Refrigeration apparatus
The refrigeration device addresses compressor unreliability in adsorption-type cycles by continuously operating the compressor and managing pressure through state transitions and valve adjustments, ensuring stable operation.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2025-09-30
- Publication Date
- 2026-04-02
AI Technical Summary
Refrigeration systems with adsorption-type cycles face reliability issues due to repeated starting and stopping of the compressor, leading to potential compressor unreliability.
A refrigeration device with a refrigerant flow path, compressor, adsorbers, switching mechanism, bypass flow path, and control unit that allows continuous operation by alternating the refrigerant flow path states and adjusting compressor rotational speed and bypass valve opening to maintain stable pressures.
The solution maintains compressor reliability by continuously driving the compressor and controlling pressures within a predetermined range, preventing repeated start-stop cycles.
Smart Images
Figure JP2025034578_02042026_PF_FP_ABST
Abstract
Description
Refrigeration equipment
[0001] Regarding refrigeration equipment.
[0002] Conventionally, refrigeration systems equipped with adsorption-type refrigeration cycles have been used. As such a refrigeration system, Patent Document 1 (U.S. Patent Application Publication No. 2023 / 0417459) discloses a refrigeration system comprising a heat source side circuit having a pair of adsorbents that alternately adsorb and desorb a refrigerant, and a utilization side circuit through which a heat transfer medium circulates for recovering the heat of adsorption or desorption of the refrigerant. In the heat source side circuit, a mode in which the refrigerant is adsorbed by one adsorbent and desorbed by the other adsorbent is alternately switched between a mode in which the refrigerant is desorbed by the one adsorbent and adsorbed by the other adsorbent. As a result, heat is continuously recovered from the heat source side circuit by the heat transfer medium in the utilization side circuit.
[0003] If the compressor is stopped each time the heat source circuit mode is switched, the compressor may become unreliable due to repeated starting and stopping of the compressor during refrigeration operation.
[0004] The refrigeration device of the first aspect includes a refrigerant flow path through which refrigerant flows, a compressor, a first adsorber, a second adsorber, a switching mechanism, a bypass flow path, a bypass valve, and a control unit. The compressor sucks in and compresses low-pressure refrigerant and discharges it as high-pressure refrigerant. The first adsorber and the second adsorber have an adsorbent that adsorbs and desorbs refrigerant in response to changes in the pressure of the refrigerant. In the first adsorber and the second adsorber, the heat generated when the adsorbent adsorbs the refrigerant and the cold heat generated when the adsorbent desorbs the refrigerant are recovered. The bypass flow path connects the first adsorber and the second adsorber without passing through the compressor. The bypass valve is provided in the bypass flow path. The bypass valve can adjust its opening degree. The control unit controls the switching mechanism and the bypass valve to be able to switch the refrigerant flow path among a first state, a second state, and a third state. The first state is a state in which the inside of the first adsorber is in a high-pressure state and the inside of the second adsorber is in a low-pressure state. The second state is a state in which the inside of the first adsorber is in a low-pressure state and the inside of the second adsorber is in a high-pressure state. The third state is a state in which the opening degree of the bypass valve is a first opening degree and the first adsorber and the second adsorber are in communication. The control unit repeatedly executes a first cycle operation of sequentially switching the refrigerant flow path in the order of the first state, the third state, the second state, and the third state. The control unit continuously drives the compressor during the execution of the first cycle operation.
[0005] Since the refrigeration device of the first aspect can continuously drive the compressor, it is possible to suppress a decrease in the reliability of the compressor.
[0006] The refrigeration device of the second aspect is the refrigeration device of the first aspect, and the control unit changes the rotational speed of the compressor during the execution of the first cycle operation.
[0007] The refrigeration device of the second aspect can maintain the reliability of the compressor and execute control based on a predetermined capacity by controlling the rotational speed of the compressor to maintain the pressures inside the first adsorber and the second adsorber within a predetermined range.
[0008] The refrigeration apparatus of the third aspect is the refrigeration apparatus of the second aspect, wherein the control unit makes the average rotational speed of the compressor in the first period higher than the average rotational speed of the compressor in the second period following the first period, while the refrigerant flow path is in the first or second state. The first period includes the time when the first or second state begins. The second period includes the time when the first or second state ends.
[0009] The refrigeration system of the fourth aspect is a refrigeration system of the second or third aspect, wherein the control unit reduces the rotational speed of the compressor when the pressure in the first or second adsorbent reaches a predetermined value while the refrigerant flow path is in the first or second state.
[0010] The refrigeration system of the fifth aspect is a refrigeration system of any one of the second to fourth aspects, wherein the control unit makes the average rotational speed of the compressor when the refrigerant flow path is in the first or second state higher than the rotational speed of the compressor when the refrigerant flow path is in the third state.
[0011] The refrigeration system of the sixth aspect is a refrigeration system of any one of the second to fifth aspects, wherein the control unit changes the opening degree of the bypass valve during the execution of the first cycle operation. The control unit sets the opening degree of the bypass valve to zero for a predetermined period including the time when the first or second state begins, while the refrigerant flow path is in the first or second state.
[0012] The refrigeration system in the sixth aspect can maintain the reliability of the compressor while performing control based on a predetermined capacity by controlling the opening degree of the bypass valve to maintain the pressure in the first and second adsorbents within a predetermined range.
[0013] The refrigeration system of the seventh aspect is the refrigeration system of the sixth aspect, wherein the control unit performs a first control, which reduces the rotational speed of the compressor while the refrigerant flow path is in a first or second state. The control unit performs a second control, which increases the opening degree of the bypass valve from zero while the refrigerant flow path is in a first or second state. The control unit starts the second control after starting the first control.
[0014] The refrigeration apparatus of the eighth aspect is the refrigeration apparatus of the seventh aspect, wherein the control unit starts the second control when the pressure in the first adsorbent or the second adsorbent reaches a predetermined value.
[0015] The refrigeration system of the ninth aspect is a refrigeration system of the seventh or eighth aspect, wherein the control unit starts the second control after the compressor rotation speed has decreased to a first value during the execution of the first control.
[0016] The refrigeration device of the tenth aspect is a refrigeration device of any one of the seventh to ninth aspects, wherein the control unit, when executing the second control, raises the opening degree of the bypass valve from zero to a second opening degree that is smaller than the first opening degree.
[0017] The refrigeration apparatus of the 11th aspect is a refrigeration apparatus of any one of the seventh to tenth aspects, wherein the control unit starts the second control when the pressure in the first adsorbent rises to a second value or the pressure in the second adsorbent falls to a third value while the refrigerant flow path is in a first state. The control unit starts the second control when the pressure in the second adsorbent rises to a second value or the pressure in the first adsorbent falls to a third value while the refrigerant flow path is in a second state.
[0018] The refrigeration apparatus of the twelfth aspect is a refrigeration apparatus of any one of the seventh to eleventh aspects, wherein the control unit performs a first control so as to increase the pressure in the first adsorbent while the refrigerant flow path is in a first state. The control unit performs a first control so as to increase the pressure in the second adsorbent while the refrigerant flow path is in a second state.
[0019] The refrigeration apparatus of the 13th aspect is a refrigeration apparatus of any one of the first to 12th aspects, wherein the adsorbent includes a metal-organic structure containing a metal ion and an organic ligand.
[0020] The refrigeration apparatus of the 14th aspect is a refrigeration apparatus of any one of the first to 13th aspects, wherein the refrigerant includes at least one of carbon dioxide, hydrocarbons, ammonia, water, HFCs, and HFOs.
[0021] This is a schematic diagram of the refrigeration device 100 of the first embodiment. This is a block diagram of the refrigeration device 100 of the first embodiment. This is a schematic diagram of the first adsorbent 121 and the second adsorbent 122 of the first embodiment. This is a control time chart of the refrigeration device 100 of the first embodiment. This is a control time chart of the refrigeration device 100 of the second embodiment. This is a control time chart of the refrigeration device 100 of the third embodiment. This is a control flowchart of the first and second states of the third embodiment. This is a control flowchart of the third state of the third embodiment.
