JPH0659770U - Multi-source refrigerator - Google Patents

Abstract

(57) [Summary] [Purpose] To be able to perform defrosting efficiently and in a short time. [Structure] A cooler 8 on the low side is provided by a hot gas supply pipe 14 provided with a solenoid valve 13 on the discharge side of the high side compressor 1.
The drain pan temperature raising coil 15a of No. 1 is connected to the heating coil 16 of the cooler 8, and the outlet of the heating coil 16 is connected to the suction side of the high-end compressor 1 via the defrost heat exchanger 18.
The cooling coil 8a of the cooler 8 is provided by the hot gas supply pipe 20 provided with the solenoid valve 19 on the discharge side of the low-pressure compressor 5.
It was connected to the inlet so that the cooler 8 can be defrosted by the hot gas discharged from the compressors 1 and 5 on the low side and the high side.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a multi-source refrigeration system in which a plurality of refrigerators are connected in multiple stages, and more particularly, to a multi-stage refrigeration system improved so as to perform efficient defrosting.

[0002]

[Prior art]

 Recently, the freezing storage temperature of fresh fish such as tuna has been as low as -60 to -70 ° C, and a multi-source freezing device is used to cool the storage of fresh fish to such a low temperature. In this multi-source refrigeration system, the condenser of the high-side refrigerator is cooled by cooling water, and at the same time, the high-side cooling coil is condensed to condense the refrigerant gas discharged from the compressor of the low-side refrigerator. By connecting multiple refrigerators to a refrigerator and connecting them with a heat exchanger, it is possible to cool the heat load of the freezer etc. to a low temperature by the cooler on the low side.

By the way, in such a multi-source refrigeration system, defrosting of the cooler is mainly performed by an electric heater or a water spray defrost, and even when hot gas defrost is used, the low temperature that contributes to the cooling is reduced. Side heat source of the refrigerant only.

[0004]

[Problems to be solved by the device]

 By the way, if defrosting is performed only by the heat source of the low-side refrigerant (CFC 13, CFC 23, or other refrigerant), only the sensible heat of the refrigerant can be used due to the nature of the low-side refrigerant. Particularly in a device using a large-sized cooler, problems such as defrosting failure and long defrosting time occur.

This is because of the following reasons. As shown in FIG. 3, a Mollier diagram in a dual refrigeration system using a low-source side refrigerator and a high-source side refrigerator, the portion of the refrigerant state on the low source side that can be used as a heat source for defrost (shown by a chain line) ) Are portions A to B on the diagram, and it can be seen that only the sensible heat portion of the total heat of condensation of the refrigerant is present. The reason is that, for example, when Freon 23 (R-23) is used as the low temperature side refrigerant, the condensing temperature is −26 ° C., which is lower than the melting temperature of frost, which is 0 ° C., so the points below A in the figure cannot be used. Yes.

Further, even if a design is made to utilize the sensible heat of the refrigerant up to the point A (+ 10 ° C.), the point A may shift to the point F side due to load fluctuations such as frosting. When the temperature is on the negative side, defrost defects are likely to occur.

Further, since only 18% of the condensation heat amount I2 (11 Kcal / kg) is available for the total amount I1 (61 Kcal / kg) of the low side refrigerant condensation heat amount, the defrost time becomes long.

The present invention has been proposed in order to solve the problems of the prior art, and an object thereof is to provide a multi-source refrigeration system capable of performing defrosting efficiently and in a short time. To do.

[0009]

[Means for Solving the Problems]

 In order to achieve this object, the present invention is a multi-source refrigeration system in which a plurality of refrigerators are connected in multiple stages by cascading condensers that form condensers, and a solenoid valve is provided in the middle of the discharge side of the high-side compressor. The hot gas supply pipe provided is connected to the cooler on the lowest source side, and the hot gas discharged from the compressor on the higher source side is used to defrost this cooler.

