JPH08303932A - Defroster for freezer refrigeration showcase - Google Patents

Abstract

(57) [Summary] [Purpose] As a defroster for a cooler mounted on a showcase, the heat pipe for defrosting incorporated in a fin-tube cooler has been improved to improve the heat transfer capacity of the heat pipe and cooler. Defrost can be performed more effectively. [Structure] As a defrosting means for a fin tube type cooler 5 mounted on a freezing / refrigerating showcase, a loop-shaped heat pipe 9 in which both ends of a condenser 9a are connected to an evaporator 9b.
Is installed in the cooler, and the condensing part of the heat pipe is arranged above the evaporating part so as to be heat-transferably inserted into the row of the plate fins 5b of the cooler, and the evaporating part is operated at the time of defrosting. 10, the pipe line of the loop-shaped heat pipe excluding the condensing part and the peripheral surface of the evaporating part are covered with a heat insulating material 13, and the defrosting heat given from the heater to the evaporating part of the heat pipe is transferred to the condensing part. Then, heat is radiated to the plate fins from here to defrost the cooler.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a defrosting device for a freezer-refrigerating showcase equipped with a refrigerator for an open showcase or the like.

[0002]

2. Description of the Related Art In the above-mentioned freezing / refrigerating showcase, a fin-tube cooler (evaporator of a refrigerator) and a blower fan are arranged in a cool air circulation duct formed so as to surround a product display room in the case body. However, during cold-warming operation, the cold air that has exchanged heat with the cooler is circulated to keep the products displayed in the refrigerator cool, and frost forms on the refrigerant tubes and plate fins of the cooler during cold-warming operation. Frost is formed, and the amount of frost grows with the lapse of time in the cold insulation operation.

This frost causes heat exchange between the cooler and the circulating air flow,
In addition, since the cold insulation performance of the showcase is deteriorated by obstructing ventilation, the operation mode of the showcase is normally switched from cold insulation operation to defrosting at a rate of about several times a day, and the frost adhering to the cooler is changed. Is melted and removed to defrost. In addition, as this defrosting method, a heat pipe defrosting method has recently been developed in which a heat pipe is used to apply defrosting heat to a cooler.
It is known from Japanese Patent No. 42191, Japanese Patent Laid-Open No. 5-346284, and the like.

[0004]

Although the heat pipe defrosting method can efficiently defrost the frost adhering to the cooler by utilizing the heat transfer function peculiar to the heat pipe, the conventional heat pipe defrosting method is used. The structure has the following problems. That is, as seen in each of the above publications, in the conventional heat pipe, the upper condensing part and the lower evaporating part are connected by one pipe. Therefore, the vapor of the working fluid that is vaporized by the heater heating in the evaporation section and diffuses and moves in the pipe toward the condensation section, and the working fluid that is condensed and liquefied in the condensation section and returns to the evaporation section by gravity (the vapor (The flow direction is opposite) and the flow of steam and hydraulic fluid interfere with each other in the same pipe, resulting in a limit to the moving speed of the hydraulic fluid and steam in the pipe. The heat transfer capacity of the heat pipe is kept low. Although it is possible to use a heat pipe with a large pipe diameter as the heat pipe, a large number of refrigerant tubes are piped inside the fin-tube cooler, and there is not enough room for the heat pipe piping space. In addition, if the heat pipe becomes thick, the ventilation resistance during the cold insulation operation increases, which is not preferable.

Further, when the showcase itself is installed or the cooler incorporated in the case body is inclined at an angle from the horizontal, a part of the working liquid liquefied in the condenser is condensed depending on the inclination direction. It may not be possible to return to the evaporation part while remaining at the tip part of the part, and the heat transport capacity may be reduced accordingly. In addition, if the heat transfer capacity of the defrosting heat pipe is low, the defrosting time of the cooler is prolonged, and the influence of increasing the product temperature of the products displayed in the showcase is increased accordingly.

The present invention has been made in view of the above points, and by improving a defrosting heat pipe incorporated in a fin-tube type cooler, the heat transfer capacity of the heat pipe is enhanced to defrost the cooler. It is an object of the present invention to provide a defrosting device for a refrigerating and refrigerating showcase, which is capable of more effectively performing the above.

