Refrigeration equipment

Abstract

To provide a refrigeration device which increases cooling capacity by an evaporator while preventing abnormal high temperature of a compressor.SOLUTION: A refrigeration device 100 includes a refrigerant circuit 1 in which a compressor 2, a condenser 3, an expansion valve 4, and an evaporator 5 are connected to perform a steam compression type refrigeration cycle. The condenser 3 causes the refrigerant to exchange heat with a coolant. The refrigerant circuit 1 has a cooling heat exchanger 6 which causes the refrigerant flowing from the evaporator 5 to the compressor 2 to exchange heat with the coolant that has conducted heat exchange at the condenser 3 to cool the refrigerant.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The technology of the present disclosure relates to a refrigeration device.

Background Art

[0002] For example, the refrigeration device disclosed in Patent Document 1 includes a liquid injection pipe for preventing the compressor from becoming abnormally hot. Specifically, the liquid injection pipe of Patent Document 1 injects a part of the liquid refrigerant flowing out from the condenser into the suction pipe of the compressor. Thereby, the suction refrigerant of the compressor is cooled by the liquid refrigerant, and the abnormal high temperature of the compressor is prevented.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in the refrigeration device such as Patent Document 1 described above, there is a problem that the cooling capacity by the evaporator decreases. That is, since a part of the liquid refrigerant flowing out from the condenser bypasses the evaporator and is supplied to the suction pipe of the compressor, the refrigerant flow rate flowing from the condenser to the evaporator decreases accordingly.

[0005] The technology of the present disclosure has been made in view of such circumstances, and its object is to increase the cooling capacity by the evaporator while preventing the abnormal high temperature of the compressor.

Means for Solving the Problems

[0006] The refrigeration apparatus of this disclosure comprises a refrigerant circuit that performs a vapor compression type refrigeration cycle by connecting a compressor, a heat exchanger, an expansion mechanism, and an evaporator. The heat exchanger causes the refrigerant to exchange heat with a cooling medium. The refrigerant circuit has a cooling heat exchanger that cools the refrigerant flowing from the evaporator to the compressor by exchanging heat with the cooling medium after heat exchange in the heat exchanger.

[0007] In the above configuration, the refrigerant circulates through the refrigerant circuit to perform a vapor compression refrigeration cycle. Specifically, the refrigerant compressed by the compressor flows to the radiator, where it exchanges heat with a cooling medium such as water and dissipates heat. The refrigerant that has dissipated heat in the radiator flows to the expansion mechanism and expands. The refrigerant that has expanded in the expansion mechanism flows to the evaporator, where it exchanges heat with an object such as air and absorbs heat, cooling the object. The refrigerant evaporates due to the absorption of heat. The refrigerant that has evaporated in the evaporator returns to the compressor and is compressed again.

[0008] Here, the refrigerant evaporated in the evaporator is cooled in a cooling heat exchanger before flowing to the compressor. Specifically, refrigerant flows into the cooling heat exchanger from the evaporator, while the cooling medium that has exchanged heat with the refrigerant in the radiator is supplied. In the cooling heat exchanger, the refrigerant exchanges heat with the cooling medium and dissipates heat, thus being cooled. The refrigerant cooled in the cooling heat exchanger flows to the compressor. In this way, the refrigerant inhaled by the compressor is cooled, preventing the compressor from overheating. Furthermore, in the cooling heat exchanger, the cooling medium used in the radiator is utilized as a cooling source for the refrigerant. Therefore, the amount of refrigerant injected into the compressor's intake side, as in conventional systems, can be reduced. By reducing the injection amount, the refrigerant flow rate to the evaporator in the refrigerant circuit increases. This makes it possible to increase the cooling capacity of the evaporator while preventing the compressor from overheating.

[0009] The refrigerant circuit may further include a bypass pipe and a flow path switching mechanism. The bypass pipe has an inlet end and an outlet end connected to a suction pipe connecting the evaporator and the compressor, and is equipped with a cooling heat exchanger. The flow path switching mechanism switches between a state in which the refrigerant flowing out of the evaporator is prevented from flowing into the bypass pipe and a state in which at least a portion of the refrigerant flowing out of the evaporator flows into the bypass pipe, based on predetermined conditions.