[0022] —First Embodiment— (1) Overall Configuration of the Refrigeration System 100 The refrigeration system 100 of the first embodiment includes, as shown in Figure 1, a heat source side circuit 101, a utilization side circuit 102, a first fan 143, and a second fan 153. The heat source side circuit 101 has a refrigerant flow path 111 through which the refrigerant flows. The utilization side circuit 102 has a heat medium flow path 112 through which the heat medium flows. In Figure 1, the refrigerant flow path 111 is drawn with a thick line. The refrigeration system 100 is, for example, an air conditioning system. When the refrigeration system 100 is an air conditioning system, one of the first fan 143 and the second fan 153 is provided in the indoor unit, and the other is provided in the outdoor unit.
[0023] The refrigerant flowing through the refrigerant channel 111 includes at least one of carbon dioxide, hydrocarbons, ammonia, water, HFCs (hydrofluorocarbons), and HFOs (hydrofluoroolefins). The hydrocarbons are selected from the group consisting of, for example, propane, butane, and isobutane.
[0024] The heat transfer medium flowing through the heat transfer medium channel 112 is selected from the group consisting of, for example, water, brine, and air. Brine is a liquid with a freezing point of 0°C or lower.
[0025] The refrigeration system 100 further includes a control unit 105. As shown in Figure 2, the control unit 105 controls the operation of each element constituting the heat source side circuit 101 and the utilization side circuit 102. Here, a processor is given as an example of the control unit 105. The processor consists of various computing devices such as a CPU (Central Processing Unit), DSP (Digital Signal Processor), FPGA (Field-Programmable Gate Array), and GPU (Graphics Processing Unit). The processor reads various programs of the device into memory and executes them. The processor loads the programs stored in memory into the working area of the memory and executes them, and by controlling each component through the execution of the programs, it realizes functions that match a predetermined purpose.
[0026] (1-1) Heat source circuit 101 The heat source circuit 101 constitutes a refrigeration cycle that functions as a heat pump utilizing the heat (warmth or coldness) generated when the refrigerant is adsorbed or desorbed onto the adsorbent. The adsorbent is a powder of an adsorbent material.
[0027] The heat source circuit 101 includes a compressor 131, a first adsorbent 121, a second adsorbent 122, a switching mechanism 135, a bypass flow path 211, and a bypass valve 212. The refrigerant flow path 111 connects the compressor 131, the first adsorbent 121, the second adsorbent 122, and the switching mechanism 135.
[0028] The compressor 131 compresses the refrigerant flowing through the refrigerant passage 111. The compressor 131 is, for example, a rotary compressor. The compressor 131 has an inverter for controlling the rotational speed of the motor. The compressor 131 draws in low-pressure refrigerant from the refrigerant passage 111, compresses it, and discharges it back into the refrigerant passage 111 as high-pressure refrigerant. Low-pressure refrigerant is the refrigerant in the refrigerant passage 111 before it is compressed by the compressor 131. High-pressure refrigerant is the refrigerant in the refrigerant passage 111 after it has been compressed by the compressor 131. During operation of the compressor 131, the sliding parts of the compressor 131 are supplied with lubricating oil sealed in the refrigerant passage 111. A portion of the lubricating oil is stored at the bottom of the compressor 131 casing.
[0029] The first adsorbent 121 and the second adsorbent 122 each have an adsorbent material that adsorbs and desorbs refrigerant. In the first adsorbent 121 and the second adsorbent 122, the heat of adsorption or the heat of desorption is recovered in the heat medium flowing through the heat medium channel 112. The heat of adsorption is the warmth generated when the adsorbent material adsorbs the refrigerant. The heat of desorption is the coldness generated when the adsorbent material desorbs the refrigerant. The generation of warmth means that the temperature of the heat medium rises as the heat medium absorbs heat. The generation of coldness means that the temperature of the heat medium decreases as it absorbs heat from the heat medium. The first adsorbent 121 and the second adsorbent 122 are connected to a switching mechanism 135 in the refrigerant channel 111.
[0030] The switching mechanism 135 switches the flow direction of the refrigerant flowing through the refrigerant passage 111. The switching mechanism 135 is, for example, a four-way switching valve. The switching mechanism 135 is configured to switch the refrigerant passage 111 between a first direction, which is the flow direction shown by the solid line in Figure 1, and a second direction, which is the flow direction shown by the dashed line in Figure 1. When the flow direction of the refrigerant passage 111 is the first direction, the discharge side of the compressor 131 is connected to the first adsorbent 121, and the suction side of the compressor 131 is connected to the second adsorbent 122. When the flow direction of the refrigerant passage 111 is the second direction, the discharge side of the compressor 131 is connected to the second adsorbent 122, and the suction side of the compressor 131 is connected to the first adsorbent 121.
[0031] The bypass channel 211 connects the first adsorbent 121 and the second adsorbent 122 without passing through the compressor 131. Specifically, as shown in Figure 1, the bypass channel 211 connects the channel between the first adsorbent 121 and the switching mechanism 135, and the channel between the second adsorbent 122 and the switching mechanism 135 in the refrigerant channel 111.
[0032] The bypass valve 212 is a valve whose opening degree can be adjusted. The bypass valve 212 is, for example, an electrically operated valve. The bypass valve 212 is installed in the bypass flow path 211. Specifically, the bypass valve 212 is attached to the piping through which the refrigerant flows in the bypass flow path 211. When the bypass valve 212 is open, the space in the first adsorber 121 where the refrigerant exists is in communication with the space in the second adsorber 122 where the refrigerant exists, via the bypass flow path 211.
[0033] The control unit 105 controls the compressor 131, the switching mechanism 135, and the bypass valve 212. The control unit 105 controls the rotational speed of the compressor 131. The control unit 105 controls the timing for starting the compressor 131 and the timing for stopping the compressor 131. The control unit 105 controls the switching mechanism 135 to switch the flow direction of the refrigerant flow path 111 between the first direction and the second direction. The control unit 105 controls the opening and closing of the bypass valve 212 to allow or block the flow of refrigerant in the bypass flow path 211.
[0034] The control unit 105 controls the switching mechanism 135 and the bypass valve 212 to switch the refrigerant flow path 111 between a first state, a second state, and a third state. The first state is a state in which the first adsorbent 121 is under high pressure and the second adsorbent 122 is under low pressure. In the first state, the flow direction of the refrigerant flow path 111 is the first direction. The second state is a state in which the first adsorbent 121 is under low pressure and the second adsorbent 122 is under high pressure. In the second state, the flow direction of the refrigerant flow path 111 is the second direction. The third state is a state in which the bypass valve 212 is at a first opening and the first adsorbent 121 and the second adsorbent 122 are in communication. The first opening is a value greater than zero. The first opening is less than or equal to the opening when the bypass valve 212 is fully open. In the first and second states, the opening of the bypass valve 212 is zero. In other words, in the first and second states, the first adsorbent 121 and the second adsorbent 122 are not in communication via the bypass flow path 211. In the third state, the flow direction of the refrigerant flow path 111 switches between the first and second directions.
[0035] The control unit 105 repeatedly performs a first cycle operation, sequentially switching the refrigerant flow path 111 in the order of first state, third state, second state, and third state. The control unit 105 continuously drives the compressor 131 while the first cycle operation is being performed. Therefore, while the refrigeration system 100 is operating, the control unit 105 keeps the compressor 131 running without stopping it.
[0036] (1-2) Utilization-side circuit 102 The utilization-side circuit 102 functions as a heat transfer means for utilizing the heat generated in the heat source-side circuit 101 via a heat transfer medium. The heat transfer medium flowing through the heat transfer medium channel 112 transfers the heat of adsorption or desorption recovered by the first adsorbent 121 or the second adsorbent 122 to a predetermined location.
