JP2005201581A - Cooling system - Google Patents

Abstract

The present invention provides a cooling device capable of defrosting in a space-saving and high-efficiency manner using a thermosiphon by heating a lowermost refrigerant pipe of a low-temperature side evaporator.
A cooling device including a low-temperature side heat transfer cycle for extracting cold heat from a low-temperature part of a Stirling refrigerator, and a high-temperature side heat transfer cycle that discharges heat from a high-temperature part of the Stirling refrigerator to the outside. In the low temperature side cold transfer cycle, the loop-shaped refrigerant pipe 20 is connected to the low temperature side condenser 12 attached to the low temperature part of the Stirling refrigerator, and the low temperature side is provided below the low temperature side condenser by a part of the refrigerant pipe. The evaporator 15 is formed, and the low-temperature side evaporator meanders with its height changed in the vertical direction to form a turning point at the lowermost portions 21c and 22c of each other, and a pair of the serpentine pipe portions 21b and 22b that are horizontally opposed to each other. A plurality of flat plate fins 16 mounted in parallel across a pair of horizontally opposed pipes are provided in a straight line portion excluding the lowermost portions 21c and 22c of 21b and 22b, and an electric heater 23 is provided at the lowermost portion of the serpentine tube portion. Attached was.
[Selection] Figure 1

Description

  The present invention relates to a cooling device provided with a Stirling refrigerator, and more particularly to a cooling device with improved defrosting efficiency of a low-temperature evaporator.

  In recent years, interest in so-called non-fluorocarbon refrigerators equipped with Stirling refrigerators has increased due to concerns about environmental destruction caused by fluorocarbons and the like. Such a refrigerator is provided with a system (cooling device) for transporting cryogenic cold generated by driving a Stirling refrigerator into the cabinet and discharging waste heat to the outside.

  A cooling device equipped with a conventional Stirling refrigerator will be described. FIG. 3: is a schematic block diagram (a) of an example of the conventional cooling device, and its arrow xx sectional view (b). The cooling device 100 includes a low temperature side heat transfer cycle 5 that takes out the cold generated in the Stirling refrigerator 1 and a high temperature side heat transfer cycle 4 that releases the heat to the outside. The Stirling refrigerator 1 includes a low temperature part 3 that absorbs heat in the expansion process of a working medium (for example, helium) enclosed therein and generates cold heat, and a high temperature part 2 that generates heat in the expansion process of the working medium.

  The low-temperature side cold transfer cycle 5 includes a loop-shaped refrigerant pipe 20 connected to a low-temperature side condenser 12 attached to the low-temperature part 3, and a part of the refrigerant pipe 20 lowers the low-temperature side condenser 12 below the low-temperature side condenser 12. The evaporator 15 is formed. The refrigerant pipe 20 is composed of a down pipe 21 in which the refrigerant condensate naturally flows down and an up pipe 22 in which the refrigerant vapor having a low specific gravity rises. Both the down pipe 21 and the up pipe 22 are changed in height in the vertical direction. And a straight pipe part (21a and 22a, respectively) extending vertically downward from the low-temperature side condenser 12 and continuing to the meander parts 21b and 22b. And the upstream pipe 22 are paired with each other so as to form a turning point at the lowermost straight portions (hereinafter referred to as “lowermost portions”) 21c and 22c of the serpentine tube portions 21b and 22b. Is. A plurality of flat plate fins 16 are attached in parallel to the straight portions of the serpentine tube portions 21b and 22b so as to form a row across a pair of horizontally opposed tubes. The serpentine tube portions 21b and 22b and the flat plate fins 16 A low temperature side evaporator (cooler) 15 is configured.

  In this circuit, carbon dioxide, hydrocarbon, or the like is sealed as a refrigerant to form a thermosiphon in the circulation circuit. Moreover, the low temperature side evaporator 15 is installed in the position lower than the low temperature side condenser 12 so that natural circulation by evaporation and condensation of the refrigerant can be used. A drain pan 17 is provided below the low temperature side evaporator 15.

