Cooling system

Abstract

To provide a cooling system capable of improving a heat transfer rate by allowing a predetermined amount of oil to flow into an evaporator.SOLUTION: The cooling system 100 includes a refrigerant circuit 10 in which a refrigerant circulates between a compressor 1, a condenser 3, an expansion valve 5, and an evaporator 6 provided on refrigerant flow paths 11, 12, 13, 14, and 15 through which the refrigerant flows, and an oil amount adjustment mechanism that adjusts an amount of oil contained in the refrigerant, the oil amount adjustment mechanism includes an oil separator 2 that separates oil contained in the refrigerant flowing out of the compressor 1, and a first oil flow path 21 that mixes the oil separated by the oil separator 2 with the refrigerant. The first oil flow path 21 is connected to the refrigerant flow path 13 between the condenser 3 and the evaporator 6.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a cooling system. [Background technology]

[0002] Conventionally, cooling systems have been known that include refrigerant flow paths through which a refrigerant for heating and cooling is circulated (see, for example, Patent Document 1). In the cooling system of Patent Document 1 (referred to as a "refrigeration device" in the document), the refrigerant circulates in a refrigerant circuit in which a compressor, a condenser, an expander, and an evaporator are connected in this order. The compressor is supplied with refrigeration oil (hereinafter referred to as "oil") to lubricate its sliding parts, and the refrigerant flowing out of the compressor contains oil. Therefore, an oil separator that separates oil from the refrigerant is located downstream of the expander in the direction of refrigerant flow, preventing oil from flowing into the evaporator. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-145100 Summary of the Invention [Problem to be solved by the invention]

[0004] The cooling system of Patent Document 1 is configured to prevent oil from flowing into the evaporator, preventing the refrigeration capacity of the evaporator from decreasing due to the sensible heat of the oil. However, if no oil flows into the evaporator at all, oil foaming inside the evaporator is suppressed, which creates a problem of not being able to improve the heat transfer coefficient of the evaporator. Furthermore, if oil flows into the condenser, the oil may adhere to the heat exchanger wall, forming an oil film and impeding heat transfer.

[0005] The present invention has been made in consideration of the above-mentioned problems, and its object is to provide a cooling system that can improve the heat transfer coefficient by flowing a predetermined amount of oil into an evaporator. [Means for solving the problem]

[0006] A characteristic configuration of a cooling system according to the present invention is that it includes a refrigerant circuit in which a refrigerant circulates between a compressor, a condenser, an expansion valve, and an evaporator, which are provided on a refrigerant flow path through which the refrigerant flows, and an oil amount adjustment mechanism that adjusts the amount of oil contained in the refrigerant, wherein the oil amount adjustment mechanism has an oil separator that separates oil contained in the refrigerant that has flowed out of the compressor, and a first oil flow path that mixes the oil separated in the oil separator with the refrigerant, and the first oil flow path is connected to the refrigerant flow path between the condenser and the evaporator.

[0007] According to this configuration, the first oil flow path, which mixes the oil separated in the oil separator with the refrigerant, is connected to the refrigerant flow path between the condenser and the evaporator. This allows oil to flow into the evaporator without flowing into the condenser. This prevents the formation of an oil film in the condenser and suppresses deterioration of heat transfer. Furthermore, by adjusting the amount of oil flowing through the first oil flow path, a predetermined amount of oil can flow into the evaporator, causing oil foaming and improving the heat transfer coefficient. Therefore, by achieving a balance between the reduction in the refrigeration effect due to the sensible heat of the oil, the suppression of deterioration of heat transfer in the condenser, and the improvement in the heat transfer coefficient due to oil foaming, a cooling system capable of efficient heat management can be provided. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a circuit configuration diagram of a cooling system according to a first embodiment. [Figure 2] FIG. 6 is a circuit configuration diagram of a cooling system according to a second embodiment. [Figure 3] FIG. 10 is a Mollier diagram showing a heat cycle according to a second embodiment. [Figure 4] FIG. 10 is a circuit configuration diagram of a cooling system according to a third embodiment. [Figure 5] FIG. 10 is a Mollier diagram showing a heat cycle according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the cooling system according to the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiment, and various modifications are possible without departing from the spirit of the present invention.