[0037] The user-side circuit 102 includes a first adsorbent 121, a second adsorbent 122, a first fluid pump 141, a first heat exchanger 142, a second fluid pump 151, a second heat exchanger 152, and flow path changing sections 156-159. The heat transfer medium flow path 112 connects the first adsorbent 121, the second adsorbent 122, the first fluid pump 141, the first heat exchanger 142, the second fluid pump 151, the second heat exchanger 152, and flow path changing sections 156-159.
[0038] The first fluid pump 141 sends the heat transfer medium to the first heat exchanger 142. The first heat exchanger 142 performs heat exchange between the heat transfer medium and air. The first fan 143 generates an airflow that passes through the first heat exchanger 142 so that heat exchange can take place in the first heat exchanger 142.
[0039] The second fluid pump 151 sends the heat transfer medium to the second heat exchanger 152. The second heat exchanger 152 performs heat exchange between the heat transfer medium and air. The second fan 153 generates an airflow that passes through the second heat exchanger 152 so that heat exchange can take place in the second heat exchanger 152.
[0040] The flow path changing units 156-159 change the flow path through which the heat transfer medium flows by switching the connection mode of the heat transfer medium flow path 112. The flow path changing units 156-159 are, for example, three-way switching valves. The flow path changing units 156-159 are configured to allow the heat transfer medium flow path 112 to switch between a first mode shown by the solid line in Figure 1 and a second mode shown by the dashed line in Figure 1.
[0041] The heat medium flow path 112 has a first circulation flow path and a second circulation flow path, which are two independent flow paths in each of the first mode and the second mode. The heat medium circulates through each of the first circulation flow path and the second circulation flow path. In FIG. 1, the flow direction of the heat medium in the first mode is indicated by a solid line, and the flow direction of the heat medium in the second mode is indicated by a broken line.
[0042] In the first mode, the first circulation flow path connects the first fluid pump 141, the first heat exchanger 142, the flow path changing section 156, the first adsorber 121, and the flow path changing section 157. In the first mode, the second circulation flow path connects the second fluid pump 151, the second heat exchanger 152, the flow path changing section 158, the second adsorber 122, and the flow path changing section 159.
[0043] In the second mode, the first circulation flow path connects the first fluid pump 141, the first heat exchanger 142, the flow path changing section 156, the second adsorber 122, and the flow path changing section 157. In the second mode, the second circulation flow path connects the second fluid pump 151, the second heat exchanger 152, the flow path changing section 158, the first adsorber 121, and the flow path changing section 159.
[0044] The control unit 105 controls the first fluid pump 141, the first fan 143, the second fluid pump 151, the second fan 153, and the flow path changing sections 156-159. The control unit 105 controls the capacities of the first fluid pump 141 and the second fluid pump 151. The control unit 105 controls the rotational speeds of the first fan 143 and the second fan 153. The control unit 105 controls the flow path changing sections 156-159 to switch the heat medium flow path 112 between the first mode and the second mode.
[0045] (1-3) The first adsorber 121 and the second adsorber 122 The first adsorber 121 and the second adsorber 122 each include a heat recovery member, an adsorbent, and a casing. The first adsorber 121 and the second adsorber 122 each have a first space through which the refrigerant flows and a second space through which the heat medium flows. The first space is a part of the refrigerant flow path 111. The second space is a part of the heat medium flow path 112. The first space and the second space do not communicate with each other.
[0046] The heat recovery member partitions the first space and the second space. The adsorbent is provided in the first space. The adsorbent adsorbs and desorbs the refrigerant in the first space according to the change in the pressure of the refrigerant in the first space. The adsorbent is supported on the first surface which is the surface of the heat recovery member.
[0047] The adsorbent supported on the first surface contains a metal-organic framework (MOF: Metal-Organic Framework) including metal ions and organic ligands. A metal-organic framework is a porous material having a very large specific surface area obtained by the reaction between metal ions and organic ligands. In a metal-organic framework, by linking organic ligands with metal ions, a polymer structure having innumerable openings inside is obtained. The metal-organic framework can adjust the aperture diameter and topology by selectively selecting and combining metal ions and organic ligands respectively. Therefore, the metal-organic framework can adjust the aperture diameter by the selection and combination of metal ions and organic ligands, and can selectively adsorb the target substance. The metal-organic framework is used, for example, as a porous material having functions of selective storage and separation of molecules and ions.
[0048] In the refrigeration device 100, the metal-organic framework is used as an adsorbent for adsorbing and desorbing the refrigerant flowing through the refrigerant flow path 111. The metal-organic framework is, for example, MOF-5, MOF-200, UiO-66, and MIL-101. The adsorbent used in the refrigeration device 100 is, for example, a powder of the metal-organic framework or a molded product of the metal-organic framework. In this case, the adsorbent is supported on the first surface by adhering a mixture of the adsorbent and a binder to the first surface after molding. The binder is, for example, an acrylic resin, a polyester resin, a polyolefin resin, and a polyurethane resin.
[0049] The heat recovery member is of the cross-fin type. As shown in Figure 3, the heat recovery member includes a plurality of fins 161 and a heat transfer tube 162. The heat transfer tube 162 has a plurality of straight pipe sections 162a that extend in a straight line and a folded section 162b that connects two straight pipe sections 162a. In Figure 3, the thickness of the heat transfer tube 162 is omitted. The plurality of fins 161 have through holes in their thickness direction through which the straight pipe sections 162a of the heat transfer tube 162 pass. The plurality of fins 161 are arranged around the straight pipe sections 162a of the heat transfer tube 162 so as to be stacked at predetermined intervals along the direction in which the straight pipe sections 162a extend. The first end 162c and the second end 162d of the heat transfer tube 162 are connected to the heat transfer medium flow path 112. The plurality of fins 161 and the heat transfer tube 162 are housed in a casing 163. The casing 163 has an inlet 163a that is connected to the refrigerant flow path 111.
[0050] The refrigerant flowing through the refrigerant channel 111 flows into the casing 163 through the inlet 163a and flows out of the casing 163 through the inlet 163a. The heat transfer medium flowing through the heat transfer medium channel 112 flows into the heat transfer tube 162 through the first end 162c and flows out of the heat transfer tube 162 through the second end 162d.
[0051] As shown in Figure 3, the first space 164a through which the refrigerant flows is the space inside the casing 163 and outside the heat transfer tubes 162. The second space 164b through which the heat transfer medium flows is the space inside the casing 163 and inside the heat transfer tubes 162. The first surface 182 on which the adsorbent 181 on which the refrigerant is adsorbed and desorbed is supported includes at least a portion of the outer surfaces of the plurality of fins 161 and the heat transfer tubes 162. The first surface 182 is, for example, the surface of the plurality of fins 161 and the outer surface of the heat transfer tubes 162. The first surface 182 is in contact with the first space 164a. Therefore, the refrigerant in the first space 164a is in contact with the adsorbent 181 supported on the first surface 182.
[0052] The adsorbent 181 adsorbs the refrigerant in the first space 164a when the pressure of the refrigerant in the first space 164a is equal to or greater than the adsorption pressure. The adsorbent 181 desorbs the refrigerant in the first space 164a when the pressure of the refrigerant in the first space 164a is equal to or less than the desorption pressure. The adsorption pressure is the minimum pressure range in which the adsorbent 181 can adsorb the refrigerant at the temperature of the first space 164a. The desorption pressure is the maximum pressure range in which the adsorbent 181 can desorb the refrigerant at the temperature of the first space 164a. The adsorption pressure and desorption pressure vary depending on the type of adsorbent 181 and the refrigerant.
[0053] (2) Operation of the refrigeration system 100 The operation of the refrigeration system 100 will be explained in the case where the refrigeration system 100 is an air conditioning system. In this case, the first heat exchanger 142 is an indoor heat exchanger, and the second heat exchanger 152 is an outdoor heat exchanger.