  On the other hand, the high temperature side heat transfer cycle 4 is composed of a thermosiphon using a natural refrigerant such as water or hydrocarbon, and roughly, a high temperature side evaporator 6 attached to the high temperature portion 2 of the Stirling refrigerator 1, A high-temperature side condenser 8 that is disposed higher than the high-temperature side evaporator 6 and condenses the natural refrigerant, and a vapor-side refrigerant pipe 7 that connects the high-temperature side evaporator 6 and the high-temperature side condenser 8 to circulate the refrigerant and the condensation It is a circulation circuit comprised from the liquid side refrigerant | coolant piping 11. FIG. In this circuit, natural refrigerants such as water (including aqueous solutions) and hydrocarbons are sealed as refrigerants. Thus, by using water (including an aqueous solution) or hydrocarbon as a refrigerant, adverse effects on the environment and the human body can be eliminated. Note that the condensate-side refrigerant pipe 11 is connected to the uppermost end of the high-temperature side evaporator 6 in order to facilitate natural circulation due to refrigerant evaporation and condensation. A plurality of flat plate fins 18 are attached to the high temperature side condenser 8 in order to expand the heat exchange area. A pair of heat dissipating fans 19 are provided behind the high temperature side condenser 8, and heat is exhausted to the outside by the heat dissipating fans 19.

  With such a configuration, by operating the Stirling refrigerator 1 during the cold storage operation of the refrigerator, a thermosiphon is formed in the low-temperature side cold transfer cycle 5, and the refrigerant condensate condensed in the low-temperature side condenser 12 is descended by gravity. 21 descends in the straight pipe portion 21a, flows into the serpentine tube portion 21b, and is heated by taking heat from the outside air through the flat fins 16 while meandering and flowing down the serpentine tube portion 21b. The refrigerant condensate turns back at the lowermost part 21 c and starts to evaporate by taking latent heat from the outside through the flat fins 16 when it flows into the serpentine tube portion 22 b of the upstream pipe 22. Then, the inside of the serpentine tube portion 22b meanders and naturally rises, flows into the straight tube portion 22a, further rises in the straight tube portion 22a, and returns to the low temperature side condenser 12. By repeating this cycle, the air around the low-temperature side evaporator 15 is cooled to a low temperature, so that the inside of the warehouse can be cooled by sending this cold air into the warehouse by a fan or the like.

  During the cold storage operation of the refrigerator, frost is generated in the low-temperature side evaporator 15 to form frost, and the amount of the frost grows with the passage of time of the cold storage operation of the refrigerator. Since this frost impedes heat exchange between the low-temperature evaporator 15 and the circulating air flow and ventilation and lowers the cooling performance of the refrigerator, the refrigerator operating mode is normally kept at a rate of several times a day. The operation is switched to the defrosting operation, and the frost adhering to the low temperature side evaporator 15 is melted and removed to defrost.

As this defrosting method, a heat pipe defrosting system that uses a heat pipe to apply defrosting heat to a cooler has been developed, and is described in, for example, Patent Documents 1 to 4.
JP-A-8-303932 (see FIG. 1) JP-A-8-303933 (see FIG. 1) JP-A-8-313144 (see FIG. 1) JP-A-9-264657 (see FIG. 1)

  However, in such a heat pipe defrosting method, in the defrosting of the low temperature side evaporator (cooler) 15 in which the serpentine tube portions 21b and 22b meander multiple times as shown in FIG. Therefore, it is necessary to disperse and arrange a plurality of heat pipes as shown in FIG. 1 of Patent Documents 1 and 2 or to arrange the heat pipes in a meandering manner as shown in FIG. 1 of Patent Document 3. . Therefore, there is a problem that it cannot be applied when it is difficult to sufficiently secure the heat pipe piping space in the cabinet.

  Further, the heater built-in heat pipe shown in FIG. 1 of Patent Document 4 is intended for a cooler in which all the tubes share one flat fin through the vertical direction of the serpentine tube, and as shown in FIG. The present invention is not applicable to a case where 16 is provided in a vertically divided form.

