Patent Application
20090277195
The present invention relates to refrigeration systems and, more particularly, to refrigeration systems including desiccants.
Large tractors or trucks (e.g., semi-tractors) are commonly used to transport cargo within a trailer or container. Existing tractors in a tractor-trailer combination typically include cabins that are conditioned by multiple mechanically driven vapor compression air conditioning systems. In some constructions, the air conditioning systems include a desiccant to adsorb moisture from an airflow prior to the airflow passing over a cooling coil. Typically, waste heat from an engine (e.g., from a coolant fluid of the engine) is circulated through passages in the desiccant to drive out moisture from the desiccant.
In one embodiment, the invention provides a refrigeration system for providing conditioned air to a space. The refrigeration system includes a compressor operable to compress a refrigerant, a condenser configured to receive the refrigerant from the compressor, an expansion device configured to receive the refrigerant from the condenser, a desiccant operable to adsorb moisture from an airflow flowing through the desiccant such that the airflow is substantially dehumidified, and an evaporator assembly configured to receive the refrigerant from the expansion device and the airflow from the desiccant. The evaporator assembly is operable to condition the airflow prior to discharge from the evaporator assembly. The refrigeration system also includes a heat exchanger configured to selectively receive the refrigerant from at least one of the compressor and the condenser. The heat exchanger is in communication with the desiccant such that the refrigerant in the heat exchanger desorbs moisture from the desiccant.
In another embodiment, the invention provides a method of providing conditioned air to a space with a refrigeration system. The refrigeration system includes a compressor operable to compress a refrigerant, a condenser configured to receive the refrigerant from the compressor, an expansion device configured to receive the refrigerant from the condenser, a desiccant configured to receive an airflow, and an evaporator assembly configured to receive the refrigerant from the expansion valve and the airflow from the desiccant. The method includes providing a heat exchanger configured to selectively receive the refrigerant from at least one of the compressor and the condenser. The heat exchanger is in communication with the desiccant. The method also includes adsorbing moisture from the airflow flowing through the desiccant such that the airflow is substantially dehumidified, directing the airflow from the desiccant through the evaporator assembly, conditioning the airflow with the evaporator assembly prior to discharge from the evaporator assembly, and desorbing moisture from the desiccant with the refrigerant in the heat exchanger.
Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.
Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings.
In the illustrated construction, the vehicle 10 includes a frame 14, wheels 18, an alternator 22 or direct current (“DC”) generator, a prime mover 26, and a fuel reservoir 30. The wheels 18 are rotatably coupled to the frame 14 to permit movement of the vehicle 10. The alternator 22 is coupled to the prime mover 26 so that mechanical energy produced by the prime mover 26 can be converted into electrical energy, or electricity.
The prime mover 26 is coupled to the frame 14 and is disposed in a compartment 34 that is located adjacent to a forward end of the vehicle 10. The prime mover 26 is operable in a first mode and a second mode, and includes an “On” state and an “Off” state. The first mode corresponds to the prime mover 26 being engaged so that the vehicle 10 can be driven. The first mode further corresponds to when the prime mover 26 is idling, but is not engaged so that the operator can drive the vehicle 10. In other words, the prime mover 26 is operable in the first mode when the prime mover 26 is in the “On” state.
The prime mover 26 is in the second mode during standby operation of the vehicle 10 (e.g., when the vehicle 10 is parked, etc.). Generally, standby operation of the vehicle 10 corresponds to the prime mover 26 being disengaged. In other words, the prime mover 26 is operating in the second mode when the prime mover is in the “Off” state.
The illustrated fuel reservoir 30 is in fluid communication with the prime mover 26 to deliver fuel (e.g., diesel fuel, gasoline, etc.) to the prime mover 26 when the prime mover 26 is in the “On” state. As shown in
The prime mover 26 is in communication with one or more of the wheels 18 to power the wheels 18 when the vehicle 10 is in the first mode. The prime mover 26 can be an internal combustion engine (e.g., a diesel engine, etc.), or alternatively, a hybrid engine that includes an electrical power system coupled to the internal combustion engine. In other constructions, the prime mover 26 can be a fully electrical power system without a corresponding internal combustion engine. Hereinafter, the term “prime mover” shall be used to represent all such propulsion systems, and shall not be construed to limit the scope of the invention solely to internal combustion engines.
