JP2005098581A - Freezing circuit and cooling device using the freezing circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a freezing circuit which increases the degree of supercooling of a refrigerant to improve cooling performance, and also provide a cooling device using the freezing circuit. <P>SOLUTION: In an indoor machine 2, a double pipe heat exchanger having a double pipe structure comprising an outer pipe 76 and an inner pipe 77 is provided below an evaporator 11. The dual pipe heat exchanger is configured to exchange heat by flowing a hot liquid refrigerant 17 liquefied by a condenser 5 through the outer pipe, and flowing a cold gas refrigerant 18 vaporized by the evaporator 11 through the inner pipe. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a refrigeration circuit that performs supercooling of a refrigerant by exchanging heat between the refrigerants and a cooling device that uses the refrigeration circuit, and in particular, a gas refrigerant vaporized by an evaporator and a liquid condensed by a condenser. The present invention relates to a refrigeration circuit capable of increasing the degree of supercooling and performing a highly efficient refrigeration cycle by exchanging heat with a refrigerant using a double pipe heat exchanger, and a cooling device using the refrigeration circuit. .

Conventionally, in the refrigeration circuit, the refrigerant is supercooled by further cooling the high-pressure refrigerant compressed by the condenser from the saturation temperature. By increasing the degree of supercooling, the cooling capacity and COP (Coefficient of OF) are increased. (Performance: coefficient of performance) is known to improve. And as a method of increasing the degree of supercooling of the refrigerant, Japanese Utility Model Publication No. 4-38219 discloses that a cooling coil and a drain pan are installed in the lower part of the drain pan by attaching a heating coil that circulates the discharge gas discharged from the compressor. A cooling device is described that can take heat away from the heating coil and increase the degree of supercooling in the cooled state.
Japanese Utility Model Publication 4-38219 (page 1-2, Fig. 1-3)

However, in the conventional cooling device, the cooled drain pan and the heating coil are in contact with each other by line contact, and heat exchange rate is poor because direct heat exchange is not performed with the drain pan. The degree could not be increased. Further, heat exchange could not be performed sufficiently unless a certain amount of time has passed after the device was driven and the inside of the cooling device and the drain pan were cooled.
The present invention has been made to solve the above-described problems in the prior art, and a double pipe heat exchange is performed between a low-temperature gas refrigerant vaporized by an evaporator and a high-temperature liquid refrigerant condensed by a condenser. In addition to improving the heat exchange performance and increasing the degree of supercooling of the liquid refrigerant by exchanging heat using a heat exchanger, it is also possible that frost adheres to the exchanger by flowing a high-temperature liquid refrigerant in the outer tube. It is an object of the present invention to provide a refrigeration circuit that can be prevented and a cooling device using the refrigeration circuit.

  In order to achieve the above object, according to the refrigeration circuit according to claim 1, a compressor that compresses the refrigerant, a condenser that condenses the refrigerant compressed by the compressor, and the refrigerant liquefied by the condenser is vaporized. In the refrigeration circuit in which the evaporator is connected by a pipe, a double pipe heat exchanger comprising an inner pipe through which the refrigerant flows, and an outer pipe through which the refrigerant flows is provided on the outer periphery of the inner pipe, The double pipe heat exchanger is provided below the evaporator, causes the refrigerant liquefied by the condenser to flow to the outer pipe, and causes the refrigerant vaporized by the evaporator to flow to the inner pipe. It is characterized in that heat exchange is performed.

  The refrigeration circuit according to claim 2 is characterized in that, in the refrigeration circuit according to claim 1, the double pipe heat exchanger has a substantially U shape.

  Furthermore, the cooling device using the refrigeration circuit according to claim 3 is the cooling device using the refrigeration circuit according to claim 1 or 2, wherein the cooling device includes a drain pan, and the double pipe heat exchanger includes the drain pan. It is provided inside.

