Refrigeration equipment

Abstract

To provide a refrigerating device that can be operated more stably.SOLUTION: A refrigerating device comprises: a first compressor and a second compressor arranged in series on a main circuit; an intermediate heat exchanger; a condenser; a first expansion valve; a receiver; a second expansion valve; an evaporator; a three-way valve provided between the intermediate heat exchanger and the second compressor; a first bypass flow passage for connecting the three-way valve and the receiver; a second bypass flow passage for connecting the receiver and a section between the three-way valve and the second compressor; a first solenoid valve for switching an opening state of the second bypass flow passage; and a second solenoid valve provided between the receiver and the second expansion valve, and for switching an opening state of the main circuit.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to refrigeration devices. [Background technology]

[0002] A typical refrigeration system comprises a compressor, a condenser, an expansion valve, and an evaporator. The high-temperature, high-pressure gaseous refrigerant generated by the compressor is first sent to the condenser. In the condenser, heat exchange occurs between the refrigerant and air, turning the refrigerant into a high-temperature, high-pressure liquid refrigerant. The refrigerant then passes through an expansion valve, where its temperature and pressure decrease, turning it into a low-temperature, low-pressure liquid refrigerant. Furthermore, in the evaporator, heat exchange occurs with air, turning the refrigerant into a low-temperature, low-pressure gaseous refrigerant. During this process, the temperature of the space in which the condenser or evaporator is installed is adjusted.

[0003] In order to improve the output of refrigeration equipment, a two-stage compression configuration in which multiple compressors are arranged in series has recently been adopted (see Patent Document 1 below). In this case, an intermediate heat exchanger is generally arranged between the low-pressure compressor and the high-pressure compressor. The intermediate heat exchanger is provided to improve the efficiency of the refrigeration equipment. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2017 / 081781 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when the intermediate heat exchanger is provided as described above, if the outside air temperature is excessively low, there is a risk that liquid refrigerant may remain in the intermediate heat exchanger. If this liquid refrigerant is sent directly to the high-pressure compressor when the refrigeration system is started, liquid compression will occur, affecting the stable operation of the compressor.

[0006] The present disclosure has been made to solve the above-mentioned problems, and has an object to provide a refrigeration device that can be operated more stably. [Means for solving the problem]

[0007] In order to solve the above problems, a refrigeration device according to the present disclosure includes a main circuit which is a circulation flow path through which a refrigerant flows, a first compressor and a second compressor which are arranged in series on the main circuit, an intermediate heat exchanger which is arranged between the first compressor and the second compressor, a condenser which is arranged downstream of the second compressor, a first expansion valve which is arranged downstream of the condenser, a receiver which is arranged downstream of the first expansion valve, a second expansion valve which is arranged downstream of the receiver, an evaporator which is arranged downstream of the second expansion valve, and an evaporator which is arranged downstream of the intermediate heat exchanger and the a three-way valve provided between the receiver and the second compressor; a first bypass flow path connecting the three-way valve and the receiver; a second bypass flow path connecting the receiver, the three-way valve and the second compressor; a check valve provided in the first bypass flow path and allowing the refrigerant to flow only in a direction from the three-way valve toward the receiver; a first solenoid valve provided in the second bypass flow path and switching an open state of the second bypass flow path; and a second solenoid valve provided in the main circuit between the receiver and the second expansion valve and switching an open state of the main circuit. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to provide a refrigeration device that can be operated more stably. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a circuit diagram illustrating a configuration of a refrigeration device according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a circuit diagram showing the configuration of a refrigeration device according to an embodiment of the present disclosure, illustrating an operating state when only the second compressor is started. [Figure 3]FIG. 1 is a circuit diagram showing the configuration of a refrigeration device according to an embodiment of the present disclosure, illustrating an operating state when only a first compressor is started. DETAILED DESCRIPTION OF THE INVENTION

[0010] (Configuration of refrigeration device) A refrigeration device 100 according to an embodiment of the present disclosure will be described below with reference to Figures 1 to 3. The refrigeration device 100 is a heat pump type device that operates on a refrigeration cycle to exchange heat between a refrigerant and air.