[0010] In the above configuration, the bypass pipe has its inlet and outlet ends connected to the suction pipe, bypassing a portion of the suction pipe. The flow path of the refrigerant from the evaporator to the compressor is then switched based on predetermined conditions. In other words, when the refrigerant can be cooled by the cooling heat exchanger, all or part of the refrigerant flowing out of the evaporator passes through the bypass pipe and flows to the compressor. Therefore, the refrigerant can be cooled by the cooling heat exchanger before flowing to the compressor. Consequently, abnormally high temperatures in the compressor can be prevented.

[0011] The flow path switching mechanism may, if the temperature of the upstream refrigerant, which is the refrigerant upstream of the inlet end of the bypass pipe in the suction pipe, is less than or equal to the target temperature, which is the temperature of the cooling medium after heat exchange in the heat exchanger, prevent the upstream refrigerant from flowing into the bypass pipe, and if the temperature of the upstream refrigerant is higher than the target temperature, allow the upstream refrigerant to flow into the bypass pipe.

[0012] In the above configuration, if the temperature of the upstream refrigerant is below the target temperature, the upstream refrigerant flows to the compressor through the suction pipe without passing through the bypass pipe. In other words, the upstream refrigerant flows to the compressor without passing through the cooling heat exchanger. Therefore, it is possible to prevent the suction refrigerant of the compressor from being heated by the cooling medium. On the other hand, if the temperature of the upstream refrigerant is higher than the target temperature, the upstream refrigerant flows to the compressor through the bypass pipe. In other words, the upstream refrigerant flows to the compressor after passing through the cooling heat exchanger. Therefore, the suction refrigerant of the compressor can be cooled by the cooling medium. In this way, the upstream refrigerant can be cooled before flowing to the compressor. Therefore, it is possible to more reliably prevent the compressor from overheating.

[0013] The refrigerant circuit may further include an injection tube and an adjustment mechanism. The inlet end of the injection tube is connected to a high-pressure liquid pipe connecting the radiator and the expansion mechanism, and the outlet end is connected to the suction pipe, injecting a portion of the refrigerant from the high-pressure liquid pipe into the suction pipe. The adjustment mechanism adjusts the injection amount of the injection tube according to the temperature of the refrigerant downstream of the outlet end of the bypass pipe and the outlet end of the injection tube in the suction pipe.

[0014] In the above configuration, when a portion of the refrigerant in the high-pressure liquid pipe is injected into the suction pipe via the injection pipe, the refrigerant in the suction pipe is cooled by the refrigerant in the high-pressure liquid pipe. Therefore, the refrigerant in the suction pipe can be cooled in two stages: by the cooling heat exchanger and by the injection pipe. In other words, the amount of cooling by the injection pipe only needs to cover a portion of the required cooling amount for the refrigerant in the suction pipe. Therefore, the amount of injection by the injection pipe is reduced compared to conventional designs. The amount of injection is adjusted by an adjustment mechanism according to the amount of cooling that the injection pipe must provide. The required cooling amount for the refrigerant in the suction pipe is the amount of cooling required to cool the refrigerant that has flowed out of the evaporator into the suction pipe to a predetermined temperature (i.e., the target value of the compressor's suction temperature).

[0015] The outlet end of the injection pipe may be connected to the portion of the suction pipe downstream of the outlet end of the bypass pipe.

[0016] In the above configuration, the refrigerant in the suction pipe is cooled by the cooling heat exchanger and then further cooled by injection through the injection pipe. Therefore, compared to, for example, the case where the refrigerant in the suction pipe is cooled by injection through the injection pipe and then cooled by the cooling heat exchanger, it is not necessary to set the target temperature to a lower value. As a result, it is not necessary to prepare a low-temperature cooling medium as the cooling medium supplied to the heat sink. [Effects of the Invention]

[0017] The refrigeration system of this disclosure can increase the cooling capacity of the evaporator while preventing abnormally high temperatures in the compressor. [Brief explanation of the drawing]

[0018] [Figure 1] This is a piping diagram showing the refrigeration system. [Figure 2] This is a block diagram of a control device and its peripheral equipment. [Modes for carrying out the invention]

[0019] The following exemplary embodiments will be described in detail with reference to the drawings.

[0020] Figure 1 is a piping diagram showing a refrigeration system 100. The refrigeration system 100 is installed, for example, in an environmental testing apparatus to cool the test chamber to a set temperature. The refrigeration system 100 comprises a refrigerant circuit 1 in which a refrigerant circulates to perform a vapor compression refrigeration cycle, and a control device 9. The refrigerant circuit 1 is formed as a closed circuit by connecting a compressor 2, a condenser 3, an expansion valve 4, and an evaporator 5 with piping.