According to the first aspect of the present invention, the refrigerant liquefied from the condenser is caused to flow to the outer pipe using the double pipe heat exchanger composed of the double pipe of the inner pipe and the outer pipe, and the evaporator Since heat exchange is performed by flowing the vaporized refrigerant through the inner pipe, the heat exchange area when performing heat exchange can be increased. Accordingly, the amount of heat deprived of the liquid refrigerant flowing through the outer pipe increases, and the degree of supercooling of the refrigerant increases, so that the cooling capacity and COP of the apparatus are improved. In addition, since heat exchange is performed between the refrigerants, it is not necessary to provide a separate cooling unit to exchange heat with the liquid refrigerant, so that stable heat exchange is always possible. Furthermore, it is possible to prevent frost from adhering to the surface of the double-pipe heat exchanger during the operation by flowing a high-temperature liquid refrigerant through the outer pipe.
Further, since the double pipe heat exchanger is provided below the evaporator, the high temperature liquid refrigerant flows through the outer pipe without hindering the flow of the cold air flowing from the evaporator direction by the double pipe heat exchanger. Thus, even when the surface temperature of the double pipe heat exchanger is high, the cooling air is not heated and the cooling capacity is not lowered. Furthermore, since the frost dropped from the surface of the evaporator can be melted by the double pipe heat exchanger, the efficiency of drainage is also increased.

  According to the invention of claim 2, since the double pipe heat exchanger has a substantially U-shaped shape, piping can be concentrated and connected in one direction of the double pipe heat exchanger, It is possible to easily perform welding work of piping and maintenance work of the apparatus. Further, the installation space can be saved, and the heat exchange area can be increased.

  Further, according to the invention described in claim 3, since the double pipe heat exchanger is provided inside the drain pan, a space for installing the double pipe heat exchanger is additionally required inside the apparatus. Therefore, the cooling device can be downsized. It is also possible to heat the drain pan by the surface temperature of the double pipe heat exchanger that becomes high temperature and to serve as a heater that melts frost that has fallen on the drain pan.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment in which a refrigeration circuit and a cooling device using the refrigeration circuit according to the present invention are embodied in a refrigeration air conditioner will be specifically described with reference to the drawings. First, the overall schematic configuration of the refrigerated air conditioner 1 will be described with reference to FIG. FIG. 1 is a schematic configuration diagram of a refrigeration circuit according to the present embodiment.
As shown in FIG. 1, the refrigeration air conditioner 1 according to this embodiment is installed separately into an indoor unit 2 and an outdoor unit 3, and further includes a compressor 4, a condenser 5, a liquid reservoir 6, a dryer 7, and a double layer. The refrigeration circuit 15 in the refrigeration air conditioner 1 is configured by connecting the pipe heat exchanger 8, the electromagnetic valve 9, the expansion valve 10, the evaporator 11, the low pressure switch 12, and the accumulator 13 in order through the refrigerant pipe 14.

In the refrigeration circuit 15, the low-temperature and low-pressure refrigerant is first compressed in the compressor 4 to become high-temperature and high-pressure refrigerant vapor, flows into the condenser 5 through the refrigerant pipe 14, and condensed in the condenser 5. It becomes the liquid refrigerant 17. Thereafter, the liquefied refrigerant is stored in the liquid reservoir 6, and the stored liquid refrigerant is sent to the expansion valve 10 through the refrigerant pipe 14 via the dryer 7, the double pipe heat exchanger 8 and the electromagnetic valve 9.
In the dryer 7, the moisture of the refrigerant is removed. The double pipe heat exchanger 8 exchanges heat between the high-temperature liquid refrigerant 17 condensed by the condenser 5 and the low-temperature gas refrigerant 18 that has passed through the expansion valve 10 and the evaporator 11, thereby obtaining a liquid refrigerant. 17 is cooled (see FIG. 10). Further, the solenoid valve 9 can adjust the flow rate of the refrigerant by electrically controlling the valve opening degree. The details of the double pipe heat exchanger 8 will be described later.

The expansion valve 10 depressurizes and expands the condensed liquid refrigerant, sends it to the evaporator 11 in a state where it is easily vaporized. Then, the low-temperature and low-pressure refrigerant sent to the evaporator 11 takes heat from the periphery of the evaporator 11 and vaporizes to become a low-temperature gas refrigerant 18 and passes through the double pipe heat exchanger 8 again. In the double pipe heat exchanger 8, the liquid refrigerant 17 is supercooled by taking heat from the high-temperature liquid refrigerant 17 as described above. Thereafter, it returns to the compressor 5 again through the accumulator 13 through the low pressure pipe 19 in which the low pressure switch 12 is arranged.
The low pressure switch 12 is connected to the low pressure pipe 19, measures the pressure in the low pressure pipe 19 (pressure on the suction side of the compressor), and stops driving the compressor 4 when the pressure is below a certain value. It is something to be made. The accumulator 13 is a liquid return prevention container, prevents liquid refrigerant from being sucked into the compressor 4, and supplies only the vaporized refrigerant to the compressor 4.