[0010] First Embodiment 1, a cooling system 100 according to a first embodiment includes a refrigerant circuit 10 through which a refrigerant circulates, and an oil amount adjustment mechanism that adjusts the amount of oil contained in the refrigerant. The cooling system 100 performs heating and cooling of a vehicle interior, for example.

[0011] The refrigerant circuit 10 is a closed circuit in which a compressor 1, a condenser 3, an expansion valve 5, and an evaporator 6 are connected in this order on a refrigerant flow path. An oil separator 2 that constitutes an oil amount adjustment mechanism is disposed on the refrigerant flow path between the compressor 1 and the condenser 3. Furthermore, a receiver 4 that stores refrigerant is disposed on the refrigerant flow path between the condenser 3 and the expansion valve 5. A refrigerant such as a hydrofluorocarbon (HFC) or a hydrofluoroolefin (HFO) flows through the refrigerant circuit 10.

[0012] Of the refrigerant flow paths, the first refrigerant path 11 is a path through which the refrigerant flows between the compressor 1 and the oil separator 2. The second refrigerant path 12 is a path through which the refrigerant flows between the oil separator 2 and the condenser 3. The third refrigerant path 13 is a path through which the refrigerant flows between the condenser 3 and the expansion valve 5, and the receiver 4 is disposed on the third refrigerant path 13. The fourth refrigerant path 14 is a path through which the refrigerant flows between the expansion valve 5 and the evaporator 6, and the fifth refrigerant path 15 is a path through which the refrigerant flows between the evaporator 6 and the compressor 1.

[0013] The compressor 1 compresses the gaseous refrigerant that has flowed in from the fifth refrigerant passage 15. This increases the pressure of the refrigerant, and the temperature of the refrigerant increases. The high-temperature, high-pressure gaseous refrigerant is sent to the oil separator 2 via the first refrigerant passage 11. The compressor 1 is, for example, a compressor.

[0014] The compressor 1 is supplied with lubricating oil to lubricate its sliding parts, and some of the oil becomes mist and flows out of the compressor 1 together with the refrigerant. As a result, the refrigerant flowing out of the compressor 1 contains high-temperature, high-pressure oil mist. The oil separator 2 separates this mist into liquid oil. The oil separator 2 may be, for example, a centrifugal separator, an impingement separator, a baffle separator that separates oil using a baffle plate, or a demister separator that separates oil using metal fibers such as wire mesh. The oil separator 2 may also have a reservoir that stores the separated oil. The oil content of the refrigerant from which the oil has been separated by the oil separator 2 may be, for example, 10% or less, preferably 5% or less, and more preferably 1% or less.

[0015] The refrigerant from which oil has been separated in the oil separator 2 flows through the second refrigerant passage 12 and into the condenser 3. A passage (not shown) different from the second refrigerant passage 12 and the third refrigerant passage 13 is connected to the condenser 3, and a cooling liquid flows through this passage. In the condenser 3, the high-temperature, high-pressure gaseous refrigerant loses heat to the cooling liquid. As a result, the high-temperature, high-pressure gaseous refrigerant condenses and becomes a medium-temperature, high-pressure liquid refrigerant. The condenser 3 is, for example, a water-cooled condenser. The cooling liquid is, for example, an antifreeze liquid mainly containing ethylene glycol or the like, a long-life coolant (LLC), a fluorine-based inert liquid, or other cooling liquid with high electrical insulation. The cooling liquid may be air or oil.

[0016] By separating a portion of the oil contained in the refrigerant in the oil separator 2, the amount of oil flowing into the condenser 3 can be reduced, thereby suppressing the formation of an oil film due to oil adhering to the heat exchange wall of the condenser 3. This prevents the heat transfer between the coolant and the refrigerant in the condenser 3 from being impeded, enabling efficient thermal management of the cooling system 100.

[0017] The refrigerant that has become liquid in the condenser 3 flows through the third refrigerant passage 13 and flows into and is stored in the receiver 4. The receiver 4 is, for example, a receiver or a surge tank, and it is preferable that a certain amount of refrigerant is stored therein.

