature, and at or below the space humidity, generally in the range of about 70 0 F to 85°F and a moisture level of about 45 to about 71 gr/lb. Ranges somewhat lower and higher than those proposed by ASHRAE can also be achieved by this invention when design space conditions vary from stated ASHRAE conditions.
• Another object of the present invention is to provide such treatment of outdoor, fresh, ambient air very efficiently with lower energy input than most treatments systems currently available.
• Yet another object of the present invention is to provide a system that can provide varying capacity of dehumidification and cooling to react to and overcome varying cooling and dehumidification loads of the fresh or outdoor supply air and/or the building itself.
• a further object of the present invention is to provide heating to the outdoor or fresh supply air with the use of an energy recovery device during cold weather periods to lower the heating input requirement to heat air to the space temperature condition. More specifically, the system utilizes exhaust air with heat transferred to fresh or outdoor supply air with an energy recovery heat exchanger to substantially increase the temperature and/or the humidity of the air prior to being heated by a heating device. Thus, a temperature as such as -10° F would be heated to approximately a temperature of 50° F or higher as needed.
• an air conditioning system includes a means for recovering energy from an exhaust air stream by passing the exhaust air stream across an energy recovery device such as an enthalpy wheel.
• Fresh, outdoor, ambient supply air is passed over the other "side" of the energy recovery device.
• the energy recovery device transfers energy from one air stream to the other without air transferring across the device. This allows for a reduction in temperature and, in some devices, reduction in humidity in the supply air when the ambient condition is warmer and more humid than the space condition. It also allows for the increase in temperature and, in some devices, the increase of humidity in the supply air when the ambient condition is colder and dryer than the space condition.
• the system of the present invention utilizes a cooling coil to lower the temperature and humidity of the supply air before supplying it to the space at which it is required.
• a desiccant dehumidification device that utilizes reactivation heat from a refrigeration system provides additional dehumidification while increasing the temperature of the supply air. Additional cooling of the air is an option to provide lower temperature supply air and overcome internal building sensible load if desired.
• Systems according to the present invention can also utilize the exhaust air that has passed through an energy recovery device to provide the reactivation air source for the desiccant dehumidification cycle.
• a condenser coil from a conventional refrigeration system is utilized to increase the temperature of the exhaust air and then passes this air through another segment of the desiccant device to provide regeneration of the desiccant device.
• the exhaust air stream is cooled and humidified during this regeneration process and allows it to be passed through an additional condenser coil to receive additional heat rejected from the refrigeration system.
• An evaporate cooling device can also be added prior to the second condenser coil to lower the exhaust air entering the second condenser coil to improve the refrigeration systems efficiency and/or increase the capacity of the heat rejection of the condenser.
• Figure 1 is a schematic diagram of a conventional prior art energy recovery air conditioning or ventilator, using a DX cooling and condenser reheat system
• Figure 2 is a psychrometric chart describing the effects of the components of the system on the supply air stream of the system shown in Figure 1;
• Figure 3 is a schematic diagram of a prior art condenser reactivated desiccant system;
• Figure 4 is a psychrometric chart describing the effects of the system components on the supply air stream of the system shown in Figure 3;
• Figure 5 is a schematic diagram of a prior art condenser reactivated desiccant system using an enthalpy energy recovery pre-treatment system;
• Figure 6 is a psychrometric chart describing the effects of the system components on the supply air stream shown in Figure 5;
• Figure 7 is a schematic view of an air conditioning system according to the present invention;
• Figure 8 is a psychrometric chart showing the effects of the components on the supply air stream in the system shown in Figure 7;
• Figure 9 is a psychrometric chart showing the effects of the components on the exhaust air stream in the system shown in Figure 7;
• Figure 10 is a schematic illustration of a second embodiment of the present invention.
• Figure 1 1 is a psychrometric chart showing the effects of the components on the exhaust air stream in the system shown in Figure 10;
• Figure 12 is a schematic illustration of a third embodiment of the invention.
• Figure 13 is a schematic illustration of a fourth embodiment of the invention.
• Figure 14 is a schematic illustration of a fifth embodiment of the invention.
• Figure 15 is a schematic illustration of a sixth embodiment of the invention.
• Figure 16 is a schematic illustration of a seventh embodiment of the invention.
• FIG. 17 is a schematic illustration of an eighth embodiment of the invention.
• FIG. 7 an air conditioning system 10 according to one embodiment of the invention is illustrated in which a stream of ambient air 12 is treated to desired temperature and humidity conditions for use in a room, enclosure or space 14.
• the system is used in areas where the ambient outside air has a high temperature and high humidity content or ratio as described above.
