JP2006300454A - Low temperature showcase - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low temperature showcase capable of improving cooling efficiency while achieving miniaturization of a device. <P>SOLUTION: In the low temperature showcase 1, cold air having exchanged heat with an evaporator 19 of a cooling device R arranged in a duct 5 is delivered into a storage chamber 8 to carry out cooling. A refrigerant circuit is composed by carrying out piping connection of the cooling device R, a compressor 24, a radiator 22, a capillary tube 20, and the evaporator 19. An internal heat exchanger 41 is provided using carbon dioxide as a refrigerant, capable of providing a supercritical pressure in a high pressure side, and carrying out heat exchange between a refrigerant of the high pressure side of the refrigerant circuit, and a refrigerant of a low pressure side. The internal heat exchanger 41 is attached to a cover 40 of the evaporator 19 provided in the duct 5. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a low temperature showcase in which cool air exchanged with an evaporator of a cooling device arranged in a duct is discharged into a cabinet and cooled to a predetermined temperature.

  In this type of low temperature showcase, for example, as shown in Patent Document 1, an evaporator of a cooling device is vertically installed in a duct formed on the back of the showcase, for example, and the inside of the cabinet sucked into the duct After air is heat-exchanged with the evaporator, it is discharged into the cabinet, thereby forming a cooling region with a predetermined temperature in the cabinet.

A machine room is formed at the lower part of the low temperature showcase. In the machine room, equipment that constitutes a cooling device excluding an evaporator and an expansion valve as a decompression means, that is, a compressor, a radiator, and a blower for discharging waste heat generated from these equipment to the outside are arranged. Established.
JP-A-8-94238

  In a conventional low temperature showcase, a chlorofluorocarbon refrigerant is used as a refrigerant in the refrigerant pipe constituting the cooling device. On the other hand, in recent years, in order to cope with global environmental problems, a cooling apparatus that uses carbon dioxide, which is a natural refrigerant, as a refrigerant and operates at a high pressure side as a supercritical pressure has been developed.

  In this case, in order to improve the refrigerating capacity, heat exchange may be performed in the internal heat exchanger between the high-pressure side refrigerant pipe through which the refrigerant from the radiator flows and the low-pressure side flow path through which the refrigerant from the evaporator flows. It is done. However, in order to obtain sufficient cooling efficiency, the internal heat exchanger requires a considerable pipe length, for example, about 3 m of a pipe having a pipe diameter of about 10 mm, so that it is difficult to secure an installation space. For this reason, there is a disadvantage that the apparatus itself must be enlarged.

  In particular, when installed in a machine room, the refrigerant pipe through which the low-temperature refrigerant of the internal heat exchanger flows forms dew, and thus requires special treatment such as covering with a heat insulating material. For this reason, the arrangement of the internal heat exchanger in the machine room requires a heat insulating material or the like, which causes a problem of an increase in cost.

  Therefore, the present invention has been made to solve the conventional technical problems, and provides a low-temperature showcase capable of improving the cooling efficiency while realizing downsizing of the apparatus.

  The low-temperature showcase of the present invention is a showcase that discharges and cools cold air that has exchanged heat with the evaporator of the cooling device disposed in the duct, and the cooling device includes a compressor, a radiator, A refrigerant circuit is configured by connecting a decompression device and an evaporator, etc., using carbon dioxide as a refrigerant, the high pressure side can be a supercritical pressure, and heat is exchanged between the high pressure side refrigerant and the low pressure side refrigerant of the refrigerant circuit An internal heat exchanger is provided, and this internal heat exchanger is attached to a cover of an evaporator provided in the duct.

  In the low temperature showcase of the invention of claim 2, in the above invention, the internal heat exchanger is arranged such that the refrigerant on the low pressure side of the refrigerant circuit flows from top to bottom.

  According to a third aspect of the present invention, there is provided a low-temperature showcase according to each of the above-mentioned inventions, comprising a drain water evaporation device for evaporating drain water from the evaporator, and the drain water evaporation device is connected to the high pressure side of the refrigerant circuit of the cooling device. It is heated by this refrigerant.