[0007]

In order to achieve the above object, according to the present invention, as a defrosting means for a cooler, a loop-shaped heat pipe in which both ends of a condenser are communicated with an evaporator is a cooler. And the heat pipe condensing part is arranged above the evaporating part so as to be inserted into the plate fin array of the cooler in a heat transfer manner, and the evaporating part is provided with a heater that operates during defrosting. I shall.

Further, the above configuration can be implemented in a mode in which the following requirements are added. 1) The loop heat pipe is provided with a plurality of condensing sections arranged in parallel in the loop with a common evaporation section. 2) The evaporation part of the loop heat pipe is housed in a recess formed in the cooler by cutting out a part of the plate fin array.

3) The heat-insulating material is coated on the pipe line of the loop heat pipe excluding the condensing part and the peripheral surface of the evaporating part.

[0010]

In the above structure, when defrosting the showcase, when the heater provided in the evaporation portion of the heat pipe is energized to heat the working fluid in the heat pipe, the vapor of the working fluid vaporized in the evaporation portion forms a loop. It diffuses and moves to the condenser part on the upper side through the pipe, and from there, heat is dissipated to the plate fins of the cooler to condense and liquefy, and then the evaporation / condensation cycle is repeated so as to recirculate to the evaporator part on the lower side to Melts and removes frost adhering to the refrigerant tubes, plate fins, and heat pipe itself. In this case, since the loop heat pipe has both ends of the condensing section communicating with the evaporating section,
Compared to a heat pipe with a structure that connects the evaporation part and the condensation part with a book pipe, the flow of steam that rises in the pipe toward the condensation part and the working fluid that descends in the pipe and returns to the evaporation part The interference due to the intersection with the flow is greatly reduced and the flow is smooth, and the heat transfer amount of the heat pipe is increased accordingly, and the defrosting of the cooler can be performed efficiently in a short time.

Moreover, even if the posture of the showcase or the cooler is tilted from the normal horizontal posture, the working liquid liquefied in the condenser does not remain in the condenser, and the both sides of the working fluid flow into the evaporator. Make sure to return to the evaporation section by flowing down any downward slope route that leads to it. Also, do not pull out the evaporation part of the defrosting heat pipe, which also serves as a reservoir for the working fluid, into the recess formed by cutting out part of the plate fin of the cooler without pulling it out of the cooler. Since the defrosting device can be compactly accommodated within the outer dimensions of the cooler, it is convenient to install the cooler in the cool air circulation duct of the showcase.

Further, by removing the condenser part of the loop-shaped heat pipe and covering the evaporator part and the pipe line between the evaporator part and the condenser part with a heat insulating material, a space between the evaporator part and the condenser part is provided. It is possible to efficiently defrost by suppressing the heat radiation from the conduit to the surroundings and sending the heat energy applied from the heater to the evaporation section to the condensation section without heat loss.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. First, FIG. 4 shows the configuration of an open showcase that is an implementation target of the present invention. In the figure, 1 is a case body of a showcase, 2 is a product display rack provided in the cabinet, 3 is an inner duct that circulates cool air, 4 is an outer duct, 5
Is a fin-tube type cooler (evaporator of refrigerator) arranged in the inner duct 3, 5v is an expansion valve, 6 is a condensing unit of the refrigerator, and 7 and 8 are inner fans and outer fans. At times, the refrigerator is operated, and the cool air that has exchanged heat with the cooler 5 is circulated and blown by the blower fans 7 and 8 as shown by the arrows, and the inner and outer two-layer air curtains are blown out at the front opening of the case body 1. It is well known that the inside of the refrigerator is kept cool.

In contrast to the showcase having such a structure, the cooler 5 is equipped with the defrosting means of each of the following embodiments. Embodiment 1 In FIGS. 1A and 1B, a cooler 5 is a fin-tube type evaporator in which a large number of plate fins 5b are provided over a refrigerant tube 5a arranged in a meandering shape. As a means, a loop-shaped heat pipe 9 is installed separately in a plurality of upper and lower stages. The pipe path of the loop heat pipe 9 is formed in a loop shape so that both ends of the condenser section 9a communicate with the evaporation section 9b, and the heat pipe 9 is filled with a working fluid 9c. The working fluid 9c has a low boiling point whose freezing point is lower than the refrigerant evaporation temperature of the cooler 5, such as a halogenated hydrocarbon refrigerant,
Freon-based alternative refrigerants, fluorocarbons, alcohols, etc. are used. And the loop-shaped heat pipe 9 is arranged such that the condensing part 9a is located at the upper level and the condensing part 9b is located at the lower level,
The condenser 10 is fitted into the row of the plate fins 5b of the cooler 5 for heat transfer coupling, and a heater 10 is provided for each heat pipe in the evaporator 9b drawn out to the side of the cooler 5.
Reference numeral 11 denotes an opening / closing contact connected to the power supply circuit of the heater 10, and a command from the energization control unit 12 causes the heater 1 to be defrosted.
0 is energized.

