CN117597551A

CN117597551A - Air conditioning system and control method

Info

Publication number: CN117597551A
Application number: CN202280047311.6A
Authority: CN
Inventors: 罗斯·邦纳; 马修·H·道森
Original assignee: Kaiwai Gas Co ltd
Current assignee: Kaiwai Gas Co ltd
Priority date: 2021-05-04
Filing date: 2022-05-04
Publication date: 2024-02-23
Also published as: EP4334647A4; WO2022235782A1; EP4334647A1; JP2024517285A; WO2022235782A8; US20220373200A1; US20250043970A1

Abstract

A refrigeration and dehumidification system comprising: at least one passive heat transfer device coated with a desiccant on a portion of the exposed surface; another passive heat transfer device without a desiccant coating; a compressor through which refrigerant flows; expansion devices; refrigerant control valves; and valves associated with passive heat transfer devices for directing air flow.

Description

Air conditioning system and control method

Technical Field

The present invention relates to systems and methods for providing refrigeration and dehumidification to a space.

Background

The ever-increasing refrigeration demands place tremendous pressure on the environment, grid infrastructure, and global climate. Meeting the world's demand for refrigeration while minimizing its negative impact would be one of the decisive challenges in our age. This challenge can be addressed by redesigning the present day air conditioning system to utilize new materials and chemical processes.

Conventional vapor compression-based air conditioning systems provide refrigeration and dehumidification by passing air through a refrigeration coil. By flowing the refrigerant through the coil, the coil is maintained at a temperature below that of air. The cooling is realized by the following modes: the air is passed through a refrigeration coil that is cooler than the incoming air, resulting in heat transfer from the air to the refrigerant and a decrease in the temperature of the air. The sub-cooling or dehumidification is achieved by passing the air through a refrigeration coil below the dew point of the incoming air. This causes moisture from the air to form condensate on the coil surface and transfer the latent heat of evaporation to the refrigerant. In such systems, sensible heat removal and latent heat removal are coupled such that either sensible or latent cooling can be controlled, but not both. Furthermore, to meet the high potential load, the refrigeration coils must operate at very low temperatures, resulting in inefficiency of the vapor compression system.

Disclosure of Invention

The present disclosure overcomes the shortcomings of the prior art by providing a refrigeration and dehumidification system comprising: at least one passive heat transfer device coated with a desiccant on a portion of the exposed surface; another passive heat transfer device without a desiccant coating; a compressor through which a refrigerant flows; an expansion device; a refrigerant control valve; and a valve associated with the passive heat transfer device for directing the flow of air.

In an illustrative embodiment, an air treatment system and method includes a heat pump configured to move thermal energy between a plurality of passive heat transfer devices. The plurality of passive heat transfer devices define a first surface of at least one of the plurality of passive heat transfer devices in thermal contact with the heat pump and a second surface of at least one of the plurality of passive heat transfer devices exposed to allow transfer of heat to or from the heat pump. The desiccant may be in thermal contact with an exposed surface of the at least one passive heat transfer device and configured to exchange moisture with air. The plurality of air directing valves are configured to direct process air and regeneration air to and from the plurality of passive heat transfer devices with desiccant. The heat pump reversing device may be configured to change the direction of heat flow in the heat pump between two modes of operation, and a control system having a communication line may control the air-directing valve, the reversing device, and the heat pump operation. The control operation may operate a control mode in which the desiccant regeneration time is adjusted. Illustratively, the passive heat transfer device may include a tube and fin heat exchanger or a microchannel heat exchanger. The desiccant may form a coating on the exposed surfaces of the heat exchanger fins, the coating may be a partial coating, with the uncoated portion exposed to the air flow first, and then a second portion of the coated desiccant exposed to the air flow. The passive heat transfer device without desiccant may be configured to exchange sensible heat with ambient air and/or the passive heat transfer device without desiccant may be configured to exchange sensible heat with indoor air. The desiccant may comprise any acceptable material or combination of materials including at least one of silica gel, aluminum oxide, zeolite, or metal-organic framework (MOF) materials.

Drawings

The following description of the invention refers to the accompanying drawings, in which:

fig. 1A depicts a refrigeration and dehumidification system in a first mode of operation having two desiccant-coated passive heat transfer devices and an uncoated third passive heat transfer device.

Fig. 1B depicts the refrigeration and dehumidification system in a second mode of operation with two desiccant-coated passive heat transfer devices and an uncoated third passive heat transfer device.

Fig. 2A depicts the refrigeration and dehumidification system in a first mode of operation with two desiccant-coated passive heat transfer devices and an uncoated third passive heat transfer device.

Fig. 2B depicts the refrigeration and dehumidification system in a second mode of operation with two desiccant-coated passive heat transfer devices and an uncoated third passive heat transfer device.

Fig. 3A depicts the refrigeration and dehumidification system in a first mode of operation with one desiccant-coated passive heat transfer device and two uncoated passive heat transfer devices.

Fig. 3B depicts the refrigeration and dehumidification system in a second mode of operation with one desiccant-coated passive heat transfer device and two uncoated passive heat transfer devices.

Fig. 4A depicts the refrigeration and dehumidification system in a first mode of operation with two desiccant-coated passive heat transfer devices.

Fig. 4B depicts the refrigeration and dehumidification system in a second mode of operation with two desiccant-coated passive heat transfer devices.

Fig. 5A-5D depict embodiments of a refrigerant flow directing and metering device in two modes of operation.

Fig. 6A depicts a cross-sectional view of an embodiment of an indoor refrigeration and dehumidification device in a first mode of operation.

Fig. 6B depicts a cross-sectional view of an embodiment of the indoor refrigeration and dehumidification device in a second mode of operation.

Fig. 7 depicts a control method of a desiccant refrigeration and dehumidification system.