  According to the present invention, in the low-temperature showcase that cools the cool air that is exchanged with the evaporator of the cooling device disposed in the duct by discharging the cool air into the warehouse, the cooling device includes a compressor, a radiator, a decompression device, and A refrigerant circuit is configured by connecting an evaporator and the like, using carbon dioxide as a refrigerant, the high pressure side can be supercritical pressure, and the internal heat exchange that exchanges heat between the high pressure side refrigerant and the low pressure side refrigerant of the refrigerant circuit By installing this internal heat exchanger on the evaporator cover installed in the duct, it is possible to secure a sufficient installation space for the internal heat exchanger, realizing efficient heat exchange can do. As a result, the apparatus can be reduced in size and the cooling efficiency can be improved.

  Carbon dioxide, which is used as a refrigerant, is non-flammable and non-corrosive, does not destroy ozone, and has a global warming coefficient that is less than one-thousand that of fluorocarbon refrigerants. It is possible to provide a low-temperature showcase, that is, an apparatus realizing non-fluorocarbon. Moreover, since carbon dioxide is remarkably easy to obtain compared to other refrigerants, convenience is improved.

  According to the invention of claim 2, in the above invention, the internal heat exchanger is arranged so that the refrigerant on the low pressure side of the refrigerant circuit flows from the top to the bottom. It becomes possible to flow down the refrigerant from the top to the bottom, and this makes it possible to suppress oil return.

  According to the invention of claim 3, in each of the above inventions, a drain water evaporation device for evaporating drain water from the evaporator is provided, and the drain water evaporation device is connected to the high pressure side of the refrigerant circuit of the cooling device. By heating with this refrigerant, the heat of the high-temperature refrigerant can be efficiently used for drain water evaporation treatment.

  In particular, since carbon dioxide is used as a refrigerant, a high-pressure refrigerant flows in the high-temperature refrigerant pipe as compared with a conventional chlorofluorocarbon refrigerant, so even if the pipe diameter of the high-temperature refrigerant pipe is reduced. Pressure loss can be ignored. Thereby, by making the said pipe diameter thin, heat dissipation efficiency can be improved and cooling capacity can be improved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a partially transparent front view of a low-temperature showcase 1 to which the present invention is applied, and FIG. 2 is a longitudinal side view of the low-temperature showcase 1. The low-temperature showcase 1 according to the present embodiment includes a heat insulating wall 6 having a substantially U-shaped cross section that constitutes a main body, and side plates 7 and 7 attached to both sides of the heat insulating wall 6. A partition plate 4 is attached to the inside of the heat insulating wall 6 serving as a main body with a space therebetween, and a duct 5 is defined between the partition plate 4 and the heat insulating wall 6.

  A bottom plate 10 is attached in front of the lower end of the partition plate 4 with a space for forming a duct 5 between the bottom wall 6A of the heat insulating wall 6 and stored inside the partition plate 4 and the bottom plate 10. The chamber 8 is partitioned. A drain receiving part D for receiving drain water generated on the surface of the evaporator 19 is formed on the upper surface of the bottom wall 6A. The drain receiving part D is a machine chamber 2 which will be described later with a drain pipe (not shown). It is communicated to. A cold air discharge port 14 provided with a honeycomb material 13 is formed at the upper edge of the front opening 12 of the heat insulating wall 6, and the cold air discharge port 14 communicates with the duct 5. A cold air inlet 15 is formed at the lower edge of the opening 12. A plurality of backside cold air discharge ports (not shown) are formed in the lower part of the partition plate 4 so that a part of the cold air flowing through the duct 5 can be directly discharged into the storage chamber 8. Yes. In addition, a plurality of shelves 9... A fluorescent lamp (not shown) is attached to the front of the lower surface of each shelf 9.