[0018] The refrigerant flowing out of the receiver 4 flows through the third refrigerant passage 13 and into the expansion valve 5. The expansion valve 5 is configured so that the flow path area is suddenly narrower than that of the third refrigerant passage 13, allowing only a small amount of refrigerant to flow through. This reduces the pressure of the refrigerant, and with this reduction in pressure, the temperature of the refrigerant drops, causing gaseous refrigerant to mix with the liquid refrigerant. The flow path area of ​​the expansion valve 5 can be adjusted as needed.

[0019] The refrigerant that has been made low-temperature and low-pressure by the expansion valve 5 is sent to the evaporator 6 via a fourth refrigerant passage 14. In the evaporator 6, heat is applied to the low-temperature, low-pressure refrigerant, causing it to become a medium-temperature, low-pressure gaseous refrigerant. The evaporator 6 is, for example, an evaporator that takes in outside air and performs heat exchange between the outside air and the refrigerant, or a chiller that performs heat exchange between a coolant and the refrigerant. The refrigerant circuit 10 may be provided with both an evaporator and a chiller. In this case, an expansion valve other than the expansion valve 5 and either an evaporator or a chiller may be provided in a passage that branches from the third refrigerant passage 13 and connects to the fifth refrigerant passage 15.

[0020] The medium-temperature, low-pressure gaseous refrigerant flowing out of the evaporator 6 flows through the fifth refrigerant passage 15 and enters the compressor 1, where it is compressed again to become a high-temperature, high-pressure gaseous refrigerant. In this way, the refrigerant circulates through the refrigerant circuit 10 while its pressure and temperature change. An accumulator may be disposed on the fifth refrigerant passage 15. In this case, the refrigerant flowing out of the evaporator 6 is separated into liquid refrigerant in the accumulator and flows into the compressor 1.

[0021] In addition to the oil separator 2, the oil amount adjustment mechanism has a first oil passage 21 that mixes the oil separated in the oil separator 2 with the refrigerant, a second oil passage 22 that returns the oil to the compressor 1, and a switching valve 7 that switches between the first oil passage 21 and the second oil passage 22. The oil separator 2 and the switching valve 7 are connected by a third oil passage 23. The first oil passage 21, the second oil passage 22, and the third oil passage 23 preferably have a passage area smaller than that of the refrigerant pipes that form the refrigerant passages.

[0022] The switching valve 7 is, for example, a three-way valve, and connects the third oil flow path 23 to the first oil flow path 21, or connects the third oil flow path 23 to the second oil flow path 22. The switching valve 7 can also simultaneously connect the third oil flow path 23 to the first oil flow path 21 and the third oil flow path 23 to the second oil flow path 22. This allows the oil separated in the oil separator 2 to circulate through both the first oil flow path 21 and the second oil flow path 22. The amount of oil flowing through the first oil flow path 21 and the second oil flow path 22 can be adjusted by adjusting the aperture of the switching valve 7.

[0023] In this embodiment, the first oil flow path 21 is connected to the receiver 4 downstream in the oil flow direction. Therefore, the oil separated in the oil separator 2 flows through the third oil flow path 23, the switching valve 7, and the first oil flow path 21 into the receiver 4 and is mixed with the refrigerant stored in the receiver 4. The first oil flow path 21 is preferably connected to the receiver 4 at a lower portion in the vertical direction of the receiver 4. When oil is supplied from the lower portion of the receiver 4, the oil discharge pressure causes the oil to move from the bottom to the top of the refrigerant stored in the receiver 4, stirring the refrigerant and oil to achieve a uniform oil concentration in the refrigerant. When the oil pressure is lower than the internal pressure of the receiver 4, the first oil flow path 21 is preferably connected to the receiver 4 at an upper portion thereof, and the oil is preferably supplied from the upper portion of the receiver 4. The oil content of the refrigerant after mixing with the oil is preferably, for example, 2% to 6%, more preferably 3% to 5%. The switching valve 7 may control the amount of oil flowing through the first oil flow path 21 so that the amount of oil in the refrigerant falls within the above-mentioned range. The amount of oil in the refrigerant may be measured by a measuring device disposed on the third refrigerant path 13, for example.