Detailed Description

Fig. 1A and 1B illustrate schematic diagrams of an exemplary desiccant refrigeration and dehumidification system 100. In operation, the system 100 cycles between two modes of operation: a first mode (also referred to as a first half cycle) and a second mode (also referred to as a second half cycle). Fig. 1A shows a first operation mode, and fig. 1B shows a second operation mode. The system 100 includes: including a heat pump of the compressor 103, an uncoated (i.e., without desiccant material) passive heat transfer device 104, a refrigerant reversing valve 105, a desiccant coated first passive heat transfer device 107, an expansion valve 108, and a desiccant coated second passive heat transfer device 109. The system 100 further includes a first air directing valve 113, a second air directing valve 114, and a first fan 115. The system 100 further includes a first air duct 119, a third air directing valve 120, a fourth air directing valve 121, a second fan 122, and a second air duct 123. The system 100 also includes a third fan 128.

As shown in the example of fig. 1A and 1B, the compressor 103, the uncoated passive heat transfer device 104, the refrigerant reversing valve 105, and the fan 128 are located outside of the conditioned space within one or more housing structures and form the outdoor unit 102. The desiccant coated passive heat transfer devices 107 and 109, air directing valves 113, 114, 120 and 121, fans 115 and 122, and expansion valve 108 are located inside the conditioned space in one or more housing structures and form the indoor unit 101. The indoor space and the outdoor space are partitioned by a partition wall 125. The indoor unit 101 and the outdoor unit 102 are thermally connected by refrigerant lines 106 and 110 passing through the partition wall 125. In addition, the indoor unit 101 is physically connected to the air ducts 113 and 118 passing through the partition wall 125 to the outdoor space.

The system 100 operates in a cyclic manner, alternating between two modes of operation as shown in fig. 1A and 1B. During the first half cycle, the desiccant-coated passive heat transfer device 109 is in the process mode and the desiccant-coated passive heat transfer device 107 is in the regeneration mode. During the second half cycle, the roles of the desiccant-coated passive heat transfer device 109 and the desiccant-coated passive heat transfer device 107 are interchanged such that the desiccant-coated passive heat transfer device 109 is in the regeneration mode and the desiccant-coated passive heat transfer device 107 is in the treatment mode.

As a non-limiting example, the desiccant may comprise any suitable material that is apparent to those skilled in the art that is designed to capture moisture using a desiccant material such as silica gel, alumina, zeolite, or metal-organic framework (MOF) materials. Desiccant media comprising a variety of desiccant structures may be manufactured/applied based on known techniques and equipment, such as using a composite material comprising active desiccant powder embedded within a rigid binder material such as ceramic or plastic that does not affect the ability of the desiccant material to absorb moisture. Such desiccant media may be applied to heat exchangers using conventional coating or layering techniques, or otherwise applied to fins of, for example, heat exchange elements.

Fig. 1A shows a first half cycle of the operation of the system 100. The low pressure refrigerant in the first pressure state enters the compressor 103 and is compressed to a second pressure state (e.g., a high pressure state) higher than the first pressure state. The refrigerant then flows through the uncoated passive heat transfer device 104, releasing some of the heat to the ambient airflow 126. The refrigerant then flows through the refrigerant reversing valve 105 (configured to a first valve state) and is directed to the refrigerant line 106. The refrigerant then flows from the outdoor unit 102 through the refrigerant line 106 to the indoor unit 101. The refrigerant then flows through the desiccant coated passive heat transfer device 107 releasing some of the heat to the regeneration air stream 118. The refrigerant then flows through the expansion valve 108, and the expansion valve 108 changes the refrigerant from a high-pressure state to a low-pressure state. The refrigerant then flows through the desiccant-coated passive heat transfer device 109, absorbing some heat from the process air 111. The refrigerant then flows from the indoor unit 101 through the refrigerant line 110 to the outdoor unit 102. The refrigerant then flows through the reversing valve 105 (in the first valve state) and back to the compressor 103, completing the circuit.

Process air 111 to be cooled and dehumidified enters the indoor unit 101 through an air inlet 112 and is directed through an air directing valve 113 to the desiccant-coated passive heat transfer device 109. The process air passes over the exposed surfaces of the desiccant coated passive heat transfer device 109, thereby cooling and dehumidifying the air. Moisture from the air is absorbed onto the desiccant, increasing the moisture content of the desiccant. Heat absorbed from the desiccant is transferred by conduction to the passive heat transfer device 109 and to the refrigerant flowing therethrough. Sensible heat from the process gas stream is also transferred to the passive heat transfer device 109 and to the refrigerant flowing therethrough. The refrigerated and dehumidified air is then drawn through the air directing valve 114 by the process fan 115 and through the air outlet 116 to the conditioned space 117.

Regeneration air 118 enters the indoor unit 101 through an inlet duct 119 and is directed to the desiccant-coated passive heat transfer device 107 through an air directing valve 120. The regeneration air passes over the exposed surface of the desiccant coated passive heat transfer device 107. Heat is transferred from the refrigerant to the passive heat transfer device 107 and is transferred to the desiccant, desorbing moisture from the desiccant to the passing air. In this way, the desiccant regenerates, starting the next cycle. The regeneration air is then drawn through the air directing valve 121 by the fan 122 and through the outlet duct 123 to the outdoor space 124.

Ambient air 126 from the environment enters the outdoor unit 102 through an inlet 127. Air passes over the exposed surfaces of the passive heat transfer device 104. Heat is transferred from the refrigerant to the passive heat transfer device 104 and from the passive heat transfer device 104 to the air. Air is drawn from the passive heat transfer device 104 through the outlet 129 by the fan 128 and back to the outdoor space 130.

Fig. 1B illustrates a second half cycle of the operation of system 100. The low pressure refrigerant in the first pressure state enters the compressor 103 and is compressed to a second pressure state (e.g., a high pressure state) higher than the first pressure state. The refrigerant then flows through the uncoated passive heat transfer device 104, releasing some of the heat to the ambient airflow 126. The refrigerant then flows through the refrigerant reversing valve 105 (configured to a second valve state) and is directed to the refrigerant line 110. The refrigerant then flows from the outdoor unit 102 through the refrigerant line 110 to the indoor unit 101. The refrigerant then flows through the desiccant-coated passive heat transfer device 109, releasing some of the heat to the regeneration air stream 118. The refrigerant then flows through the expansion valve 108, and the expansion valve 108 changes the refrigerant from a high-pressure state to a low-pressure state. The refrigerant then flows through the desiccant-coated passive heat transfer device 107, absorbing some heat from the process air 111. The refrigerant then flows from the indoor unit 101 through the refrigerant line 106 to the outdoor unit 102. The refrigerant then flows through the reversing valve 105 (in the second valve state) and returns to the compressor 103, completing the circuit.