  On the other hand, a fan case 17 is installed on the bottom wall 6 </ b> A of the heat insulating wall 6 below the bottom plate 10, and a fan 18 is attached to the fan case 17. Further, in the duct 5 positioned behind the partition plate 4, an evaporator 19 and an internal heat exchanger 41 constituting the cooling device R are vertically provided via an evaporator cover 40 as will be described later. The evaporator cover 40 is a plate-like member made of a heat-conducting material, and is provided behind the rear cold air discharge port formed in the lower part of the partition plate 4. Therefore, it is possible to positively send out the cool air from the rear of the evaporator cover 40, and a part of the cool air is branched from the upper end of the evaporator cover 40 and lowered to the front side of the evaporator 19, Cold air can be discharged into the storage chamber 8 from the rear cold air discharge port. A capillary tube 20 as a decompression device is connected to the refrigerant inflow side of the evaporator 19.

  On the other hand, the machine room 2 is formed on the base 21 below the bottom wall 6 </ b> A of the heat insulating wall 6. In the machine room 2, a radiator 22 of the cooling device R is installed on the base 21 at the front, and a condensing fan 23 as a blower is attached to the rear side thereof. A drain water evaporator 3, which will be described in detail later, is installed on the base 21 behind the condensing fan 23, and the compressor 24 of the cooling device R is located on the side of the radiator 22 in the machine room 2. It is installed on 21.

  Here, the refrigerant circuit of the cooling device R in the present embodiment will be described with reference to FIG. The cooling device R in the present embodiment is configured by connecting the compressor 24, the radiator 22, the capillary tube 20, the evaporator 19 and the like in an annular shape. That is, the refrigerant discharge pipe 42 of the compressor 24 is connected to the inlet of the radiator 22 through the evaporation pipe 43. Here, the compressor 24 of the embodiment is an internal intermediate pressure type two-stage compression rotary compressor, and an electric element as a driving element in the hermetic container, and first and second rotations driven by the electric element. It is composed of compression elements.

  One end of the refrigerant introduction pipe 44 for introducing the refrigerant into the first rotary compression element of the compressor 24 is in communication with the cylinder of the first rotary compression element, and the other end is a low pressure of the internal heat exchanger 41. It is connected to the outflow side of the side channel 41A. On the other hand, the refrigerant introduction pipe 45 for introducing the refrigerant compressed by the second rotary compression element of the compressor 24 into the second rotary compression element passes through the intermediate cooling circuit 50 outside the compressor 24. Is provided. The intermediate cooling circuit 50 is provided with a heat exchanger 22A for cooling the refrigerant compressed by the first rotary compression element, and the intermediate pressure refrigerant compressed by the first rotary compression element is After being cooled by the heat exchanger 22A, the second rotary compression element is sucked. The heat exchanger 22A is formed integrally with the radiator 22, and the heat exchanger 22A and the radiator 22 are air-cooled by a blower (not shown).

  On the other hand, the refrigerant pipe 46 connected to the outlet side of the radiator 22 is connected to the inflow side of the high-pressure side passage 41 </ b> B of the internal heat exchanger 41. In the internal heat exchanger 41, the low-pressure side channel 41A and the high-pressure side channel 41B are provided in a heat exchange manner, whereby the high-pressure side refrigerant exiting from the radiator 22 and the evaporator 19 exiting. Heat exchange with the low-pressure side refrigerant is performed. Then, the refrigerant pipe 47 connected to the outlet side of the high-pressure side channel 41B is connected to the evaporator 19 via the capillary tube 20. The refrigerant pipe 48 connected to the outlet side of the evaporator 19 is connected to the inlet side of the low-pressure side passage 41 </ b> A of the internal heat exchanger 41.

  In the present embodiment, the internal heat exchanger 41 is attached to the evaporator cover 40. That is, as shown in the front view of the evaporator cover 40 in FIG. 4, the evaporator cover 40 is provided on the front side of the evaporator 19 provided vertically in the duct 5, and the internal heat exchange is provided below the evaporator cover 40. A vessel 41 is attached. In this case, the rear surface of the evaporator cover 40 is provided with a low-pressure side passage 41A constituting the internal heat exchanger 41, and the front surface of the evaporator cover 40 is provided with a high-pressure side constituting the internal heat exchanger 41. A flow path 41B is provided.