[0054] The adsorbent material 181 of the first adsorbent 121 and the second adsorbent 122 adsorbs and desorbs refrigerant in the refrigerant flow path 111. The adsorbent material 181 adsorbs refrigerant when it is in contact with refrigerant in the first space 164a whose pressure is equal to or greater than the adsorption pressure. The adsorbent material 181 desorbs refrigerant when it is in contact with refrigerant in the first space 164a whose pressure is equal to or less than the desorption pressure.
[0055] When the refrigerant flow path 111 is in the first state, it is possible to create a high-pressure state inside the first adsorbent 121 and a low-pressure state inside the second adsorbent 122. When the first adsorbent 121 is in a high-pressure state, the adsorbent material 181 of the first adsorbent 121 is in contact with the high-pressure refrigerant in the first space 164a. When the second adsorbent 122 is in a low-pressure state, the adsorbent material 181 of the second adsorbent 122 is in contact with the low-pressure refrigerant in the first space 164a.
[0056] When the refrigerant flow path 111 is in the second state, it is possible to create a low-pressure state inside the first adsorbent 121 and a high-pressure state inside the second adsorbent 122. When the first adsorbent 121 is in a low-pressure state, the adsorbent material 181 of the first adsorbent 121 is in contact with the low-pressure refrigerant in the first space 164a. When the second adsorbent 122 is in a high-pressure state, the adsorbent material 181 of the second adsorbent 122 is in contact with the high-pressure refrigerant in the first space 164a.
[0057] The following describes the change in the adsorption amount, which is the amount of refrigerant adsorbed on the adsorbent material 181, when the refrigerant flow path 111 is in the first state. When the control unit 105 switches the refrigerant flow path 111 from the second state to the first state via the third state, the adsorption amount of the adsorbent material 181 of the first adsorber 121 is the first adsorption amount, and the adsorption amount of the adsorbent material 181 of the second adsorber 122 is the second adsorption amount. The second adsorption amount is greater than the first adsorption amount. The second adsorption amount is the maximum amount of refrigerant that the adsorbent material 181 can adsorb. The second adsorption amount includes not only the theoretical maximum amount, but also an amount that can change depending on the high pressure or the time the high pressure state is maintained. The pressure of the high-pressure refrigerant is greater than or equal to the adsorption pressure, and the pressure of the low-pressure refrigerant is less than or equal to the desorption pressure.
[0058] When the refrigerant flow path 111 is in the first state, the adsorbent 181 of the first adsorbent 121 is in contact with the high-pressure refrigerant, and the adsorbent 181 of the second adsorbent 122 is in contact with the low-pressure refrigerant. In the first adsorbent 121, the adsorbent 181 gradually adsorbs the refrigerant, and in the process, the adsorbent 181 releases heat. In the second adsorbent 122, the adsorbent 181 gradually desorbs the refrigerant, and in the process, the adsorbent 181 absorbs heat. Therefore, the amount of adsorbent 181 in the first adsorbent 121 increases from the first adsorption amount to the second adsorption amount, and the amount of adsorbent 181 in the second adsorbent 122 decreases from the second adsorption amount to the first adsorption amount.
[0059] The following describes the change in the amount of refrigerant adsorbed on the adsorbent material 181 when the refrigerant flow path 111 is in the second state. When the control unit 105 switches the refrigerant flow path 111 from the first state to the second state via the third state, the amount of adsorbent on the adsorbent material 181 of the first adsorber 121 is the second adsorbent amount, and the amount of adsorbent on the adsorbent material 181 of the second adsorber 122 is the first adsorbent amount.
[0060] When the refrigerant flow path 111 is in the second state, the adsorbent 181 of the first adsorbent 121 is in contact with the low-pressure refrigerant, and the adsorbent 181 of the second adsorbent 122 is in contact with the high-pressure refrigerant. In the first adsorbent 121, the adsorbent 181 gradually desorbs the refrigerant, and in the process, the adsorbent 181 absorbs heat. In the second adsorbent 122, the adsorbent 181 gradually adsorbs the refrigerant, and in the process, the adsorbent 181 releases heat. Therefore, the amount of adsorbent 181 in the first adsorbent 121 decreases from the second adsorption amount to the first adsorption amount, and the amount of adsorbent 181 in the second adsorbent 122 increases from the first adsorption amount to the second adsorption amount.
[0061] When the refrigerant flow path 111 is in a first state and the heat transfer fluid flow path 112 is in a first mode, in the first adsorbent 121, the heat generated during the process in which the adsorbent 181 adsorbs the refrigerant in the first space 164a is recovered into the heat transfer fluid in the second space 164b. On the other hand, in the second adsorbent 122, the cold energy generated during the process in which the adsorbent 181 desorbs the refrigerant adsorbed on it is recovered into the heat transfer fluid in the second space 164b. Therefore, in the first adsorbent 121, heat is recovered into the heat transfer fluid flowing through the first circulation flow path, and in the second adsorbent 122, cold energy is recovered into the heat transfer fluid flowing through the second circulation flow path.
[0062] Subsequently, when the amount of adsorption by the adsorbent material 181 of the first adsorber 121 reaches the second adsorption amount, the adsorbent material 181 of the first adsorber 121 becomes less able to adsorb refrigerant. When this state is reached, the control unit 105 switches the refrigerant flow path 111 from the first state to the third state and then to the second state, and switches the heat transfer medium flow path 112 from the first mode to the second mode.
[0063] When the refrigerant flow path 111 is in the second state and the heat transfer fluid flow path 112 is in the second mode, in the second adsorbent 122, the heat generated during the process in which the adsorbent 181 adsorbs the refrigerant in the first space 164a is recovered into the heat transfer fluid in the second space 164b. On the other hand, in the first adsorbent 121, the cold energy generated during the process in which the adsorbent 181 desorbs the refrigerant adsorbed on it is recovered into the heat transfer fluid in the second space 164b. Therefore, in the first adsorbent 121, cold energy is recovered into the heat transfer fluid flowing through the second circulation flow path, and in the second adsorbent 122, heat energy is recovered into the heat transfer fluid flowing through the first circulation flow path.
[0064] Subsequently, when the amount of adsorption by the adsorbent material 181 of the second adsorbent 122 reaches the second adsorption amount, the adsorbent material 181 of the second adsorbent 122 becomes less able to adsorb refrigerant. When this state is reached, the control unit 105 switches the refrigerant flow path 111 from the second state to the third state and then to the first state, and switches the heat transfer medium flow path 112 from the second mode to the first mode.
[0065] As described above, by the refrigerant flow path 111 alternately transitioning between a first state and a second state via a third state, the refrigerant can be continuously adsorbed or desorbed onto the adsorbent material 181 in either the first adsorbent material 121 or the second adsorbent material 122. By switching the heat transfer medium flow path 112 alternately between a first mode and a second mode in conjunction with the switching of the refrigerant flow path 111 to the first to third states, the heat generated when the adsorbent material 181 adsorbs the refrigerant can be continuously recovered by the heat transfer medium flowing through the first circulation flow path.
[0066] Furthermore, when the refrigerant flow path 111 is in the first state and the heat transfer medium flow path 112 is in the second mode, heat is recovered in the heat transfer medium flowing through the second circulation path in the first adsorbent 121, and cold energy is recovered in the heat transfer medium flowing through the first circulation path in the second adsorbent 122. When the refrigerant flow path 111 is in the second state and the heat transfer medium flow path 112 is in the first mode, cold energy is recovered in the heat transfer medium flowing through the first circulation path in the first adsorbent 121, and heat is recovered in the heat transfer medium flowing through the second circulation path in the second adsorbent 122. Therefore, by switching the heat transfer medium flow path 112 alternately between the second mode and the first mode in accordance with the switching of the refrigerant flow path 111 to the first to third states, the cold energy generated when the adsorbent 181 desorbs the refrigerant can be continuously recovered by the heat transfer medium flowing through the first circulation path.