Process air 111 to be cooled and dehumidified enters the indoor unit 101 through an air inlet 112 and is directed to the desiccant-coated passive heat transfer device 107 through an air directing valve 113. The process air passes over the exposed surfaces of the desiccant coated passive heat transfer device 107, thereby cooling and dehumidifying the air. Moisture from the air is absorbed onto the desiccant, increasing the moisture content of the desiccant. Heat absorbed from the desiccant is transferred by conduction to the passive heat transfer device 107 and to the refrigerant flowing therethrough. Sensible heat from the process gas stream is also transferred to the passive heat transfer device 107 and to the refrigerant flowing therethrough. The refrigerated and dehumidified air is then drawn through an air directing valve 114 by a process fan 115 and through an air outlet 116 to an conditioned space 117.

Regeneration air 118 enters the indoor unit 101 through an inlet duct 119 and is directed to the desiccant-coated passive heat transfer device 109 through an air directing valve 120. The regeneration air passes over the exposed surfaces of the desiccant coated passive heat transfer device 109. Heat is transferred from the refrigerant to the passive heat transfer device 109 and onto the desiccant, desorbing moisture from the desiccant to the passing air. In this way, the desiccant regenerates, starting the next cycle. Regeneration air is drawn through the air directing valve 121 by the fan 122 and through the outlet duct 123 to the outdoor space 124.

In some embodiments of the system 100, a common fan is used to perform the functions of fans 115 and 122. In some embodiments of system 100, fan 122 may be positioned at any other location along the airflow path between 118 and 124, and similarly, fan 115 may be positioned at any other location along the airflow path between 111 and 117.

Fig. 2A and 2B illustrate schematic diagrams of an exemplary desiccant refrigeration and dehumidification system 200. In operation, the system 200 cycles between two modes of operation: a first mode (also referred to as a first half cycle) and a second mode (also referred to as a second half cycle). Fig. 2A shows a first operation mode, and fig. 2B shows a second operation mode. The system 200 includes: including a heat pump of a compressor 203, an uncoated passive heat transfer device 209, a refrigerant reversing valve 204, a desiccant coated first passive heat transfer device 206, a refrigerant flow directing and metering device 208, and a desiccant coated second passive heat transfer device 211. The system 200 also includes a first air directing valve 215, a second air directing valve 216, and a first fan 217. The system 200 further includes a first air duct 221, a third air directing valve 222, a fourth air directing valve 223, a second fan 224, and a second air duct 225. The system 200 also includes a third fan 230.

As shown in the example of fig. 2A and 2B, the compressor 203, the uncoated passive heat transfer device 209, the refrigerant flow directing and metering device 208, the refrigerant reversing valve 204, and the fan 230 are located outside of the conditioned space within one or more housing structures and form the outdoor device 202. The desiccant-coated passive heat transfer devices 206 and 211, the air directing valves 215, 216, 222, and 223, and the fans 217 and 224 are located inside the conditioned space within one or more housing structures and form the indoor unit 201. The indoor space and the outdoor space are partitioned by a partition wall 227. The indoor unit 201 and the outdoor unit 202 are thermally connected by refrigerant lines 205, 207, 210, and 212 passing through a partition wall 227. In addition, the indoor unit 201 is physically connected to the air pipes 221 and 225 passing through the partition wall 227 to the outdoor space.

The system 200 operates in a cyclic manner, alternating between two modes of operation as shown in fig. 2A and 2B. During the first half cycle, the desiccant-coated passive heat transfer device 211 is in the process mode and the desiccant-coated passive heat transfer device 206 is in the regeneration mode. During the second half cycle, the desiccant-coated passive heat transfer device 211 and the desiccant-coated passive heat transfer device 206 are inverted such that the desiccant-coated passive heat transfer device 211 is in the regeneration mode and the desiccant-coated passive heat transfer device 206 is in the treatment mode. In both modes, the refrigerant flow directing and metering device 208 passes high pressure refrigerant first through an uncoated passive heat transfer device 209 and then through an expansion valve included therein. Fig. 3 shows a possible embodiment of a refrigerant flow guiding and metering device 208.

Fig. 2A shows a first half cycle of the operation of system 200. The low pressure refrigerant in the first pressure state enters the compressor 203 and is compressed to a second pressure state (e.g., a high pressure state) higher than the first pressure state. The refrigerant then flows through the refrigerant reversing valve 204 (configured to a first valve state) and is directed to the refrigerant line 205. The refrigerant then flows from the outdoor unit 202 through the refrigerant line 205 to the indoor unit 201. The refrigerant then flows through the desiccant-coated passive heat transfer device 206, releasing some of the heat to the regeneration air stream 220. The refrigerant then flows from the indoor unit 201 through the refrigerant line 207 to the outdoor unit 202. The refrigerant then flows through the refrigerant flow directing and metering device 208 to the uncoated passive heat transfer device 209, releasing some of the heat to the ambient air stream 228, and then through an expansion valve in the refrigerant flow directing and metering device 208. The refrigerant then flows from the outdoor unit 202 through the refrigerant line 210 to the indoor unit 201. The refrigerant then flows through the desiccant-coated passive heat transfer device 211, absorbing some heat from the process air 213. The refrigerant then flows from the indoor unit 201 through the refrigerant line 212 to the outdoor unit 202. The refrigerant then flows through the reversing valve 204 (in the first valve state) and back to the compressor 203, completing the circuit.

