Freezer

Abstract

To provide a freezer in which a heat transfer performance and a COP of a heat exchanger are improved when a laminate-type micro channel heat exchanger is used as a full-liquid-type evaporator.SOLUTION: A freezer includes: a compressor for compressing a primary refrigerant; a condenser; a high-pressure receiver provided on a downstream side of the condenser; at least one ejector provided on a downstream side of the high-pressure receiver and configured to operate the primary refrigerant supplied from the high-pressure receiver as a drive fluid; and a micro channel heat exchanger for evaporating the primary refrigerant by exchanging heat between the primary refrigerant and a secondary refrigerant. In the freezer, an outlet side of the primary refrigerant of the micro channel heat exchanger is connected to the ejector such that the primary refrigerant flowing in the micro channel heat exchanger is sucked by the ejector.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a refrigerator. [Background technology]

[0002] There is known a refrigerator configured to use the evaporator as a flooded evaporator by providing a surge drum in the refrigerant flow path on the low-pressure side of the refrigerator and supplying refrigerant liquid to the evaporator via a thermosiphon (see, for example, Patent Document 1). A flooded evaporator can bring the degree of superheat at the evaporator outlet close to zero and has small pressure loss, making it possible to increase the COP of the refrigerator compared to a dry evaporator. Also, as a heat exchanger, a stacked microchannel heat exchanger is known, which is configured by stacking a large number of fine flow channels with hydraulic diameters of several millimeters or less in a densely arranged parallel arrangement, thereby providing high heat transfer performance and a large heat transfer area with a small volume (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-074509 [Patent Document 2] Japanese Patent Publication No. 2023-097857 Summary of the Invention [Problem to be solved by the invention]

[0004] When a stacked microchannel heat exchanger is used as a flooded evaporator, the steam generated by boiling and evaporation of the refrigerant does not escape well in a stacked microchannel heat exchanger with fine flow paths, and the circulation of the refrigerant is poor in a thermosiphon system, preventing the heat exchanger from fully demonstrating its performance.

[0005] One possible solution is to supply refrigerant liquid from the surge drum to the heat exchanger using a liquid pump, but this comes with issues such as increased initial costs, the need to take measures against cavitation, and a decrease in COP due to increased power consumption.

[0006] In view of the above circumstances, at least one embodiment of the present disclosure aims to provide a refrigerator that can improve the heat transfer performance and COP of a heat exchanger when a stacked microchannel heat exchanger is used as a flooded evaporator. [Means for solving the problem]

[0007] A refrigerator according to at least one embodiment of the present disclosure includes: a compressor for compressing a primary refrigerant; a condenser for condensing the primary refrigerant compressed by the compressor; a high-pressure receiver provided downstream of the condenser for storing the primary refrigerant; at least one ejector provided downstream of the high-pressure receiver and configured to operate using the primary refrigerant supplied from the high-pressure receiver as a driving fluid; a microchannel heat exchanger having a plurality of fine flow paths through which the primary refrigerant flows, for evaporating the primary refrigerant in the plurality of fine flow paths by heat exchange between the primary refrigerant and the secondary refrigerant; Equipped with The outlet side of the microchannel heat exchanger for the primary refrigerant is connected to the ejector, and the ejector is configured to suck the primary refrigerant flowing through the microchannel heat exchanger. [Effects of the Invention]

[0008] According to at least one embodiment of the present disclosure, when a stacked microchannel heat exchanger is used as a flooded evaporator in a refrigerator, the heat transfer performance and COP of the heat exchanger can be improved. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a system diagram of a refrigerator according to an embodiment. [Figure 2] FIG. 10 is a system diagram of a refrigerator according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, several embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present disclosure. For example, expressions expressing relative or absolute arrangement such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" not only express such an arrangement exactly, but also express a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained. For example, expressions such as "identical," "equal," and "homogeneous" that indicate that something is in an equal state not only indicate a state of strict equality, but also indicate a state in which there is a tolerance or a difference to the extent that the same function is obtained. For example, expressions representing shapes such as a square shape or a cylindrical shape not only represent shapes such as a square shape or a cylindrical shape in the strict geometric sense, but also represent shapes including uneven portions, chamfered portions, etc., to the extent that the same effect can be obtained. On the other hand, the expressions "comprise," "include," "have," "includes," or "have" of one element are not exclusive expressions that exclude the presence of other elements.