[0021] The compressor 2 compresses the refrigerant inhaled from the suction side and discharges it from the discharge side, and is, for example, a rotary compressor of a scroll type or a rotary type. A discharge pipe 11 is connected to the discharge side of the compressor 2, and the discharge pipe 11 is connected to the condenser 3. That is, the discharge pipe 11 connects the compressor 2 and the condenser 3.

[0022] The condenser 3 is a heat exchanger that exchanges heat between the refrigerant sent from the compressor 2 and the cooling water. Specifically, the condenser 3 has a first flow path 31 and a second flow path 32. The discharge pipe 11 is connected to the inflow end of the first flow path 31, and the high-pressure liquid pipe 12 is connected to the outflow end of the first flow path 31. An inflow pipe 16a for supplying cooling water is connected to the inflow end of the second flow path 32, and an outflow pipe 16b from which the cooling water flows out of the second flow path 32 is connected to the outflow end of the second flow path 32. In the condenser 3, the refrigerant in the first flow path 31 exchanges heat with the cooling water in the second flow path 32 and condenses. That is, the refrigerant releases heat to the cooling water and condenses, and the cooling water is heated. The condenser 3 is an example of a radiator, and the cooling water is an example of a cooling medium.

[0023] The expansion valve 4 expands the liquid refrigerant condensed in the condenser 3. The high-pressure liquid pipe 12 is connected to the inflow side of the expansion valve 4, and the evaporator 5 is connected to the outflow side of the expansion valve 4 via the low-pressure liquid pipe 13. That is, the high-pressure liquid pipe 12 connects the condenser 3 and the expansion valve 4, and the low-pressure liquid pipe 13 connects the expansion valve 4 and the evaporator 5. The expansion valve 4 is an example of an expansion mechanism, and is, for example, an electric valve with variable opening degree.

[0024] The evaporator 5 is a heat exchanger that exchanges heat between the liquid refrigerant expanded by the expansion valve 4 and the air. The refrigeration device 100 has a fan 5a provided in the vicinity of the evaporator 5. The fan 5a circulates the air in the test chamber between the evaporator 5. In the evaporator 5, the liquid refrigerant exchanges heat with the air sent by the fan 5a and evaporates. That is, the liquid refrigerant absorbs heat from the air and evaporates, and the air is cooled. The suction pipe 14 is connected to the outflow side of the evaporator 5, and the suction pipe 14 is connected to the suction side of the compressor 2. That is, the suction pipe 14 connects the evaporator 5 and the compressor 2. The gaseous refrigerant evaporated in the evaporator 5 is sucked into the suction side of the compressor 2 through the suction pipe 14.

[0025] Thus, in the refrigerant circuit 1, the refrigerant circulates in the order of compressor 2, condenser 3, expansion valve 4, and evaporator 5, thereby performing a vapor compression refrigeration cycle.

[0026] Furthermore, the refrigerant circuit 1 includes a bypass pipe 17, a cooling heat exchanger 6, a flow path switching mechanism 7, an injection pipe 18, and a flow control valve 8.

[0027] The bypass pipe 17 is a pipe in which the cooling heat exchanger 6 is installed, with its inlet end 17a and outlet end 17b connected to the suction pipe 14. In other words, the bypass pipe 17 is connected to the suction pipe 14 at both ends and bypasses a portion of the suction pipe 14. Naturally, in the suction pipe 14, the outlet end 17b of the bypass pipe 17 is connected downstream of the inlet end 17a of the bypass pipe 17.

[0028] The cooling heat exchanger 6 cools the refrigerant flowing from the evaporator 5 to the compressor 2 by exchanging heat with the cooling water that has undergone heat exchange in the condenser 3. The cooling heat exchanger 6 is located in the middle of the bypass pipe 17. Hereinafter, the refrigerant flowing from the evaporator 5 to the compressor 2 may be referred to as the refrigerant in the suction pipe 14.

[0029] Specifically, the cooling heat exchanger 6 has a first flow path 61 and a second flow path 62. A bypass pipe 17 is connected to the first flow path 61, and an outlet pipe 16b is connected to the second flow path 62. The refrigerant from the suction pipe 14 flows into the first flow path 61 via the bypass pipe 17. The cooling water heated in the condenser 3 flows into the second flow path 62 via the outlet pipe 16b. In the cooling heat exchanger 6, the refrigerant in the first flow path 61 is cooled by heat exchange with the cooling water in the second flow path 62.