[0011] As shown in FIG. 1 , the refrigeration system 100 includes a main circuit 90 formed as a circulation flow path, a first compressor 1, a second compressor 2, an intermediate heat exchanger 3, a condenser 4, a first expansion valve 5, a receiver 6, a second expansion valve 7, an evaporator 8, a first three-way valve 9, a first bypass flow path 10, a second bypass flow path 11, a first check valve 12, a first solenoid valve 13, a second solenoid valve 14, an accumulator 15, a third bypass flow path 16, a second three-way valve 17, a second check valve 18, and a control unit 80.

[0012] (Configuration of the first and second compressors) The main circuit 90 is filled with a refrigerant in a liquid or gas state. The first compressor 1 and the second compressor 2 are arranged in series on the main circuit 90. That is, the discharge side of the first compressor 1 faces the suction side of the second compressor 2. As the first compressor 1 and the second compressor 2, for example, a scroll compressor, a rotary compressor, or a scroll-rotary compressor can be used. In the following description, the side of the main circuit 90 where the second compressor 2 is located as viewed from the first compressor 1 may be referred to as the downstream side, and the opposite side may be referred to as the upstream side.

[0013] A first three-way valve 9 and a second check valve 18 are arranged in this order downstream of the first compressor 1. Details of the first three-way valve 9 will be described later. The second check valve 18 is configured to allow the refrigerant to flow only in the direction from the upstream side to the downstream side.

[0014] (Configuration of intermediate heat exchanger) An intermediate heat exchanger 3 is disposed between the first compressor 1 and the second compressor 2. In the intermediate heat exchanger 3, the high-temperature refrigerant discharged from the first compressor 1 is cooled by exchanging heat with external air in the intermediate heat exchanger 3, and then sent to the second compressor 2. The intermediate heat exchanger 3 is provided to improve the efficiency of the refrigeration device 100.

[0015] (Condenser configuration) A condenser 4 is disposed downstream of the second compressor 2. The condenser 4 is a heat exchanger for exchanging heat between the external air and the refrigerant. A fan (not shown) is provided near the condenser 4, which enables forced heat exchange between the air and the refrigerant. The high-temperature, high-pressure gas refrigerant generated by the second compressor 2 is condensed as it passes through the condenser 4, becoming a high-temperature, high-pressure liquid refrigerant.

[0016] A first expansion valve 5 is provided downstream of the condenser 4. The high-temperature, high-pressure liquid refrigerant supplied from the condenser 4 passes through the first expansion valve 5, whereby its pressure and temperature decrease, turning it into a low-temperature, low-pressure liquid refrigerant.

[0017] (Receiver configuration) A receiver 6 is connected downstream of the first expansion valve 5. The receiver 6 is a container for storing at least a portion of the liquid refrigerant that has passed through the first expansion valve 5. The amount of liquid refrigerant that can be present in the main circuit 90 varies depending on the operating conditions. The receiver 6 is provided to accommodate this variation.

[0018] Further downstream of the receiver 6, a second solenoid valve 14 and a second expansion valve 7 are arranged in this order. As will be described in detail later, the second solenoid valve 14 is provided to switch the open state of the main circuit 90. The second expansion valve 7 is provided to further reduce the temperature and pressure of the low-temperature, low-pressure liquid refrigerant that has passed through the receiver 6. The first expansion valve 5 and the second expansion valve 7 are solenoid expansion valves that can be switched between open and closed states by external electrical signals.

[0019] (Evaporator configuration) An evaporator 8 is provided downstream of the second expansion valve 7. The evaporator 8 is a heat exchanger for exchanging heat between the outside air and the refrigerant. A fan (not shown) is provided near the evaporator 8, which allows for forced heat exchange between the air and the refrigerant. The low-temperature, low-pressure liquid refrigerant that has passed through the second expansion valve 7 evaporates by exchanging heat with the outside air as it passes through the evaporator 8, and becomes a low-temperature, low-pressure gaseous refrigerant.