[0011] Fig. 1 is a system diagram of a refrigerator 10 according to one embodiment. Fig. 2 is a system diagram of a refrigerator 10 according to another embodiment. A chiller 10 according to some embodiments includes a primary refrigerant circuit 12 through which a primary refrigerant circulates and a secondary refrigerant circuit 14 through which a secondary refrigerant circulates. The primary refrigerant circuit 12 is provided with refrigeration cycle components including an evaporator 16, and the refrigeration cycle is formed by the primary refrigerant circulating through these components. The secondary refrigerant circulating through the secondary refrigerant circuit 14 is cooled and condensed by the primary refrigerant in the evaporator 16. The secondary refrigerant liquid condensed in the evaporator 16 is supplied to a cooling load 18 via a secondary refrigerant receiver tank 30 and a secondary refrigerant pump 32, and is used as a cold source for the cooling load 18. For example, a natural refrigerant such as ammonia is used as the primary refrigerant, and a natural refrigerant such as carbon dioxide is used as the secondary refrigerant. The arrows on the oil passages in the primary refrigerant circuit 12 and the secondary refrigerant circuit 14 indicate the flow directions of the primary refrigerant and the secondary refrigerant.

[0012] In some embodiments, the primary refrigerant circuit 12 includes a compressor 20, a condenser 22, a high-pressure receiver tank (high-pressure receiver) 23, an expansion valve 24, an ejector 26, and a surge drum 28.

[0013] The primary refrigerant compressed by the compressor 20 is cooled and condensed in the condenser 22, and the condensed primary refrigerant liquid is stored in the high-pressure receiver 23. In some embodiments, the high-pressure receiver 23 is provided with a liquid level sensor 54 for detecting the liquid level of the primary refrigerant liquid in the high-pressure receiver 23 . In the chiller 10 shown in FIG. 1, the primary refrigerant liquid stored in the high-pressure receiver 23 flows into the surge drum 28 via the expansion valve 24 and the ejector 26 provided on a flow path 42 connecting the high-pressure receiver 23 and a primary refrigerant gas storage section 282 (described later) of the surge drum 28. The refrigerator 10 shown in FIG. 1 has one expansion valve 24 and one ejector 26.

[0014] In the chiller 10 shown in FIG. 2, the primary refrigerant liquid stored in the high-pressure receiver 23 flows into the surge drum 28 via at least one of a plurality of control valves 56 and at least one of a plurality of ejectors 26 provided on a flow path 42 connecting the high-pressure receiver 23 and a primary refrigerant gas storage section 282 (described later) of the surge drum 28. 2, the multiple ejectors 26 are arranged in parallel downstream of the high-pressure receiver 23 and include two ejectors 261 and 262 having different nozzle diameters. Control valves 561 and 562 are provided upstream of the flow path 42 in the two ejectors 261 and 262, respectively.

[0015] In the refrigerator 10 shown in FIG. 2, the two ejectors 261 and 262 have different nozzle diameters, but they may have the same nozzle diameter. Furthermore, in the refrigerator 10 shown in FIG. 2, the two ejectors 261 and 262 are arranged in parallel with each other downstream of the high-pressure receiver 23, but they may also be connected in series. Although the refrigerator 10 shown in FIG. 2 has two ejectors 26, it may have three or more ejectors.

[0016] In some embodiments, the ejector 26 is provided downstream of the high-pressure receiver 23 and is configured to draw the primary refrigerant flowing through the evaporator 16 from the primary refrigerant outlet 16b of the evaporator 16 using the primary refrigerant liquid supplied from the high-pressure receiver 23 as a driving fluid.

