Defrosting system of refrigerating device

Abstract

The invention provides a defrosting system which can prevent frost in a coil pipe area from not completely melting even if a cross-blowing cooler is used. The system is provided with: a cooler (11) provided inside a freezer (10); a refrigeration cycle (50) in which the gaseous CO2 refrigerant is cooled and re-liquefied by a refrigerant circulating in the interior; a circulation line (30) that is connected to a coil region (13) having a length in the vertical direction shorter than the length in the short-side direction of the bottom surface, and that circulates the CO2 refrigerant, which has been liquefied by the refrigeration cycle, through the coil region; a defrost circuit (21) that is provided branching from the circulation line and forms a CO2 circulation path together with the coil area; opening / closing valves (34A, 34B) which are closed during defrosting and which turn the CO2 circulation path into a closed circuit; a secondary refrigerant circuit (22) through which a secondary refrigerant circulates; and a heat exchange unit (23) that is provided below the coil region and exchanges heat between the secondary refrigerant circulating in the secondary refrigerant circuit and the CO2 refrigerant circulating in the defrosting circuit.

Description

Technical Field

[0001] The present invention relates to a defrosting system for a refrigeration device, which is applicable to a refrigeration device that circulates a CO2 refrigerant in a cooler provided in a cold storage to cool the inside of the cold storage, and is used to remove frost adhering to the coil area provided in the cooler. Background Art

[0002] From the viewpoints of preventing ozone layer depletion and global warming, as a refrigerant for indoor air conditioners, refrigeration of foods, etc., a refrigeration device that uses ammonia, which has high cooling performance but is toxic, as a primary refrigerant and non-toxic and odorless CO2 as a secondary refrigerant is widely used.

[0003] In such a refrigeration device, a primary refrigerant circuit for circulating an ammonia refrigerant and a secondary refrigerant circuit for circulating a CO2 refrigerant are connected by a cascade condenser, and heat is exchanged between the ammonia refrigerant and the CO2 refrigerant in the cascade condenser. The CO2 refrigerant that has been cooled and liquefied by the ammonia refrigerant is transported to a cooler provided inside the cold storage, and cools the air inside the cold storage via a heat exchanger (hereinafter, also referred to as a "coil area") provided inside the housing of the cooler. By cooling the air inside the cold storage, a part of the vaporized CO2 refrigerant returns to the CO2 liquid reservoir via the secondary refrigerant circuit and is recooled and liquefied by the cascade condenser.

[0004] In such a refrigeration device, as the cooling operation is carried out, it is inevitable that moisture in the air inside the cold storage freezes on the outer surface of the heat exchanger and frost adheres. If the amount of frost adhesion increases, it will hinder the heat transfer performance and ventilation of the heat exchanger, and the cooling efficiency will decrease. Therefore, after a certain period of cooling operation, it is necessary to perform a defrost operation at a frequency of about several times a day.

[0005] As a method of defrost operation, the following methods have been used in the past: a sprinkling method in which water is sprinkled on the heat exchanger to melt the frost, a heater defrosting method in which the heat exchanger is heated by a heater to melt the frost, a thermosiphon defrosting method in which the refrigerant remaining in the heat exchanger is heated to melt the frost from the inside of the heat exchanger, etc.

[0006] In this regard, since the above-mentioned thermosiphon defrosting method defrosts near 0°C by utilizing the latent heat of condensation of the refrigerant, it can defrost at low temperatures compared to other defrosting methods. In addition, in recent years, it has been in use because it does not require a water sprinkling tank and can use the heat discharged from the refrigerator as a heat source. For example, in Patent Document 1 described below, a defrosting system is disclosed. In this defrosting system, a defrosting circuit (thermosiphon defrosting circuit) and a warm secondary refrigerant circuit are installed, and a first heat exchange unit is provided for heating the CO2 refrigerant circulating in the defrosting circuit by the warm secondary refrigerant. According to the defrosting system configured in this way, the liquid CO2 refrigerant in the closed loop descends in the defrosting circuit under the action of gravity to the first heat exchange unit, and is heated by the warm secondary refrigerant in the first heat exchange unit and gasifies. The gasified CO2 refrigerant rises in the defrosting circuit by thermosiphon action, and the rising CO2 refrigerant gas heats the frost adhering to the outer surface of the coil area provided inside the cooler to melt it. The liquefied CO2 refrigerant after heating the coil area descends in the defrosting circuit under the action of gravity. The CO2 refrigerant liquid descending to the first heat exchange unit is again heated by the warm secondary refrigerant in the first heat exchange unit and gasifies.