• Figure 7 is a schematic drawing and it will be understood by those skilled in the art that the described air streams are contained in appropriate duct work and moved with appropriate fans, which are not illustrated.
• fresh, outdoor, ambient supply air 12 is first passed through a section 13 of an energy recovery device 16.
• the air is cooled and dehumidified as it passes through the energy recovery device 16.
• this device may be a conventional rotating enthalpy wheel or other form of heat exchanger, such as a heat pipe, to exchange heat between the supply air stream 12 and an exhaust air stream 18 drawn from space 14.
• the ambient air will be cooled but not dehumidified.
• the cooled and dehumidified supply air stream is then passed through the cooling or evaporator coil 20 of a conventional DX refrigerant unit 22, which includes a compressor 23, to further reduce its temperature and humidity.
• the supply air then passes through a segment of a desiccant device 26, such as a conventional silica coated rotating corrugated desiccant wheel, to further reduce its humidity while increasing its temperature. At this point the supply air is at or close to the desired temperature in space 14 and is equal to or below the desired humidity in that space.
• a desiccant device 26 such as a conventional silica coated rotating corrugated desiccant wheel
• the supply air on leaving desiccant wheel 26 has a humidity ratio less than that desired in space 14 the supply air will provide dehumidification capacity to the space to overcome internal latent load.
• the supply air can be directly supplied to the space at that point or it can be further cooled using an optional cooling or evaporator coil 28 between the desiccant wheel and space 14 to provide cooling effect to the space and overcome internal sensible load.
• the exhaust air stream 18 is drawn from the space 14 with a fan or blower (not shown), and then passed over another section 30 of energy recovery device 16. The exhaust air is heated by the heat absorbed in section 13 and humidified as it passes through section 30 and then is passed through a condenser coil 32 of the refrigeration system 22 to increase its temperature.
• the exhaust air leaving condenser 32 is at a higher temperature than when it entered and is then utilized to regenerate the desiccant of wheel 26 by passing the exhaust air through a separate section 34 of the desiccant device.
• the exhaust air stream is cooled and humidified during this regeneration process.
• the now cooler exhaust air can then be used to pass over a second condenser coil 36 in system 22 to recover still more from the refrigeration system and then is rejected to the atmosphere.
• the system of the present invention utilizes the exhaust air stream to recover heat from the ambient supply air stream and to regenerate the desiccant wheel. It is also used to recover or absorb heat from the refrigeration system through the condensers 32 and/or 36.
• FIG. 8 is a psychrometric chart which shows the effect of the components of the invention illustrated in Figure 7 on the supply air stream 12. As seen therein the effects are similar to those achieved in the prior art device of Figure 5, although the present invention allows for the inclusion of an additional cooling coil 28 for treating the supply air stream after it leaves the desiccant wheel 26.
• the present invention recaptures heat wasted in the exhaust air stream of the Figure 5 system.
• the exhaust air stream leaving space 14 and entering segment 30 of enthalpy wheel 16 has a temperature of about 72 0 F and a humidity ratio of about 64 gr/lb, on leaving the enthalpy wheel it has a temperature of about 83 0 F and a humidity ratio of 80 gr/lb.
• the exhaust air stream absorbs the heat rejected from the coil so that when it leaves the coil and enters the regeneration segment 34 of the desiccant wheel it has a temperature of about 108 0 F and humidity ratio of 80gr/lb.
• FIG. 10 illustrates another embodiment of the invention shown in Figure 7 and the same reference numerals are used to identify like parts.
• an evaporative cooling device 38 is added between desiccant wheel 26 and the second condenser coil 36 in the exhaust air stream.
• the evaporative cooling device may be of conventional construction using, for example, cross corrugated sheet materials of known construction through which a supply of water is passed cross or countercurrent to the air steam to cool the air stream. This additional evaporative cooling of the exhaust air stream further lowers its temperature. The exhaust stream at that lower temperature has additional heat rejection capacity when it enters condenser coil 36 and thus allows for lower and more efficient condenser temperatures and lower refrigerant head pressure.
• Figure 11 is a psychrometric chart showing the effects of the invention as illustrated in Figure 10.
• the exhaust air stream temperature is reduced further to about 77°F and its humidity ratio increased to about 130 gr/lb to provide additional cooling and lower temperature upon entering the second condenser.
• the present invention provides significant advantages over prior art.
• the use of a single air stream for exhaust, regeneration and condenser heat rejection significantly lowers the required fan horsepower (for moving various air streams) to accomplish these three tasks. While the system does require increased total static pressure to overcome the different heat exchangers, the total airflow is substantially reduced. As fan power is proportional to the square of the static pressure and the cube of the airflow, reduced airflow is a more important factor in reducing fan power requirements.