[0017] In some embodiments, the surge drum 28 has a liquid reservoir 281 in which liquid-phase primary refrigerant, i.e., primary refrigerant liquid, is stored, and a gas-phase portion above the liquid reservoir 281, i.e., a primary refrigerant gas reservoir 282 in which primary refrigerant gas is stored. In some embodiments, the primary refrigerant gas reservoir 282 is connected to the suction side of the compressor 20 via the compressor suction passage 46 .

[0018] In some embodiments, the liquid reservoir 281 is connected to the primary refrigerant inlet 16a of the evaporator 16 via the flow path 44. Note that in some embodiments, the flow path 44 is configured to allow the primary refrigerant to flow from the liquid reservoir 281 of the surge drum 28 to the primary refrigerant inlet 16a of the evaporator 16 without passing through a throttle or a throttle valve. This reduces the pressure loss from the liquid reservoir 281 of the surge drum 28 to the primary refrigerant inlet 16a of the evaporator 16, which contributes to increasing the amount of primary refrigerant flowing through the evaporator 16. This contributes to improving the heat transfer performance of the evaporator 16.

[0019] In some embodiments, the primary refrigerant gas that has flowed into the surge drum 28 and is stored in the primary refrigerant gas storage section 282 is compressed again by the compressor 20 .

[0020] In some embodiments, of the primary refrigerant that has flowed into the surge drum 28, the primary refrigerant liquid that has accumulated in the liquid reservoir 281 is sent to the evaporator 16, which functions as the evaporator of the primary refrigerant circuit 12, via a flow path 44 that connects the liquid reservoir 281 with the primary refrigerant inlet 16a of the evaporator 16. In some embodiments, the primary refrigerant liquid absorbs heat from the secondary refrigerant in the evaporator 16 and is vaporized, and the vaporized primary refrigerant and the liquid-phase primary refrigerant that has not been completely vaporized are returned to the surge drum 28 via the ejector 26. In other words, the ejector 26 is configured to suck the two-phase primary refrigerant from the primary refrigerant outlet 16b of the evaporator 16.

[0021] In some embodiments, the refrigeration oil separated from the primary refrigerant in the surge drum 28 is periodically returned to the compressor suction passage 46 via a valve 52 provided on the passage connecting the liquid reservoir 281 and the compressor suction passage 46.

[0022] In some embodiments, the evaporator 16 is a stacked microchannel heat exchanger in which a large number of microchannels with hydraulic diameters of several millimeters or less are densely arranged in parallel and stacked. In some embodiments, the hydraulic diameter of the microchannels in the evaporator 16 is, for example, 1 mm or less.

[0023] In the refrigerator 10 shown in FIG. 1, the amount of primary refrigerant liquid supplied from the high-pressure receiver 23 to the ejector 26 is adjusted by the expansion valve 24. The opening degree of the expansion valve 24 is controlled by a first control device 61, which is the control device 60 of the refrigerator 10 shown in FIG.

[0024] In the refrigerator 10 shown in FIG. 2, switching to the ejector 26 that supplies the primary refrigerant liquid from the high-pressure receiver 23 is performed depending on which of the plurality of control valves 56 is opened or closed. The opening and closing of the plurality of control valves 56 is controlled by a second control device 62, which is the control device 60 of the refrigerator 10 shown in FIG.

[0025] In some embodiments, the control device 60 (first control device 61 and second control device 62) is configured with, for example, a central processing unit (CPU), random access memory (RAM), read-only memory (ROM), and a computer-readable storage medium. A series of processes for realizing various functions is stored in a storage medium or the like in the form of a program, for example. The CPU reads this program into the RAM or the like and executes information processing and arithmetic operations to realize various functions. The program may be pre-installed in a ROM or other storage medium, provided in a state stored in a computer-readable storage medium, or distributed via wired or wireless communication means. Examples of computer-readable storage media include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, and semiconductor memories.