[0024] By including a predetermined amount of oil in the refrigerant flowing into the expansion valve 5 and the evaporator 6, oil foaming can occur in the evaporator 6. Oil foaming is a phenomenon in which the refrigerant dissolves in oil and bubbles up, as if the refrigerant is boiling, which promotes evaporation of the refrigerant and improves the heat transfer coefficient. That is, according to this embodiment, by not flowing oil into the condenser 3 but flowing a predetermined amount of oil into the evaporator 6, the heat transfer coefficient of the cooling system 100 can be improved.

[0025] Furthermore, oil foaming in the evaporator 6 is more likely to occur as the refrigerant temperature decreases. Therefore, after the oil is mixed with the refrigerant in the receiver 4, the refrigerant is decompressed and cooled in the expansion valve 5 before flowing into the evaporator 6, which makes it easier for oil foaming to occur. This improves the heat transfer coefficient. Furthermore, by maintaining a constant oil concentration in the refrigerant and a constant refrigerant temperature, oil foaming can be generated uniformly.

[0026] The temperature of the refrigerant flowing into the evaporator 6 rises by the amount of heat contained in the oil compared to when no oil is mixed with the refrigerant. This reduces the refrigeration capacity of the evaporator 6 by the amount of sensible heat of the oil. Therefore, the amount of oil mixed with the refrigerant should be controlled by balancing the effect of suppressing the decrease in heat transfer in the condenser 3 and the effect of improving the heat transfer coefficient by oil foaming.

[0027] A portion of the oil separated in the oil separator 2 flows through the third oil flow path 23, the switching valve 7, and the second oil flow path 22 and is returned to the compressor 1. The amount of oil returned to the compressor 1 may be adjusted according to the flow rate of the refrigerant flowing through the compressor 1.

[0028] Second Embodiment Next, a cooling system 100 according to a second embodiment will be described with reference to Figures 2 and 3. Of the cooling system 100 according to the second embodiment, descriptions of parts that overlap with those of the first embodiment will be omitted.

[0029] As shown in Fig. 2, the oil amount regulating mechanism according to the second embodiment has a cooler 8 that cools the high-temperature oil separated in the oil separator 2. The cooler 8 is provided on the first oil flow path 21, and the oil that has been cooled in the cooler 8 to a medium to low temperature flows into the receiver 4. The cooler 8 can be any type, such as an air-cooled type or a water-cooled type.

[0030] FIG. 3 is a Mollier diagram showing the heat cycle in the cooling system 100. In FIG. 3, the horizontal axis represents the specific enthalpy of the refrigerant, and the vertical axis represents the pressure of the refrigerant. The Mollier diagram is divided into three regions according to the combination of specific enthalpy and pressure: region R1 where the refrigerant exists in a supercooled state (liquid state), region R2 where the refrigerant exists as wet vapor (gas-liquid mixed state), and region R3 where the refrigerant exists as superheated vapor (gas state). The boundary between the supercooled state and the wet vapor state is the saturated liquid line L1, and the boundary between the wet vapor state and the superheated vapor state is the saturated vapor line L2. The boundary between the saturated liquid line L1 and the saturated vapor line L2 corresponds to the critical point A.

[0031] When the refrigerant is pressurized (compressed) in the compressor 1, its specific enthalpy increases, and the medium-temperature, low-pressure gaseous refrigerant shown in FIG. 3(a) becomes the high-temperature, high-pressure gaseous refrigerant shown in FIG. 3(b). The high-temperature, high-pressure refrigerant shown in FIG. 3(b) is sent to the condenser 3 and condenses, decreasing its specific enthalpy under isobaric conditions. This results in a medium-temperature, high-pressure liquid refrigerant, which is then mixed with oil in the receiver 4 and becomes the liquid refrigerant shown in FIG. 3(c). The medium-temperature, high-pressure refrigerant shown in FIG. 3(c) expands in the expansion valve 5 and its pressure decreases. This results in a low-temperature, low-pressure gas-liquid mixture refrigerant shown in FIG. 3(d). The low-temperature, low-pressure refrigerant shown in FIG. 3(d) evaporates in the evaporator 6 and increases its specific enthalpy under isobaric conditions. This results in a medium-temperature, low-pressure gaseous refrigerant shown in FIG. 3(a).