Process air 213 to be cooled and dehumidified enters the indoor unit 201 through an air inlet 214 and is directed to the desiccant-coated passive heat transfer unit 211 through an air directing valve 215. The process air passes over the exposed surfaces of the desiccant coated passive heat transfer device 211, thereby cooling and dehumidifying the air. Moisture from the air is absorbed onto the desiccant, increasing the moisture content of the desiccant. Heat absorbed from the desiccant is transferred by conduction to the passive heat transfer device 211 and to the refrigerant flowing therethrough. Sensible heat from the process gas stream is also transferred to the passive heat transfer device 211 and to the refrigerant flowing therethrough. The refrigerated and dehumidified air is then drawn through an air directing valve 216 by a process fan 217 and through an air outlet 218 to an conditioned space 219.

Regeneration air 220 enters the indoor unit 201 through an inlet duct 221 and is directed to the desiccant-coated passive heat transfer device 206 through an air directing valve 222. The regeneration air passes over the exposed surface of the desiccant coated passive heat transfer device 206. Heat passes from the refrigerant to the passive heat transfer device 206 and onto the desiccant, desorbing moisture from the desiccant to the passing air. In this way, the desiccant regenerates, starting the next cycle. The regeneration air is then drawn through the air directing valve 223 by the fan 224 and through the outlet duct 225 to the outdoor space 226.

Ambient air 228 from the environment enters the outdoor unit 202 through the inlet 229. Air passes over the exposed surfaces of the passive heat transfer device 209. Heat is transferred from the refrigerant to the passive heat transfer device 209 and from the passive heat transfer device 209 to the air. Air is drawn from the passive heat transfer device 209 through the outlet 231 and back to the outdoor space 232 by the fan 230.

Fig. 2B illustrates a second half cycle of the operation of system 200. The low pressure refrigerant in the first pressure state enters the compressor 203 and is compressed to a second pressure state (e.g., a high pressure state) higher than the first pressure state. The refrigerant then flows through the refrigerant reversing valve 204 (configured to a second valve state) and is directed to the refrigerant line 212. The refrigerant then flows from the outdoor unit 202 through the refrigerant line 212 to the indoor unit 201. The refrigerant then flows through the desiccant-coated passive heat transfer device 211, releasing some of the heat to the regeneration air stream 220. The refrigerant then flows from the indoor unit 201 through the refrigerant line 210 to the outdoor unit 202. The refrigerant then flows through the refrigerant flow directing and metering device 208 to the uncoated passive heat transfer device 209, releasing some of the heat to the ambient air stream 228, and then through an expansion valve in the refrigerant flow directing and metering device 208. The refrigerant then flows from the outdoor unit 202 through the refrigerant line 207 to the indoor unit 201. The refrigerant then flows through the desiccant-coated passive heat transfer device 206, absorbing some heat from the process air 213. The refrigerant then flows from the indoor unit 201 through the refrigerant line 205 to the outdoor unit 202. The refrigerant then flows through the reversing valve 204 (in the second valve state) and returns to the compressor 203, completing the circuit.

Process air 213 to be cooled and dehumidified enters the indoor unit 201 through an air inlet 214 and is directed to the desiccant-coated passive heat transfer device 206 through an air directing valve 215. The process air passes over the exposed surfaces of the desiccant coated passive heat transfer device 206, thereby cooling and dehumidifying the air. Moisture from the air is absorbed onto the desiccant, increasing the moisture content of the desiccant. Heat absorbed from the desiccant is transferred by conduction to the passive heat transfer device 206 and to the refrigerant flowing therethrough. Sensible heat from the process gas stream is also transferred to the passive heat transfer device 206 and to the refrigerant flowing therethrough. The refrigerated and dehumidified air is then drawn through an air directing valve 216 by a process fan 217 and through an air outlet 218 to an conditioned space 219.

Regeneration air 220 enters the indoor unit 201 through inlet duct 221 and is directed to the desiccant-coated passive heat transfer device 211 through air directing valve 222. The regeneration air passes over the exposed surface of the desiccant coated passive heat transfer device 211. Heat is transferred from the refrigerant to the passive heat transfer device 211 and onto the desiccant, desorbing moisture from the desiccant to the passing air. In this way, the desiccant regenerates, starting the next cycle. The regeneration air is then drawn through the air directing valve 223 by the fan 224 and through the outlet duct 225 to the outdoor space 226.

In some embodiments of the system 200, the refrigerant flow directing and metering device 208 is located within the indoor device 201 rather than the outdoor device 202.

In some embodiments of systems 100 and 200, the air switching valves are arranged in an alternative configuration such that two intake valves are arranged to select between return air from the conditioned space and outside air through the intake duct. Furthermore, two outlet valves are arranged to select between an air conditioned space supply duct and the passage of exhaust air to the outside air. In this embodiment, each desiccant-coated passive heat transfer device is associated with a single inlet valve and a single outlet valve.

Fig. 3A and 3B illustrate schematic diagrams of an exemplary desiccant refrigeration and dehumidification system 300. In operation, the system 300 cycles between two modes of operation: a first mode (also referred to as a first half cycle) and a second mode (also referred to as a second half cycle). Fig. 3A shows a first operation mode, and fig. 3B shows a second operation mode. The system 300 includes: a heat pump comprising a compressor 304, an uncoated passive heat transfer device 305, a refrigerant reversing valve 307, a desiccant coated passive heat transfer device 320, an expansion valve 308, and an uncoated second passive heat transfer device 310. The system 300 further includes a first air directing valve 319, a second air directing valve 322, and a first fan 321. The system 300 also includes air ducts 331 and 332, a second fan 327, and a third fan 314.