[0067] Therefore, the refrigeration device 100 can continuously supply the first heat exchanger 142 connected to the first circulation channel with a heat transfer medium heated by the recovered thermal energy, or a heat transfer medium cooled by the recovered cold energy. The air that has exchanged heat with the heat transfer medium in the first heat exchanger 142 is sent to a predetermined location by the first fan 143.
[0068] (3) Control of the refrigeration system 100 Figure 4 is a control time chart of the refrigeration system 100 of this embodiment. The time chart in Figure 4(a) shows the state of the compressor 131. "Operating" in Figure 4(a) shows the state in which the compressor 131 is running. "Stopped" in Figure 4(a) shows the state in which the compressor 131 is stopped. The time chart in Figure 4(b) shows the opening degree of the bypass valve 212. "Zero" in Figure 4(b) shows the state in which the opening degree of the bypass valve 212 is zero and the bypass valve 212 is closed. "First opening degree" in Figure 4(b) shows the state in which the opening degree of the bypass valve 212 is a first opening degree greater than zero and the bypass valve 212 is open. The time chart in Figure 4(c) shows the state of the switching mechanism 135. "First direction" in Figure 4(c) shows the state in which the flow direction of the refrigerant flow path 111 is the first direction. In Figure 4(c), "Second Direction" indicates the state where the flow direction of the refrigerant flow path 111 is the second direction. The time chart in Figure 4(d) shows the change in refrigerant pressure in the first space 164a of the first adsorbent 121. The time chart in Figure 4(e) shows the change in refrigerant pressure in the first space 164a of the second adsorbent 122. In Figures 4(d) and (e), "Adsorption Setting Pressure" is a predetermined target pressure that is greater than or equal to the adsorption pressure. In Figures 4(d) and (e), "Desorption Setting Pressure" is a predetermined target pressure that is less than or equal to the desorption pressure. Hereafter, as necessary, the refrigerant pressure in the first space 164a of the first adsorbent 121 will be described as "Pressure in the First Adsorbent 121," and the refrigerant pressure in the first space 164a of the second adsorbent 122 will be described as "Pressure in the Second Adsorbent 122."
[0069] As shown in Figure 4, the control unit 105 repeatedly performs a first cycle operation in which it sequentially switches the refrigerant flow path 111 in the order of first state, third state, second state, and third state. When the control unit 105 transitions from the first or second state to the third state, it raises the opening degree of the bypass valve 212 from zero to the first opening degree. When the control unit 105 transitions from the third state to the first or second state, it lowers the opening degree of the bypass valve 212 from the first opening degree to zero. Therefore, in the third state, the first adsorbent 121 and the second adsorbent 122 are in communication via the bypass flow path 211. In the third state following the first state, the control unit 105 controls the switching mechanism 135 to switch the flow direction of the refrigerant flow path 111 from the first direction to the second direction. In the third state following the second state, the control unit 105 controls the switching mechanism 135 to switch the flow direction of the refrigerant flow path 111 from the second direction to the first direction.
[0070] (4) Features As shown in Figure 4, when the refrigerant flow path 111 is in the first state, the pressure in the first adsorbent 121 increases and the pressure in the second adsorbent 122 decreases. In the first state, the pressure in the first adsorbent 121 approaches the adsorption setting pressure, and the pressure in the second adsorbent 122 approaches the desorption setting pressure. When the pressure in the first adsorbent 121 reaches a predetermined pressure that is less than or equal to the adsorption setting pressure, or when the pressure in the second adsorbent 122 reaches a predetermined pressure that is greater than or equal to the desorption setting pressure, the control unit 105 raises the opening of the bypass valve 212 from zero to the first opening. As a result, the refrigerant flow path 111 transitions from the first state to the third state. In the third state, the first adsorbent 121 and the second adsorbent 122 are in communication via the bypass flow path 211. Therefore, in the third state following the first state, the increase in pressure in the first adsorbent 121 and the decrease in pressure in the second adsorbent 122 are suppressed without stopping the compressor 131.
[0071] As shown in Figure 4, when the refrigerant flow path 111 is in the second state, the pressure in the first adsorbent 121 decreases and the pressure in the second adsorbent 122 increases. In the second state, the pressure in the first adsorbent 121 approaches the desorption setting pressure, and the pressure in the second adsorbent 122 approaches the adsorption setting pressure. When the pressure in the first adsorbent 121 reaches a predetermined pressure equal to or greater than the desorption setting pressure, or when the pressure in the second adsorbent 122 reaches a predetermined pressure equal to or less than the adsorption setting pressure, the control unit 105 increases the opening of the bypass valve 212 from zero to the first opening. As a result, the refrigerant flow path 111 transitions from the second state to the third state. In the third state, the first adsorbent 121 and the second adsorbent 122 are in communication via the bypass flow path 211. Therefore, in the third state following the second state, the decrease in pressure in the first adsorbent 121 and the increase in pressure in the second adsorbent 122 are suppressed without stopping the compressor 131.
[0072] As a result, the refrigeration system 100 can continuously drive the compressor 131 while maintaining the pressure in the first adsorbent 121 and the second adsorbent 122 at a predetermined value or range during the execution of the first cycle operation by setting the opening of the bypass valve 212 to the first opening while the refrigerant flow path 111 is in the third state. If the compressor 131 is stopped each time the refrigerant flow path 111 is switched between the first and second states, the compressor 131 will be started and stopped repeatedly during the operation of the refrigeration system 100, which may reduce the reliability of the compressor 131. Therefore, the refrigeration system 100 can suppress the reduction in the reliability of the compressor 131 by having the control unit 105 repeatedly execute the first cycle operation in which the refrigerant flow path 111 is sequentially switched in the order of first state, third state, second state, and third state.
[0073] —Second Embodiment— The basic configuration and operation of the refrigeration system 100 of the second embodiment are the same as those of the refrigeration system 100 of the first embodiment. The main difference between the refrigeration system 100 of the second embodiment and the refrigeration system 100 of the first embodiment is the control by the control unit 105.
[0074] (1) Control of the refrigeration system 100 In this embodiment, the control unit 105 changes the opening degree of the bypass valve 212 in the third state during the execution of the first cycle operation, similar to the first embodiment. The control unit 105 also changes the rotational speed of the compressor 131 during the execution of the first cycle operation.
[0075] Figure 5 is a control time chart for the refrigeration system 100 of this embodiment. The time chart in Figure 5(a) represents the rotational speed of the compressor 131. The "set value" in Figure 5(a) is the set value for the rotational speed of the compressor 131 during normal operation of the refrigeration system 100. The "lower limit" in Figure 5(a) is the lower limit for the rotational speed of the compressor 131 during normal operation of the refrigeration system 100. The "lower limit" is greater than zero. During the execution of the first cycle operation, the control unit 105 changes the rotational speed of the compressor 131 within the range from the "lower limit" to the "set value". Therefore, as in the first embodiment, the control unit 105 continues to operate the compressor 131 without stopping it while the refrigeration system 100 is operating. The time charts in Figures 5(b) to (e) correspond to the time charts in Figures 4(b) to (e), respectively.
[0076] As shown in Figure 5(a), the control unit 105 reduces the rotational speed of the compressor 131 while the refrigerant flow path 111 is in the first or second state. Specifically, the control unit 105 makes the average rotational speed of the compressor 131 in the first period P1 higher than the average rotational speed of the compressor 131 in the second period P2, which is after the first period P1. The first period P1 is the initial period of the first and second states. In other words, the first period P1 is the period that includes the time when the first or second state begins. The second period P2 is the final period of the first and second states. In other words, the second period P2 is the period that includes the time when the first or second state ends. The start of the second period P2 is after the end of the first period P1. The average rotational speed is the average of the rotational speeds over a predetermined period. In Figure 5(a), the first period P1 is the period during which the average rotational speed of the compressor 131 is at a set value, and the second period P2 is the period during which the average rotational speed of the compressor 131 is at a lower limit. The period from the end of the first period P1 to the start of the second period P2 is the period during which the rotational speed of the compressor 131 decreases. During the period during which the rotational speed of the compressor 131 decreases, the control unit 105 may monotonically decrease the rotational speed of the compressor 131, or it may decrease the rotational speed of the compressor 131 while increasing or maintaining it.
