JPH0737867B2 - Defroster for dual cryogenic refrigerator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement of a binary refrigerator for cryogenic temperatures of -50 ° C to -60 ° C or less.

(Prior Art) A conventional example of a binary type cryogenic refrigerator is shown in FIG.

This refrigerator has a high temperature part A that uses a high temperature refrigerant having a high critical temperature such as R22 (chemical formula CHClF ₂ ) and R13 (chemical formula CClF 2).
And a low temperature part B using a low temperature refrigerant having a low critical temperature such as F ₃ ).

First, the high temperature portion A will be described. After the high temperature refrigerant is compressed by the high temperature refrigerant side compressor 1, the high temperature refrigerant side oil separator 2 is compressed.
While the oil is separated and collected in this way, it is supplied to the high temperature refrigerant side condenser 3 and liquefied. When the liquefied high-temperature refrigerant is supplied to the high-temperature refrigerant-side expansion valve 5 via the high-temperature refrigerant-side dryer 4, it is depressurized suddenly here and vaporized in the high-temperature refrigerant-side evaporator 6 and then again on the high-temperature refrigerant side. Returned to the compressor 1.

Next, the low temperature section B will be described. After the low temperature refrigerant is compressed by the low temperature refrigerant side compressor 7, the low temperature refrigerant side oil separator 8
At the same time, the oil is separated and collected and is supplied to the low temperature refrigerant side condenser 9 and liquefied. The liquefied refrigerant is supplied to the low-temperature refrigerant-side expansion valve 11 via the low-temperature refrigerant-side dryer 10, vaporized in the low-temperature refrigerant-side evaporator 12, and then returned to the low-temperature refrigerant-side compressor 7 again.

Here, the high temperature refrigerant side evaporator 6 of the high temperature part A and the low temperature refrigerant side condenser 9 of the low temperature part B form a different refrigerant heat exchanger 15, and cool and condense the low temperature refrigerant by latent heat of evaporation of the high temperature refrigerant. To do.

The low temperature refrigerant side evaporator 12 of the low temperature section B is provided in the freezer 14, and thereby cools the air in the freezer.

Reference numeral 13 is a gas storage tank for storing the vaporized refrigerant during operation stoppage to prevent damage to the device and leakage of the refrigerant.

Then, since the moisture of the air in the freezer 14 is frozen to generate frost on the coil surface of the low temperature refrigerant side evaporator 12, it is necessary to remove it.

By the way, in the binary refrigerator, since the critical temperature of the refrigerant of the evaporator 12 to be defrosted is low, the gas pressure of the hot gas system becomes too high and cannot be used. Therefore, conventionally, the frost is melted by heating with an electric heater or sprinkling water.

(Problems to be Solved by the Invention) However, in the case of using a heater or water sprinkling, there is a problem that refrigeration efficiency is lowered and it is difficult to maintain an extremely low temperature because the temperature inside the freezer is increased.

In view of these points, an object of the present invention is to provide a defroster for a binary low-temperature refrigerator that does not reduce refrigeration efficiency.

(Means for Solving the Problems) In order to achieve this object, the present invention is configured as follows.

That is, the present invention, in a binary type cryogenic refrigerator using a high temperature refrigerant having a high critical temperature and a low temperature refrigerant having a low critical temperature, a heat receiver is heat-exchangeably connected to the low temperature refrigerant side evaporator, and the liquefied gas circulation pump is delivered. The side is switchably connected to the inlet of the heat receiver and the inlet of the defrosting re-evaporation coil to supply liquefied gas having a critical temperature higher than that of the low-temperature refrigerant, and the outlet of the heat receiver is The outlet of the evaporation coil is connected to the inlet of the air / liquefied gas heat exchanger, and the outlet of the air / liquefied gas heat exchanger is connected to the suction side of the liquefied gas circulation pump via the liquefied gas receiver. However, a heating means is attached to the defrosting re-evaporation coil.

(Operation) In the present invention thus configured, during the cooling operation, the liquefied gas circulation pump 20 circulates the liquefied gas in the cooling circuit including the heat receiver 22 and the air / liquefied gas heat exchanger 24.

As a result, the liquefied gas cooled in the low-temperature refrigerant side evaporator 12 is guided to the air / liquefied gas heat exchanger 24, where the air in the freezer 26 is cooled by heat exchange by sensible heat.

On the other hand, during the defrosting operation, the liquefied gas circulation pump 20 supplies the liquefied gas to the defrosting evaporation coil 29 and the air / liquefied gas heat exchanger 24.
Circulating the defrost circuit consisting of.

As a result, the liquefied gas is heated by the re-evaporation coil for defrosting.
It vaporizes in 29 and its hot gas is guided to the air / liquefied gas heat exchanger 24 to condense and remove frost.