Next, the structure of the indoor unit 2 of the refrigeration air conditioner 1 according to the present embodiment will be described with reference to FIGS. FIG. 2 is a perspective view showing the appearance of the indoor unit of the refrigerated air conditioner according to the present embodiment, FIG. 3 is a perspective view showing the internal structure of the indoor unit of the refrigerated air conditioner according to the present embodiment, and FIG. It is a side view which shows the internal structure of the indoor unit of the frozen air conditioner which concerns on this embodiment.
The outline of the indoor unit 2 basically includes a base 22, side plates 23 attached to the left and right of the base 22, an attachment angle 24 attached to the top plate of the base 22, and a fan attached to the front of the base 22. It is comprised from the cover 25 and the drain pan 26 attached to the downward direction of the base 22 so that opening and closing was possible.
In addition, internal devices such as the double pipe heat exchanger 8, the electromagnetic valve 9, the expansion valve 10, and the evaporator 11 are housed in the outer shell and are connected to each other by pipes 14.

  In addition, a refrigerant inlet 27 through which refrigerant flows from the outdoor unit 3 and a refrigerant outlet 28 that sends the refrigerant to the outdoor unit 3 are provided on the back surface of the base 22. The mounting angle 24 is a mounting tool for mounting the indoor unit 2 in a freezing room or the like, and the indoor unit 2 is fixed to a ceiling or the like of the freezing room with a screw or the like through a mounting hole 29 provided in the mounting angle 24. Is done.

In the indoor unit 2, a blower fan 30 that discharges ambient outside air cooled by the evaporator 11 to the outside is provided. A fan cover 25 is attached to the front surface of the blower fan 30, and cool air is discharged from the inside of the apparatus through the fan cover 25. The fan cover 25 is configured by arranging a plurality of wire rods at equal intervals so that a finger or the like does not accidentally contact the blower fan 30 to be injured. Furthermore, a fan cover heater 31 for melting frost adhering to the wire is attached to the back surface side of the fan cover 25.
The water melted by the fan cover heater 31 is first collected in a water receiving tray 32 provided below the fan cover 25. The water receiver 32 is inclined toward the base 22, and five elongated holes 33 are provided at corners at the boundary with the base 22. Accordingly, the water received by the water receiver 32 flows down to the drain pan 26 from the long hole 33 and is discharged from the drainage portion 35 provided in the drain pan 26 to the outside of the apparatus (see FIG. 8). The drainage mechanism of the drain pan 26 will be described later.

Next, the structure of the drain pan 26 will be described in detail with reference to FIGS. FIG. 5 is a perspective view showing the drain pan according to the present embodiment, and FIG. 6 is a side view showing the drain pan and the heater in the vicinity of the center of the drain pan according to the present embodiment.
The drain pan 26 is made of aluminum, and is supported so as to be openable and closable with respect to the base 22 via a fixture 36. When closed, the drain pan 26 collects frost and water generated inside the apparatus at one place, and goes out of the apparatus. It is possible to discharge. On the other hand, maintenance work and the like inside the apparatus can be performed from the opening of the base 22 when opened.

  The drain pan 26 is formed into a substantially V shape by welding the first inclined portion 37 and the second inclined portion 38, and a guide groove 39 that is also a welded portion is formed at the center of the V shape. . The first inclined portion 37 and the second inclined portion 38 include inclined surfaces 40 and 41, front plates 42 and 43, rear plates 44 and 45, and side plates 46 and 47, and the rear plates 44 and 45 on the guide groove 39. A drainage portion 35 formed in a cylindrical shape is separately welded to a portion located on the side in order to drain water outside the apparatus. Further, the front plates 42 and 43 are formed with screw holes 50, and when the drain pan 26 is closed, the drain pan 26 is fixed to the base by screwing it with the screw holes 51 provided in the water receiving tray 32. (See FIG. 2). In addition, the inclined surfaces 40 and 41 are inclined at a constant angle from the front plates 42 and 43 to the rear plates 44 and 45, and when the drain pan 26 is closed, the point where the drainage portion 35 is provided is the most. It is comprised so that it may become a low position (refer FIG. 8).