[0020] An accumulator 15 is provided downstream of the evaporator 8. The accumulator 15 is a container for storing liquid refrigerant that has not been completely evaporated in the evaporator 8. After the liquid component is removed in the accumulator 15, the gaseous refrigerant is sent again to the first compressor 1 and compressed. The refrigeration device 100 operates by continuously repeating this cycle (refrigeration cycle).

[0021] (Configuration of the first bypass flow path, the second bypass flow path, and the third bypass flow path) The first bypass flow path 10 is a flow path that connects the first three-way valve 9 and the receiver 6. In other words, the first bypass flow path 10 branches off from the main circuit 90 via the first three-way valve 9 and extends to the receiver 6. A first check valve 12 is provided on the first bypass flow path 10. This first check valve 12 is configured to allow the refrigerant to flow only in the direction from the first three-way valve 9 toward the receiver 6.

[0022] The second bypass flow path 11 connects the receiver 6 with the space between the second check valve 18 and the second compressor 2. A first solenoid valve 13 is provided on the second bypass flow path 11. The first solenoid valve 13 can be switched between an open state and an closed state in response to an external electric signal.

[0023] The third bypass flow path 16 is a flow path that bypasses the downstream side of the accumulator 15 and between the first compressor 1 and the intermediate heat exchanger 3. A second three-way valve 17 is provided on the upstream side of the third bypass flow path 16. That is, the third bypass flow path 16 branches off from the main circuit 90 via this second three-way valve 17.

[0024] (Configuration of control unit) The control unit 80 is provided to switch the open / closed states of the above-mentioned valve devices and the operating states of the first compressor 1 and the second compressor 2 by means of electric signals. Specifically, the control unit 80 can switch the open / closed states of the first expansion valve 5, the first three-way valve 9, the second three-way valve 17, the first solenoid valve 13, and the second solenoid valve 14. The control unit 80 can also put at least one of the first compressor 1 and the second compressor 2 into an operating state and the other into a stopped state.

[0025] (Action and effect) Next, an example of the operation of the refrigeration apparatus 100 will be described. As shown in Fig. 1 , in normal operation of the refrigeration apparatus 100, the control unit 80 closes the first solenoid valve 13. The control unit 80 also switches the open state of the first three-way valve 9 so that it is open only in the direction from the intermediate heat exchanger 3 to the second compressor 2. The control unit 80 also switches the open state of the second three-way valve 17 so that it is open only in the direction from the accumulator 15 to the first compressor 1. As a result, the first bypass flow path 10, the second bypass flow path 11, and the third bypass flow path 16 are closed, and the refrigerant circulates only through the main circuit 90. The above-described refrigeration cycle occurs continuously while the refrigerant circulates through the main circuit 90.

[0026] Here, a portion of the gas refrigerant may condense inside the intermediate heat exchanger 3, generating a liquid refrigerant. In particular, if the outside air temperature is excessively low, there is a risk that the liquid refrigerant may remain inside the intermediate heat exchanger 3. If this liquid refrigerant is sent as is to the compressor when the refrigeration apparatus 100 is started, liquid compression will occur, affecting the stable operation of the compressor.

[0027] Therefore, in this embodiment, the first bypass flow path 10, the second bypass flow path 11, and the third bypass flow path 16 are provided as described above. For example, a case where only the second compressor 2 is started will be described. As shown in FIG. 2 , in this case, the control unit 80 switches the open state of the first three-way valve 9 so that it is open only in the direction from the intermediate heat exchanger 3 to the receiver 6. That is, the first bypass flow path 10 is opened. Furthermore, the control unit 80 opens the first solenoid valve 13 to open the second bypass flow path 11. Furthermore, the control unit 80 switches the open state of the second three-way valve 17 to allow the refrigerant to flow into the third bypass flow path 16.