[0007] Prior Art Documents Patent Documents Patent Document 1: Japanese Re-Publication No. 2015 / 093233 Summary of the Invention Technical Problems to be Solved by the Invention The thermosiphon defrosting method can be applied to coolers with vertical or horizontal blowing, but preferably the first heat exchange unit is provided at a position lower than the coil area. In the case of a horizontally blown cooler, since it is provided near the top, if there is the height of the cooler body, it will affect the storage capacity of goods in the warehouse, so it will impose restrictions on the height of the cooler body. Therefore, in a horizontally blown cooler, there are also restrictions on setting the first heat exchange unit at a position lower than the coil area. Therefore, in a horizontally blown cooler, there is a case where the installation positions of the first heat exchange unit and the coil area overlap in the vertical direction. When starting defrosting, it is necessary to accumulate the refrigerant liquid for thermosiphon defrosting in the first heat exchange unit. However, if the installation positions of the first heat exchange unit and the coil area overlap in the vertical direction, the refrigerant remains in the coil area in a low-temperature liquid state up to the same height as the first heat exchange unit. In this case, the refrigerant liquid remaining in the coil area hinders defrosting, and the frost adhering to the outer surface of the area where the refrigerant liquid exists in the coil area (the area where the coil area and the first heat exchange unit overlap in the vertical direction) may not be completely melted.

[0008] The present invention is invented to solve the above problems, and its purpose is to provide a defrosting system that can prevent the frost in the coil area from not being completely melted even in a horizontally blown cooler.

[0009] Technical solution for solving technical problems The defrosting system related to the present invention for achieving the above object has: a cooler disposed inside the freezer, having a cross-blowing fan, a housing, and a coil area disposed inside the housing, and the vertical length of the coil area is shorter than the length of the short side of the bottom surface; a refrigeration cycle that cools and re-liquefies the gaseous CO2 refrigerant through the refrigerant circulating inside; a circulation line connected to the coil area for circulating the liquefied CO2 refrigerant through the refrigeration cycle in the coil area; a defrosting circuit branched from the circulation line and forming a CO2 circulation path together with the coil area; an on-off valve that closes during defrosting to make the CO2 circulation path a closed loop; a secondary refrigerant circuit for circulating the secondary refrigerant; and a heat exchange section disposed at a position below the coil area and performing heat exchange between the secondary refrigerant circulating in the secondary refrigerant circuit and the CO2 refrigerant circulating in the defrosting circuit. During defrosting, in the closed loop, the CO2 refrigerant naturally circulates through thermosiphon action.

[0010] According to the defrosting system configured as described above, the coil area is structured such that the vertical length is shorter than the length of the short side of the bottom surface, so that the heat exchange section can be disposed below the coil area inside the housing. Therefore, the heat exchange section that performs heat exchange between the secondary refrigerant circulating in the secondary refrigerant circuit and the CO2 refrigerant circulating in the defrosting circuit is disposed at a position below the coil area. Therefore, it is not necessary to accumulate the CO2 refrigerant liquid to the height of the coil area. In other words, there is no CO2 refrigerant liquid contained in the coil area that is an additional heating object other than the frost during defrosting. Therefore, it is possible to provide a defrosting system for a refrigeration device that can prevent the frost in the coil area from not melting completely even for a cross-blowing cooler. Brief Description of the Drawings

[0011] Figure 1 is an overall structure diagram of the refrigeration device according to the present embodiment.

[0012] Figure 2 is a structure diagram of the cooler according to the first embodiment.

[0013] Figure 3 is a schematic perspective view showing the coil area.