Further, a round bar heater 54 processed into a U-shape is attached to the upper surface of the drain pan 26. The heater 54 melts the ice block that has fallen on the drain pan 26 in the defrosting operation, and heats the drain pan 26 so that the melted and dropped water does not freeze again on the drain pan.
The heater 54 is attached to the inclined surfaces 40 and 41 of the drain pan 26 by being fixed at four places by fixing members 55. At that time, the heater 54 is attached in contact with the inclined surfaces 40 and 41, and in the central portion where the guide groove 39 is formed, a horizontal shape having a horizontal shape facing the guide groove 39. A portion 56 is provided (see FIG. 6). A gap 57 is formed in an inverted triangular shape between the guide groove 39 and the horizontal portion 56 of the heater 54.

Next, a method for attaching the heater 54 to the drain pan 26 will be described in detail with reference to FIG. FIG. 7 is an explanatory view showing a heater support structure for the fixing member according to this embodiment.
In the drain pan 26, a positioning member 58 is attached to the inclined surface 40 in parallel with the side plate 46 along with the fixing member 55. When the heater 54 is attached to the drain pan 26, first, the distal end portion 54A of the heater 54 is brought into contact with the positioning member 58 to perform horizontal positioning. Thereafter, the heater 54 is slid in one direction (downward in FIG. 5) and fixed by the fixing member 55.

The fixing member 55 is made of thin plate-shaped aluminum, and has a long plate shape so that it can be covered in the length direction of the heater 54. The fixing member 55 includes a fixing portion 60 fixed to the inclined surfaces 40 and 41, a wall portion 61 positioned perpendicular to the inclined surface 40, a bent portion 62 that is bent, and a heater 54. The support part 63 is sandwiched and supported together with 61, the curved part 64 is curved upward with respect to the support part 63, and the free end 65.
The fixing portion 60 is in contact with the inclined surfaces 40 and 41 of the drain pan 26 and is fixed to the inclined surfaces 40 and 41 with screws 66. The support portion 63, the curved portion 64, and the free end 65 are elastically deformed in the vertical direction with respect to the wall portion 61 (see FIG. 7). When the heater 54 is inserted from the free end 65 (leftward in FIG. 7), its circumferential surface is in contact with the bending portion 64 and moves while pushing up the bending portion 64 upward. When the heater 54 further enters and passes through the lowest point 67 of the bending portion 64, the bending portion 64 is now deformed downward along the circumferential surface of the heater 54 due to elasticity, and the heater 54 is moved to the wall portion 61 and the wall portion 61. It is fixed when it comes into contact with the support part 63.

  Since the heater 54 is fixed to the upper surface of the drain pan 26 by the above method, it is not necessary to use a separate screw when fixing the heater 54, and the heater 54 is fixed by using the elastic force of the fixing member 55. Since it can fix by making it slide, its attachment and removal become easy.

Here, the heater 54 attached to the drain pan 26 by the above method heats the drain pan 26 so that the water that has fallen on the drain pan 26 does not freeze, and the frost that has fallen on the drain pan 26 is melted. It is for draining from 35.
Hereinafter, the drainage mechanism of the drain pan 26 will be described with reference to the drawings. FIG. 8 is an explanatory view schematically showing a drain pan drainage mechanism according to the present embodiment.

As shown in FIG. 8, the indoor unit 2 performs cooling by sending the ambient outside air cooled by the evaporator 11 to the outside of the apparatus by the blower fan 30. At that time, since the evaporator 11 becomes very low temperature, the moisture of the outside air becomes frost and adheres to the surface of the evaporator 11 and grows. Here, the grown frost is melted by the defrosting operation, falls on the drain pan 26, and is further discharged from the drainage unit 35 to the outside of the apparatus.
However, not all frost is melted even by the defrosting operation, and a part of the frost falls on the drain pan 26 as an ice block. In order to prevent the drainage part 35 from being blocked by the ice blocks that have fallen in this way, the drain pan 26 is heated by the heater 54 to melt the dropped ice blocks. Further, even when the water is melted and dropped, the drain pan 26 is heated so that it does not freeze again on the cooled drain pan 26.