  At this time, since the evaporator cover 40 is made of a heat conductive material, the evaporator cover 40 exchanges heat between the low-pressure side passage 41A and the high-pressure side passage 41B of the internal heat exchanger 41. Can be done efficiently. In this case, the refrigerant temperature flowing out from the low-pressure channel 41A is, for example, + 25 ° C., and the refrigerant temperature flowing into the high-pressure channel 41B is, for example, + 30 ° C. Therefore, by providing the low pressure side channel 41A having a relatively low temperature on the rear surface of the evaporator cover 40, that is, on the evaporator 19 side, and providing the high pressure side channel 41B having a relatively high temperature on the front surface of the evaporator cover 40, The influence on the cooling action in the evaporator 19 can be minimized. In particular, in the present embodiment, the inside of the storage chamber 8 is set at a refrigeration temperature, so that the cooling capacity of the evaporator 19 is not greatly affected.

  Further, the low-pressure side flow path 41A is formed such that the refrigerant inlet side is formed at the upper end and the outlet side is formed at the lower end so that the refrigerant flows in the evaporator cover 40 from the top to the bottom. Thereby, the low-pressure side refrigerant that has flowed out of the evaporator 19 can enter the low-pressure channel 41A from the upper inlet side and exit the low-pressure channel 41A from the lower outlet side.

  On the other hand, the high-pressure side channel 41B is formed such that the refrigerant inlet side is formed at the lower end and the outlet side is formed at the upper end so that the refrigerant flows in the evaporator cover 40 from below to above. Thereby, the high pressure side refrigerant | coolant which came out from the heat radiator 22 can enter into the high voltage | pressure side flow path 41B from the inlet side of a lower end, and can be set as the structure which exits the high voltage | pressure side flow path 41B from the outlet side of an upper end.

  Therefore, the refrigerant flowing through the low pressure side flow path 41A and the high pressure side flow path 41B becomes a counter flow, and the heat exchange efficiency in the internal heat exchanger 41 can be improved. In addition, since the low-pressure refrigerant flows from top to bottom, oil return can be suppressed.

  Note that the refrigerant sealed in the refrigerant circuit is non-flammable and non-corrosive, does not destroy ozone, and has a global warming coefficient that is one-thousandth that of chlorofluorocarbon refrigerant. Used, the high pressure side of the refrigerant circuit is supercritical pressure.

  Next, the drain water evaporation apparatus 3 is demonstrated with reference to FIG.5 and FIG.6. FIG. 5 is a perspective view of the drain water evaporator 3, and FIG. 6 is a partially exploded perspective view of the drain water evaporator 3. The drain water evaporator 3 in the present embodiment is configured to include columns 51 provided at four corners, and three evaporating dishes 52 held by the columns 51 at a predetermined interval in the vertical direction. Has been. Each evaporating dish 52 includes an upper member 52A having a predetermined depth and a rectangular shape, and a lower member 52B that covers the bottom surface of the upper member 52A from below, and these upper members 52A, The evaporation pipe 43 is disposed in a heat exchange manner between the lower member 52B and the lower member 52B. The evaporating pipes 43 provided in each evaporating dish 52 are continuously configured by connection pipes 43 </ b> A provided on the columns 51.

  Each evaporating dish 52 is provided with an evaporating plate 53 through which drain water permeates and easily diffuses from the surface thereof. In the present embodiment, uni-bex (trade name) is used as an example of the evaporation plate 53. This is formed by using a non-woven fabric such as polyester fiber as a base material, heat-curing fine phenol on the base material to form a fixing agent, further imparting hydrophilicity and immersing in an alcohol-based solvent, followed by drying. Is.

  It is assumed that overflow pipes (not shown) are attached to the evaporating dishes 52 other than the evaporating dish 52 constituting the lowest stage at positions that do not overlap each other in the vertical direction.

  With the above configuration, when the compressor 24 and the blower 18 of the cooling device R are operated, the low-pressure refrigerant gas is sucked into the first rotary compression element of the compressor 24 and compressed to become an intermediate pressure. Discharged. The refrigerant discharged into the sealed container is temporarily discharged from the refrigerant introduction pipe 45 to the outside of the sealed container, enters the intermediate cooling circuit 50, and passes through the heat exchanger 22A. Therefore, the refrigerant dissipates heat by receiving ventilation from the blower.