[0077] The control unit 105 reduces the rotational speed of the compressor 131 when the pressure in the first adsorbent 121 or the second adsorbent 122 reaches a predetermined value while the refrigerant flow path 111 is in the first or second state. As shown in Figure 5, in the first state, when the pressure in the first adsorbent 121 reaches a predetermined first pressure that is higher than the desorption setting pressure and lower than the adsorption setting pressure, the control unit 105 reduces the rotational speed of the compressor 131. This reduces the change in pressure in the first adsorbent 121. Subsequently, when the pressure in the first adsorbent 121 reaches a predetermined third pressure that is lower than the adsorption setting pressure and higher than the first pressure, the control unit 105 maintains the rotational speed of the compressor 131 at the lower limit. Also, in the second state, when the pressure in the first adsorbent 121 reaches a predetermined second pressure that is higher than the desorption setting pressure and lower than the adsorption setting pressure, the control unit 105 reduces the rotational speed of the compressor 131. This reduces the change in pressure in the first adsorbent 121. Subsequently, when the pressure inside the first adsorber 121 reaches a predetermined fourth pressure that is higher than the desorption setting pressure and lower than the second pressure, the control unit 105 maintains the rotational speed of the compressor 131 at its lower limit.
[0078] The control unit 105 sets the average rotational speed of the compressor 131 while the refrigerant flow path 111 is in the first or second state to be higher than the rotational speed of the compressor 131 while the refrigerant flow path 111 is in the third state. In Figure 5, the rotational speed of the compressor 131 while the refrigerant flow path 111 is in the third state is the lower limit. When the refrigerant flow path 111 transitions from the third state to the first or second state and the first period P1 begins, the control unit 105 increases the rotational speed of the compressor 131 from the lower limit to the set value, as shown in Figure 5.
[0079] The control unit 105 performs control to reduce the rotational speed of the compressor 131 so that the pressure in the first adsorbent 121 increases and the pressure in the second adsorbent 122 decreases while the refrigerant flow path 111 is in the first state. The control unit 105 performs control to reduce the rotational speed of the compressor 131 so that the pressure in the second adsorbent 122 increases and the pressure in the first adsorbent 121 decreases while the refrigerant flow path 111 is in the second state.
[0080] (2) Features As shown in Figure 5, when the refrigerant flow path 111 is in the first state, the pressure in the first adsorbent 121 increases and the pressure in the second adsorbent 122 decreases. In the first state, after the start of the first period P1, when the pressure in the first adsorbent 121 reaches a predetermined first pressure lower than the adsorption setting pressure, or when the pressure in the second adsorbent 122 reaches a predetermined second pressure higher than the desorption setting pressure, the first period P1 ends and the control unit 105 reduces the rotational speed of the compressor 131. As a result, the rate of increase in the pressure in the first adsorbent 121 and the rate of decrease in the pressure in the second adsorbent 122 become smaller. Subsequently, when the pressure in the first adsorbent 121 reaches a predetermined third pressure lower than the adsorption setting pressure and higher than the first pressure, or when the pressure in the second adsorbent 122 reaches a predetermined fourth pressure higher than the desorption setting pressure and lower than the second pressure, the rotational speed of the compressor 131 reaches its lower limit and the second period P2 begins. As a result, the rate of increase in pressure in the first adsorbent 121 and the rate of decrease in pressure in the second adsorbent 122 are further reduced. During the second period P2, the control unit 105 maintains the rotational speed of the compressor 131 at the lower limit. During the second period P2, the pressure in the first adsorbent 121 approaches the adsorption set pressure, and the pressure in the second adsorbent 122 approaches the desorption set pressure. When the second period P2 ends, the system transitions from the first state to the third state. Therefore, in the first state and the subsequent third state, the increase in pressure in the first adsorbent 121 and the decrease in pressure in the second adsorbent 122 are suppressed without stopping the compressor 131.
[0081] As shown in Figure 5, when the refrigerant flow path 111 is in the second state, the pressure in the first adsorbent 121 decreases and the pressure in the second adsorbent 122 increases. In the second state, after the start of the first period P1, when the pressure in the first adsorbent 121 reaches the second pressure, or the pressure in the second adsorbent 122 reaches the first pressure, the first period P1 ends, and the control unit 105 reduces the rotational speed of the compressor 131. As a result, the rate of decrease in the pressure in the first adsorbent 121 and the rate of increase in the pressure in the second adsorbent 122 become smaller. Subsequently, when the pressure in the first adsorbent 121 reaches the fourth pressure, or the pressure in the second adsorbent 122 reaches the third pressure, the rotational speed of the compressor 131 reaches its lower limit and the second period P2 begins. As a result, the rate of decrease in the pressure in the first adsorbent 121 and the rate of increase in the pressure in the second adsorbent 122 become even smaller. During the second period P2, the control unit 105 maintains the rotational speed of the compressor 131 at a lower limit. During the second period P2, the pressure inside the first adsorbent 121 approaches the desorption setting pressure, and the pressure inside the second adsorbent 122 approaches the adsorption setting pressure. When the second period P2 ends, the system transitions from the second state to the third state. Therefore, in the second state and the subsequent third state, the decrease in pressure inside the first adsorbent 121 and the increase in pressure inside the second adsorbent 122 are suppressed without stopping the compressor 131.
[0082] As a result, the refrigeration system 100 can continuously drive the compressor 131 while maintaining the pressure in the first adsorbent 121 and the second adsorbent 122 at a predetermined value or range during the execution of the first cycle operation by reducing the rotational speed of the compressor 131 while the refrigerant flow path 111 is in the first or second state. Therefore, the refrigeration system 100 can suppress a decrease in the reliability of the compressor 131, similar to the first embodiment.
[0083] —Third Embodiment— The basic configuration and operation of the refrigeration system 100 of the third embodiment are the same as those of the refrigeration system 100 of the second embodiment. The main difference between the refrigeration system 100 of the third embodiment and the refrigeration system 100 of the second embodiment is the control by the control unit 105.
[0084] (1) Control of the refrigeration system 100 In this embodiment, during the execution of the first cycle operation, the control unit 105 changes the opening degree of the bypass valve 212 in the third state and changes the rotational speed of the compressor 131, similar to the second embodiment. During the execution of the first cycle operation, the control unit 105 further changes the opening degree of the bypass valve 212 in the first state and the second state.
[0085] Figure 6 is a control time chart for the refrigeration system 100 of this embodiment. The time charts in Figures 6(a) to 6(e) correspond to the time charts in Figures 5(a) to 5(e), respectively.
[0086] As shown in Figure 6(a), the control unit 105 performs a first control to reduce the rotational speed of the compressor 131 while the refrigerant flow path 111 is in the first or second state. As shown in Figure 6(b), the control unit 105 performs a second control to increase the opening degree of the bypass valve 212 from zero while the refrigerant flow path 111 is in the first or second state. The control unit 105 starts the second control after the start of the first control. In Figure 6, the control unit 105 starts the first control at the end of the first period P1 and starts the second control at the start of the second period P2. When the second control is executed, the control unit 105 increases the opening degree of the bypass valve 212 from zero to a second opening degree which is smaller than the first opening degree. Therefore, as shown in Figure 6(b), the opening degree of the bypass valve 212 while the refrigerant flow path 111 is in the third state is higher than the opening degree of the bypass valve 212 at the end of the second period P2.