As shown in the example of fig. 3A and 3B, the compressor 304, the uncoated passive heat transfer device 305, and the fan 327 are located outside of the conditioned space within one or more housing structures and form the outdoor device 303. The desiccant-coated passive heat transfer device 320, air directing valves 319 and 322, fan 321, reversing valve 307, and expansion valve 308 are located inside the conditioned space in one or more housing structures and form the indoor unit 302. The uncoated passive heat transfer device 310 and fan 314 are located inside the conditioned space in one or more housing structures and form the indoor unit 301. The indoor space and the outdoor space are partitioned by a partition wall 334. The indoor unit 301 is thermally connected to the indoor unit 302 by a refrigerant line 335. The indoor unit 301 is thermally connected to the outdoor unit 303 through a refrigerant line 311 passing through the partition wall 334. The indoor unit 302 is thermally connected to the outdoor unit 303 through the refrigerant line 306 passing through the partition wall 334. In addition, the indoor unit 302 is physically connected to the air pipes 331 and 332 passing through the partition wall 334 to the outdoor space.

The system 300 operates in a cyclic manner, alternating between two modes of operation as shown in fig. 3A and 3B. During the first half cycle, the desiccant-coated passive heat transfer device 320 is in the process mode. During the second half cycle, the desiccant-coated passive heat transfer device 320 is in a regeneration mode.

Fig. 3A illustrates a first half cycle of the operation of system 300. The low pressure refrigerant at the first pressure state enters the compressor 304 and is compressed to a second pressure state (e.g., a high pressure state) that is higher than the first pressure state. The refrigerant then flows through the uncoated passive heat transfer device 305, releasing some of the heat to the ambient airflow 325. The refrigerant then flows from the outdoor unit 303 through the refrigerant line 306 to the indoor unit 302. The refrigerant then flows through the reversing valve 307 (configured to a first valve state) and is directed to the expansion valve 308, the expansion valve 308 changing the refrigerant from a high pressure state to a low pressure state. The refrigerant then flows through the desiccant-coated passive heat transfer device 320, absorbing some heat from the process air 317. The refrigerant then flows through the reversing valve 307 (in the first valve state) and is directed to the refrigerant line 335. Refrigerant flows from indoor unit 302 through refrigerant line 335 to indoor unit 301. The refrigerant then flows through the uncoated passive heat transfer device 310, absorbing heat from the process air 312. The refrigerant then flows from the indoor unit 301 through the refrigerant line 311 to the outdoor unit 303 and returns to the compressor 304, thereby completing the refrigerant circuit.

The process air 312 to be cooled enters the indoor unit 301 through the air inlet 313 and passes over the exposed surfaces of the uncoated passive heat transfer unit 310, thereby cooling the air.

Process air 317 to be cooled and dehumidified enters the indoor unit 302 through an air inlet 318 and is directed to a desiccant-coated passive heat transfer device 320 through an air directing valve 319. The process air passes over the exposed surfaces of the desiccant coated passive heat transfer device 320, thereby cooling and dehumidifying the air. Moisture from the air is absorbed onto the desiccant, increasing the moisture content of the desiccant. Heat absorbed from the desiccant is transferred by conduction to the passive heat transfer device 320 and to the refrigerant flowing therethrough. Sensible heat from the process gas stream is also transferred to the passive heat transfer device 320 and to the refrigerant flowing therethrough. Then, the cooled and dehumidified air is blown through the air guide valve 322 by the processing fan 321, and passes through the air outlet 323 to the air-conditioned space 324.

Ambient air 325 from the environment enters the outdoor unit 303 through inlet 326. Air passes over the exposed surfaces of the passive heat transfer device 305. Heat is transferred from the refrigerant to the passive heat transfer device 305 and from the passive heat transfer device 305 to the air. Air is drawn from the passive heat transfer device 305 through the outlet 328 and back to the outdoor space 329 by the fan 327.

Fig. 3B illustrates a second half-cycle operation of the system 300. The low pressure refrigerant at the first pressure state enters the compressor 304 and is compressed to a second pressure state (e.g., a high pressure state) that is higher than the first pressure state. The refrigerant then flows through the uncoated passive heat transfer device 305, releasing some of the heat to the ambient airflow 325. The refrigerant then flows from the outdoor unit 303 through the refrigerant line 306 to the indoor unit 302. The refrigerant then flows through the reversing valve 307 (configured to a second valve state) and is directed to the desiccant-coated passive heat transfer device 320. The refrigerant then flows through the desiccant-coated passive heat transfer device 320, releasing some of the heat to the regeneration air stream 333. The refrigerant then flows through the expansion valve 308, and the expansion valve 308 changes the refrigerant from a high pressure state to a low pressure state. The refrigerant then flows through the reversing valve 307 (in the second valve state) and is directed to the refrigerant line 335. Refrigerant flows from indoor unit 302 through refrigerant line 335 to indoor unit 301. The refrigerant then flows through the uncoated passive heat transfer device 310, absorbing heat from the process air 312. The refrigerant then flows from the indoor unit 301 through the refrigerant line 311 to the outdoor unit 303 and returns to the compressor 304, thereby completing the refrigerant circuit.

Regeneration air 333 enters the indoor unit 302 through the inlet duct 332 and is directed to the desiccant-coated passive heat transfer device 320 through the air directing valve 319. The regeneration air passes over the exposed surface of the desiccant coated passive heat transfer device 320. Heat is transferred from the refrigerant to the passive heat transfer device 320 and onto the desiccant, desorbing moisture from the desiccant to the passing air. In this way, the desiccant regenerates, starting the next cycle. Then, the regeneration air is blown through the air guide valve 322 by the fan 321, and reaches the outdoor space 330 through the outlet duct 331.

In some embodiments of the system 300, the indoor units 301 and 302 may be combined within a common housing structure. Various embodiments are possible in which the devices 301, 302 and 303 are located inside or outside the conditioned space as separate devices or are combined in a common housing structure. In some modes of operation of the system 300, the uncoated passive heat transfer device 310 may operate below the dew point of the process air 312. Such an operating mode allows the uncoated passive heat transfer device 310 to dehumidify and cool the process air 312. In some embodiments, an additional expansion valve is added to the refrigerant line 335 between the reversing valve 307 and the uncoated passive heat transfer device 310.