[0032] FIG. 3(e) shows the medium-temperature, high-pressure liquid refrigerant condensed in the condenser 3 and mixed with high-temperature oil in the receiver 4 in the first embodiment. FIG. 3(f) shows the low-temperature, low-pressure gas-liquid mixed refrigerant expanded in the expansion valve 5 in the first embodiment. That is, in the first embodiment, the refrigerant flowing out of the condenser 3 and mixed with oil in the receiver 4 expands along the dashed lines shown in FIG. 3(e) to (f). In contrast, in the second embodiment, medium- to low-temperature oil cooled in the cooler 8 is mixed with the refrigerant condensed in the condenser 3, resulting in a smaller specific enthalpy of the refrigerant compared to the first embodiment. Therefore, in the second embodiment, the refrigerant sent to the expansion valve 5 is in a more subcooled state. As a result, in the second embodiment, the heating capacity of the condenser 3 and the refrigeration capacity of the evaporator 6 can be increased compared to the first embodiment, thereby improving the coefficient of performance of the cooling system 100.

[0033] In this way, by providing a cooler 8 that cools the oil flowing through the first oil flow path 21, it is possible to suppress a decrease in heating capacity and refrigeration capacity compared to a cooling system 100 that does not have an oil amount adjustment mechanism.

[0034] Third Embodiment Next, a cooling system 100 according to a third embodiment will be described with reference to Figures 4 and 5. Of the cooling system 100 according to the third embodiment, descriptions of parts that overlap with those of the first embodiment will be omitted.

[0035] As shown in Fig. 4, the oil amount adjustment mechanism according to the third embodiment has a cooler 9 that cools the high-temperature oil separated in the oil separator 2. The cooler 9 is an internal heat exchanger that exchanges heat between the medium-temperature refrigerant flowing out of the evaporator 6 and the high-temperature oil separated in the oil separator 2. As a result, the oil that has been cooled by the refrigerant receiving heat flows into the receiver 4, and the refrigerant that has been heated by the oil receives heat flows into the compressor 1.

[0036] FIG. 5 is a Mollier diagram showing the thermal cycle in the cooling system 100 according to the third embodiment. In FIG. 5, the thermal cycle according to the second embodiment is indicated by a dashed line. In the third embodiment, as shown in FIG. 5(g), the specific enthalpy of the refrigerant that has absorbed heat from the oil in the cooler 9 is greater than the specific enthalpy of the refrigerant not heated by oil in the first and second embodiments, as shown in FIG. 5(a). Therefore, the medium-temperature, low-pressure gaseous refrigerant flowing into the compressor 1 is pressurized by the compressor 1 to become a high-temperature, high-pressure gaseous refrigerant as shown in FIG. 5(h).

[0037] In the third embodiment, the oil separated in the oil separator 2 is cooled by the refrigerant flowing out from the evaporator 6, as heat is absorbed by the cooler 9. If the temperature of the oil is lower than that of the refrigerant in the receiver 4, the refrigerant in the receiver 4 is cooled by the oil and becomes a lower-temperature liquid refrigerant. Therefore, in the third embodiment, as shown in FIG. 5(i), the specific enthalpy of the refrigerant condensed in the condenser 3 and mixed with low-temperature oil is smaller than the specific enthalpy of the refrigerant in the second embodiment, as shown in FIG. 5(c). The medium-temperature, high-pressure refrigerant shown in FIG. 5(i) expands in the expansion valve 5 to become a low-temperature, low-pressure gas-liquid mixed refrigerant shown in FIG. 5(j). The gas-liquid mixed refrigerant then evaporates in the evaporator 6 and is heated in the cooler 9, increasing its specific enthalpy and becoming a high-temperature, low-pressure gas refrigerant shown in FIG. 5(g).