[0014] Figure 4 is a structure diagram of the cooler according to the second embodiment. Detailed Description of the Embodiment

[0015] Refer to Figures 1 to 4The embodiments of the present invention will be described. In the description of the drawings, the same reference numerals are assigned to the same elements, and redundant descriptions are omitted. For ease of explanation, the dimensional ratios in the drawings are exaggerated and may sometimes be different from the actual ratios.

[0016] Figure 1 It is an overall structural diagram of the refrigeration device 1 according to this embodiment. Figure 2 It is a structural diagram of the cooler 11 according to the first embodiment. Figure 3 It is a schematic perspective view showing the coil section 13. Figure 4 It is a structural diagram of the cooler 11 according to the second embodiment.

[0017] As Figure 1 shown, the refrigeration device 1 has: a cooler 11 provided in the freezer 10; a defrosting unit 20 for removing the frost adhering to the outer surface of the coil section 13; a circulation line 30 for circulating the CO2 refrigerant; a CO2 liquid reservoir 40 for storing the CO2 refrigerant; a refrigeration cycle 50 having a circulation line 56 for circulating the ammonia refrigerant; a cooling water circuit 60 for circulating the cooling water; and a cooling tower 70 connected to the cooling water circuit 60.

[0018] As Figure 1 shown, a cooler 11 is provided in the freezer 10.

[0019] As Figure 1 shown, the cooler 11 has: a housing 12; a coil section 13 provided inside the housing 12; and a fan 15 for forming an air flow that circulates inside and outside the housing 12.

[0020] The housing 12 is configured to be substantially rectangular. The coil section 13 is disposed inside the housing 12.

[0021] The coils in the coil section 13 are formed in a meandering shape in the vertical and horizontal directions inside the housing 12. The coil section 13 is, for example, a finned tube heat exchanger.

[0022] As Figure 1 shown, the fan 15 is disposed on the side of the housing 12. That is, the cooler 11 according to the present invention is a cross-blow type. By operating the fan 15, an air flow that circulates inside and outside the housing 12 is formed.

[0023] The detailed structure of the cooler 11 will be described later.

[0024] The defrosting unit 20 is provided to melt and remove (defrost) the frost adhering to the outer surface of the coil section 13. As Figure 1 shown, the defrosting unit 20 has a defrosting circuit 21, a secondary refrigerant circuit 22, and a heat exchange section 23.

[0025] As Figure 1 shown, the defrosting circuit 21 is provided to branch from the CO2 supply line 31 of the circulation line 30, and forms a CO2 circulation path together with the coil area 13.

[0026] As Figure 1 shown, an electromagnetic on-off valve 21A is arranged in the defrosting circuit 21. When defrosting, the electromagnetic on-off valves 34A and 34B described later are closed, and the electromagnetic on-off valve 21A is opened, thereby forming a CO2 circulation path for CO2 circulation. On the other hand, during refrigeration operation, the defrosting circuit 21 opens the electromagnetic on-off valves 34A and 34B and closes the electromagnetic on-off valve 21A.

[0027] As Figure 1 shown, the defrosting circuit 21 is installed inside the heat exchange part 23.

[0028] The secondary refrigerant circuit 22 allows the secondary refrigerant to circulate. The secondary refrigerant circuit 22 is arranged on the lower surface of the drain pan 83 and is guided into the cooler 11. According to this structure, the heat retained by the secondary refrigerant circulating in the secondary refrigerant circuit 22 during defrosting can suppress the re-freezing of the drain water falling onto the drain pan 83.

[0029] In addition, the secondary refrigerant circuit 22 is installed inside the heat exchange part 23.

[0030] The secondary refrigerant circuit 22 is connected to the heat exchanger 25. On the other hand, a cooling water branch circuit 65 branched from the cooling water circuit 60 described later is installed on the heat exchanger 25.

[0031] The cooling water circulating in the cooling water circuit 60 is heated by absorbing the exhaust heat of the ammonia refrigerant in the condenser 53. A part of the heated cooling water is transported to the heat exchanger 25 by the pump 65P, exchanges heat with the secondary refrigerant circulating in the secondary refrigerant circuit 22, and heats the secondary refrigerant. As the secondary refrigerant, for example, an aqueous solution of ethylene glycol, propylene glycol, etc. can be used.