[0026] In the refrigerator 10 shown in FIG. 1, the first control device 61 is configured to control the opening degree of the expansion valve 24 based on the liquid level in the high-pressure receiver 23 detected by the liquid level sensor 54. In the refrigerator 10 shown in Figure 2, the second control device 62 is configured to control which of the multiple control valves 56 (control valves 561, 562) to open or close based on the liquid level in the high-pressure receiver 23 detected by the liquid level sensor 54.

[0027] The secondary refrigerant circuit 14 includes the above-mentioned secondary refrigerant receiver tank 30 for storing secondary refrigerant liquid. The secondary refrigerant liquid stored in the secondary refrigerant receiver tank 30 is discharged from a secondary refrigerant pump 32 and sent to the cooling load 18. After cooling the cooling load 18, the secondary refrigerant liquid is returned to the secondary refrigerant receiver tank 30.

[0028] In some embodiments, cooling load 18 is an air cooler that is provided in a refrigerator (not shown) that keeps food and other items cold, for example, for cooling the interior of the refrigerator.

[0029] In the refrigerator 10 configured as above, the evaporator 16 is a stacked microchannel heat exchanger, so vapor generated in the microchannels due to boiling or evaporation of the primary refrigerant tends to have difficulty escaping from the microchannels. Therefore, in the refrigerator 10 according to some embodiments, the outlet 16b of the primary refrigerant of the evaporator 16 is connected to an ejector 26, and the ejector 26 sucks the primary refrigerant flowing through the evaporator 16. According to the chiller 10 of some embodiments, the vapor of the primary refrigerant generated in the evaporator 16 due to boiling or evaporation of the primary refrigerant can be sucked in by the ejector 26, which makes it easier for the primary refrigerant to flow through the evaporator 16 and improves the heat transfer performance of the evaporator 16. Furthermore, according to the chiller 10 of some embodiments, there is no need to use a liquid pump to supply primary refrigerant liquid from the surge drum 28 to the evaporator 16, which avoids the increase in power consumption that would otherwise be caused by using a liquid pump and improves the COP.

[0030] The refrigeration machine 10 shown in Figure 1 includes a liquid level sensor 54 provided in the high-pressure receiver 23, an expansion valve 24 provided between the high-pressure receiver 23 and the ejector 26, and a first control device 61 for controlling the opening degree of the expansion valve 24 based on the detection result of the liquid level sensor 54. This allows the amount of liquid in the surge drum 28 to be adjusted by adjusting the amount of primary refrigerant liquid in the high-pressure receiver 23, thereby preventing refrigerant liquid from returning to the compressor 20 and enabling stable operation of the refrigerator 10.

[0031] The chiller 10 shown in Fig. 2 includes a plurality of ejectors 26 provided on the flow path 42. The chiller 10 shown in Fig. 2 includes a liquid level sensor 54 provided in the high-pressure receiver 23, and a second control device 62 for controlling, based on the detection result of the liquid level sensor 54, to which of the plurality of ejectors 26 the primary refrigerant is to flow. According to the refrigerator 10 shown in FIG. 2, the amount of liquid in the surge drum 28 can be adjusted by adjusting the amount of primary refrigerant liquid in the high-pressure receiver 23, thereby preventing refrigerant liquid from returning to the compressor 20, thereby enabling stable operation of the refrigerator 10.

[0032] 2, the multiple ejectors 26 are arranged in parallel with one another downstream of the high-pressure receiver 23, and have different nozzle diameters. In the chiller 10 shown in FIG. 2, the second control device 62 can perform control based on the detection result of the liquid level sensor 54 to switch between the multiple ejectors 26 having different nozzle diameters that allow the primary refrigerant to flow. This makes it easier to control the circulation amount of the primary refrigerant in the refrigerator 10, allowing the refrigerator 10 to operate more stably.