  Thus, after the refrigerant compressed by the first rotary compression element is cooled by the heat exchanger 22A, the refrigerant is discharged from the first rotary compression element of the compressor 24 by being sucked into the second rotary compression element. The temperature of the refrigerant gas can be reduced.

  Thereafter, the refrigerant is sucked into the second rotary compression element and compressed, becomes a high-temperature and high-pressure refrigerant gas, and is discharged from the refrigerant discharge pipe 42 to the outside of the compressor 24. At this time, the refrigerant is compressed to an appropriate supercritical pressure.

  The refrigerant discharged from the refrigerant discharge pipe 42 flows into the radiator 22 through the evaporation pipe 43, radiates heat at the evaporation pipe 43 and the radiator 22, and then enters the high-pressure channel 41 </ b> B of the internal heat exchanger 41. Inflow. The refrigerant that has flowed into the high-pressure channel 41B flows from the bottom to the top in the high-pressure channel 41B. Here, as described above, since the high pressure side flow path 41B and the low pressure side flow path 41A are arranged in a heat exchange manner, the refrigerant from the radiator 22 flowing through the high pressure side flow path 41B passes through the low pressure side flow path 41A. The refrigerant from the flowing evaporator 19 is deprived of heat and cooled.

  Thereby, since the temperature of the refrigerant | coolant which flows in into the capillary tube 20 from the heat radiator 22 can be lowered | hung, the entropy difference in the evaporator 19 can be expanded. Therefore, the cooling capacity in the evaporator 19 can be improved.

  Thereafter, the refrigerant cooled by the internal heat exchanger 41 and flowing out from the high-pressure channel 41 </ b> B reaches the capillary tube 20. The refrigerant gas is still in a gaseous state at the inlet of the capillary tube 20. The refrigerant is made into a gas / liquid two-phase mixture due to a pressure drop in the capillary tube 20 and flows into the evaporator 19 in this state. Therefore, the refrigerant evaporates to exert a cooling action and cool the air in the duct 5.

  Accordingly, since the blower 18 is operated, the cold air exchanged with the evaporator 19 is raised in the duct 5 and discharged from the cold air discharge port 14 toward the cold air suction port 15. Then, the cold air sucked from the cold air inlet 15 is again accelerated by the blower 18. As a result, a cold air curtain is formed in the opening 12, and a part of the cold air curtain is circulated in the storage chamber 8 to cool the interior of the storage chamber 8 to a predetermined temperature.

  Thereafter, the refrigerant flows out of the evaporator 19 and flows into the low-pressure channel 41 </ b> A of the internal heat exchanger 41. The refrigerant that has flowed into the low-pressure channel 41A flows from top to bottom. Here, the refrigerant evaporated by the evaporator 19 and having a low temperature may not be completely in a gaseous state but may be in a mixed liquid state, but is allowed to pass through the low-pressure channel 41A of the internal heat exchanger 41. Thus, the refrigerant is heated by exchanging heat with the refrigerant flowing through the high-pressure side passage 41B, and at this time, the degree of superheat of the refrigerant is ensured and is completely in a gas state. As a result, it is possible to avoid inconveniences such as the liquid refrigerant being sucked into the compressor 24 and the compressor 24 being damaged. The refrigerant heated by the internal heat exchanger 41 returns from the refrigerant introduction pipe 44 into the first rotary compression element of the compressor 24.

  With the above-described configuration, the internal heat exchanger 41 is attached to the evaporator cover 40 provided in the duct 5 through which the cold air flows, so that a sufficient installation space for the internal heat exchanger 41 can be secured. It becomes possible. Therefore, when the low-pressure side flow path 41A and the high-pressure side flow path 41B are configured with a refrigerant pipe having a pipe diameter of about 10 mm, for example, as a length dimension necessary for realizing efficient heat exchange, Even when it is configured with about 3 mm, a sufficient installation space can be ensured. Thereby, the cooling efficiency can be improved.

  Therefore, for example, the showcase itself can be downsized as compared with the case where the internal heat exchanger 41 is disposed in the machine room 2. Further, since the inside of the duct 5 in which the internal heat exchanger 41 is disposed is cooled by the evaporator 19 in advance, it is not necessary to cover the internal heat exchanger 41 with a heat insulating material or the like, thereby reducing the cost. Can be achieved.