[0028] In this state, the refrigerant flows as shown by the arrows in Figure 2. When only the second compressor 2 is started, the pumping force of the second compressor 2 is transmitted to the receiver 6 through the second bypass passage 11. This reduces the pressure in the receiver 6. The reduction in pressure in the receiver 6 causes the liquid refrigerant remaining in the intermediate heat exchanger 3 to flow toward the receiver 6 through the first bypass passage 10. This makes it possible to recover the liquid refrigerant in the intermediate heat exchanger in the receiver 6. In the receiver 6, only the liquid component is separated from the refrigerant and stored in the receiver 6. By performing this operation for, for example, several minutes, the liquid refrigerant is removed from the intermediate heat exchanger 3. Thereafter, the normal operation described above begins.

[0029] The third bypass passage 16 is opened to prevent the first compressor 1, which is stopped, from being in a back pressure state when only the second compressor 2 is started.

[0030] As another example, when only the first compressor 1 is started, the state shown in Fig. 3 is established. In this case, the control unit 80 closes the first solenoid valve 13 and switches the opening state of the first three-way valve 9 to open the first bypass flow path 10. Furthermore, the control unit 80 opens the second solenoid valve 14. Also, the third bypass flow path 16 is closed.

[0031] In this state, a refrigerant flow occurs as shown by the arrows in Fig. 3. When only the first compressor 1 is started, the pumping force of the first compressor 1 causes the liquid refrigerant in the intermediate heat exchanger 3 located downstream thereof to be pumped through the first bypass passage 10. The liquid refrigerant pumped through the first bypass passage 10 is stored in the receiver 6. In this way, the liquid refrigerant in the intermediate heat exchanger 3 can be recovered in the receiver 6. In the receiver 6, only the liquid component is separated from the refrigerant and stored in the receiver 6. By performing this operation for, for example, several minutes, the liquid refrigerant is removed from the intermediate heat exchanger 3. Thereafter, the above-described normal operation starts.

[0032] In this way, in the refrigeration apparatus 100 according to this embodiment, it is possible to remove the liquid refrigerant remaining in the intermediate heat exchanger 3 in advance of normal operation. This reduces the possibility of liquid compression occurring in the second compressor 2. As a result, damage to the second compressor 2 is avoided, and the refrigeration apparatus 100 can be operated stably for a longer period of time.

[0033] (Other embodiments) The above describes in detail the embodiments of the present disclosure with reference to the drawings, but the specific configuration is not limited to this embodiment, and design changes and the like are also included within the scope that does not deviate from the gist of the present disclosure.

[0034] <Additional Notes> The refrigeration device 100 described in each embodiment can be understood, for example, as follows.

[0035] (1) A refrigeration device 100 according to a first aspect includes a main circuit 90 which is a circulation flow path through which a refrigerant flows, a first compressor 1 and a second compressor 2 which are arranged in series on the main circuit 90, an intermediate heat exchanger 3 which is arranged between the first compressor 1 and the second compressor 2, a condenser 4 which is arranged downstream of the second compressor 2, a first expansion valve 5 which is arranged downstream of the condenser 4, a receiver 6 which is arranged downstream of the first expansion valve 5, a second expansion valve 7 which is arranged downstream of the receiver 6, an evaporator 8 which is arranged downstream of the second expansion valve 7, and an evaporator 8 which is arranged between the intermediate heat exchanger 3 and the second compressor 2 on the main circuit 90. a first three-way valve 9 connected to the receiver 6; a first bypass flow path 10 connecting the first three-way valve 9 and the receiver 6; a second bypass flow path 11 connecting the receiver 6, the first three-way valve 9 and the second compressor 2; a first check valve 12 provided in the first bypass flow path 10 and allowing the refrigerant to flow only in a direction from the first three-way valve 9 toward the receiver 6; a first solenoid valve 13 provided in the second bypass flow path 11 and switching an open state of the second bypass flow path 11; and a second solenoid valve 14 provided in the main circuit 90 between the receiver 6 and the second expansion valve 7 and switching an open state of the main circuit 90.

[0036] According to the above configuration, even if liquid refrigerant remains in the intermediate heat exchanger 3, the liquid refrigerant can be made to flow through the first bypass passage 10 to the receiver 6 and recovered.