[0033] In some embodiments, the hydraulic diameter of the microchannels in the evaporator 16 is 1 mm or less. The smaller the hydraulic diameter of the fine flow passages, the better the heat transfer performance generally becomes, but the smaller the escape of the vapor of the primary refrigerant generated in the evaporator 16 due to boiling and evaporation of the primary refrigerant tends to become. According to the refrigerator 10 of some embodiments, the primary refrigerant flows easily through the evaporator 16, so that the heat transfer performance of the evaporator 16 can be improved even if the hydraulic diameter of the fine flow passage is 1 mm or less.

[0034] In some embodiments, the inlet 16a of the evaporator 16 for the primary refrigerant is located below the liquid level in the liquid reservoir 281 of the surge drum . This contributes to increasing the flow rate of the primary refrigerant flowing through the evaporator 16 by utilizing the head difference between the liquid level in the liquid reservoir 281 of the surge drum 28 and the primary refrigerant inlet 16a of the evaporator 16. This contributes to improving the heat transfer performance of the evaporator 16.

[0035] In some embodiments, as described above, the ejector 26 is configured to draw two-phase primary refrigerant from the primary refrigerant outlet 16b of the evaporator 16. This allows the two-phase flow of primary refrigerant to flow out from the primary refrigerant outlet 16b of the evaporator 16, making it possible to reduce the degree of superheat of the primary refrigerant in the evaporator 16 to zero and reducing the vapor quality in the heat exchanger, thereby increasing the heat transfer coefficient while reducing pressure loss and improving the COP.

[0036] The present disclosure is not limited to the above-described embodiments, but also includes modifications to the above-described embodiments and appropriate combinations of these modifications.

[0037] The contents described in each of the above embodiments can be understood, for example, as follows. (1) A refrigerator 10 according to at least one embodiment of the present disclosure includes a compressor 20 for compressing a primary refrigerant, a condenser 22 for condensing the primary refrigerant compressed by the compressor 20, a high-pressure receiver 23 provided downstream of the condenser 22 for storing the primary refrigerant, at least one ejector 26 provided downstream of the high-pressure receiver 23 and configured to operate using the primary refrigerant supplied from the high-pressure receiver 23 as a driving fluid, and a microchannel heat exchanger (evaporator 16) having a plurality of fine flow paths through which the primary refrigerant flows and evaporating the primary refrigerant in the plurality of fine flow paths by heat exchange between the primary refrigerant and a secondary refrigerant. The refrigerator 10 according to at least one embodiment of the present disclosure is configured such that a primary refrigerant outlet 16b of the microchannel heat exchanger (evaporator 16) is connected to the ejector 26, and the ejector 26 draws in the primary refrigerant flowing through the microchannel heat exchanger (evaporator 16).

[0038] According to the above configuration (1), the vapor of the primary refrigerant generated in the microchannel heat exchanger (evaporator 16) due to boiling and evaporation of the primary refrigerant can be sucked in by the ejector 26, which makes it easier for the primary refrigerant to flow through the microchannel heat exchanger (evaporator 16) and improves the heat transfer performance of the microchannel heat exchanger (evaporator 16). Furthermore, according to the above configuration (1), there is no need to use a liquid pump to supply primary refrigerant liquid to the microchannel heat exchanger (evaporator 16), which avoids the increase in power consumption due to the use of a liquid pump and improves the COP.

[0039] (2) In some embodiments, the configuration of (1) above may include a surge drum 28 having a gas phase section (primary refrigerant gas storage section 282) that communicates with the outlet side of the ejector 26, and a liquid reservoir 281 for the primary refrigerant. The liquid reservoir 281 may communicate with the inlet 16a for the primary refrigerant of the microchannel heat exchanger (evaporator 16). The gas phase section (primary refrigerant gas storage section 282) may communicate with the outlet side of the ejector 26.

[0040] According to the above configuration (2), there is no need to use a liquid pump to supply the primary refrigerant liquid from the surge drum 28 to the microchannel heat exchanger (evaporator 16), so the increase in power consumption due to the use of a liquid pump can be avoided and the COP can be improved.

[0041] (3) In some embodiments, the configuration of (2) above may include a liquid level sensor 54 provided in the high-pressure receiver 23, an expansion valve 24 provided between the high-pressure receiver 23 and the ejector 26, and a first control device 61 for controlling the opening degree of the expansion valve 24 based on the detection result of the liquid level sensor 54.