As shown in
Referring to
The HVAC system 66 is coupled to the vehicle 10 and is in communication with the cabin 58 to condition the space 74. The illustrated vehicle 10 includes a single HVAC system 66 that is located adjacent to and in communication with the space 74. In other constructions, one HVAC system can be positioned in the vehicle 10 to condition the driving portion and another HVAC system can be positioned to condition the sleeping portion. Generally, the number of HVAC systems in the vehicle 10 depends at least in part on the size and number of zones to be conditioned within the cabin 58.
Referring to
The illustrated sorption system 78 includes a first inlet 90, a second inlet 94, a first outlet 98, a second outlet 102, and a desiccant 106 that is disposed between the inlets 90, 94 and the outlets 98, 102. In some constructions (see
The desiccant 106 is operable to adsorb moisture from the airflow 110 so that a substantially dehumidified airflow 112 is discharged through the first outlet 98. Generally, the sorption system 78 is in communication with a heat source so that moisture adsorbed from the airflow 110 by the desiccant 106 can be desorbed from the desiccant 106 and vented into the atmosphere via the second outlet 102. The sorption system 78 is also in communication with a cooling source (e.g., ambient air) so that the desorbed, or regenerated, desiccant 106 can be cooled prior to the desiccant 106 continuing to adsorb moisture from the airflow 110.
The illustrated cooling circuit 82, or refrigeration system, includes a condenser assembly 114, an expansion device 118, a heat exchanger or evaporator assembly 122, and a refrigerant that flows through the condenser assembly 114, the expansion device 118, and the evaporator assembly 122. The illustrated condenser assembly 114 includes a compressor 126, a condenser coil 130, and a condenser fan 134. In other constructions, the cooling circuit 82 may also include other components (e.g., flow control valves, multiple or multi-stage compressors, etc.).
The compressor 126 and the condenser coil 130 can be located anywhere on the vehicle 10. In some constructions, the condenser coil 130 can be mounted to an exterior surface of one of the walls 70. The condenser fan 134 is positioned adjacent to the condenser coil 130 to assist with transferring heat from the refrigerant in the condenser coil 130 to the atmosphere by directing air over the condenser coil 130.
The evaporator assembly 122 is located adjacent to and in communication with the sorption system 78 and the bypass 113 to selectively receive the dehumidified airflow 112 exiting the sorption system 78 through the outlet 98, and the non-dehumidified airflow 110 from the bypass 113. In some constructions, the evaporator assembly 122 is attached to the vehicle 10 adjacent a rear of the cabin 58. In other constructions, the evaporator assembly 122 can be positioned in the compartment 34. In still other constructions, the evaporator assembly 122 may have a compact design and be installed in a sleeping portion, or other convenient location, of the cabin 58.
As shown in
The heating circuit 86 includes a heater 150, a fuel reservoir 154, and a heating coil 158. In some constructions, the fuel reservoir 154 can be the same as the fuel reservoir 30 of the vehicle 10. The heater 150 is a direct-fired diesel heater that is positioned in communication with the coolant in the coolant system 38 and that includes heating elements (e.g., a glow pin, a heat exchanger, etc.) that help heat the coolant. In the illustrated construction, the heating coil 158 is disposed in the housing 138 of the evaporator assembly 122 and is in communication with the sorption system 78 and the bypass 113 to receive one of the airflows 110, 112 and to heat the respective airflow 110, 112. The airflows 110, 112 can be heated by the heat source that is used to desorb the desiccant 106, or alternatively, by another heat source. In other constructions, the heating coil 158 can be located elsewhere in the vehicle 10. The cooling coil 142 and the heating coil 158 are separated from each other so that the heating circuit 86 and the cooling circuit 82 are not mixed.
During operation of the heating circuit 86 it may not be necessary for air that is directed over the heating coil 158 to be dehumidified by the sorption system 78. For example, the airflow 110 can bypass the sorption system 78 via the bypass 113 prior to heating the airflow 110 via heat exchange with heated coolant in the heating coil 158. Alternatively, the airflow 110 can be dehumidified by the sorption system 78, and the dehumidified airflow 112 can then be directed into the housing 138 to be heated by the heating coil 158. A heated airflow is then discharged into the space 74.