[0087] The control unit 105 performs a first control to reduce the rotational speed of the compressor 131 when the pressure in the first adsorbent 121 or the second adsorbent 122 reaches a predetermined value while the refrigerant flow path 111 is in a first or second state. As shown in Figure 6, in the first state, when the pressure in the first adsorbent 121 reaches a predetermined pressure that is higher than the desorption setting pressure and lower than the adsorption setting pressure, the control unit 105 starts the first control. This reduces the change in pressure in the first adsorbent 121. Subsequently, when the pressure in the first adsorbent 121 reaches the adsorption setting pressure, the control unit 105 maintains the rotational speed of the compressor 131 at the lower limit. Also, in the second state, when the pressure in the first adsorbent 121 reaches a predetermined pressure that is higher than the desorption setting pressure and lower than the adsorption setting pressure, the control unit 105 starts the first control. This reduces the change in pressure in the first adsorbent 121. Subsequently, when the pressure inside the first adsorber 121 reaches the desorption setting pressure, the control unit 105 maintains the rotational speed of the compressor 131 at the lower limit.
[0088] The control unit 105 may start the second control when the pressure in the first adsorbent 121 or the second adsorbent 122 reaches a predetermined value. For example, while the refrigerant flow path 111 is in the first state, the control unit 105 starts the second control when the pressure in the first adsorbent 121 rises to a predetermined pressure below the adsorption setting pressure, or when the pressure in the second adsorbent 122 falls to a predetermined pressure above the desorption setting pressure. Alternatively, while the refrigerant flow path 111 is in the second state, the control unit 105 starts the second control when the pressure in the first adsorbent 121 falls to a predetermined pressure above the desorption setting pressure, or when the pressure in the second adsorbent 122 rises to a predetermined pressure below the adsorption setting pressure.
[0089] The control unit 105 may start the second control after the rotational speed of the compressor 131 has decreased to a predetermined value during the execution of the first control. For example, as shown in Figure 6, the control unit 105 starts the second control when the rotational speed of the compressor 131 reaches a lower limit in the first or second state.
[0090] Figure 7 is a flowchart of the control by the control unit 105 when the refrigerant flow path 111 is in the first and second states. Figure 8 is a flowchart of the control by the control unit 105 when the refrigerant flow path 111 is in the third state. While the control unit 105 is performing the first cycle operation, the "end" step in Figure 7 means transitioning to the "start" step in Figure 8, and the "end" step in Figure 8 means transitioning to the "start" step in Figure 7.
[0091] When the refrigerant flow path 111 is in the first state or the second state, the control unit 105 executes the processes shown in steps S11 to S16 of Figure 7.
[0092] In step S11, the control unit 105 sets the rotational speed of the compressor 131 to a set value. Then, the process proceeds to step S12.
[0093] In step S12, the control unit 105 determines whether the pressure in the first adsorbent 121 has reached the adsorption setting pressure, or whether the pressure in the second adsorbent 122 has reached the desorption setting pressure, if the refrigerant flow path 111 is in the first state. If the refrigerant flow path 111 is in the second state, the control unit 105 determines whether the pressure in the first adsorbent 121 has reached the desorption setting pressure, or whether the pressure in the second adsorbent 122 has reached the adsorption setting pressure. If it is determined that the pressure in the first adsorbent 121 or the second adsorbent 122 has reached the adsorption setting pressure or the desorption setting pressure, the process proceeds to step S13. If it is not determined that the pressure has reached the set2 again after a predetermined period of time has elapsed.
[0094] In step S13, the control unit 105 determines whether it is time to switch the flow direction of the refrigerant flow path 111 by the switching mechanism 135. If it is determined that it is time to switch the flow direction of the refrigerant flow path 111, the system proceeds to the "Start" step in Figure 8; otherwise, it proceeds to step S14.
[0095] In step S14, the control unit 105 determines whether the rotational speed of the compressor 131 is at the lower limit. If it is determined that the rotational speed of the compressor 131 is at the lower limit, the process proceeds to step S15; otherwise, the process proceeds to step S16.
[0096] In step S15, the control unit 105 increases the opening degree of the bypass valve 212 from zero to the second opening degree. Then, the process proceeds to step S12.
[0097] In step S16, the control unit 105 reduces the rotational speed of the compressor 131. Then, the process proceeds to step S12.
[0098] When the refrigerant flow path 111 is in the third state, the control unit 105 executes the processes shown in steps S21 to S24 of Figure 8.
[0099] In step S21, the control unit 105 increases the opening degree of the bypass valve 212 from the second opening degree to the first opening degree. Then, the process proceeds to step S22.
[0100] In step S22, the control unit 105 determines whether the pressure in the first adsorbent 121 and the second adsorbent 122 has been equalized. Specifically, the control unit 105 determines whether the difference between the pressure in the first adsorbent 121 and the pressure in the second adsorbent 122 is less than or equal to a predetermined value. If it is determined that the pressure has been equalized, the process proceeds to step S23; otherwise, the process proceeds to step S24.
[0101] In step S23, the control unit 105 switches the flow direction of the refrigerant flow path 111 using the switching mechanism 135. After that, the process proceeds to step S24.
[0102] In step S24, the control unit 105 reduces the opening degree of the bypass valve 212 to zero. Then, the process proceeds to the "start" step shown in Figure 7.
[0103] (2) Features As shown in Figure 6, when the refrigerant flow path 111 is in the first state, the pressure in the first adsorbent 121 increases and the pressure in the second adsorbent 122 decreases. In the first state, when the rotational speed of the compressor 131 reaches the lower limit, the control unit 105 increases the opening of the bypass valve 212 from zero to the second opening. As a result, in the first state, the first adsorbent 121 and the second adsorbent 122 are in communication via the bypass flow path 211. Therefore, in the first state and the subsequent third state, the increase in pressure in the first adsorbent 121 and the decrease in pressure in the second adsorbent 122 are suppressed without stopping the compressor 131.
[0104] As shown in Figure 6, when the refrigerant flow path 111 is in the second state, the pressure in the first adsorbent 121 decreases and the pressure in the second adsorbent 122 increases. In the second state, when the rotational speed of the compressor 131 reaches its lower limit, the control unit 105 increases the opening of the bypass valve 212 from zero to the second opening. As a result, in the second state, the first adsorbent 121 and the second adsorbent 122 are in communication via the bypass flow path 211. Therefore, in the second state and the subsequent third state, the decrease in pressure in the first adsorbent 121 and the increase in pressure in the second adsorbent 122 are suppressed without stopping the compressor 131.
[0105] As a result, the refrigeration system 100 can continuously drive the compressor 131 while maintaining the pressure in the first adsorbent 121 and the second adsorbent 122 at a predetermined value or range during the execution of the first cycle operation by increasing the opening of the bypass valve 212 from zero to the second opening while the refrigerant flow path 111 is in the first or second state. Therefore, the refrigeration system 100 can suppress a decrease in the reliability of the compressor 131, similar to the first embodiment.
[0106] Furthermore, the refrigeration system 100 can accommodate multiple adsorption setting pressures and multiple desorption setting pressures by appropriately setting the lower limit of the rotational speed of the compressor 131 and the second opening degree of the bypass valve 212. Therefore, the refrigeration system 100 can perform control based on a predetermined capacity while maintaining the reliability of the compressor 131.
[0107] —Modifications— (1) Modification A In the first to third embodiments, the bypass flow path 211 connects the flow path between the first adsorbent 121 and the switching mechanism 135 and the flow path between the second adsorbent 122 and the switching mechanism 135 in the refrigerant flow path 111. However, the position of the bypass flow path 211 is not limited as long as the bypass flow path 211 connects the first adsorbent 121 and the second adsorbent 122 without passing through the compressor 131.
[0108] The bypass channel 211 may directly connect the first adsorbent 121 and the second adsorbent 122 in the refrigerant channel 111. In this case, the piping through which the refrigerant flows in the bypass channel 211 is connected to the casings 163 of the first adsorbent 121 and the second adsorbent 122. The bypass channel 211 is connected to the first space 164a of the first adsorbent 121 and the first space 164a of the second adsorbent 122.