[0042] According to the above configuration (3), the amount of liquid in the surge drum 28 can be adjusted by adjusting the amount of primary refrigerant liquid in the high-pressure receiver 23, thereby preventing the refrigerant liquid from returning to the compressor 20, thereby enabling stable operation of the refrigerator 10.

[0043] (4) In some embodiments, in the configuration of (2) above, the at least one ejector 26 may include a plurality of ejectors 26 (ejectors 261, 262). In some embodiments, the system may include a liquid level sensor 54 provided in the high-pressure receiver 23, and a second control device 62 for controlling, based on a detection result of the liquid level sensor 54, to which of the plurality of ejectors 26 (ejectors 261, 262) the primary refrigerant is to flow.

[0044] According to the configuration (4) above, the amount of liquid in the surge drum 28 can be adjusted by adjusting the amount of primary refrigerant liquid in the high-pressure receiver 23, thereby preventing the refrigerant liquid from returning to the compressor 20, thereby enabling stable operation of the chiller 10.

[0045] (5) In some embodiments, in the configuration of (4) above, the multiple ejectors 26 (ejectors 261, 262) may be arranged in parallel with each other downstream of the high-pressure receiver 23 and may have different nozzle diameters. The second control device 62 may be capable of controlling, based on the detection result of the liquid level sensor 54, to switch between the multiple ejectors 26 (ejectors 261, 262) having different nozzle diameters that allow the primary refrigerant to circulate.

[0046] According to the configuration (5) above, it becomes easier to control the circulation amount of the primary refrigerant in the refrigerator 10, so that the refrigerator can be operated more stably.

[0047] (6) In some embodiments, in any of the configurations (1) to (5) above, the hydraulic diameter of the plurality of microchannels may be 1 mm or less.

[0048] According to the above configuration (6), the primary refrigerant can easily flow through the microchannel heat exchanger (evaporator 16), thereby improving the heat transfer performance of the microchannel heat exchanger (evaporator 16) even if the hydraulic diameter of the multiple fine flow paths is 1 mm or less.

[0049] (7) In some embodiments, in any of the configurations (2) to (5) above, the inlet 16a for the primary refrigerant of the microchannel heat exchanger (evaporator 16) may be located below the liquid level in the liquid reservoir 281 of the surge drum 28.

[0050] According to the above configuration (7), by utilizing the head difference between the liquid level in the liquid reservoir 281 of the surge drum 28 and the primary refrigerant inlet 16a of the microchannel heat exchanger (evaporator 16), the flow rate of the primary refrigerant flowing through the microchannel heat exchanger (evaporator 16) is increased, thereby contributing to improving the heat transfer performance of the microchannel heat exchanger (evaporator 16).

[0051] (8) In some embodiments, in any of the configurations (1) to (5) or (7) above, at least one ejector 26 may be configured to draw in two-phase primary refrigerant from the primary refrigerant outlet 16b of the microchannel heat exchanger (evaporator 16).

[0052] According to the above configuration (8), two-phase flow of the primary refrigerant is allowed to flow out from the primary refrigerant outlet 16b of the microchannel heat exchanger (evaporator 16). This makes it possible to reduce the degree of superheat of the primary refrigerant in the microchannel heat exchanger (evaporator 16) to zero, and also to reduce the vapor quality in the heat exchanger. This increases the heat transfer coefficient while reducing pressure loss, thereby improving the COP.

[0053] (9) In some embodiments, in any of the configurations (2) to (5) or (7) above, the flow path 44 connecting the liquid reservoir 281 of the surge drum 28 and the primary refrigerant inlet 16a of the microchannel heat exchanger (evaporator 16) may be configured to allow the primary refrigerant to flow from the liquid reservoir 281 of the surge drum 28 to the primary refrigerant inlet 16a of the microchannel heat exchanger (evaporator 16) without passing through a throttle or throttle valve.