In operation, the HVAC system 66 selectively conditions the space 74 using the sorption system 78, the cooling circuit 82, and/or the heating circuit 86. When the space 74 is cooled, the evaporator fan 146 draws the airflow 110 through the first inlet 90 of the sorption system 78, over the desiccant 106, and through the first outlet 98. As the airflow 110 passes through the desiccant 106, the airflow 110 is substantially dehumidified via adsorption of moisture by the desiccant 106 as is known in the art. The dehumidified airflow 112 is then directed through the evaporator assembly 122, where the airflow 112 is conditioned so that a conditioned airflow 166 can be discharged into the space 74. In some constructions, at least a portion of the airflow 110 can be directed through the bypass 113 during operation of the cooling circuit 82 to bypass the sorption system 78 (e.g., when previously conditioned air from the cabin 58 is recirculated through the HVAC system 66).
Eventually, the desiccant 106 that has been adsorbing moisture from the airflow 110 becomes saturated and can no longer dehumidify the airflow 110. Once the desiccant 110 is saturated, a regeneration process of the sorption system 78 is begun to desorb the moisture from the desiccant 106. During the regeneration process, the HVAC system 66 conditions the space 74 with the non-dehumidified airflow 110 via the bypass 113. The flow control devices redirect the airflow 110 through the bypass 113 toward the evaporator assembly 122, and inhibit or prevent the airflow 110 from entering the sorption system 78. In some constructions, one or more of the components of the HVAC system 66 can be shutdown during the regeneration process.
For example, during operation of the sorption system 78, moisture in the airflow 110 is adsorbed by the desiccant 106 for approximately ninety percent of the operation time. In this example, regeneration (e.g., desorption and cooling) of the desiccant 106 lasts for approximately ten percent of the operation time. The time duration for adsorption by and regeneration of the desiccant 106 can be different from time frames discussed herein. During the regeneration process, the HVAC system 66 may operate under a relatively large load due to the non-dehumidified nature of the airflow 110 from the bypass 113. However, the duration of the regeneration process is relatively short and does not substantially affect the efficiency of the HVAC system 66. Furthermore, air from the cabin 74 that is recirculated through the HVAC system 66 can have a relatively low humidity due to adsorption of moisture from the air during a previous adsorption cycle, and may limit the impact of the airflow 110 on the load of the HVAC system 66.
The cooling circuit 82 conditions the dehumidified airflow 112 by heat transfer with the cooling coil 142. The conditioned airflow 166 is then directed from the evaporator assembly 122 into the space 74 via the evaporator fan 146. During operation of the cooling circuit 82 (i.e., a typical cooling mode), refrigerant is circulated through the cooling circuit 82 to cool the dehumidified airflow 112 via heat transfer with the cooling coil 142. Relatively warm refrigerant is compressed by the compressor 126, and the compressed refrigerant is then cooled within the condenser coil 130 by heat transfer with air that is adjacent to or directed over (e.g., with the condenser fan 134) the condenser coil 130. The cooled refrigerant is then directed through the expansion device 118 and into the evaporator assembly 122 through the cooling coil 142. The previously cooled refrigerant is heated and the dehumidified airflow 112 is cooled. The evaporator fan 146 directs the cooled, dehumidified airflow 166 into the cabin 58 to condition the space 74.
During operation of the heating circuit 86, the space 74 is conditioned using the non-dehumidified airflow 110 from the bypass 113. Generally, the airflow 110 bypasses the sorption system 78 during operation of the heating circuit 86 and is conditioned by the heating coil 158. In some constructions, some or all of the airflow 110 can be dehumidified by the sorption system 78, and the dehumidified airflow 112 can then be conditioned by the heating coil 158. Coolant is circulated to heat the non-dehumidified airflow 110 via heat transfer with the heating coil 158. A heated airflow (instead of the cooled, dehumidified airflow 166) is then propelled by the evaporator fan 146 into the cabin 58 to condition the space 74. When the prime mover 26 is in the first mode, heat from the prime mover 26 heats the coolant in the coolant circuit, which in turn can selectively provide heat to the space 74. When the prime mover 26 is in the second mode, the heater 150 can be selectively engaged to heat the coolant in the coolant system 38 to provide heat to the space 74. In addition, the coolant heated by the heater 150 can keep the prime mover 26 relatively warm as needed when the prime mover 26 is in the “Off” state.