  The present invention has been made in view of the above-mentioned conventional problems, and by heating the lowermost part of the refrigerant pipe of the low-temperature evaporator, it is possible to defrost the space-saving and highly efficiently by using a thermosiphon. An object is to provide a cooling device.

In order to achieve the above object, in the present invention, a low temperature side cold transfer cycle for taking out the cold generated in the low temperature part of the Stirling refrigerator, and a high temperature side heat transfer that releases the heat generated in the high temperature part of the Stirling refrigerator to the outside A cooling device with a cycle,
In the low temperature side cold transfer cycle, a low temperature side condenser attached to a low temperature part of a Stirling refrigerator is connected to a low temperature side evaporator located below the low temperature side condenser with a refrigerant pipe so as to constitute a thermosyphon. ,
An electric heater is attached to the low temperature side evaporator.

  According to this configuration, when the operation mode of the refrigerator is switched from the cold insulation operation to the defrosting, the operation of the Stirling refrigerator is stopped, the electric heater is energized, the refrigerant condensate sealed in the serpentine tube is vaporized, and the vapor and And rises toward the low-temperature side condenser. The rising refrigerant vapor dissipates heat to the low-temperature side condenser, condenses and liquefies, then flows down naturally, recirculates to the bottom, and evaporates again, repeating the evaporation / condensation cycle.

  The electric heater may be attached to the low temperature side evaporator by attaching an electric heater to a refrigerant pipe constituting the low temperature side evaporator. Moreover, it is better to attach an electric heater to the upstream pipe side refrigerant pipe. The electric heater may be attached to the low temperature side evaporator by attaching an electric heater to a flat fin constituting the low temperature side evaporator.

  According to this configuration, when the operation mode of the refrigerator is switched from the cold insulation operation to the defrosting, the operation of the Stirling refrigerator is stopped and the electric heater is energized, and the electric heater attached to the lower part of the upstream side of the refrigerant pipe or the flat fin The refrigerant condensate sealed in the refrigerant tube is vaporized by heat transfer from the gas and becomes vapor and rises toward the low-temperature side condenser. The rising refrigerant vapor dissipates heat to the low-temperature side condenser, condenses and liquefies, then flows down naturally, recirculates to the bottom, and evaporates again, repeating the evaporation / condensation cycle.

  According to the present invention, the refrigerant can be naturally circulated in the refrigerant pipe using the thermosiphon, and in this process, frost and flat fins adhering to the serpentine tube part itself due to heat dissipation and heat transfer from the serpentine tube unit The frost adhering to the surface is melted and removed, and the defrosting of the low-temperature side evaporator can be performed efficiently.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The cooling device 100 of the present invention is equipped with the low-temperature side cold transfer cycle 5 of each embodiment as follows.

  FIG. 1A and FIG. 1B are a schematic configuration diagram of an example of a cooling device according to the first embodiment and a cross-sectional view taken along line xx. In this figure, the same parts as those of the conventional configuration shown in FIG. 3 are denoted by the same reference numerals, and detailed description thereof is omitted. The flat fins 16 are not disposed at the lowermost portions 21c and 22c of the serpentine tube portions 21b and 22b, and an electric heater 23 having an equivalent length is attached to the lowermost portions 21c and 22c.

  On the other hand, when the operation mode of the refrigerator is switched from the cold insulation operation to the defrosting, the operation of the Stirling refrigerator 1 is stopped, the electric heater 23 is energized, the refrigerant condensate sealed in the refrigerant pipe 20 is vaporized, and the vapor and And rises in the up-tube 22 toward the low-temperature side condenser 12. Then, after the heat is released to the low temperature side condenser 12 to be condensed and liquefied, the evaporation / condensation cycle is repeated so that it naturally flows in the downcomer 21 and recirculates to the lowermost parts 21c and 22c to evaporate again. In this process, the frost adhering to the serpentine tube portions 21b and 22b itself and the frost adhering to the surface of the flat fin 16 are melted and removed by heat radiation and heat transfer from the serpentine tube portion 22b of the upstream pipe 22, and the low temperature side The evaporator 15 can be defrosted efficiently.