[0030] The flow path switching mechanism 7 switches between a state in which the refrigerant discharged from the evaporator 5 is prevented from flowing into the bypass pipe 17 and a state in which at least a portion of the refrigerant discharged from the evaporator 5 flows into the bypass pipe 17, based on predetermined conditions.

[0031] Specifically, the flow path switching mechanism 7 prevents the upstream refrigerant from flowing into the bypass pipe 17 if the temperature of the upstream refrigerant (the refrigerant upstream of the inlet end 17a of the bypass pipe 17 in the suction pipe 14) is below the target temperature, which is the temperature of the cooling water after heat exchange in the condenser 3. Conversely, the flow path switching mechanism 7 allows the upstream refrigerant to flow into the bypass pipe 17 if the temperature of the upstream refrigerant is higher than the aforementioned target temperature. In other words, the flow path switching mechanism 7 switches between a flow path in which the upstream refrigerant flows to the compressor 2 without passing through the cooling heat exchanger 6, and a flow path in which the upstream refrigerant flows to the compressor 2 after passing through the cooling heat exchanger 6, depending on the relative magnitudes of the upstream refrigerant temperature and the aforementioned target temperature. Furthermore, the flow path switching mechanism 7 uses the aforementioned predetermined conditions to determine the relative magnitudes of the upstream refrigerant temperature and the target temperature. In this example, the temperature of the upstream refrigerant in the suction pipe 14 corresponds to the evaporation temperature of the refrigerant in the evaporator 5.

[0032] Specifically, the flow path switching mechanism 7 includes a first on-off valve 71 and a second on-off valve 72. In this example, both the first on-off valve 71 and the second on-off valve 72 are solenoid valves that can be switched between a fully open state and a fully closed state. The first on-off valve 71 is located in the suction pipe 14 between the inlet end 17a and the outlet end 17b of the bypass pipe 17. The second on-off valve 72 is located in the bypass pipe 17 upstream of the cooling heat exchanger 6. The flow path switching mechanism 7 switches the flow path by switching the open and closed states of the first on-off valve 71 and the second on-off valve 72.

[0033] The injection pipe 18 has an inlet end 18a connected to the high-pressure liquid pipe 12 and an outlet end 18b connected to the suction pipe 14, injecting a portion of the refrigerant from the high-pressure liquid pipe 12 into the suction pipe 14. More specifically, the outlet end 18b of the injection pipe 18 is connected to the portion of the suction pipe 14 downstream of the outlet end 17b of the bypass pipe 17. By injecting a portion of the refrigerant from the high-pressure liquid pipe 12 into the suction pipe 14, the injection pipe 18 cools the refrigerant in the suction pipe 14 with the injected refrigerant.

[0034] The flow control valve 8 adjusts the injection amount of the injection pipe 18 according to the temperature of the refrigerant downstream of the outlet end 17b of the bypass pipe 17 and the outlet end 18b of the injection pipe 18 in the suction pipe 14. The temperature of the refrigerant downstream of the outlet end 17b of the bypass pipe 17 and the outlet end 18b of the injection pipe 18 in the suction pipe corresponds to the temperature of the suction refrigerant just before it is drawn into the compressor 2, and may hereafter be referred to as the temperature of the suction refrigerant of the compressor 2.

[0035] Specifically, the flow control valve 8 is installed in the injection pipe 18. The flow control valve 8 is configured to have a variable opening. The flow control valve 8 adjusts the injection amount by changing its opening so that the temperature of the refrigerant intake of the compressor 2 reaches its target temperature. The target temperature of the refrigerant intake of the compressor 2 is set to a temperature that prevents liquid refrigerant from being drawn into the compressor 2 while also preventing the compressor 2 from overheating. The flow control valve 8 is an example of an adjustment mechanism, for example, a so-called temperature-sensitive expansion valve. A temperature-sensitive expansion valve automatically changes its opening according to the temperature difference between the temperature of the refrigerant intake of the compressor 2 and the target temperature, and is sometimes called a temperature-automatic expansion valve.