• the use of a single air stream to provide these functions also provides lower humidity levels to the desiccant wheel for the reactivation process.
• Building exhaust air is taken from the space at space humidity. It then goes through an energy recovery device. This device either does not increase its humidity (when using a sensible heat recovery device) or it increases it some proportion between the outdoor condition and the indoor condition based on the efficiency of the enthalpy recovery device. In either case the humidity leaving the energy recovery device and entering the desiccant wheel is lower than the outdoor condition.
• the temperature of the exhaust air is at the same temperature regardless of humidity. The temperature is determined by the exhaust recovery process where temperature exchange is independent of humidity level and the added condenser heat, again independent of humidity.
• the desiccant wheel acts as a relative humidity exchanger, a lower humidity condition in an air stream with determined temperature provides a lower relative humidity.
• the lower humidity in the air gives the desiccant device increased capacity through enhanced regeneration.
• the lower entering air temperature to the condenser allows for a lower refrigeration temperature leaving the condenser and provides a lower head pressure. As the head pressure lowers, the amount of work the compressor must do to raise the pressure of the refrigerant is reduced allowing the compressor to operate with a lower power requirement.
• Yet another enhancement of the present art is the ability and efficiency of the exhaust air stream to reject more heat in the second condenser.
• the evaporative cooling effect of the desiccant wheel lowers the temperature back to a temperature that allows the same air stream to perform more heat rejection. This again reduces total airflow and provides reduced fan horsepower.
• the addition of an evaporative cooling device before this second condenser further lowers that temperature to provide the same efficiency for the second condenser as discussed above for the first condenser. It gives the second condenser the ability to reject more heat to a smaller air stream and save fan power. It also lowers the temperature and reduces head pressure in the refrigerant circuit reducing compressor power.
• one or more air stream bypasses are provided using conventional duct work, baffles and controls to selectively bypass a portion of one or both of the air streams around the desiccant wheel.
• Figure 12 illustrates the use of a bypass 42 to direct a portion of the supply air stream around the dehumidification section of desiccant wheel 26.
• Figure 13 illustrates the use of the bypass 42 along with a bypass 44 which bypasses a part of the exhaust air stream around the regeneration section
• Figure 14 simply illustrates the use of the single bypass 44 at the regeneration section 34 of the desiccant wheel.
• Providing one or more such bypasses around a desiccant wheel allows for several advantages. Modulating the bypass on either the supply or regeneration side provides capacity modulation of the desiccant effect on the supply air stream. In addition, the pressure drop of the desiccant wheel can be avoided during times when dehumidification is not required, allowing for reduced fan power requirements and more efficient operation. It also allows for greater flexibility in unit design, providing the ability for the unit to supply more air than the desiccant wheel can accommodate. This flexibility can lower the cost of the equipment to meet specific unit performance requirements.
• Figure 15 is another embodiment of the invention as shown in Figure 10, again with similar parts identified with the same reference numerals.
• the condensate from evaporator coil 20 is recovered in a sump 50 or the like and supplied to the evaporative cooler by a pump 52.
• Recovering the condensate for evaporative cooling requirements allows for increased efficiency without the need for make up water. This will also achieve lower water usage costs and lower installation cost.
• Figure 16 is yet another variant on the invention as described above with respect to Figure 7.
• the configuration of the duct work relative to the desiccant wheel is rearranged so that the ambient/supply air stream flows through the desiccant wheel in a direction opposite to the flow of the exhaust/regeneration air stream rather than in the same direction shown in Figure 7.
• This counter flow arrangement provides greater desiccant performance for greater efficiency.
• the physical layout of this arrangement is more difficult to build than the other embodiments and potentially would require more cost. All other previous indicated embodiments shown in the other figures can also be added to this embodiment to provide many options and variations of the present invention.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Central Air Conditioning (AREA)
• Drying Of Gases (AREA)
• Air Conditioning Control Device (AREA)

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• 2009
  • 2009-02-13 JP JP2010546907A patent/JP2011512507A/ja active Pending
  • 2009-02-13 WO PCT/US2009/033988 patent/WO2009102910A1/en not_active Ceased
  • 2009-02-13 MX MX2010008800A patent/MX2010008800A/es active IP Right Grant
  • 2009-02-13 US US12/745,433 patent/US8631661B2/en active Active
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  • 2009-02-13 EP EP09710305.5A patent/EP2257750A4/en not_active Withdrawn
  • 2009-02-13 CA CA2707793A patent/CA2707793C/en active Active
  • 2009-02-13 KR KR1020107016224A patent/KR101481706B1/ko active Active
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