Fig. 4A and 4B illustrate schematic diagrams of an exemplary desiccant refrigeration and dehumidification system 400. In operation, the system 400 cycles between two modes of operation: a first mode (also referred to as a first half cycle) and a second mode (also referred to as a second half cycle). Fig. 4A shows a first operation mode, and fig. 4B shows a second operation mode. The system 400 includes: a heat pump comprising a compressor 402, a refrigerant reversing valve 403, a desiccant coated first passive heat transfer device 406, an expansion valve 405, and a desiccant coated second passive heat transfer device 404. The system 400 also includes a first air directing valve 409, a second air directing valve 415, a first fan 410, a second fan 416, and an air duct 419.

As shown in the examples of fig. 4A and 4B, all components are located inside an air conditioning space within one or more housing structures and form an indoor unit 401. The indoor space and the outdoor space are partitioned by a partition wall 417. The indoor unit 401 is physically connected to an air duct 419 passing through the partition wall 417 to the outdoor space.

The system 400 operates in a cyclical manner, alternating between two modes of operation as shown in fig. 4A and 4B. During the first half cycle, the desiccant-coated passive heat transfer device 404 is in the process mode and the desiccant-coated passive heat transfer device 406 is in the regeneration mode. During the second half cycle, the desiccant-coated passive heat transfer device 404 is in the regeneration mode and the passive heat transfer device 406 is in the process mode.

Fig. 4A shows a first half cycle of the operation of system 400. The low pressure refrigerant at the first pressure state enters the compressor 402 and is compressed to a second pressure state (e.g., a high pressure state) that is higher than the first pressure state. The refrigerant then flows through the reversing valve 403 (configured to a first valve state) and is directed to the desiccant-coated passive heat transfer device 406. The refrigerant then flows through the desiccant-coated passive heat transfer device 406, releasing some of the heat to the regeneration air stream 413. The refrigerant then flows through the expansion valve 405, and the expansion valve 405 changes the refrigerant from a high-pressure state to a low-pressure state. The refrigerant then flows through the desiccant-coated passive heat transfer device 404, absorbing some heat from the process air 407. The refrigerant then flows through the reversing valve 403 (in the first valve state) and returns to the compressor 402, completing the refrigerant circuit.

Process air 407 to be cooled and dehumidified enters the indoor unit 401 through air inlet 408. The process air passes over the exposed surfaces of the desiccant coated passive heat transfer device 404, thereby cooling and dehumidifying the air. Moisture from the air is absorbed onto the desiccant, increasing the moisture content of the desiccant. Heat absorbed from the desiccant is transferred by conduction to the passive heat transfer device 404 and to the refrigerant flowing therethrough. Sensible heat from the process gas stream is also transferred to the passive heat transfer device 404 and to the refrigerant flowing therethrough. The refrigerated and dehumidified air is then drawn through the air directing valve 409 by the processing fan 410 and through the air outlet 411 to the conditioned space 412.

Regeneration air 413 enters the indoor unit 401 through inlet duct 414. The regeneration air passes over the exposed surface of the desiccant coated passive heat transfer device 406. Heat is transferred from the refrigerant to the passive heat transfer device 406 and onto the desiccant, desorbing moisture from the desiccant to the passing air. In this way, the desiccant regenerates, starting the next cycle. The regeneration air is then drawn through the air directing valve 415 by the fan 416 and through the outlet duct 418 to the outdoor space 419.

Fig. 4B illustrates a second half cycle of the operation of system 400. The low pressure refrigerant at the first pressure state enters the compressor 402 and is compressed to a second pressure state (e.g., a high pressure state) that is higher than the first pressure state. The refrigerant then flows through the reversing valve 403 and is directed to the desiccant-coated passive heat transfer device 404. The refrigerant then flows through the desiccant coated passive heat transfer device 404, releasing some of the heat to the regeneration air stream 407. The refrigerant then flows through the expansion valve 405, and the expansion valve 405 changes the refrigerant from a high-pressure state to a low-pressure state. The refrigerant then flows through the desiccant-coated passive heat transfer device 406, absorbing some heat from the process air 413. The refrigerant then flows through the reversing valve 403 (configured to a second valve state) and back to the compressor 402, completing the refrigerant circuit.

Process air 413 to be cooled and dehumidified enters the indoor unit 401 through the air inlet 414. The process air passes over the exposed surfaces of the desiccant coated passive heat transfer device 406, thereby cooling and dehumidifying the air. Moisture from the air is absorbed onto the desiccant, increasing the moisture content of the desiccant. Heat absorbed from the desiccant is transferred by conduction to the passive heat transfer device 406 and to the refrigerant flowing therethrough. Sensible heat from the process gas stream is also transferred to the passive heat transfer device 406 and to the refrigerant flowing therethrough. The refrigerated and dehumidified air is then drawn through the air directing valve 415 by the processing fan 410 and through the air outlet 411 to the conditioned space 412.

Regeneration air 407 enters the indoor unit 401 through inlet duct 408. The regeneration air passes over the exposed surface of the desiccant coated passive heat transfer device 404. Heat is transferred from the refrigerant to the passive heat transfer device 404 and onto the desiccant, desorbing moisture from the desiccant to the passing air. In this way, the desiccant regenerates, starting the next cycle. Regeneration air is then drawn through the air directing valve 409 by the fan 416 and through the outlet duct 418 to the outdoor space 419.

In some embodiments of system 400, air inlets 408 and 414 are shared and process air is diverted to passive heat transfer devices 404 and 406 after entering the device. In some embodiments of the system 400, all or some of the components of the apparatus are located outside the conditioned space and exchange of air with the indoor space is accomplished by additional piping through the dividing wall 417. In some embodiments of the system 400, a second conduit through the partition 417 and two additional air directing valves are included so that in regeneration mode air is provided from the outdoor space rather than from the indoor space.

In some embodiments of systems 100 through 400, a liquid line suction line heat exchanger is used. The direction of air flow through the desiccant coated passive heat transfer devices schematically illustrated in systems 100 through 400 is arbitrary. Specifically, each system includes such embodiments: wherein the direction of the air flow through the desiccant-coated passive heat transfer device is the same (parallel flow) in both modes of operation, and wherein the direction of the air flow through the desiccant-coated passive heat transfer device is reversed (opposite flow) between the first mode of operation and the second mode of operation.