[0036] Furthermore, the refrigerant circuit 1 is equipped with a first temperature sensor 96, a second temperature sensor 97, and a third temperature sensor 98. The first temperature sensor 96 detects the temperature of the upstream refrigerant in the suction pipe 14, that is, the temperature of the refrigerant upstream of the inlet end 17a of the bypass pipe 17 in the suction pipe 14. The first temperature sensor 96 is located in the suction pipe 14 upstream of the inlet end 17a of the bypass pipe 17. The second temperature sensor 97 detects the aforementioned target temperature, that is, the temperature of the cooling water after heat exchange in the condenser 3. The second temperature sensor 97 is located in the outlet pipe 16b upstream of the cooling heat exchanger 6. The third temperature sensor 98 detects the temperature of the suction refrigerant of the compressor 2. The third temperature sensor 98 is located in the suction pipe 14 downstream of the outlet end 18b of the injection pipe 18. The third temperature sensor 98 is a so-called temperature-sensing tube and is connected to the flow control valve 8. The flow control valve 8 receives the detection value from the third temperature sensor 98 and automatically changes its opening degree according to the input detection value.

[0037] Figure 2 is a block diagram of the control device 9 and its peripheral equipment. The control device 9 controls the entire refrigerant circuit 1. For example, the control device 9 controls the rotational speed of the compressor 2, the opening degree of the expansion valve 4, the rotational speed of the fan 5a, etc. Specifically, the control device 9 has an input unit 91 and, as a functional block, an acquisition unit 92 and a valve control unit 93.

[0038] The input unit 91 accepts input operations from the user. The user can set various conditions related to the operation of the refrigeration system 100 using the input unit 91. For example, the user can set the target temperature in the test chamber and the target temperature of the refrigerant intake of the compressor 2. The input unit 91 can be, for example, a keyboard, mouse, or touch panel.

[0039] The acquisition unit 92 is capable of communicating with the first temperature sensor 96 and the second temperature sensor 97. The acquisition unit 92 acquires the temperature of the upstream refrigerant in the suction pipe 14 by receiving the detection value from the first temperature sensor 96. The acquisition unit 92 also acquires the target temperature by receiving the detection value from the second temperature sensor 97.

[0040] The valve control unit 93 controls the flow path switching mechanism 7. Specifically, the valve control unit 93 controls the first on-off valve 71 and the second on-off valve 72 according to the relationship between the temperature of the upstream refrigerant in the suction pipe 14 and the target temperature, as acquired by the acquisition unit 92. More specifically, the valve control unit 93 opens the first on-off valve 71 and closes the second on-off valve 72 when the temperature of the upstream refrigerant in the suction pipe 14 is less than or equal to the target temperature. The valve control unit 93 closes the first on-off valve 71 and opens the second on-off valve 72 when the temperature of the upstream refrigerant in the suction pipe 14 is higher than the target temperature.

[0041] Next, the operation of the refrigeration system 100 configured in this way will be described.

[0042] The high-pressure refrigerant compressed by the compressor 2 flows to the condenser 3 via the discharge pipe 11. In the condenser 3, the high-pressure refrigerant condenses through heat exchange with the cooling water. A portion of the liquid refrigerant that flows out of the condenser 3 into the high-pressure liquid pipe 12 flows into the injection pipe 18, while the remaining liquid refrigerant expands in the expansion valve 4 and then flows to the evaporator 5 via the low-pressure liquid pipe 13. Meanwhile, the cooling water that has undergone heat exchange in the condenser 3 is supplied to the cooling heat exchanger 6 via the outlet pipe 16b. In the evaporator 5, the liquid refrigerant evaporates through heat exchange with the air in the test chamber, cooling the air. This cools the test chamber to a predetermined set temperature.

[0043] The refrigerant evaporated in the evaporator 5 flows out into the suction pipe 14. Here, if the temperature of the upstream refrigerant in the suction pipe 14 is higher than the target temperature, the valve control unit 93 closes the first on-off valve 71 and opens the second on-off valve 72. As a result, the entire amount of upstream refrigerant in the suction pipe 14 flows to the cooling heat exchanger 6 via the bypass pipe 17. In the cooling heat exchanger 6, since the cooling water is at a lower temperature than the refrigerant, the refrigerant is cooled by heat exchange with the cooling water.

[0044] The refrigerant cooled in the cooling heat exchanger 6 returns to the suction pipe 14 through the bypass pipe 17. The refrigerant returning to the suction pipe 14 is mixed with the refrigerant injected into the suction pipe 14 from the injection pipe 18 and further cooled. Here, the injection amount in the injection pipe 18 is appropriately adjusted by the flow control valve 8. In other words, the flow control valve 8 automatically changes its opening to adjust the injection amount so that the temperature of the suction refrigerant in the compressor 2 reaches its target temperature. In this way, the temperature of the suction refrigerant in the compressor 2 is maintained at its target temperature by adjusting the injection amount. Therefore, abnormal overheating of the compressor 2 is prevented.