[0032] In the outlet path of the secondary refrigerant circuit 22, there are: a receiver 26 for storing the secondary refrigerant, and a secondary refrigerant pump 27 for circulating the secondary refrigerant. In addition, a temperature sensor (not shown) for detecting the temperature of the secondary refrigerant is arranged in the secondary refrigerant circuit 22.

[0033] In the heat exchange part 23, heat exchange is performed between the CO2 refrigerant passing through the defrosting circuit 21 and the secondary refrigerant circulating in the secondary refrigerant circuit 22.

[0034] As Figure 1As shown, the heat exchange unit 23 is provided at a position lower than the coil region 13. With this structure, there is no need to accumulate the CO2 refrigerant liquid to the height of the coil region 13. In other words, there is no CO2 refrigerant liquid contained in the coil region that is an additional heating object other than the frost during defrosting. Therefore, it is possible to provide a defrosting system for the refrigeration device 1 that can prevent incomplete melting of frost even in the case of a cooler 11 with cross-blowing.

[0035] The circulation line 30 is configured to circulate the CO2 refrigerant. As Figure 1 shown, the circulation line 30 has: a CO2 delivery line 31 that delivers the liquid CO2 refrigerant from the CO2 reservoir 40 to the cooler 11; a CO2 return line 32 that returns the gas-liquid mixed CO2 refrigerant from the cooler 11 to the CO2 reservoir 40; and a re-liquefaction line 33 that re-liquefies the vaporized CO2 refrigerant.

[0036] As Figure 1 shown, the CO2 delivery line 31 is connected to the lower part of the CO2 reservoir 40. Additionally, as Figure 1 shown, the CO2 return line 32 is connected to the upper part of the CO2 reservoir 40.

[0037] Furthermore, a first pump P1 is provided in the CO2 delivery line 31, and the liquid CO2 refrigerant in the CO2 reservoir 40 is delivered to the cooler 11 by the first pump P1.

[0038] The CO2 delivery line 31 is connected to the CO2 return line 32 via the cooler 11.

[0039] As Figure 1 shown, an electromagnetic on-off valve (on-off valve) 34A is arranged in the CO2 delivery line 31. As Figure 1 shown, an electromagnetic on-off valve (on-off valve) 34B is arranged in the CO2 return line 32.

[0040] As Figure 1 shown, a pressure sensor 34 is connected to the CO2 return line 32. A control unit 35 that inputs the detection value of the pressure sensor 34 is connected to the pressure sensor 34.

[0041] Furthermore, a branch circuit 37 branched from the CO2 return line 32 is provided in the CO2 return line 32. A pressure regulating valve 38 is provided in the branch circuit 37, and when the pressure is higher than a given pressure, the pressure regulating valve 38 opens to reduce the pressure.

[0042] The re-liquefaction line 33 is connected above the CO2 liquid storage vessel 40. When the gaseous CO2 refrigerant in the CO2 liquid storage vessel 40 passes through the re-liquefaction line 33, it is re-liquefied by the heat exchanger 51 of the refrigeration cycle 50 described later. Then, the re-liquefied liquid CO2 refrigerant returns to the CO2 liquid storage vessel 40.

[0043] The refrigeration cycle 50 circulates the ammonia refrigerant. The refrigeration cycle 50 cools and liquefies the gaseous CO2 refrigerant. As Figure 1 shown, the refrigeration cycle 50 includes a heat exchanger 51 as an evaporator, a refrigerator 52 as a compressor, a condenser 53, an ammonia liquid storage vessel 54, an expansion valve 55, and a circulation line 56 for circulating the ammonia refrigerant.

[0044] The ammonia refrigerant gas evaporated due to the heat of the gaseous CO2 refrigerant in the heat exchanger 51 is compressed by the refrigerator 52. The compressed high-temperature and high-pressure ammonia refrigerant gas is cooled and condensed in the condenser 53. The condensed and liquefied ammonia refrigerant liquid is stored in the ammonia liquid storage vessel 54. The ammonia refrigerant liquid in the ammonia liquid storage vessel 54 is delivered to the expansion valve 55 and expanded. The expanded low-pressure ammonia refrigerant liquid is delivered to the heat exchanger 51 and used for cooling the gaseous CO2 refrigerant.