As discussed above, in some scenarios, it is desired to regenerate the desiccant 106 of the sorption system 78 after or between operations of the HVAC system 66. In the illustrated construction, the desiccant 106 can be desorbed using waste heat from the cooling circuit 82.
In some constructions (see, for example,
In the typical cooling mode, the first valve 204 is opened and the second valve 208 is closed such that warm refrigerant from the compressor 126 is directed toward the condenser coil 130. In addition, the condenser and evaporator fans 134, 146 are turned “On”, while the secondary fan (if present) is turned “Off”. The refrigerant flows through the condenser coil 130, through the expansion device 118, and through the evaporator coil 142 back to the compressor 126. Wet air from the environment is pulled through the first inlet 90 of the sorption system 78 and passes through the desiccant 106 such that dehumidified air exits the sorption system 78 through the first outlet 98. The dehumidified air enters the evaporator assembly 122 and passes over the evaporator coil 142 where it is conditioned (e.g., cooled) by refrigerant in the coil 142. Conditioned air then exits the evaporator assembly 122 and enters the surrounding environment (e.g., the cabin 58 of the vehicle 10 shown in
To regenerate the desiccant 106, the first valve 204 is closed and the second valve 208 is opened such that warm refrigerant from the compressor 126 is directed toward the secondary coil 190. The condenser and evaporator fans 134, 146 are turned “Off”, while the secondary fan (if present) is turned “On”. In some constructions, the evaporator fan 146 may also be turned “On”. The warm refrigerant flows through the secondary coil 190, desorbing moisture from the desiccant 106 directly (e.g., when the secondary coil 190 is embedded in the desiccant 106) or indirectly (e.g., when the secondary fan 194 is provided to propel an airflow over the secondary coil 190 and through the desiccant 106). The refrigerant then flows through the expansion device 118 and the evaporator coil 142 back to the compressor 126. This process, or cycle, is continued until the desiccant 106 is sufficiently desorbed.
To cool (i.e., pre-cool) the desiccant 106 after regeneration, the first valve 204 is opened, the second valve 208 is closed, and the condenser fan 135 is turned “On”. If the secondary fan 194 is present, it is also turned “On”. Warm refrigerant flows from the compressor 126 and through the condenser coil 130 such that the refrigerant is cooled and reduced in pressure. Since the refrigerant from the condenser coil 130 has a relatively lower pressure, refrigerant in the secondary coil 190 is drawn from the secondary coil 190 toward the expansion device 118. As the refrigerant is drawn out of the secondary coil 190, the temperature of the refrigerant drops, thereby cooling the desiccant 106 directly or indirectly.
In the typical cooling mode, the first valve 204 is opened and the second, third, and fourth valves 208, 212, 220 are closed such that warm refrigerant from the compressor 126 is directed toward the condenser coil 130. In addition, the condenser and evaporator fans 134, 146 are turned “On”, while the secondary fan (if present) is turned “Off”. The refrigerant flows through the condenser coil 130, through the expansion device 118, and through the evaporator coil 142 back to the compressor 126 such that the cooling circuit 200′ operates in a similar manner to the cooling circuit 200 discussed above.
To regenerate the desiccant 106, the first and fourth valves 204, 220 are closed and the second and third valves 208, 212 are opened such that warm refrigerant from the compressor 126 is directed toward the secondary coil 190. The condenser and evaporator fans 134, 146 are turned “Off”, while the secondary fan (if present) is turned “On”. In some constructions, the evaporator fan 146 may also be turned “On”. The warm refrigerant flows through the secondary coil 190, desorbing moisture from the desiccant 106 directly or indirectly. The refrigerant then flows through the expansion device 118 and the evaporator coil 142 back to the compressor 126. This process, or cycle, is continued until the desiccant 106 is sufficiently desorbed.
To pre-cool the desiccant 106 after regeneration, the first and fourth valves 204, 220 are opened, the second and third valves 208, 212 are closed, and the condenser fan 134 is turned “On”. If the secondary fan 194 is present, it is also turned “On”. Warm refrigerant flows from the compressor 126 and through the condenser coil 130 such that the refrigerant is cooled. The cooled refrigerant then flows through the expansion device 118 and the evaporator coil 142 such that the refrigerant is further cooled and reduced in pressure. Since the refrigerant exiting the evaporator coil 142 has a relatively lower pressure than the refrigerant in the secondary coil 190, the refrigerant in the secondary coil 190 is drawn through the bypass 216 toward the compressor 126. As the refrigerant is drawn out of the secondary coil 190, the temperature of the refrigerant drops, thereby cooling the desiccant 106 directly or indirectly.