[0045] Thus, the refrigerant in the suction pipe 14 is cooled not only by the injection pipe 18 but also by the cooling heat exchanger 6. Therefore, compared to the conventional method of cooling by the injection pipe alone, the amount of cooling required by the injection pipe 18 is reduced. As a result, the amount of injection required by the injection pipe 18 is reduced, and the amount of refrigerant flowing from the condenser 3 to the evaporator 5 increases accordingly.

[0046] On the other hand, if the temperature of the upstream refrigerant in the suction pipe 14 is below the target temperature, the valve control unit 93 opens the first on-off valve 71 and closes the second on-off valve 72. As a result, the entire amount of upstream refrigerant in the suction pipe 14 flows directly through the suction pipe 14 without passing through the bypass pipe 17 and the cooling heat exchanger 6. This refrigerant in the suction pipe 14 is mixed with the refrigerant injected into the suction pipe 14 from the injection pipe 18 and cooled, as described above. The amount of refrigerant injected from the injection pipe 18 is automatically adjusted by the flow rate control valve 8 so that the temperature of the suction refrigerant in the compressor 2 reaches the target temperature. By adjusting the injection amount in this way, abnormal overheating of the compressor 2 is prevented.

[0047] With the refrigeration system 100 configured as described above, it is possible to increase the cooling capacity of the evaporator 5 while preventing the compressor 2 from overheating.

[0048] Specifically, the refrigeration system 100 includes a refrigerant circuit 1 that performs a vapor compression type refrigeration cycle, with a compressor 2, a condenser 3, an expansion valve 4, and an evaporator 5 connected to it. The condenser 3 exchanges heat between the refrigerant and the cooling water. The refrigerant circuit 1 also includes a cooling heat exchanger 6 that cools the refrigerant flowing from the evaporator 5 to the compressor 2 by exchanging heat between it and the cooling water that has already exchanged heat in the condenser 3.

[0049] In this configuration, the refrigerant evaporated in the evaporator 5 is cooled by the cooling heat exchanger 6 as it flows to the compressor 2. Therefore, the refrigerant drawn into the compressor 2 is cooled, preventing the compressor 2 from overheating. In the cooling heat exchanger 6, the cooling water remaining after heat exchange in the condenser 3 is used as the cooling source for the refrigerant. As a result, the amount of refrigerant injected into the compressor's intake side after flowing out of the condenser, as in conventional systems, can be reduced. This reduction in injection volume increases the amount of refrigerant flowing into the evaporator 5 in the refrigerant circuit 1. Consequently, the cooling capacity of the evaporator 5 can be increased while preventing the compressor 2 from overheating.

[0050] Furthermore, the refrigerant circuit 1 has a bypass pipe 17 in which the inlet end 17a and outlet end 17b are connected to the suction pipe 14 and a cooling heat exchanger 6 is provided. The refrigerant circuit 1 also has a flow path switching mechanism 7 that, based on predetermined conditions, switches between a state in which the refrigerant flowing out of the evaporator 5 is prevented from flowing into the bypass pipe 17 and a state in which at least a portion of the refrigerant flowing out of the evaporator 5 flows into the bypass pipe 17. Specifically, the flow path switching mechanism 7 prevents the upstream refrigerant flowing into the bypass pipe 17 when the temperature of the upstream refrigerant upstream of the inlet end 17a of the bypass pipe 17 in the suction pipe 14 is below the target temperature, which is the temperature of the cooling water after heat exchange in the condenser 3, and allows the upstream refrigerant to flow into the bypass pipe 17 when the temperature of the upstream refrigerant is higher than the target temperature.

[0051] With this configuration, if the temperature of the upstream refrigerant is below the target temperature, the upstream refrigerant flows to the compressor 2 through the suction pipe 14 without passing through the bypass pipe 17. In other words, the upstream refrigerant flows to the compressor 2 without passing through the cooling heat exchanger 6. Therefore, it is possible to prevent the suction refrigerant of the compressor 2 from being heated by the cooling water. On the other hand, if the temperature of the upstream refrigerant is higher than the target temperature, the upstream refrigerant flows to the compressor 2 through the bypass pipe 17. In other words, the upstream refrigerant flows to the compressor 2 after passing through the cooling heat exchanger 6. Therefore, the suction refrigerant of the compressor 2 is cooled by the cooling water. In this way, since the suction refrigerant of the compressor 2 is cooled by the cooling water, abnormal high temperatures of the compressor 2 can be further prevented.