[0045] A cooling water circuit 60 is installed in the condenser 53. The cooling water circulating in the cooling water circuit 60 is heated by absorbing the exhaust heat of the ammonia refrigerant in the condenser 53.

[0046] The cooling water circuit 60 is connected to the cooling tower 70. The cooling water circulates in the cooling water circuit 60 by the cooling water pump 61. The cooling water that has absorbed the exhaust heat of the ammonia refrigerant in the condenser 53 passes through the coil disposed in the cooling tower 70. At this time, the surface of the coil contacts the external air and the sprayed water, and is indirectly cooled by the latent heat of evaporation of the sprayed water.

[0047] Above, the structure of the refrigeration device 1 has been described. Next, with reference to Figure 1 , the usage method of the refrigeration device 1 according to the present embodiment will be described separately for the refrigeration operation and the defrosting operation.

[0048] During the refrigeration operation, the electromagnetic on-off valves 34A and 34B are open, and the electromagnetic on-off valve 21A is closed. Thus, the CO2 refrigerant supplied from the CO2 supply line 31 circulates in the coil area 13. On the other hand, inside the cooler 11, by the operation of the fan 15, a circulating flow of the air in the cooler 11 is formed. The air in the cooler 11 is cooled by the CO2 refrigerant circulating in the coil area 13, and the inside of the freezer 10 is maintained at a low temperature of, for example, -25°C. During the refrigeration operation, as Figure 4 shown, the cold air is supplied into the freezer via the sock duct 120.

[0049] During defrosting, electromagnetic on-off valves 34A and 34B are closed, and electromagnetic on-off valve 21A is open. Thus, a closed CO2 circulation path including the coil section 13 and the defrosting circuit 21 is formed. During defrosting, as Figure 4 shown, the Sock duct 120 is used to block the air inside the storage, preventing the leakage of the warm air inside the cooler during defrosting.

[0050] The CO2 refrigerant liquid in the closed loop descends in the defrosting circuit 21 under the action of gravity, and in the heat exchange section 23, it is heated by the coolant circulating in the coolant circuit 22 and vaporizes. The vaporized CO2 refrigerant rises in the defrosting circuit 21 due to the principle of thermosiphon, and the rising CO2 refrigerant gas heats the frost adhering to the outer surface of the coil section 13 provided inside the cooler 11 to melt it. The CO2 refrigerant liquefied due to heating the coil section 13 descends in the defrosting circuit 21 under the action of gravity and is heated by the coolant again to vaporize.

[0051] The melted water formed by the melted frost after heating falls into the drain pan 83.

[0052] <Cooler 11 according to the first embodiment> Next, with reference to Figure 2 the detailed structure of the cooler 11 according to the first embodiment will be described. In the following description of the cooler 11, part of it may be repeated with the above description. In addition, Figure 2 the cooler 11 shown Figure 1 shows a structure that is reversed left and right with respect to the cooler 11 shown

[0053] As Figure 2 shown, the cooler 11 according to the first embodiment has, inside the freezer 10: a cooler 11, a housing 12, a coil section 13, a CO2 delivery line 31, a defrosting circuit 21, a CO2 return line 32, a coolant circuit 22, a heat exchange section 23, a fan 15, a drain pan 83, a longitudinal wall section 18, a space section 19, an inlet header H1 for CO2 refrigerant, and an outlet header H2 for CO2 refrigerant.

[0054] The structures of the cooler 11, the housing 12, the CO2 delivery line 31, the defrosting circuit 21, the CO2 return line 32, and the coolant circuit 22 are as described above, so the description thereof is omitted here. The moving directions of the CO2 refrigerant and the coolant are as Figure 2 indicated by the arrows.