The loop-shaped heat pipe 9 is in contact with the plate fins 5b of the cooler 5 in order to reduce heat loss due to heat radiation from the pipe lines excluding the area of the condenser portion 9a and the peripheral surface of the evaporator portion 9b. This part is covered with a heat insulating material 13 shown by a dotted line after being separated so as not to. The connecting conduit connecting the condenser 9a and the evaporator 9b is piped through a recess 5c formed in a side edge of the plate fin 5b so as to fit within the outer dimensions of the cooler 5.

With such a structure, during the cold-keeping operation of the showcase, the refrigerant is supplied from the condensing unit side of the refrigerator through the expansion valve 5a to the refrigerant tube 5a of the cooler 5 while the heater 10 is turned off. To cool the airflow flowing through the cooler 5. On the other hand, when the operation mode of the showcase is switched from the cold insulation operation to the defrosting operation, the operation of the refrigerator is stopped to stop the supply of the refrigerant to the cooler 5, and the opening / closing contact 11 is closed by a command from the control unit 12 to close the heater. 10 is energized to heat the working fluid 9c enclosed in the evaporation portion 9b of the loop heat pipe 9. The working liquid heated here evaporates to boiling, becomes superheated vapor, and diffuses and moves toward the condensing portion 9a. And the condensing part 9a
After the heat is radiated to the plate fins 5b of the cooler 5 to condense and liquefy, the evaporation / condensation cycle is repeated so that gravity returns to the evaporator 9b to evaporate again. In this process, heat is radiated from the condenser 9a to cool the cooler. Frost adhering to the surface of 5 is removed by melting.

In this case, in the heat pipe 9, the condensing portion 9a and the evaporating portion 9b are connected in a loop shape, whereby the vapor of the working fluid rising in the heat pipe and the condensing fluid descending are looped. Since the steam and the liquid flow so as to circulate in a pipe, there is no interference in which the vapor and the liquid intersect with each other in the same pipe to hinder the flow. As a result, the limit of the working fluid circulation amount in the heat pipe is significantly increased, and high heat transfer capacity can be exhibited. In this regard, according to the results of tests conducted by the inventors, it has been confirmed that the heat transfer capacity of the loop-shaped heat pipe 9 can be increased about twice as compared with the conventional heat pipe. Also,
Even if the piping posture of the heat pipe 9 incorporated in the cooler 5 is inclined obliquely from the horizontal due to the inclination of the installation posture of the showcase, the working liquid condensed and liquefied in the condensing part 9a does not remain in the condensing part and faces downward. It surely flows back to the evaporation portion 9b by following the route on the side of the pipeline that is inclined to. In addition, by covering the pipes, excluding the condenser 9a, and the peripheral surface of the evaporator 9b with the heat insulating material 13, the heat radiation in the middle of the pipes is reduced, so that the heat energy given by the heater 10 is reduced. The heat can be transferred to the condenser 9a with almost no heat loss.

Embodiment 2 FIGS. 2 (a) and 2 (b) show an applied embodiment of the present invention. In this embodiment, the evaporation section 9b of the loop-shaped heat pipe 9 is located at the center of the lower side of the loop. In the same manner as in the first embodiment, the plate fins 5b are arranged so that the evaporation portion 9b and the heater 10 attached to the evaporation portion 9b can be compactly accommodated within the outer dimensions of the cooler 5.
It is arranged to be housed in a recess 5c formed by cutting out a part of its side edge. Note that, in FIG. 2, the refrigerant tube of the cooler 5 is omitted for simplicity of illustration.
Further, as in the first embodiment, the loop-shaped heat pipe 9 has a conduit except the condenser 9a, an evaporator 9b, and a heater 10.
Is covered with a heat insulating material 13.