Further, according to the present invention, the hot gas supply pipe provided with a solenoid valve in the middle of the discharge side of the compressor on the high side is used as a drain pan heating coil of the cooler on the lowest side and a heating coil of this cooler. Connect the outlet of this heating coil through the defrost heat exchanger to the suction side of the compressor on the high side, and the discharge side of the compressor on the lowest side to provide hot gas supply with a solenoid valve in the middle. It is connected to the cooling coil inlet of the cooler by a pipe, and is configured so that defrosting of the cooler can be performed by hot gas discharged from the compressors on the lower and higher sources.

[0011]

[Action]

 When the heat source of the high-side refrigerant is used for defrosting, as shown in the Mollier diagram of FIG. 3, all the heat of condensation from point a to point d can be used. For example, when Freon 502 (R-502) is used as the refrigerant, the refrigerant condensation heat amount I3 of 33 Kcal / kg can be used.

Although the ratio of the refrigerant circulation amount on the low-source side to the high-source side varies depending on the operating state and the size of the cascade condenser, in the state of FIG. 3, the ratio of the refrigerant circulation amount is approximately as follows. . High source side: Low source side = 265: 100 Compared with the case where only the low heat source side refrigerant heat quantity is used, when the high heat source side heat quantity is used for defrost, it is about 7.9 times, Approximately 8. 9 times the amount of heat can be obtained.

[0013]

【Example】

 Hereinafter, specific embodiments of the multi-source refrigeration system according to the present invention will be described in detail with reference to the drawings. An example of a multi-source refrigeration system configured as a dual refrigeration system is shown in the system diagram of FIG. In this figure, the discharge pipe extending from the high-pressure side compressor 1 is connected to a water-cooled condenser 2, and the outlet of this condenser 2 is connected to an evaporation coil 4 a of a cascade condenser 4 via an expansion valve 3. To be done. The outlet of the evaporation coil 4a is connected to the high-pressure compressor 1 by a suction pipe.

Further, the discharge pipe of the low side compressor 5 on the low side is connected to a cascade condenser 4 via an oil separator 6, and the outlet of this condenser 4 is connected to a cooler 8 via an expansion valve 7. It is connected to the cooling coil 8a. The outlet of the cooling coil 8a is connected to the low-grade compressor 5 by a suction pipe via a liquid separator 9 and a suction pressure adjusting valve 10. In addition, 11 and 12 are pressure protection containers.

Next, a connection system for defrost will be described. The discharge port of the high-source compressor 1 is a drain pan installed in the drain pan 15 of the cooler 8 by a high-source hot gas supply pipe 14 provided with a high-source hot gas supply solenoid valve 13 in the middle thereof. It is connected to the heating coil 15a, and the outlet of this coil 15a is connected to the heating coil 16 installed in the cooler 8 so as to surround the cooling coil 8a. The outlet of the heating coil 16 is connected to a defrost air heat exchanger 18 via a refrigerant flow control valve 17. The outlet of the heat exchanger 18 is connected to the suction pipe of the high-pressure compressor 1. The heat exchanger 18 may be configured by another system other than the pneumatic system.

Further, the outlet of the oil separator 6 on the discharge side of the low-source compressor 5 has a low-source hot gas supply pipe 20 provided with a low-source hot gas supply solenoid valve 19 in the middle of the cooling coil 8a. Connected to the entrance.

In the multi-source refrigerating apparatus U1 configured as described above, the gas refrigerant from the high-pressure compressor 1 is condensed by the cooling water in the condenser 2 during the refrigerating operation, and the liquid refrigerant discharged from the condenser 2 is expanded by the expansion valve. It is sent to the coil 4a of the cascade condenser 4 via 3 to be evaporated in the coil 4a. By this evaporation action, the gas refrigerant from the low-pressure compressor 5 is condensed, and the liquefied refrigerant is sent to the cooling coil 8a through the expansion valve 7, so that the refrigerator 8 can reduce the heat load of the freezer warehouse N or the like. Cooling is performed.

On the other hand, at the time of defrost, the hot gas refrigerant exiting the high-pressure compressor 1 enters the drain pan heating coil 15a through the solenoid valve 13 and the hot gas supply pipe 14 as shown by the arrow of the refrigerant flow. After warming the drain pan 15, it is sent to the heating coil 16. As a result, these parts are usually heated from 10 ° C to 15 ° C and defrosted. The refrigerant liquid condensed at the time of defrosting is decompressed by the refrigerant flow rate adjusting valve 17 after leaving the heating coil 16, and is supplied to the defrosting air heat exchanger 18. The refrigerant evaporated and gasified in the heat exchanger 18 is returned to the high-pressure compressor 1 by the suction pipe.