  Further, frost adhering to the wire material of the fan cover 25 is melted by the fan cover heater 31 and collected in a water receiving tray 32 provided below the fan cover 25. The water receiver 32 is inclined toward the base 22, and the melted water flows down to the drain pan 26 from the elongated hole 33 provided in the corner portion, and is similarly discharged from the drainage portion 35 to the outside of the apparatus. . At that time, the drain pan 26 is heated by the heater 54 so that the water flowing on the drain pan 26 does not freeze.

  As shown in FIG. 5, the heater 54 is fixed by a fixing member 55 and a positioning member 58 so as to cover most of the linear portion, suppresses heat radiation to the surroundings, and heat from the heater 54 is fixed to the fixing member 55. In addition, it can be efficiently transmitted to the drain pan 26 through the positioning member 58. The drain pan 26, the fixing member 55, and the positioning member 58 are formed of aluminum as described above, and are effective because of their high thermal conductivity.

The heater 54 and the fixing member 55 are attached so as to have a linear shape along the inclination direction of the inclined surfaces 40 and 41, and water flowing from the evaporator 11 and the fan cover 25 flows through the inclined surfaces 40 and 41. At that time, the flow is not disturbed.
The water that has fallen on the inclined surfaces 40 and 41 and reaches the guide groove 39 from the inclined surfaces 40 and 41 is guided to the drainage portion 35 along the guide groove 39. At this time, the horizontal direction of the guide groove 39 and the heater 54 is reduced. Since a gap 57 is formed in an inverted triangle shape with the part 56 (see FIG. 6), the flow of water can be reliably passed through the gap 57 to the drainage part 35 without being blocked by the heater 54. Is possible.
Here, since the horizontal portion 56 of the heater 54 is not in direct contact with the drain pan 26, heat cannot be transferred to the drain pan 26 by heat conduction, but the nearby drain pan 26 can be heated by radiant heat.

Next, the internal structure of the indoor unit 2 will be described. FIG. 9 is a schematic diagram showing the internal structure of the indoor unit according to the present embodiment.
As shown in FIGS. 3, 4, and 9, the evaporator 11 is held in a state of being suspended from the top plate portion in the base 22. The lower ends of the tube plates 70 and 71 forming the left and right side portions of the evaporator 11 are bent inward, and mounting flanges 72 and 73 are formed. And the both ends of the double pipe heat exchanger 8 which has a U-shape are being fixed to the attachment flanges 72 and 73 by the fixing band 74, respectively (refer FIG. 3). The fixing band 74 is formed by bending a long plate into a convex shape, and is fixed to the mounting flanges 72 and 73 by a fixing screw 75.

The high-temperature liquid refrigerant 17 sent from the outdoor unit 3 enters the indoor unit 2 through the refrigerant inlet 27 and is conveyed to the electromagnetic valve 9 through the outer pipe 76 of the double pipe heat exchanger 8. The high-temperature liquid refrigerant 17 that has passed through the electromagnetic valve 9 is expanded by the expansion valve 10 to become a low-temperature and low-pressure refrigerant, and further vaporized by the evaporator 11 to become a gaseous refrigerant 18. The refrigerant passes through the inner pipe 77 and is conveyed again from the refrigerant outlet 28 to the outdoor unit 3.
Here, in the double pipe heat exchanger 8, the heat exchange between the high-temperature liquid refrigerant 17 and the low-temperature gas refrigerant 18 causes the gas refrigerant 18 flowing through the inner pipe 77 to take heat away from the liquid refrigerant 17. Perform supercooling.

Next, the structure of the double pipe heat exchanger 8 will be described in detail with reference to FIGS. FIG. 10 is a cross-sectional view showing the internal structure of the double pipe heat exchanger according to this embodiment, and FIG. 11 is a cross-sectional view taken along the line AA in FIG.
The double pipe heat exchanger 8 is made of the same copper as the pipe 14 and has a surface coated with anticorrosion. The outer pipe 76 is formed in a substantially U shape as shown in FIG. Is made smaller and the inner tube 77, which is also formed in a substantially U shape, is combined with each other. The outer tube 76 is attached so as to cover the outer side of the inner tube 77, and has a two-layered tube structure via an inner tube wall 78.