[0055] As Figure 3 shown, a curved surface 13S is provided on the surface near the front side of the coil section 13. A hole portion 13H through which the cooling pipe passes is formed in the curved surface 13S. In Figure 3In this case, the vertical direction corresponds to the column direction (wind direction), and the left - right direction corresponds to the segment direction (direction orthogonal to the wind direction). As Figure 2 and Figure 3 shown, the coil area 13 is configured such that, inside the housing 12, the length in the vertical direction (also referred to as the height) is shorter than the length in the short - side direction of the bottom surface. The height of the coil area 13 is, for example, approximately 25% of the height of the housing 12. Additionally, as Figure 2 shown, the heat - exchange section 23 is arranged in an inclined manner. According to this structure, the height of the coil area 13 can be suppressed, and within the limited height of the housing 12, the coil area 13 and the heat - exchange section 23 can be arranged without overlapping in the vertical direction, and the height of the cooler 11 can be suppressed. The heat - exchange section 23 is not particularly limited, and for example, a plate - type heat exchanger can be used.

[0056] The drain pan 83 is arranged below the housing 12. The frost attached to the outer surface of the coil area 13 is melted by the heated CO2 and falls as a liquid into the drain pan 83. The liquid that has fallen into the drain pan 83 is discharged to the outside from the discharge port 83A.

[0057] As Figure 2 shown, the space area 19 is arranged above the coil area 13. By arranging the space area 19 above the coil area 13 in this way, warm air can be accumulated in the space area 19 during defrosting, so a cover for retaining warm air is not required. The height of the space area 19 is not particularly limited and is 20% or more of the horizontal - direction length on the curved side of the coil area 13.

[0058] When observed in the horizontal direction, the fan 15 is arranged at a position lower than the coil area 13. The fan 15 is arranged to exhaust air in the horizontal direction. According to this structure, warm air can be retained in the space area 19 without installing a damper or the like, and even when there is not enough space above the coil area 13, the warm air during defrosting can be retained at a position above the fan 15 when observed in the horizontal direction. In this embodiment, for example, two fans 15 are provided, and the fan 15 is, for example, a centrifugal fan.

[0059] As Figure 2 shown, the vertical wall portion 18 is arranged on the fan 15 side of the coil area 13. The uppermost part of the vertical wall portion 18 is configured to be substantially flush with the uppermost part of the coil area 13. The air sucked into the cooler 11 by the fan 15 is guided upward by the vertical wall portion 18.

[0060] In the cooler 11 according to the first embodiment, the air inside the storage is sucked from the side opposite to the fan 15. The sucked air inside the storage is guided upward by the vertical wall portion 18 and passes through the coil area 13. When moving through the coil area 13, the air inside the storage is cooled by the CO2 refrigerant and is discharged into the storage by the fan 15 via the space area 19 (see the gray arrows in Figure 2 ).

[0061] As described above, the defrosting system of the refrigeration device 1 includes: a cooler 11 disposed inside the freezer 10, having a cross-blow type fan 15, a housing 12, and a coil section 13 disposed inside the housing 12, and the vertical length of the coil section 13 is shorter than the length of the short side of the bottom surface; a refrigeration cycle 50 that cools and re-liquefies the gaseous CO2 refrigerant by the ammonia refrigerant circulating inside; a circulation line 30 connected to the coil section 13 for circulating the CO2 refrigerant liquefied by the refrigeration cycle 50 in the coil section 13; a defrosting circuit 21 branched from the circulation line 30 and forming a CO2 circulation path together with the coil section 13; electromagnetic on-off valves 34A and 34B that are closed during defrosting to make the CO2 circulation path a closed loop; a secondary refrigerant circuit 22 for circulating the secondary refrigerant; and a heat exchange section 23 disposed at a position lower than the coil section 13 and performing heat exchange between the secondary refrigerant circulating in the secondary refrigerant circuit 22 and the CO2 refrigerant circulating in the defrosting circuit 21. During defrosting, in the closed loop, the CO2 refrigerant naturally circulates by thermosiphon action. According to the defrosting system of the refrigeration device 1 configured as such, the coil section 13 is structured such that the vertical length is shorter than the length of the short side of the bottom surface, so that the heat exchange section 23 can be disposed below the coil section 13 inside the housing 12. Therefore, the heat exchange section 23 that performs heat exchange between the secondary refrigerant circulating in the secondary refrigerant circuit 22 and the CO2 refrigerant circulating in the defrosting circuit 21 is disposed at a position lower than the coil section 13, so that it is not necessary to accumulate the CO2 refrigerant liquid up to the height of the coil section 13. In other words, there is no CO2 refrigerant liquid contained in the coil section 13 that is an additional heating object other than the frost during defrosting. Therefore, it is possible to provide a defrosting system for the refrigeration device 1 that can prevent incomplete melting of frost even in the case of a cross-blow cooler 11.