  In the cooling device R, when the defrosting operation of the evaporator 19 is executed by a control device (not shown), the drain water received in the drain receiving portion D flows down from the drain pipe and the drain water evaporation device 3. The uppermost evaporating dish 52 is received. The drain water that has flowed into the evaporating dish 52 is efficiently evaporated by exchanging heat with the high-temperature refrigerant that flows in the evaporating pipe 43 that is exchanged heat-exchanged on the lower surface of the evaporating dish 52.

  Further, the drain water that could not be processed in the uppermost evaporating dish 52 sequentially flows down to the evaporating dish 52 provided below via the overflow pipe, and also in each evaporating dish 52, heat is exchanged on the lower surface. Evaporation processing is efficiently performed by exchanging heat with the high-temperature refrigerant flowing into the evaporation pipe 43 disposed in the pipe.

  Furthermore, since each evaporating dish 52 is provided with an evaporating plate 53, when drain water permeates into the evaporating plate 53, it can diffuse from its surface and promote evaporation of the drain water.

  Thereby, the evaporating capacity of the drain water can be improved by efficiently using the heat of the evaporating pipe 43 into which the high-temperature refrigerant flows without using an electric heater.

  In addition, the high-temperature refrigerant flowing into the evaporation pipe 43 is used for evaporation of the drain water to dissipate heat, thereby effectively increasing the capacity of the radiator 22. Therefore, the cooling capacity can be improved also by this.

  In this embodiment, since carbon dioxide is used as the refrigerant, a high-pressure refrigerant flows in the evaporating pipe 43 as compared with the conventional chlorofluorocarbon refrigerant, so the diameter of the evaporating pipe 43 is reduced. Even in this case, the pressure loss can be ignored. Thereby, by making the said pipe diameter thin, heat dissipation efficiency can be improved and cooling capacity can be improved.

  Further, by using carbon dioxide, it is possible to provide a low-temperature showcase suitable for the environment, that is, a device that realizes non-fluorocarbon. Moreover, since carbon dioxide is remarkably easy to obtain compared to other refrigerants, convenience is improved.

It is a partial see-through front view of a low-temperature showcase to which the present invention is applied. It is a vertical side view of the low-temperature showcase of FIG. It is a refrigerant circuit figure of the cooling device applied to the low temperature showcase of FIG. It is a front view of an evaporator cover. It is a perspective view of a drain water evaporator. It is a partial exploded perspective view of a drain water evaporator.

Explanation of symbols

R Cooling device 1 Low temperature showcase 2 Machine room 3 Drain water evaporation device 4 Partition plate 5 Duct 6 Thermal insulation wall 8 Storage chamber 12 Front opening 19 Evaporator 20 Capillary tube (pressure reduction device)
DESCRIPTION OF SYMBOLS 22 Radiator 24 Compressor 40 Evaporator cover 41 Internal heat exchanger 41A Low pressure side flow path 41B High pressure side flow path 42 Refrigerant discharge pipe 43 Evaporation pipe 52 Evaporation tray 53 Evaporation plate

Claims (3)

In a low-temperature showcase that cools by discharging cold air heat-exchanged with the evaporator of the cooling device arranged in the duct into the warehouse,
The cooling device has a refrigerant circuit configured by connecting a compressor, a radiator, a decompression device, the evaporator, and the like, using carbon dioxide as a refrigerant, the high pressure side can be a supercritical pressure, and the high pressure of the refrigerant circuit An internal heat exchanger that exchanges heat between the refrigerant on the side and the refrigerant on the low pressure side,
A low-temperature showcase, wherein the internal heat exchanger is attached to an evaporator cover provided in the duct.   The low-temperature showcase according to claim 1, wherein the internal heat exchanger is arranged so that a refrigerant on a low-pressure side of the refrigerant circuit flows from top to bottom. A drain water evaporation device for evaporating drain water from the evaporator;
The low-temperature showcase according to claim 1 or 2, wherein the drain water evaporator is heated by a refrigerant on a high-pressure side of a refrigerant circuit of the cooling device.

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