Fig. 5A-5D show details of two embodiments of the refrigerant flow directing and metering device 208 in two modes of operation. Fig. 5A shows embodiment a in mode 1. Fig. 5B shows embodiment a in mode 2. Fig. 5C shows embodiment B in mode 1. Fig. 5D shows embodiment B in mode 2. Embodiment a includes refrigerant check valves 502, 503, 506, and 508, expansion valve 509, and refrigerant lines 501, 504, 505, and 507. Embodiment B includes refrigerant check valves 510 and 515, expansion valves 511 and 514, and refrigerant lines 510, 514, 516, and 517.

As shown in fig. 5A, in mode 1 of embodiment a, high-pressure refrigerant enters the device through a refrigerant line 501. The refrigerant passes through the check valve 502 and is prevented from passing through the check valve 503. Refrigerant exits device 208 through refrigerant line 504. High pressure refrigerant enters the device through refrigerant line 505 and then passes through an expansion valve 509, the expansion valve 509 changing the refrigerant from a high pressure state to a low pressure state. The low pressure refrigerant then passes through check valve 506 and is prevented from passing through check valve 508. The refrigerant then exits the device 208 through refrigerant line 507.

As shown in fig. 5B, in mode 2 of embodiment a, high-pressure refrigerant enters the device through refrigerant line 507. The refrigerant passes through check valve 508 and is prevented from passing through check valve 506. Refrigerant exits device 208 through refrigerant line 504. High pressure refrigerant enters the device through refrigerant line 505 and then passes through an expansion valve 509, the expansion valve 509 changing the refrigerant from a high pressure state to a low pressure state. The low pressure refrigerant then passes through check valve 503 and is prevented from passing through check valve 502. The refrigerant then exits the device 208 through refrigerant line 501.

As shown in fig. 5C, in mode 1 of embodiment B, high-pressure refrigerant enters the device through refrigerant line 517. The refrigerant passes through the check valve 510. Refrigerant exits the device 208 through refrigerant line 512. High pressure refrigerant enters the device through refrigerant line 513. The refrigerant is prevented from passing through the check valve 515, but rather through the expansion valve 514, and the expansion valve 514 changes the refrigerant from a high pressure state to a low pressure state. The low pressure refrigerant then exits the device 208 through refrigerant line 516.

As shown in fig. 5D, in mode 2 of embodiment B, high pressure refrigerant enters the device through refrigerant line 516. The refrigerant passes through the check valve 515. The refrigerant exits the device 208 through refrigerant line 513. High pressure refrigerant enters the device through refrigerant line 512. The refrigerant is prevented from passing through the check valve 510 but passes through the expansion valve 511, and the expansion valve 511 changes the refrigerant from the high pressure state to the low pressure state. The low pressure refrigerant then exits device 208 through refrigerant line 517.

Fig. 6A and 6B illustrate, in cross-section, two modes of operation of one embodiment of an indoor unit of the system 100, 200, 300, or 400. In this embodiment, the desiccant-coated passive heat transfer device is a finned tube heat exchanger, the fins of the heat exchanger are partially coated with desiccant, and the fan is a cross-flow fan.

As shown in fig. 6A, in mode 1, the heat exchanger 604 is in the process mode. Return air 601 from the conditioned space enters the device 600 through an opening 602 and passes through an air directing valve 603 in a first position to a heat exchanger 604. The air is first exposed to the uncoated fin surface 610, thereby refrigerating the air. At surface 610, sensible heat is transferred from the air to heat exchanger 604 and to the refrigerant flowing therethrough. The air is then exposed to the desiccant coated fin surfaces 605, thereby cooling and dehumidifying the air. At the surface 605, moisture from the air is absorbed onto the desiccant, increasing the moisture content of the desiccant. Heat absorbed from the desiccant is transferred by conduction to the heat exchanger 604 and to the refrigerant flowing therethrough. Sensible heat from the process gas stream is also transferred to the heat exchanger 604 and to the refrigerant flowing therethrough. Air is then drawn through the cross-flow fan 606 and through the air-directing valve 607 in the first position through the opening 608 to the conditioned space 609.

As shown in fig. 6B, in mode 2, the heat exchanger 604 is in a regeneration mode. Outdoor air 614 enters the device 600 through opening 611 and passes through the air directing valve 603 in the second position to the heat exchanger 604. The air is first exposed to the uncoated fin surface 610, thereby heating the air. At surface 610, sensible heat is transferred from the refrigerant flowing through heat exchanger 604 to exposed surface 610 and on to the air. The air is then exposed to the desiccant coated fin surface 605, thereby heating and humidifying the air. At surface 605, heat is transferred from the refrigerant flowing through heat exchanger 604 to the desiccant coated on surface 605, desorbing moisture from the desiccant to the passing air. Then, the air is drawn through the cross flow fan 606 and through the air guide valve 607 in the second position through the opening 612 to the outdoor space 613.

In some embodiments of the apparatus 600, when the heat exchanger 604 is in the treatment mode, the additional mode of operation allows outdoor air to be drawn from the ambient air 614 through the opening 611 to cool and ventilate the air space.

In the examples described above, according to various examples, at least a portion or the entire surface of the surface of any of the passive heat transfer device(s) described above may be at least partially or completely coated with a desiccant material. In one example, the surface of the passive heat transfer device may be covered by the desiccant material by between at least one tenth (e.g., 10% coverage) and up to full coverage (100% coverage), or any coverage value between the ranges described.