[0038] As described above, in the third embodiment, the refrigerant sent to the expansion valve 5 is in a more supercooled state, and the refrigerant sent to the compressor 1 is in a more superheated vapor state. As a result, in the third embodiment, the heating capacity of the condenser 3 and the refrigeration capacity of the evaporator 6 can be increased compared to the second embodiment, thereby improving the coefficient of performance of the cooling system 100. In particular, compared to the cooling system 100 not equipped with an oil amount adjustment mechanism, it is possible to suppress a decrease in the heat transfer coefficient of the condenser 3, improve the heat transfer coefficient of the evaporator 6, and improve the heating capacity and refrigeration capacity of the cooling system 100, thereby enabling efficient heat management.

[0039] Other Embodiments (a) In the above embodiment, the receiver 4 is disposed in the refrigerant circuit 10. However, the receiver 4 does not have to be disposed in the refrigerant circuit 10. Even in this case, if the first oil flow path 21 is connected to the third refrigerant path 13 upstream of the expansion valve 5 with respect to the flow direction of the refrigerant flowing through the third refrigerant path 13, the refrigerant mixed with oil can be caused to flow into the evaporator 6 after its temperature is lowered by the expansion valve 5, which makes it easier for oil foaming to occur. Furthermore, by lowering the temperature of the refrigerant mixed with oil through the expansion valve 5, the temperature can be made uniform, which makes it possible to uniformly generate oil foaming.

[0040] (b) In the above embodiment, the oil amount adjustment mechanism has a switching valve 7 that switches between the first oil flow path 21 and the second oil flow path 22. However, the first oil flow path 21 and the second oil flow path 22 may each be directly connected to the oil separator 2, and control valves that adjust the amount of oil flowing through the first oil flow path 21 and the second oil flow path 22 may be provided on these paths.

[0041] (c) A measuring device that measures the amount of oil contained in the refrigerant may be disposed on the refrigerant circuit 10. The cooling system 100 may also be provided with a control device that controls the switching valve 7 based on the amount of oil measured by the measuring device and the amount of refrigerant circulating through the refrigerant circuit 10.

[0042] (d) The compressor 1 may have a built-in oil separator other than the oil separator 2. By separating oil from the refrigerant in both the compressor 1 and the oil separator 2, it is possible to obtain a necessary and sufficient oil separation function even when a small oil separator 2 is used.

[0043] In the above-described embodiment, the following configurations are envisioned. (1) A cooling system 100 including a refrigerant circuit 10 in which a refrigerant circulates between a compressor 1, a condenser 3, an expansion valve 5, and an evaporator 6, which are provided on refrigerant flow paths (first refrigerant path 11, second refrigerant path 12, third refrigerant path 13, fourth refrigerant path 14, fifth refrigerant path 15) through which the refrigerant flows, and an oil amount adjustment mechanism that adjusts the amount of oil contained in the refrigerant, wherein the oil amount adjustment mechanism has an oil separator 2 that separates oil contained in the refrigerant flowing out of the compressor 1, and a first oil flow path 21 that mixes the oil separated in the oil separator 2 with the refrigerant, and the first oil flow path 21 is connected to a refrigerant flow path (third refrigerant path 13) between the condenser 3 and the evaporator 6.

[0044] According to this configuration, the first oil passage 21, which mixes the oil separated in the oil separator 2 with the refrigerant, is connected to the refrigerant passage (third refrigerant passage 13) between the condenser 3 and the evaporator 6. This allows oil to flow into the evaporator 6 without flowing into the condenser 3. This prevents the formation of an oil film in the condenser 3 and suppresses deterioration of heat transfer. Furthermore, by adjusting the amount of oil flowing through the first oil passage 21, a predetermined amount of oil can be allowed to flow into the evaporator 6, thereby generating oil foaming in the evaporator 6 and improving the heat transfer coefficient. Therefore, by balancing the reduced refrigeration effect due to the sensible heat of the oil with the improved heat transfer coefficient due to oil foaming, a cooling system 100 capable of efficient heat management can be provided.

[0045] (2) In the cooling system 100 of (1), it is preferable that the first oil passage 21 is connected to the refrigerant passage (third refrigerant passage 13) upstream of the expansion valve 5.