[0052] Furthermore, the refrigerant circuit 1 has an injection pipe 18 whose inlet end 18a is connected to the high-pressure liquid pipe 12 and whose outlet end 18b is connected to the suction pipe 14, and which injects a portion of the refrigerant from the high-pressure liquid pipe 12 into the suction pipe 14. The refrigerant circuit 1 also has a flow control valve 8 that adjusts the amount of refrigerant injected by the injection pipe 18 according to the temperature of the refrigerant suctioned by the compressor 2.

[0053] In this configuration, the injection tube 18 cools the refrigerant in the suction tube 14 by injecting a portion of the refrigerant from the high-pressure liquid tube 12 into the suction tube 14. Therefore, the refrigerant in the suction tube 14 is cooled by both the injection tube 18 and the cooling heat exchanger 6. As a result, the amount of cooling required by the injection tube 18 can be reduced compared to the conventional method of cooling by the injection tube alone. This reduces the amount of injection required by the injection tube 18, and consequently increases the amount of refrigerant flowing from the condenser 3 to the evaporator 5 via the expansion valve 4. Therefore, the cooling capacity of the evaporator 5 can be increased. This configuration is effective when the required amount of cooling for the refrigerant in the suction tube 14 cannot be met by cooling water alone.

[0054] Furthermore, the outlet end 18b of the injection pipe 18 is connected to the portion of the suction pipe 14 downstream of the outlet end 17b of the bypass pipe 17.

[0055] In this configuration, the refrigerant in the suction pipe 14 is cooled by the cooling heat exchanger 6, and then further cooled by injection through the injection pipe 18. Therefore, compared to, for example, the case where the refrigerant in the suction pipe is cooled by the injection pipe and then by the cooling heat exchanger, it is not necessary to set the target temperature to a lower value. As a result, it is not necessary to prepare low-temperature cooling water as the cooling water supplied to the condenser 3.

[0056] Other embodiments As described above, the embodiments described herein have been presented as examples of the technology disclosed in this application. However, the technology in this disclosure is not limited thereto and can be applied to embodiments that have been modified, replaced, added, or omitted as appropriate. Furthermore, it is possible to combine the components described in the embodiments above to create new embodiments. In addition, the components described in the attached drawings and detailed description may include not only components essential for solving the problem, but also components that are not essential for solving the problem, in order to illustrate the technology. Therefore, the mere presence of such non-essential components in the attached drawings and detailed description should not be immediately assumed to mean that those non-essential components are essential.

[0057] For example, the flow path switching mechanism 7 may be configured not to flow the entire amount of upstream refrigerant into the bypass pipe 17, but rather to flow a portion of the upstream refrigerant into the bypass pipe 17 and the remainder into the suction pipe 14. In this case, the first on-off valve 71 and the second on-off valve 72 may be electric valves, for example, whose opening degree can be changed continuously or in steps. With this configuration, the flow rate of refrigerant flowing into the bypass pipe 17 can be adjusted continuously or in steps, so that the temperature of the suction refrigerant of the compressor 2 can be finely adjusted. In this case, one of the first on-off valve 71 and the second on-off valve 72 may be omitted, or the flow path switching mechanism 7 may be configured with a three-way valve. When the flow path switching mechanism 7 is configured with a three-way valve, the three-way valve is provided, for example, at the inlet end 17a of the bypass pipe 17.

[0058] Furthermore, the temperature of the upstream refrigerant detected by the first temperature sensor 96 may be substituted with, for example, the temperature of the test chamber of the environmental testing apparatus. The temperature of the upstream refrigerant roughly corresponds to the temperature of the refrigerant just before it flows out of the evaporator 5, and this refrigerant temperature is substantially equivalent to the temperature of the test chamber (i.e., the temperature of the air in the test chamber). In this case, the first temperature sensor 96 can be omitted.

[0059] Furthermore, the second temperature sensor 97 may be omitted. In this case, for example, the target temperature can be set to a temperature expected from the results of preliminary experiments, and the set target temperature can be stored in the control device 9.