The high-temperature liquid refrigerant 17 sent from the outdoor unit 3 through the condenser 5 passes from the outer pipe inlet 79 through the outer pipe inside 80, and further through the connecting portion 81 from the outer pipe outlet 82 to the electromagnetic valve 9.
On the other hand, the refrigerant that has become the low-temperature gas refrigerant 18 through the electromagnetic valve 9, the expansion valve 10, and the evaporator 11 is led from the inner pipe inlet 85 to the inner pipe 77 of the double pipe heat exchanger 8. . The low-temperature gas refrigerant 18 that has flowed from the inner pipe inlet 85 passes through the inner pipe interior 86, is further sent from the inner pipe outlet 88 to the outdoor unit 3 through the connecting portion 87, and is compressed again by the compressor 4.

At that time, the flow directions of the liquid refrigerant 17 flowing through the outer pipe 76 and the gas refrigerant 18 flowing through the inner pipe 77 are opposite to each other (see FIG. 10). Heat exchange is performed via the inner tube wall 78. By this heat exchange, the low-temperature gas refrigerant 18 takes heat from the high-temperature liquid refrigerant 17, thereby supercooling the liquid refrigerant 17 and increasing the degree of supercooling of the refrigerant subcooling liquid at the inlet of the expansion valve 10. It becomes possible. By increasing the degree of supercooling, the refrigerating capacity and the COP value in the evaporator 11 are improved.
Further, since the gas refrigerant 18 having a low temperature flows through the inner pipe 77 and the liquid refrigerant 17 having a high temperature flows through the outer pipe 76, the surface temperature of the double pipe heat exchanger 8 becomes high. Therefore, there is no possibility that frost is formed on the surface of the double pipe heat exchanger 8 due to moisture in the outside air.
Further, the double pipe heat exchanger 8 is formed in a substantially U shape, and most of the outer surface excluding the connecting portion 87 of the inner pipe 77 is covered with the outer pipe 78. Therefore, since the heat exchange area can be increased without requiring much arrangement space, the heat exchange performance can be improved even when the indoor unit 2 is small. Furthermore, since the double pipe heat exchanger 8 is made of copper having a high thermal conductivity, the efficiency of heat exchange is further improved. Moreover, since the anticorrosion coating is given to the double pipe | tube heat exchanger 8, the corrosion of the pipe | tube by corrosive gas can be prevented and a gas leak can be prevented.

Further, in the double pipe heat exchanger 8, welds welded to pipes such as the outer pipe inlet 79, the outer pipe outlet 82, the inner pipe inlet 85, and the inner pipe outlet 88 are concentrated in one direction. It is provided (see FIG. 10), and welding work with the pipe 14 is facilitated. In addition, the efficiency of maintenance work is improved.
Furthermore, as described above, the double pipe heat exchanger 8 is attached to the lower side of the evaporator 11 by the fixed band 74, so that the outside air cooled by the evaporator 11 is sent to the outside of the indoor unit 2 by the blower fan 30. Since the double pipe heat exchanger 8 is not positioned on the path of the outside air when released, the air flow is not obstructed, and the once cooled outside air has a high surface 2 Heating by the heavy pipe heat exchanger 8 does not lower the cooling capacity.

  Further, as shown in FIG. 9, when the drain pan 26 is closed, the double-pipe heat exchanger 8 is positioned directly above the heater 54 that is attached inside the drain pan 26 and further in a substantially U shape on the top surface of the drain pan 26. The Therefore, even when frost falls from the evaporator 11 onto the double pipe heat exchanger 8 due to the defrosting operation, the frost is melted and discharged from the drain pan 26 to the outside of the apparatus by the surface temperature having a high temperature. Is possible. Furthermore, although it does not contact the drain pan 26 directly, it can also serve as a heating device that heats the drain pan 26 together with the heater 54 by radiant heat. By arranging the double pipe heat exchanger 8 in the drain pan 26, it is possible to install the double pipe heat exchanger 8 without requiring a separate arrangement space for the double pipe heat exchanger 8 in the indoor unit 2. .