[0037] (2) The refrigeration device 100 according to the second aspect further includes a control unit 80 that switches the open / closed states of the first expansion valve 5, the first three-way valve 9, the first solenoid valve 13, and the second solenoid valve 14, as well as the operating states of the first compressor 1 and the second compressor 2, and when starting only the second compressor 2, the control unit 80 closes the first expansion valve 5, opens the first solenoid valve 13, and opens the first three-way valve 9 only in the direction from the main circuit 90 toward the first bypass flow path 10.

[0038] According to the above configuration, when only the second compressor 2 is started, the pumping force of the second compressor 2 is transmitted to the receiver 6 through the second bypass passage 11. This reduces the pressure in the receiver 6. The reduction in the pressure in the receiver 6 causes the liquid refrigerant remaining in the intermediate heat exchanger 3 to flow toward the receiver 6 through the first bypass passage 10. This makes it possible to recover the liquid refrigerant in the intermediate heat exchanger 3 in the receiver 6.

[0039] (3) In the refrigeration system 100 according to the second aspect, when starting only the first compressor 1, the control unit 80 closes the first expansion valve 5 and the first solenoid valve 13, opens the first three-way valve 9 only in the direction from the main circuit 90 toward the first bypass flow path 10, and opens the second solenoid valve 14.

[0040] According to the above configuration, when only the first compressor 1 is started, the pumping force of the first compressor 1 causes the liquid refrigerant in the intermediate heat exchanger 3 located downstream thereof to be pumped through the first bypass passage 10. The liquid refrigerant pumped through the first bypass passage 10 is stored in the receiver 6. In this way, the liquid refrigerant in the intermediate heat exchanger 3 can be recovered in the receiver 6. [Explanation of symbols]

[0041] 100 Refrigeration equipment 90 Main circuit 80 Control Unit 1. First compressor 2 Second compressor 3 Intermediate heat exchanger 4. Condenser 5 First expansion valve 6 receivers 7 Second expansion valve 8. Evaporator 9. First three-way valve (three-way valve) 10 First bypass flow path 11 Second bypass flow path 12 First check valve (check valve) 13 First solenoid valve 14 Second solenoid valve 15 Accumulator 16 Third bypass flow path 17 Second three-way valve 18 Second check valve

Claims

1. a main circuit which is a circulation flow path through which a refrigerant flows; a first compressor and a second compressor arranged in series on the main circuit; an intermediate heat exchanger disposed between the first compressor and the second compressor; a condenser disposed downstream of the second compressor; a first expansion valve disposed downstream of the condenser; a receiver disposed downstream of the first expansion valve; a second expansion valve disposed downstream of the receiver; an evaporator disposed downstream of the second expansion valve; a three-way valve provided on the main circuit between the intermediate heat exchanger and the second compressor; a first bypass flow passage connecting the three-way valve and the receiver; a second bypass passage connecting the receiver, the three-way valve, and the second compressor; a check valve provided in the first bypass flow path to allow the refrigerant to flow only in a direction from the three-way valve toward the receiver; a first solenoid valve provided in the second bypass flow path and configured to switch an open state of the second bypass flow path; a second solenoid valve provided in the main circuit between the receiver and the second expansion valve and configured to switch an open state of the main circuit; A refrigeration device comprising:

2. a control unit that switches the open / close states of the first expansion valve, the three-way valve, the first solenoid valve, and the second solenoid valve, and the operating states of the first compressor and the second compressor, 2. The refrigeration apparatus according to claim 1, wherein, when starting only the second compressor, the control unit closes the first expansion valve, opens the first solenoid valve, and opens the three-way valve only in a direction from the main circuit toward the first bypass flow path.

3. 3. The refrigeration apparatus according to claim 2, wherein, when starting only the first compressor, the control unit closes the first expansion valve and the first solenoid valve, opens the three-way valve only in a direction from the main circuit toward the first bypass flow path, and opens the second solenoid valve.

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