[0060] Furthermore, while the flow path switching mechanism 7 uses a predetermined condition regarding the relative magnitude of the temperature of the upstream refrigerant and the target temperature, it is not limited to this. For example, the predetermined condition may be the relative magnitude of the temperature inside the test chamber of the environmental test apparatus and its set temperature. In other words, the flow path switching mechanism 7 may prevent the upstream refrigerant from flowing into the bypass pipe 17 when the temperature inside the test chamber is lower than the set temperature, and allow the upstream refrigerant to flow into the bypass pipe 17 when the temperature inside the test chamber is higher than the set temperature.

[0061] Furthermore, the outlet end 18b of the injection pipe 18 may be connected to a portion of the suction pipe 14 upstream of the inlet end 17a of the bypass pipe 17. In this configuration, the refrigerant in the suction pipe 14 is cooled by the injection pipe 18 and then further cooled by the cooling heat exchanger 6. This is effective when the temperature of the refrigerant injected from the injection pipe 18 is higher than the target temperature, i.e., the temperature of the cooling water after heat exchange in the condenser 3. Conversely, the refrigeration system 100 of the above embodiment is effective when the temperature of the refrigerant injected from the injection pipe 18 is lower than the target temperature.

[0062] Furthermore, the flow control valve 8 may be one whose opening degree is controlled by the valve control unit 93. In this case, the third temperature sensor 98 is configured to communicate with the acquisition unit 92, similar to the first temperature sensor 96, etc. That is, the acquisition unit 92 obtains the temperature of the suction refrigerant of the compressor 2 by receiving the detected value from the third temperature sensor 98. The valve control unit 93 controls the opening degree of the flow control valve 8 so that the temperature of the suction refrigerant obtained by the acquisition unit 92 reaches its target temperature.

[0063] Furthermore, in the refrigerant circuit 1 of the above embodiment, the injection pipe 18 may be omitted.

[0064] The refrigeration device 100 is not limited to cooling the test chamber of the environmental testing apparatus, but may also be used to cool the inside of a refrigerator or freezer containing food or the like. [Explanation of Symbols]

[0065] 100 Refrigeration equipment 1. Refrigerant circuit 2 Compressor 3. Condenser (heat sink) 4. Expansion valve (expansion mechanism) 5. Evaporator 6 Cooling heat exchanger 7. Flow path switching mechanism 8. Flow control valve (adjustment mechanism) 12 High-pressure liquid pipes 14 Suction pipe 17 Bypass pipe 17a Inlet end 17b Outflow end 18 Injection tubes 18a Inlet end 18b Outflow end

Claims

1. It is equipped with a refrigerant circuit that performs a vapor compression type refrigeration cycle, in which a compressor, radiator, expansion mechanism, and evaporator are connected. The aforementioned heat exchanger exchanges heat between the refrigerant and the cooling medium. The aforementioned refrigerant circuit is A cooling heat exchanger cools the refrigerant flowing from the evaporator to the compressor by exchanging heat with the cooling medium after heat exchange in the heat exchanger, The inlet and outlet ends are connected to the suction pipe connecting the evaporator and the compressor, and the bypass pipe is provided with the cooling heat exchanger. A refrigeration system having a flow path switching mechanism that, based on predetermined conditions, switches between a state in which the refrigerant discharged from the evaporator is prevented from flowing into the bypass pipe and a state in which at least a portion of the refrigerant discharged from the evaporator flows into the bypass pipe.

2. In the refrigeration apparatus according to claim 1, The flow path switching mechanism prevents the upstream refrigerant from flowing into the bypass pipe when the temperature of the upstream refrigerant, which is the refrigerant upstream of the inlet end of the bypass pipe in the suction pipe, is less than or equal to the target temperature, which is the temperature of the cooling medium after heat exchange in the heat exchanger, and allows at least a portion of the upstream refrigerant to flow into the bypass pipe when the temperature of the upstream refrigerant is higher than the target temperature.

3. In the refrigeration apparatus according to claim 1 or 2, The aforementioned refrigerant circuit is An injection pipe whose inlet end is connected to a high-pressure liquid pipe connecting the heat sink and the expansion mechanism, and whose outlet end is connected to the suction pipe, and which injects a portion of the refrigerant from the high-pressure liquid pipe into the suction pipe, A refrigeration system further comprising an adjustment mechanism for adjusting the injection amount of the injection pipe according to the temperature of the refrigerant downstream of the outlet end of the bypass pipe and the outlet end of the injection pipe in the suction pipe.

4. In the refrigeration apparatus according to claim 3, The outlet end of the injection pipe is connected to a refrigeration device in which the portion of the suction pipe downstream of the outlet end of the bypass pipe is connected.

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