As described above, in the refrigeration circuit and the cooling device using the refrigeration circuit according to the present embodiment, the double pipe heat exchanger having a double pipe structure including the outer pipe 76 and the inner pipe 77 in the indoor unit 2. 8, heat exchange is performed by flowing the high-temperature liquid refrigerant 17 liquefied by the condenser 5 through the outer pipe and the low-temperature gas refrigerant 18 vaporized by the evaporator 11 through the inner pipe. The heat exchange area between the refrigerants can be increased by the heavy pipe structure, and the degree of supercooling of the refrigerant can be increased. Therefore, the refrigerating capacity and the COP value in the evaporator 11 can be improved. Further, since a low-temperature gas refrigerant flows through the inner pipe 77 and a high-temperature liquid refrigerant 17 flows through the outer pipe 76, the surface temperature of the double pipe heat exchanger 8 becomes high, and the double pipe heat exchanger. There is no risk of frost on the surface of 8 due to moisture in the outside air.
The double-pipe heat exchanger 8 is formed in a substantially U shape, and is configured to be disposed in the drain pan below the evaporator 11 when the drain pan 26 is closed. Therefore, when the outside air cooled by the evaporator 11 is discharged to the outside of the indoor unit 2 by the blower fan 30 without requiring a separate space in the indoor unit 2, a double pipe heat exchange is performed. Since the vessel 8 is not positioned on the path of the outside air, the air flow is not blocked. Moreover, the outside air once cooled is heated by the double-pipe heat exchanger 8 whose surface has become high temperature, and the cooling capacity does not drop.

Of course, the present invention is not limited to the above-described embodiments, and various improvements and modifications can be made without departing from the scope of the present invention.
For example, in the present embodiment, an expansion valve is used as the refrigerant pressure reducing mechanism, but a capillary tube may be used instead of the expansion valve.
In addition, since the drain pan 26 can be heated by the double pipe heat exchanger 8, the heater 54 can be removed from the drain pan 26. Further, a pipe 14 through which a high-temperature liquid refrigerant flows can be installed on the drain pan instead of the heater 54.

It is a schematic block diagram of the freezing circuit which concerns on this embodiment. It is a perspective view which shows the external appearance of the indoor unit which concerns on this embodiment. It is a perspective view which shows the internal structure of the indoor unit which concerns on this embodiment. It is a side view which shows the internal structure of the indoor unit which concerns on this embodiment. It is a perspective view which shows the drain pan which concerns on this embodiment. It is a side view which shows the drain pan and heater in the center vicinity of the drain pan which concerns on this embodiment. It is explanatory drawing which showed the heater support structure to the fixing member which concerns on this embodiment. It is explanatory drawing which showed typically the drainage mechanism of the drain pan which concerns on this embodiment. It is the schematic diagram which showed the internal structure of the indoor unit which concerns on this embodiment. It is sectional drawing which shows the internal structure of the double tube heat exchanger which concerns on this embodiment. It is arrow sectional drawing which cut | disconnected the double-pipe heat exchanger by the line AA of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ......... Refrigeration air conditioner 2 ......... Indoor unit 4 ......... Compressor 5 ......... Condenser 8 ...... Double pipe heat exchanger 11 ......... Evaporator 14 ......... Piping 15 ... ... Refrigeration circuit 17 ... ... High-temperature liquid refrigerant 18 ... ... Low-temperature gas refrigerant 26 ... ... Drain pan 76 ... ... Outer pipe 77 ... ... Inner pipe

Claims (3)

A compressor for compressing the refrigerant;
A condenser for condensing the refrigerant compressed by the compressor;
In a refrigeration circuit in which a pipe connected to an evaporator in which the refrigerant liquefied by the condenser is vaporized,
A double pipe heat exchanger comprising an inner pipe through which the refrigerant flows and an outer pipe provided on the outer circumference of the inner pipe, and through which the refrigerant flows,
The double pipe heat exchanger is provided below the evaporator, causes the refrigerant liquefied by the condenser to flow to the outer pipe, and causes the refrigerant vaporized by the evaporator to flow to the inner pipe. A refrigeration circuit characterized by performing heat exchange. The refrigeration circuit according to claim 1, wherein the double pipe heat exchanger has a substantially U shape. Having a drain pan,
The cooling device using the refrigeration circuit according to claim 1 or 2, wherein the double pipe heat exchanger is provided inside the drain pan.

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