[0062] In addition, inside the cooler 11, a space section 19 is provided above the coil section 13. According to the defrosting system of the refrigeration device 1 configured as such, it is possible to accumulate warm air in the space section 19 during defrosting, so that a cover for retaining the warm air is not required.

[0063] In addition, the fan 15 is disposed at a position lower than the coil section 13. According to the defrosting system of the refrigeration device 1 configured as such, it is possible to retain the warm air in the space section 19 without providing a throttle valve or the like. In addition, even when there is not enough space above the coil section 13, it is possible to retain the warm air during defrosting at a position above the fan 15 when viewed in the horizontal direction.

[0064] In addition, a vertical wall portion 18 is provided inside the cooler 11. According to the defrosting system of the refrigeration device 1 configured as such, the sucked air can pass through the coil area 13 vertically upward through the vertical wall portion 18. Therefore, the column direction of the cooling pipes in the coil area 13 can be in the vertical direction, so that the ventilation area of the coil area 13 whose length in the vertical direction is shorter than the length in the short side direction of the bottom surface increases, improving the heat exchange capacity, and the height of the cooler 11 can be suppressed. Moreover, through the vertical wall portion 18, the space where the coil area 13 is provided is isolated from the space where the fan 15 is provided, thereby suppressing the outflow of warm air during defrosting to the fan 15 side.

[0065] <The cooler 11 according to the second embodiment> Next, Figure 4 the structure of the cooler 11 according to the second embodiment will be described. Figure 4 The cooler 11 shown Figure 1 shows a structure that is reversed left and right with respect to the cooler 11 shown.

[0066] As Figure 4 shown, the cooler 11 according to the second embodiment includes, in the freezer 110: a cooler 11, a housing 12, a coil area 13, a CO2 delivery line 31, a defrosting circuit 21, a CO2 return line 32, a secondary refrigerant circuit 22, a heat exchange section 123, a fan 115, a drain pan 83, a vertical wall portion 118, a space portion 19, a sock duct 120, an inlet header H1 for CO2 refrigerant, and an outlet header H2 for CO2 refrigerant.

[0067] The structures of the cooler 11, the housing 12, the CO2 delivery line 31, the defrosting circuit 21, the CO2 return line 32, and the secondary refrigerant circuit 22 are as described above, and thus the description thereof is omitted here. The moving directions of the CO2 refrigerant and the secondary refrigerant are as Figure 4 shown by the arrows.

[0068] As Figure 3 , Figure 4 shown, the coil area 13 is configured such that the length (height) in the vertical direction is shorter than the length in the short side direction of the bottom surface inside the housing 12. The height of the coil area 13 is, for example, approximately 15% of the height of the housing 12. According to this structure, in the limited height of the housing 12, the coil area 13 and the heat exchange section 123 can be provided without overlapping in the vertical direction, and the height of the cooler 11 can be further suppressed.

[0069] As Figure 4As shown, the space part 19 is provided above the coil area 13. By providing the space part 19 above the coil area 13 in this way, it is possible to accumulate warm air in the space part 19 during defrosting, so a cover is not required. The height of the space part 19 is not particularly limited and is more than 30% of the horizontal direction length of the bending side of the coil area 13.

[0070] The fan 115 is arranged on the extension line in the horizontal direction of the coil area 13. The fan 115 is arranged horizontally to exhaust air in the horizontal direction. As will be described later, in the cooler 11 according to the second embodiment, the pressure loss of the air can be reduced, so for example, one fan 115 is provided, and the fan 115 can use an axial flow fan with low power consumption.