The hot gas refrigerant leaving the low-pressure compressor 5 is sent to the cooling coil 8 a through the solenoid valve 19 and the hot gas supply pipe 20. As a result, the cooling coil 8a portion is warmed up to about 10 ° C. and defrosting is performed. The refrigerant discharged from the cooling coil 8a is returned to the low-grade compressor 5 via the liquid separator 9.

Here, when about 15 minutes are allotted to one defrost cycle, the hot gas refrigerant from the high-pressure compressor 1 is sent to the cooler 8 to defrost for about 10 minutes in the first half. In the latter half of about 5 minutes, the hot gas refrigerant from the low-pressure compressor 5 and the high-pressure compressor 1 are both sent to the cooler 8 to perform defrosting, thereby defrosting the cooler 8 in a short time. It can be done efficiently.

Next, another embodiment shown in FIG. 2 will be described. In this embodiment, the cooler 8 is defrosted only by the hot gas from the high-source compressor 1, and the hot gas supply pipe 20 connecting the low-source compressor 5 and the cooling coil 8a is provided. It is omitted.

It should be noted that the present invention is not limited to the dual refrigeration system, and can be applied to a three-way refrigeration system including a low-grade refrigerator, a medium-grade refrigerator, and a high-grade refrigerator.

[0023]

[Effect of device]

 As described above, according to the present invention, since the heat source of the high-side refrigerant having a high condensation temperature (for example, + 40 ° C) can be used for the defrost, the defrost failure does not occur and the defroster of the cooler can be favorably performed. . In addition, by utilizing the heat quantity of the high-side refrigerant and also using the sensible heat part of the condensation heat quantity of the low-side refrigerant, a larger heat quantity can be secured compared to the conventional method, and the defrost time can be greatly reduced. can do.

[Brief description of drawings]

FIG. 1 is a system diagram showing an embodiment of a multi-source refrigeration system according to the present invention.

FIG. 2 is a system diagram showing a multi-source refrigeration system of another embodiment.

FIG. 3 is a Mollier diagram showing a refrigerant state in the dual refrigeration system.

[Explanation of symbols]

 1 High-source compressor 2 Water-cooled condenser 3, 7 Expansion valve 4 Cascade condenser 4a Evaporation coil 5 Low-source compressor 6 Oil separator 8 Cooler 8a Cooling coil 9 Liquid separator 10 Suction pressure control valve 11, 12 Pressure protection container 13 High-source hot gas supply solenoid valve 14 High-source hot gas supply pipe 15 Drain pan 15a Drain pan temperature-rising coil 16 Heating coil 17 Refrigerant flow rate control valve 18 Defrost air heat exchanger 19 Low-source hot gas supply solenoid valve 20 Low source hot gas supply pipe

Claims (2)

[Scope of utility model registration request] 1. In a multi-source refrigeration system in which a plurality of refrigerators are connected in multiple stages by a cascade condenser forming a condenser, a hot gas supply pipe having a solenoid valve is provided midway on the discharge side of a compressor on the high side. A multi-source refrigeration system characterized in that it is connected to a cooler on the lowest source side, and hot gas discharged from a compressor on the higher source side can perform defrosting on this cooler. 2. In a multi-source refrigeration system in which a plurality of refrigerators are connected in multiple stages by a cascade condenser forming a condenser, a hot gas supply pipe provided with a solenoid valve in the middle of the discharge side of the high-side compressor. Connect the drain pan temperature raising coil of the cooler on the lowest side to the heating coil of this cooler, and connect the outlet of this heating coil to the suction side of the compressor on the higher side via the defrost heat exchanger, The discharge side of the compressor is connected to the cooling coil inlet of the cooler by a hot gas supply pipe equipped with a solenoid valve in the middle, and the cooler is removed by the hot gas discharged from the compressors on the lowest side and the high side. A multi-source refrigeration system characterized by allowing frosting.