[0109] The bypass passage 211 may connect the passage between the suction side of the compressor 131 and the switching mechanism 135, and the passage between the discharge side of the compressor 131 and the switching mechanism 135, within the refrigerant passage 111. Alternatively, the bypass passage 211 may directly connect the suction side and the discharge side of the compressor 131.
[0110] (2) Modification B In the first to third embodiments, when the system transitions from the third state to the first or second state, the control unit 105 lowers the opening degree of the bypass valve 212 from the first opening degree to zero. The control unit 105 may lower the opening degree of the bypass valve 212 to zero at the same time as the start of the first and second states, or it may lower the opening degree of the bypass valve 212 to zero after the start of the first and second states. For example, the control unit 105 may lower the opening degree of the bypass valve 212 to zero during the first period P1 in Figures 5 and 6.
[0111] (3) Modification C In the first to third embodiments, the control unit 105 may control at least one of the opening degree of the bypass valve 212 and the rotational speed of the compressor 131 in accordance with the pressure in the first adsorbent 121 and the second adsorbent 122. In this case, pressure sensors are provided in the first space 164a of the first adsorbent 121 and the first space 164a of the second adsorbent 122, and the control unit 105 may control at least one of the opening degree of the bypass valve 212 and the rotational speed of the compressor 131 based on the value detected by the pressure sensors.
[0112] (4) Modification D In the third embodiment, the control unit 105 performs a second control to raise the opening degree of the bypass valve 212 from zero after starting the first control to reduce the rotational speed of the compressor 131. The control unit 105 may perform the first control after starting the second control. For example, the control unit 105 may perform the second control to raise the opening degree of the bypass valve 212 to a third opening degree which is lower than the second opening degree, then start the first control, and then perform the second control to raise the opening degree of the bypass valve 212 from the third opening degree to the second control.
[0113] (5) Modification E In the first to third embodiments, the casings 163 of the first adsorbent 121 and the second adsorbent 122 have an inlet 163a connected to the refrigerant flow path 111. The refrigerant in the refrigerant flow path 111 flows into the casing 163 through the inlet 163a and flows out from the casing 163 through the inlet 163a. The inlet 163a serves as both an inlet and an outlet for the refrigerant of the first adsorbent 121 and the second adsorbent 122.
[0114] In this modified example, the casing 163 has an inlet and an outlet. In this case, the refrigerant flowing through the refrigerant flow path 111 flows into the interior of the casing 163 through the inlet, and the refrigerant inside the casing 163 flows out from the interior of the casing 163 through the outlet. The inlet functions as the inlet for the refrigerant of the first adsorbent 121 and the second adsorbent 122. The outlet functions as the outlet for the refrigerant of the first adsorbent 121 and the second adsorbent 122.
[0115] (6) Modification F In the first to third embodiments, the adsorbent used in the refrigeration device 100 is a metal-organic structure. However, materials other than metal-organic structures may be used as the adsorbent. Examples of materials other than metal-organic structures include activated carbon, zeolite-based materials, silica-based materials, and alumina-based materials.
[0116] While embodiments of this disclosure have been described above, it should be understood that various modifications to the form and details are possible without departing from the spirit and scope of this disclosure as described in the claims.
[0117] 100: Refrigeration unit 105: Control unit 111: Refrigerant flow path 121: First adsorbent 122: Second adsorbent 131: Compressor 135: Switching mechanism 181: Adsorbent material 211: Bypass flow path 212: Bypass valve
[0118] U.S. Patent Application Publication No. 2023 / 0417459
Claims
1. The system comprises a refrigerant flow path (111) through which the refrigerant flows, a compressor (131) that inhales and compresses low-pressure refrigerant and discharges it as high-pressure refrigerant, a first adsorbent (121) and a second adsorbent (122) having an adsorbent (181) that adsorbs and desorbs refrigerant in accordance with changes in the refrigerant pressure, and from which the heat generated when the adsorbent adsorbs the refrigerant and the cold generated when the adsorbent desorbs the refrigerant are recovered, a switching mechanism (135), a bypass flow path (211) that connects the first adsorbent and the second adsorbent without passing through the compressor, a bypass valve (212) provided in the bypass flow path and whose opening degree can be adjusted, and a control unit (105), wherein the control unit controls the switching mechanism and the bypass valve to switch the refrigerant flow path between a first state, a second state, and a third state. The first state is a state in which the first adsorbent is under high pressure and the second adsorbent is under low pressure; the second state is a state in which the first adsorbent is under low pressure and the second adsorbent is under high pressure; the third state is a state in which the bypass valve is at a first opening and the first adsorbent and the second adsorbent are in communication; the control unit repeatedly performs a first cycle operation in which the refrigerant flow path is sequentially switched in the order of the first state, the third state, the second state, and the third state, and drives the compressor continuously during the execution of the first cycle operation; Refrigeration apparatus (100).
2. The refrigeration apparatus according to claim 1, wherein the control unit changes the rotational speed of the compressor during the execution of the first cycle operation.
3. The refrigeration apparatus according to claim 2, wherein the control unit makes the average rotational speed of the compressor in the first period higher than the average rotational speed of the compressor in the second period following the first period, the first period includes the time when the first or second state begins, and the second period includes the time when the first or second state ends.
4. The refrigeration apparatus according to claim 2 or 3, wherein the control unit reduces the rotational speed of the compressor when the pressure in the first adsorbent or the second adsorbent reaches a predetermined value while the refrigerant flow path is in the first state or the second state.
5. The refrigeration apparatus according to any one of claims 2 to 4, wherein the control unit makes the average rotational speed of the compressor when the refrigerant flow path is in the first or second state higher than the rotational speed of the compressor when the refrigerant flow path is in the third state.
6. The refrigeration apparatus according to any one of claims 2 to 5, wherein the control unit changes the opening degree of the bypass valve during the execution of the first cycle operation, and sets the opening degree of the bypass valve to zero for a predetermined period including the time when the first state or the second state begins while the refrigerant flow path is in the first state or the second state.
7. The refrigeration apparatus according to claim 6, wherein the control unit performs a first control, which reduces the rotational speed of the compressor while the refrigerant flow path is in the first state or the second state, and a second control, which increases the opening degree of the bypass valve from zero while the refrigerant flow path is in the first state or the second state, and the control unit starts the second control after the start of the first control.
8. The refrigeration apparatus according to claim 7, wherein the control unit starts the second control when the pressure in the first adsorbent or the second adsorbent reaches a predetermined value.
9. The refrigeration apparatus according to claim 7 or 8, wherein the control unit starts the second control after the rotational speed of the compressor has decreased to a first value during the execution of the first control.
10. The refrigeration apparatus according to any one of claims 7 to 9, wherein the control unit raises the opening degree of the bypass valve from zero to a second opening degree that is smaller than the first opening degree when the second control is executed.
11. The refrigeration apparatus according to any one of claims 7 to 10, wherein the control unit starts the second control when the pressure in the first adsorbent rises to a second value or the pressure in the second adsorbent falls to a third value while the refrigerant flow path is in the first state, and starts the second control when the pressure in the second adsorbent rises to a second value or the pressure in the first adsorbent falls to a third value while the refrigerant flow path is in the second state.
12. The refrigeration apparatus according to any one of claims 7 to 11, wherein the control unit performs the first control so as to increase the pressure in the first adsorbent while the refrigerant flow path is in the first state, and performs the first control so as to increase the pressure in the second adsorbent while the refrigerant flow path is in the second state.
13. The refrigeration apparatus according to any one of claims 1 to 12, wherein the adsorbent comprises a metal-organic structure containing a metal ion and an organic ligand.
14. The refrigeration apparatus according to any one of claims 1 to 13, wherein the refrigerant comprises at least one of carbon dioxide, hydrocarbons, ammonia, water, HFCs, and HFOs.
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