  In this case, the refrigerant pipe 20 is connected in a loop between the low-temperature side condenser 12 that is the condensing part and the lowermost parts 21c and 22c that are the evaporating parts, and thereby the refrigerant vapor rising in the up pipe 22 Since the refrigerant condensate descending in the down pipe 21 flows so as to circulate in the loop-shaped pipe line, the interference between the vapor and the liquid in the same refrigerant pipe 20 and interfering with each other does not occur. . As a result, the refrigerant circulation amount of the refrigerant pipe 20 is significantly increased, and a high heat transfer capability can be exhibited.

  FIG. 2A and FIG. 2B are a schematic configuration diagram of an example of a cooling device according to the second embodiment and a cross-sectional view taken along line xx. A pair of electric heaters 23 having a length equivalent to that of the lowermost portions 21c and 22c through the rows of the flat plate fins 16 attached to the lowermost portions 21c and 22c of the serpentine tube portions 21b and 22b are connected to the lowermost portions 21c and 22. Are attached in parallel.

  In such a configuration, when the operation mode of the refrigerator is switched from the cold insulation operation to the defrosting, the operation of the Stirling refrigerator 1 is stopped, the electric heater 23 is energized, and the flat fins 16 attached to the lowermost portions 21c and 22c are heated. Then, the refrigerant condensate sealed in the lowermost portions 21 c and 22 c is vaporized by heat transfer, and becomes vapor and rises in the upstream pipe 22 toward the low-temperature side condenser 12. Then, after the heat is released to the low temperature side condenser 12 to be condensed and liquefied, the evaporation / condensation cycle is repeated so that it naturally flows in the downcomer 21 and recirculates to the lowermost parts 21c and 22c to evaporate again. In this process, the frost adhering to the serpentine tube portions 21b and 22b itself and the frost adhering to the surface of the flat fin 16 are melted and removed by heat radiation and heat transfer from the serpentine tube portion 22b of the upstream pipe 22, and the low temperature side The evaporator 15 can be defrosted efficiently.

  The present invention relates to a cooling device provided with a Stirling refrigerator, and a so-called non-Freon refrigerator can be realized by mounting the device in a refrigerator.

These are the schematic block diagram (a) of an example of the cooling device which concerns on this invention Example 1, and its arrow xx sectional view (b). These are the schematic block diagram (a) of an example of the cooling device which concerns on this invention Example 2, and its arrow xx sectional view (b). These are the schematic block diagram (a) of an example of the conventional cooling device, and its arrow xx sectional view (b).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Stirling refrigerator 2 High temperature part 3 Low temperature part 4 High temperature side heat conveyance cycle 5 Low temperature side cold conveyance cycle 6 High temperature side evaporator 7 Steam side refrigerant piping 8 High temperature side condenser 11 Condensate side refrigerant piping 12 Low temperature side condenser 15 Low temperature Side evaporator 16, 18 Flat fin 19 Radiating fan 20 Refrigerant pipe 21 Down pipe 22 Up pipe 21a, 22a Straight pipe part 21b, 22b Serpentine pipe part 21c, 22c Bottom part 23 Electric heater

Claims (4)

In a cooling device comprising a low-temperature side heat transfer cycle for taking out the cold generated in the low-temperature part of the Stirling refrigerator, and a high-temperature side heat transfer cycle for releasing the heat generated in the high-temperature part of the Stirling refrigerator to the outside,
In the low-temperature side cold transfer cycle, a low-temperature side condenser attached to a low-temperature part of a Stirling refrigerator and a low-temperature side evaporator located below the low-temperature side condenser are connected by a refrigerant pipe so as to constitute a thermosyphon. ,
A cooling device comprising an electric heater attached to the low temperature side evaporator.   The cooling device according to claim 1, wherein an electric heater is attached to a refrigerant pipe constituting the low temperature side evaporator.   The cooling apparatus according to claim 2, wherein an electric heater is attached to an upstream pipe side refrigerant pipe constituting the low temperature side evaporator.   The cooling device according to claim 2, wherein an electric heater is attached to a flat fin constituting the low temperature side evaporator.

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