[0071] As Figure 4 shown, the vertical wall part 118 is arranged on the fan 115 side of the coil area 13. The uppermost part of the vertical wall part 118 is configured to be substantially the same as the uppermost part of the coil area 13.

[0072] In the cooler 11 according to the second embodiment, the air in the storage is sucked from the side opposite to the fan 115. The sucked air in the storage is guided upward by the vertical wall part 118 and moves in the coil area 13. When moving in the coil area 13, the air in the storage is cooled by the CO2 refrigerant and is discharged into the storage by the fan 115 via the space part 19 (refer to Figure 4 the gray arrow).

[0073] In the cooler 11 according to the second embodiment, the vertical direction length of the coil area 13 becomes shorter, the space part 19 above the coil area 13 becomes wider, and the fan 115 is arranged on the extension line in the horizontal direction of the coil area 13. Therefore, compared with the cooler 11 of the first embodiment, the cooler 11 of the second embodiment can reduce the pressure loss of the air while maintaining the retention of the warm air (refer to Figure 2 、 Figure 4 the bending when the gray arrow enters the fans 15 and 115). Therefore, as the fan 115 arranged in the cooler 11 according to the second embodiment, an axial flow fan with low power consumption can be adopted.

[0074] As described above, in the second embodiment, the vertical direction length of the coil area 13 becomes shorter, the space part 19 above the coil area 13 becomes wider, and the fan 115 of the cooler 11 is arranged on the extension line in the horizontal direction of the coil area 13. According to the defrosting system of the refrigeration device 1 configured in this way, compared with the cooler 11 of the first embodiment, the pressure loss of the air can be reduced while maintaining the retention of the warm air.

[0075] In addition, the present invention is not limited to the above embodiments, and various changes can be made within the scope of the claims.

[0076] For example, in the above-described embodiment, ammonia is used as the refrigerant for the refrigeration cycle, but it is not limited thereto, and Freon or other natural refrigerants may also be used.

[0077] In addition, in the above-described embodiment, one cooler 11 is provided, but two or more coolers 11 may also be provided in the freezer.

[0078] This application is based on Japanese Patent Application No. 2022-200809 filed on December 16, 2022, the disclosure of which is incorporated herein by reference in its entirety.

[0079] Explanation of reference numerals 1 Refrigeration device 10, 110 Freezer 11 Cooler 12 Housing 13 Coil area 15, 115 Fan 18, 118 Vertical wall portion 19 Space portion 20 Defrosting portion 21 Defrosting circuit 22 Secondary refrigerant circuit 23, 123 Heat exchange portion 30 Circulation line 34A, 34B Electromagnetic on-off valve (on-off valve) 65P Pump 83 Drain pan

Claims

1. A defrosting system for a refrigeration device, comprising: a cooler disposed inside a cold storage, having a cross-blow fan, a housing, and a coil section, the coil section being disposed inside the housing, and a vertical direction length of the coil section being shorter than a length in a short side direction of a bottom surface; a refrigeration cycle that cools and re-liquefies a gaseous CO2 refrigerant by a refrigerant circulating inside; a circulation line connected to the coil section for circulating the CO2 refrigerant liquefied by the refrigeration cycle in the coil section; a defrosting circuit branched from the circulation line and forming a CO2 circulation path together with the coil section; an on-off valve that closes during defrosting to make the CO2 circulation path a closed loop; a secondary refrigerant circuit for circulating a secondary refrigerant; and a heat exchange section disposed at a position lower than the coil section and performing heat exchange between the secondary refrigerant circulating in the secondary refrigerant circuit and the CO2 refrigerant circulating in the defrosting circuit, during defrosting, in the closed loop, the CO2 refrigerant naturally circulates by thermosiphon action.

2. The defrosting system of the refrigeration device according to claim 1, wherein, Inside the cooler, a space section is provided above the coil section.

3. The defrosting system of the refrigeration device according to claim 2, wherein, A longitudinal wall section is provided inside the cooler.

4. The defrosting system of the refrigeration device according to claim 3, wherein, The fan is disposed at a position lower than the coil section.

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