In the typical cooling mode, the first valve 204 is opened and the second, third, fourth, and fifth valves 208, 212, 220, 228 are closed such that warm refrigerant from the compressor 126 is directed toward the condenser coil 130. In addition, the condenser and evaporator fans 134, 146 are turned “On”, while the secondary fan (if present) is turned “Off”. The refrigerant flows through the condenser coil 130, through the expansion device 118, and through the evaporator coil 142 back to the compressor 126 such that the cooling circuit 200″ operates in a similar manner to the cooling circuit 200 discussed above.
To regenerate the desiccant 106, the first, fourth, and fifth valves 204, 220, 228 are closed and the second and third valves 208, 212 are opened such that warm refrigerant from the compressor 126 is directed toward the secondary coil 190. The condenser and evaporator fans 134, 146 are turned “Off”, while the secondary fan (if present) is turned “On”. In some constructions, the evaporator fan 146 may also be turned “On”. The warm refrigerant flows through the secondary coil 190, desorbing moisture from the desiccant 106 directly or indirectly. The refrigerant then flows through the expansion device 118 and the evaporator coil 142 back to the compressor 126. This process, or cycle, is continued until the desiccant 106 is sufficiently desorbed.
To pre-cool the desiccant 106 after regeneration, the first, fourth, and fifth valves 204, 220, 228 are opened, the second and third valves 208, 212 are closed, and the condenser fan 134 is turned “On”. If the secondary fan is present, it is also turned “On”. Warm refrigerant from the compressor 126 flows through the condenser coil 130 such that the refrigerant is cooled. The cooled refrigerant flows into the second bypass 224 and through the fifth valve 228 and the second expansion device 232, further cooling the refrigerant. The cooled refrigerant then flows into the secondary coil 190 and directly or indirectly cools the desiccant 106. The refrigerant exits the secondary coil 190 and flows through the bypass 216 back to the compressor 126.
To regenerate the desiccant 106, the condenser and evaporator fans 134, 146 are turned “Off”, while the secondary fan 194 is turned “On”. In some constructions, the evaporator fan 146 may also be turned “On”. Warm refrigerant from the compressor 126 flows through the condenser coil 130 substantially unchanged (e.g., the temperature of the refrigerant remains generally the same) and flows into the secondary coil 190. The secondary fan 194 propels purge air over the secondary coil 190, warming the purge air with the refrigerant in the secondary coil 190. The warm purge air enters the sorption system 78 through the second inlet 94, passes through the desiccant 106 to desorb moisture from the desiccant 106, and exits the sorption system 78 through the second outlet 102. Moisture is thereby carried by the purge air out of the desiccant 106. In some constructions, the purge air can be formed from air returning from the cabin 58, air from the environment, and/or air from other sources. Additionally or alternatively, the purge air may enter the sorption system 78 through a common inlet with the wet air (e.g., the first inlet 90). In other constructions, the secondary fan 194 may be omitted and the secondary coil 190 may be embedded in the desiccant 106 to heat the desiccant 106 directly.
Meanwhile, the warm refrigerant is cooled at the secondary coil 190 by the purge air and directed through the expansion device 118 for further cooling. The cooled refrigerant passes through the evaporator coil 142, where the evaporator fan 146 may or may not be running to propel an airflow over the coil 142. The refrigerant continues through the cooling circuit 300 and is circulated back to the compressor 126. This process, or cycle, is continued until the desiccant 106 is sufficiently desorbed.