According to this structure, as compared with the structure of the first embodiment, the evaporating portion 9b of the heat pipe 9 does not stick out from the outer dimension of the cooler 5, and the cooler is provided in the cool air circulation duct of the showcase. Also when assembling 5, it is not necessary to secure an extra space in the ventilation duct, and the space efficiency is improved. Embodiment 3 FIGS. 3 (a) and 3 (b) show still another application embodiment of the present invention. In this embodiment, the loop-shaped heat pipe 9 is in the middle of the loop with the evaporation portion 9b in common. From a plurality of condensing parts 9a-1 and 9a-2
Will be configured.

As a result, as in the above-described first and second embodiments, as compared with the case where the cooler 5 is provided with a plurality of sets each including the evaporator 9b and the heater 10 for each heat pipe 9,
The structure of the heat pipe is greatly simplified.

[0021]

As described above, according to the structure of the present invention, as the defrosting means of the cooler mounted on the showcase,
By incorporating a loop-shaped heat pipe into the cooler, compared to a conventional defrosting heat pipe in which the condensation part and the evaporation part are connected to a single pipe, the working fluid vapor The liquid flow and the liquid flow intersect in opposite directions in one pipe to suppress the interference that interferes with each other to significantly improve the heat transfer amount of the heat pipe. This greatly contributes to shortening the frost time and maintaining the quality of displayed products such as meat and fresh fish.

Further, according to the structure of claim 2, the structure of the heat pipe for defrosting is simplified, and by adopting the structure of claim 3, the heat pipe can be compactly installed within the outer dimensions of the cooler. Further, according to the structure of claim 4, while suppressing the heat loss in the middle of the pipe of the heat pipe, the heat energy input from the evaporating part is effectively transferred to the condensing part to remove the cooler. The frost can be effectively done.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a first embodiment of the present invention, in which (a) is a configuration layout diagram of the entire defrosting apparatus shown together with a cooler, and (b).
Is an enlarged perspective view of the main part structure in FIG.

2A and 2B are configuration diagrams of a second embodiment of the present invention, in which FIG. 2A is a configuration layout diagram of the entire defrosting apparatus shown together with plate fins of a cooler, and FIG. 2B is a main part structure in FIG. Enlarged side view

[Fig. 3] Fig. 3 is a configuration diagram of a third embodiment of the present invention, (a) is a configuration layout diagram of the entire defrosting apparatus represented together with a cooling plate fin, and (b) is a side view of (a) diagram.

FIG. 4 is a schematic diagram of the configuration of an open showcase that is the subject of the present invention.

[Explanation of symbols]

 1 Case body of showcase 3 Inner duct (cold air circulation duct) 5 Fin tube type cooler 5a Refrigerant tube 5b Plate fin 5c Cutout recess 9 Loop heat pipe 9a Condensing part 9b Evaporating part 9c Hydraulic fluid 10 Heater

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display area F28D 15/02 F28D 15/02 R

Claims (4)

[Claims] 1. A freezing and refrigerating show in which a fin tube type cooler of a refrigerator and blower fins are provided in a cool air circulation duct of a case main body, and cool air that has exchanged heat with the cooler is circulated to cool the inside of a refrigerator during a cool keeping operation. In the case, as a defrosting means for the cooler, a loop-shaped heat pipe in which both ends of the condenser are connected to the evaporator is incorporated in the cooler, and the condenser of the heat pipe is arranged higher than the evaporator. A defrosting device for a refrigerating and refrigerating showcase, characterized in that the defrosting device is heat-inserted into a plate fin array of a cooler and a heater is provided in an evaporation portion to operate during defrosting. 2. The defrosting apparatus according to claim 1, wherein the loop-shaped heat pipe is provided with a plurality of condensing sections that are branched in parallel in the loop with a common evaporating section. Case defroster. 3. The defrosting device according to claim 1, wherein the evaporation portion of the loop-shaped heat pipe is housed in a recess formed in the cooler by cutting out a part of the plate fin array. A defrosting device for a freezer refrigerating showcase. 4. The defrosting device according to claim 1, wherein the loop heat pipe pipe excluding the condensing part and the peripheral surface of the evaporating part are covered with a heat insulating material. A defroster for a cooler installed in a freezer refrigeration showcase.