[0046] According to this configuration, the refrigerant and oil are mixed upstream of the expansion valve 5, so that the pressure of these refrigerants is reduced by the expansion valve 5, and the refrigerant can flow into the evaporator 6 at a temperature lowered to the evaporation temperature. This facilitates oil foaming in the evaporator 6, improving the heat transfer coefficient. Furthermore, the temperature of the refrigerant flowing into the evaporator 6 can be kept constant, making it possible to generate oil foaming uniformly.

[0047] (3) In the cooling system 100 of (1) or (2), the refrigerant circuit 10 is preferably provided with a receiver 4 for storing refrigerant on the refrigerant flow path (third refrigerant path 13) between the condenser 3 and the expansion valve 5, and the first oil flow path 21 is preferably connected to the receiver 4.

[0048] According to this configuration, the oil can be uniformly dispersed in the refrigerant by mixing the refrigerant and oil in the receiver 4. This makes it possible to uniformly generate oil foaming in the evaporator 6.

[0049] (4) In the cooling system 100 of any one of (1) to (3), it is preferable that the oil amount adjustment mechanism further includes coolers 8 and 9 that cool the oil separated in the oil separator 2.

[0050] According to this configuration, the oil cooled in the coolers 8 and 9 can be mixed with the refrigerant, thereby suppressing an increase in the refrigerant temperature due to the oil. This eliminates the reduction in the refrigeration effect due to the sensible heat of the oil. Furthermore, since the refrigerant sent to the expansion valve 5 can be made more supercooled, the refrigeration capacity of the evaporator 6 can be increased, and the coefficient of performance of the refrigeration system 100 can be improved.

[0051] (5) In any of the cooling systems 100 of (1) to (4), it is preferable that the oil amount adjustment mechanism further has a second oil flow path 22 that returns the oil separated in the oil separator 2 to the compressor 1, and a switching valve 7 that switches between the first oil flow path 21 and the second oil flow path 22.

[0052] According to this configuration, the amount of oil flowing through the first oil flow path 21 and the second oil flow path 22 can be adjusted by the switching valve 7, thereby controlling the amount of oil to be mixed with the refrigerant and the amount of oil to be returned to the compressor 1. [Industrial Applicability]

[0053] The present invention can be used in a cooling system including a refrigerant circuit through which a refrigerant circulates. [Explanation of symbols]

[0054] 1: compressor, 2: oil separator, 3: condenser, 4: receiver, 5: expansion valve, 6: evaporator, 7: switching valve, 8: cooler, 9: cooler, 10: refrigerant circuit, 11: first refrigerant path (refrigerant path), 12: second refrigerant path (refrigerant path), 13: third refrigerant path (refrigerant path), 14: fourth refrigerant path (refrigerant path), 15: fifth refrigerant path (refrigerant path), 21: first oil path, 22: second oil path, 100: cooling system

Claims

1. a refrigerant circuit in which the refrigerant circulates among a compressor, a condenser, an expansion valve, and an evaporator, which are provided on a refrigerant flow path through which the refrigerant flows; an oil amount adjusting mechanism for adjusting the amount of oil contained in the refrigerant, the oil amount adjustment mechanism includes an oil separator that separates oil contained in the refrigerant flowing out from the compressor, and a first oil flow path that mixes the oil separated by the oil separator with the refrigerant, The first oil flow path is connected to the refrigerant flow path between the condenser and the evaporator.

2. The cooling system according to claim 1 , wherein the first oil flow path is connected to the refrigerant flow path upstream of the expansion valve.

3. the refrigerant circuit includes a receiver that stores the refrigerant, and the receiver is located on the refrigerant flow path between the condenser and the expansion valve; The cooling system according to claim 2 , wherein the first oil flow path is connected to the receiver.

4. The cooling system according to claim 1 , wherein the oil amount adjusting mechanism further comprises a cooler that cools the oil separated by the oil separator.

5. The oil amount adjustment mechanism includes a second oil flow path that returns the oil separated in the oil separator to the compressor; The cooling system according to claim 1 , further comprising a switching valve that switches between the first oil flow path and the second oil flow path.

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