To pre-cool the desiccant 106 after regeneration, the condenser and secondary fans 134, 194 are turned “On”. Warm refrigerant from the compressor 126 flows through the condenser coil 130 where the refrigerant is cooled by air propelled over the coil 130 with the condenser fan 134. The cooled refrigerant flows from the condenser coil 130 to the secondary coil 190. The secondary fan 194 propels purge air over the secondary coil 190, cooling the purge air with the cooled refrigerant in the coil 190. The cooled purge air flows through the desiccant 106 to cool the desiccant 106 indirectly. In constructions where the secondary fan 194 is omitted, the secondary coil 190 may be embedded in the desiccant 106 to cool the desiccant 106 directly. The constructions using the fan 194 are referred to herein as cooling (or conversely heating) “indirectly”, while the constructions not using the fan 194 and having an embedded coil 190 are referred to herein as cooling (or conversely heating) “directly”. Meanwhile, the refrigerant exits the secondary coil 190 and flows through the expansion device 118 and the evaporator coil 142 back to the compressor 126.
In the typical cooling mode, the first valve 304 is closed and the second valve 213 is opened such that refrigerant from the condenser coil 130 is directed around the secondary coil 190. In addition, the condenser and evaporator fans 134, 146 are turned “On”, while the secondary fan 194 (if present) is turned “Off”. Warm refrigerant flows from the compressor 126, through the condenser coil 130, the bypass 308, the expansion device 118, and the evaporator coil 142, and back to the compressor 126 such that the cooling circuit 300′ operates in a similar manner to the cooling circuit 300 discussed above.
To regenerate the desiccant 106, the first valve is opened 304 and the second valve 312 is closed such that refrigerant from the condenser coil 130 is directed through the secondary coil 190. The condenser and evaporator fans 134, 146 are turned “Off”, while the secondary fan 194 (if present) is turned “On”. In some constructions, the evaporator fan 146 may also be turned “On”. Warm refrigerant flows from the compressor 126 and through the condenser coil 130 substantially unchanged. The warm refrigerant then flows into the secondary coil 190, desorbing moisture from the desiccant 106 directly or indirectly. The refrigerant flows from the secondary coil 190 through the expansion device 118 and the evaporator coil 142 back to the compressor 126. This process, or cycle, is continued until the desiccant 106 is sufficiently desorbed.
To pre-cool the desiccant 106 after regeneration, the first valve 304 is closed, the second valve 312 is opened, and the condenser fan 134 is turned “On”. Warm refrigerant from the compressor 126 flows through the condenser coil 130 where the refrigerant is cooled by air propelled over the coil 130 with the condenser fan 134. The cooled refrigerant flows through the bypass 308 toward the expansion device 118 at a reduced pressure. Since the refrigerant in the bypass 308 is at a relatively lower pressure than refrigerant in the secondary coil 190, the refrigerant in the secondary coil 190 is drawn from the coil 190 toward the expansion device 118. As the refrigerant is drawn out of the secondary coil 190, the temperature of the refrigerant drops, thereby cooling the desiccant 106 directly or indirectly.
In the typical cooling mode, the first and third valves 304, 320 are closed and the second valve 312 is opened such that refrigerant from the condenser coil 130 is directed around the secondary coil 190. In addition, the condenser and the evaporator fans 134, 146 are turned “On”, while the secondary fan 194 (if present) is turned “Off”. Warm refrigerant flows from the compressor 126, through the condenser coil 130, the bypass 308, the expansion device 118, and the evaporator coil 142, and back to the compressor 126 such that the cooling circuit 300″ operates in a similar manner to the cooling circuit 300 discussed above.
To regenerate the desiccant 106, the first valve 304 is opened and the second and third valves 312, 320 are closed such that the refrigerant from the condenser coil 130 flows through the secondary coil 190. The condenser and evaporator fans 134, 146 are turned “Off”, while the secondary fan 194 (if present) is turned “On”. In some constructions, the evaporator fan 146 may also be turned “On”. Warm refrigerant flows from the compressor 126 and through the condenser coil 130 substantially unchanged. The warm refrigerant then flows into the secondary coil 190, desorbing moisture from the desiccant 106 directly or indirectly. The refrigerant flows from the secondary coil 190 through the expansion device 118 and the evaporator coil 142 back to the compressor 126. This process, or cycle, is continued until the desiccant 106 is sufficiently desorbed.