[0054] According to the above configuration (9), the pressure loss from the liquid reservoir 281 of the surge drum 28 to the primary refrigerant inlet 16a of the microchannel heat exchanger (evaporator 16) can be reduced, which contributes to an increase in the amount of primary refrigerant flowing through the microchannel heat exchanger (evaporator 16), thereby contributing to an improvement in the heat transfer performance of the microchannel heat exchanger (evaporator 16). [Explanation of symbols]

[0055] 10. Freezer 12 Primary refrigerant circuit 14 Secondary refrigerant circuit 16 Evaporator 16a Entrance 16b Exit 18 Cooling load 20 Compressor 22 Condenser 23 High-pressure receiver tank (high-pressure receiver) 24 Expansion valve 26 Ejector 28 Surge Drum 30 Secondary refrigerant receiver tank 32 Secondary refrigerant pump 42 Flow path 44 Flow path 46 Compressor intake passage 52 valves 54 Liquid level sensor 56 Control valve 60 Control device 61 First control device 62 Second control device 261 Ejector 262 Ejector 281 Liquid reservoir 282 Primary refrigerant gas reservoir 561 Control valve 562 Control valve

Claims

1. a compressor for compressing a primary refrigerant; a condenser for condensing the primary refrigerant compressed by the compressor; a high-pressure receiver provided downstream of the condenser for storing the primary refrigerant; at least one ejector disposed downstream of the high-pressure receiver and configured to operate using the primary refrigerant supplied from the high-pressure receiver as a driving fluid; a microchannel heat exchanger having a plurality of fine flow paths through which the primary refrigerant flows, for evaporating the primary refrigerant in the plurality of fine flow paths by heat exchange between the primary refrigerant and the secondary refrigerant; Equipped with An outlet side of the primary refrigerant of the microchannel heat exchanger is connected to the ejector, and the ejector is configured to suck the primary refrigerant flowing through the microchannel heat exchanger. Freezer.

2. a surge drum having a gas phase section communicating with an outlet side of the ejector and a liquid reservoir section for the primary refrigerant; Equipped with the liquid reservoir communicates with an inlet side of the microchannel heat exchanger for the primary refrigerant; The gas phase section communicates with the outlet side of the ejector. The refrigerator according to claim 1.

3. a liquid level sensor provided in the high-pressure receiver; an expansion valve provided between the high-pressure receiver and the ejector; a first control device for controlling the opening degree of the expansion valve based on the detection result of the liquid level sensor; Equipped with The refrigerator according to claim 2.

4. the at least one ejector includes a plurality of ejectors; a liquid level sensor provided in the high-pressure receiver; a second control device for controlling, based on a detection result of the liquid level sensor, to which of the plurality of ejectors the primary refrigerant is to be circulated; Equipped with The refrigerator according to claim 2.

5. the plurality of ejectors are arranged in parallel with one another downstream of the high-pressure receiver, and have different nozzle diameters; the second control device is capable of controlling, based on a detection result of the liquid level sensor, to switch an ejector through which the primary refrigerant flows, among the plurality of ejectors having different nozzle diameters. The refrigerator according to claim 4.

6. The hydraulic diameter of the plurality of microchannels is 1 mm or less. The refrigerator according to any one of claims 1 to 5.

7. an inlet of the microchannel heat exchanger for the primary refrigerant is located below the liquid level of the liquid reservoir of the surge drum; The refrigerator according to any one of claims 2 to 5.

8. the at least one ejector is configured to draw the primary refrigerant in two-phase flow from the primary refrigerant outlet of the microchannel heat exchanger; The refrigerator according to any one of claims 1 to 5.

9. a flow path connecting the liquid reservoir of the surge drum and the primary refrigerant inlet of the microchannel heat exchanger is configured to allow the primary refrigerant to flow from the liquid reservoir of the surge drum to the primary refrigerant inlet of the microchannel heat exchanger without passing through a throttle or a throttle valve. The refrigerator according to any one of claims 2 to 5.

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