Fig. 7 depicts a control method for a desiccant refrigeration and dehumidification system as described in the above examples. In an example, the method may be implemented by a process (processor) and a non-transitory storage medium (e.g., memory) having instructions stored thereon and configured to be executed by the processor. At start-up 701, the system measures the temperature and humidity 702 of the indoor and outdoor spaces. These measurements are used to set system parameters 703 for the default mode of operation. During the default mode of operation, the temperature and humidity at the inlet and outlet of each desiccant-coated passive heat transfer device are measured. After a period of time, the desiccant of the process stream will become saturated and the rate at which moisture is removed from the process gas stream will decrease. At this point, the outlet humidity ratio will be close to the inlet humidity ratio. The control system records this as the desired desiccant loading time 704. Similarly, over time, the desiccant of the regeneration stream will become unsaturated and the rate of moisture addition to the regeneration gas stream will decrease. At this point, the outlet humidity ratio will be close to the inlet humidity ratio. The control system records this as the desired desiccant unloading time 704.

When the system is operating in the default mode 703, the indoor temperature and humidity are measured over time and the sensible and latent loads are determined 705. In one mode of operation, the sensible cooling is adjusted to match the sensible load, and the latent cooling is adjusted to match the latent load. In one embodiment, the sensible cooling is adjusted by adjusting the speed of the process fan. In one embodiment, the sub-cooling is adjusted by adjusting a process duty cycle, which is defined as the required loading time relative to the switching time. In the preferred mode of operation, the desired desiccant unloading time is adjusted to be equal to the switching time by controlling the compressor speed and the regeneration fan speed.

The foregoing is a detailed description of illustrative embodiments of the invention. Various modifications and additions may be made without departing from the spirit and scope of the invention. The features of the various embodiments described above may be suitably combined with the features of the other described embodiments in order to provide various combinations of features in the associated new embodiments. Furthermore, while the foregoing describes several separate embodiments of the apparatus and method of the present invention, what is described herein is merely illustrative of the application of the principles of the invention. For example, as used herein, the terms "process" and/or "processor" should be broadly understood to include various electronic hardware and/or software based functions and components (and may alternatively be referred to as functional "modules" or "elements"). Furthermore, the depicted processes or processors may be combined with other processes and/or processors or separated into various sub-processes or processors. Such sub-processes and/or sub-processors may be variously combined according to embodiments herein. Likewise, it is expressly contemplated that any of the functions, processes, and/or processors herein can be implemented using electronic hardware, software, including non-transitory computer-readable media of program instructions, or a combination of hardware and software. In addition, various directional and arrangement terms, such as "vertical," "horizontal," "upper," "lower," "bottom," "top," "side," "front," "rear," "left," "right," and the like, as used herein are used merely as relative conventions and are not used as absolute directions/arrangements with respect to a fixed coordinate space (e.g., the direction of action of gravity). Furthermore, when the term "substantially" or "about" is used with respect to a given measurement, value or characteristic, it refers to an amount that is within the normal operating range to achieve the desired result, but includes some variation due to inherent inaccuracies and errors (e.g., 1% to 5%) within the allowable tolerances of the system. Accordingly, this description is made only by way of example and not to otherwise limit the scope of the invention.

What is claimed is as the following claims.

Claims

1. An air treatment system, comprising:

a heat pump configured to move thermal energy between a plurality of passive heat transfer devices;

the plurality of passive heat transfer devices defining a first surface of at least one of the plurality of passive heat transfer devices in thermal contact with the heat pump and a second surface of at least one of the plurality of passive heat transfer devices exposed to allow transfer of heat to or from the heat pump;

a desiccant in thermal contact with an exposed surface of the at least one passive heat transfer device and configured to exchange moisture with air;

a plurality of air directing valves configured to direct process air and regeneration air to and from the plurality of passive heat transfer devices with desiccant;

a heat pump reversing device configured to change a direction of heat flow in the heat pump between two modes of operation;

a control system having a communication line for controlling the air-directing valve, the reversing device and the heat pump operation; and

a control operation process that operates a control mode in which the desiccant regeneration time is adjusted.

2. The system of claim 1, wherein the passive heat transfer device comprises a tube and fin heat exchanger or a microchannel heat exchanger.

3. The system of claim 2, wherein the desiccant forms a coating on the exposed surfaces of the heat exchanger fins.

4. The system of claim 3, wherein the desiccant forms a partial coating, wherein an uncoated portion is first exposed to an air stream, and a second portion of the coated desiccant is then exposed to the air stream.

5. The system of claim 1, further comprising a passive heat transfer device without desiccant configured to exchange sensible heat with ambient air.

6. The system of claim 1, further comprising a passive heat transfer device without desiccant configured to exchange sensible heat with indoor air.

7. The system of claim 1, wherein the desiccant comprises at least one of a silica gel, an aluminum oxide, a zeolite, or a Metal Organic Framework (MOF) material.

8. A method for treating air in a space, comprising the steps of:

moving thermal energy between a plurality of passive heat transfer devices using a heat pump, wherein a first surface of at least one of the plurality of passive heat transfer devices is in thermal contact with the heat pump and a second surface of at least one of the plurality of passive heat transfer devices is exposed to allow transfer of heat to or from the heat pump;

Providing a desiccant in thermal contact with an exposed surface of the at least one passive heat transfer device and configured to exchange moisture with air;

directing process air and regeneration air through a plurality of air directing valves to and from the plurality of passive heat transfer devices with desiccant;

changing the direction of heat flow in the heat pump between two modes of operation; and

the plurality of air directing valves, the reversing device, and the heat pump are controlled to operate in a control mode of operation to adjust desiccant regeneration time.

9. The method of claim 8, wherein the passive heat transfer device comprises a tube and fin heat exchanger or a microchannel heat exchanger.

10. The method of claim 9, wherein the desiccant forms a coating on the exposed surfaces of the heat exchanger fins.

11. The method of claim 10, wherein the desiccant forms a partial coating, the uncoated portion being exposed to the airflow first, and the second portion of the coated desiccant being exposed to the airflow subsequently.

12. The method of claim 8, further comprising exchanging sensible heat with ambient air using a passive heat transfer device without a desiccant.

13. The method of claim 8, further comprising exchanging sensible heat with indoor air using a passive heat transfer device without a desiccant.

14. The method of claim 8, wherein the desiccant comprises at least one of silica gel, aluminum oxide, zeolite, or metal-organic framework (MOF) material.