To pre-cool the desiccant 106 after regeneration, the first valve 304 is closed, the second and third valves 312, 320 are opened, and the condenser fan 134 is turned “On”. If the secondary fan 194 is present, it is also turned “On”. Warm refrigerant from the compressor 126 flows through the condenser coil 130 where the refrigerant is cooled by air propelled over the coil 130 with the condenser fan 134. The cooled refrigerant continues through the first bypass 308, the expansion device 118, and the evaporator coil 142 toward the compressor 126. Since the refrigerant exiting the evaporator coil 142 has a relatively lower pressure than refrigerant in the secondary coil 190, the refrigerant in the secondary coil 190 is drawn through the bypass 316 toward the compressor 126. As the refrigerant is drawn out of the secondary coil 190, the temperature of the refrigerant drops, thereby cooling the desiccant 106 directly or indirectly.
In the typical cooling mode, the first, third, and fourth valves 304, 320, 332 are closed and the second valve 312 is opened such that the refrigerant from the condenser coil 130 is directed around the secondary coil 190. In addition, the condenser and evaporator fans 134, 146 are turned “On”, while the secondary fan 194 (if present) is turned “Off”. Warm refrigerant flows from the compressor 126, through the condenser coil 130, the bypass 308, the expansion device 118, and the evaporator coil 142, and back to the compressor 126 such that the cooling circuit 300′″ operates in a similar manner to the cooling circuit 300 discussed above.
To regenerate the desiccant, 106, the first valve 304 is opened and the second, third, and fourth valves 312, 320, 332 are closed. In addition, the condenser and evaporator fans 134, 146 are turned “Off”, while the secondary fan 194 (if present) is turned “On”. In some constructions, the evaporator fan 146 may also be turned “On”. Warm refrigerant flows from the compressor 126 and through the condenser coil 130 substantially unchanged. The warm refrigerant then flows into the secondary coil 190, desorbing moisture from the desiccant 106 directly or indirectly. The refrigerant flows from the secondary coil 190 through the expansion device 118 and the evaporator coil 142 back to the compressor 126. This process, or cycle, is continued until the desiccant 106 is sufficiently desorbed.
To pre-cool the desiccant 106 after regeneration, the first valve 304 is closed, the third and fourth valves 320, 332 are opened, and the condenser fan 134 is turned “On”. The second valve 312 may be either opened or closed. If the secondary fan 194 is present, it is also turned “On”. Warm refrigerant from the compressor 126 flows through the condenser coil 130 where the refrigerant is cooled by air propelled over the coil 130 with the condenser fan 134. The cooled refrigerant flows through the third bypass 328 and the second expansion device 336 and into the secondary coil 190. As the refrigerant flows through the second expansion device 336, the refrigerant is further reduced in temperature. The cooled refrigerant in the secondary coil 190 thereby cools the desiccant 106 directly or indirectly and flows out of the second coil 190 through the second bypass 316 toward the compressor 126. If the second valve 312 is opened, a portion of the refrigerant from the condenser coil 130 may flow through the first bypass 308 and the expansion device 118 toward the evaporator coil 142 such that the evaporator assembly 122 may begin or continue to operate while the desiccant 106 is pre-cooled.
In some constructions, such as the construction shown in
Providing a two-stage sorption system 478 allows one of the first and second desiccants 482, 486 to be desorbed or regenerated while the other desiccant 482, 486 adsorbs moisture from an airflow. For example, in the illustrated construction, the first desiccant 482 is regenerated while the second desiccant 486 adsorbs moisture from the airflow. Once the second desiccant 486 becomes saturated with moisture or the first desiccant 482 is substantially desorbed, the first and second desiccants 482, 486 may be reversed (e.g., flipped or switched) such that the second desiccant 486 is regenerated while the first desiccant 482 adsorbs moisture from the airflow. In some constructions, the sorption system 478 may include one or more sensors to determine when to reverse the desiccants 482, 486. In other constructions, the sorption system may include a timer to automatically reverse the desiccants 482, 486 after a predetermined period of time.
Sorption systems increase the efficiency of HVAC systems by reducing the load required to condition an airflow. For example, in some constructions, a sorption system may decrease the load of an HVAC system by up to about fifty percent. Using a secondary heat exchanger to transfer heat from a refrigerant to help desorb moisture from a desiccant also reduces energy and fuel consumption by decreasing the power normally required cool the refrigerant with a condenser. Furthermore, when using a secondary heat exchanger in vehicle applications, a diesel fired heater is not required to heat engine coolant to help desorb moisture from a desiccant.
Various features and advantages of the invention are set forth in the following claims.