(Example) FIG. 1 is a piping diagram of an example of the present invention.

This embodiment is obtained by adding a novel constituent part according to the present invention to the conventional example shown in FIG. Therefore, the same parts as those in FIG. 2 are designated by the same reference numerals and the description thereof will be omitted.

In FIG. 1, 20 is a liquefied gas circulation pump, 21 is a cooling solenoid valve, 22 is a heat receiver for exchanging heat with the low temperature refrigerant side evaporator 12 of the low temperature part B, and these evaporators 12 and 22 The heat exchanger 23 is configured.

If a double pipe is used to increase the heat exchange efficiency, the inner pipe is the low-temperature refrigerant side evaporator 12, and the outer portion of the double pipe is the heat receiver 22, heat can be efficiently exchanged through the pipe wall. Two
Instead of the heavy pipe, a structure in which two or more thin pipes are inserted into a large diameter pipe may be used. Also in that case, the low-temperature refrigerant is caused to flow through the thin tube. The outer periphery of the heat exchanger 23 is covered with a heat insulating material to block the outside air.

24 is an air / liquefied gas heat exchanger, and 25 is a liquefied gas receiver.

Then, these components are sequentially piped to form a cooling circuit, and the air / liquefied gas heat exchanger 24 is connected to the freezer 26.
Place it inside.

Reference numeral 27 is a defrosting solenoid valve, 28 is a one-way valve, 29 is a defrosting re-evaporation coil buried in the heat storage tank 30, and 31 is a one-way valve, which are sequentially connected in series. Then, those connected in series are connected in parallel between the delivery side of the liquefied gas circulation pump 20 and the inlet side of the air / liquefied gas heat exchanger 23, thereby forming a defrosting circuit.

Then, the cooling circuit and the defrosting circuit are filled with the same liquefied gas R22 as the high-temperature refrigerant of the binary cooler.

Further, at the bottom of the heat storage tank 30, the heat storage tank heating coil 32
The heat storage tank heating coil 32 is interposed between the high temperature refrigerant side oil separator 2 and the high temperature refrigerant side condenser 3 of the high temperature section A. Thus, the heat storage tank 30 is heated by utilizing a part of the heat of condensation of the high temperature refrigerant. The means for heating the heat storage tank 30 may use an electric heater or the like instead of the coil 32.

Next, the cooling operation operation of the embodiment of the present invention thus configured will be described.

During the cooling operation, the high temperature refrigerant side compressor 1 in the high temperature portion A,
And the low temperature refrigerant side compressor 7 of the low temperature part B is operated, respectively. Also, the cooling solenoid valve 21 is opened, the defrosting solenoid valve 27 is closed, and the liquefied gas circulation pump 20 is operated.

As a result, the liquefied gas in the liquefied gas receiver 25 is pumped.
20, solenoid valve 21, heat receiver 22, heat exchanger 24, and liquid receiver 25
The cooling circuit is circulated in this order.

Therefore, this liquefied gas is the heat receiver that constitutes the heat exchanger 23.
After being cooled to -60 ° C or less at 22, heat is exchanged with air in the air / liquefied gas heat exchanger 24 to cool the inside of the freezer 26. Since this cooling is performed by the sensible heat of the liquefied gas, the liquefied gas does not evaporate.

During this cooling operation period, the high temperature refrigerant side compressor 1 in the high temperature portion A is
When the refrigerant compressed by is condensed in the heat storage tank heating coil 32, the heat storage tank 30 is warmed.

Next, the case of the defrosting operation will be described.

During the defrosting operation, the operation of the high temperature refrigerant side compressor 1 in the high temperature portion A and the operation of the low temperature refrigerant side compressor 7 in the low temperature portion B are stopped. Contrary to the case of the cooling operation, the cooling electromagnetic valve 21 is closed and the defrosting electromagnetic valve 27 is opened, and the liquefied gas circulation pump 20 continues to operate.

As a result, the liquefied gas in the liquefied gas receiver 25 is pumped.
The solenoid valve 27, the one-way valve 28, the coil 29, the one-way valve 31, the heat exchanger 24, and the liquid receiver 25 are circulated through the defrosting circuit in this order.

Here, the liquefied gas is heated and vaporized by the heat storage tank 30 when passing through the defrosting re-evaporation coil 29, and this hot gas is condensed and liquefied when passing through the air / liquefied gas heat exchanger 24. Therefore, the condensation heat melts the frost adhering to the surface of the air / liquefied gas heat exchanger 24.

While repeating such a circulation cycle, the temperature of the air / liquefied gas heat exchanger 24 gradually rises, so when the temperature reaches about 20 ° C and defrosting ends, this is detected. Then, the defrosting operation is automatically switched to the cooling operation.

(Effects of the Invention) As described above, in the present invention, the liquid liquefied gas having excellent heat conduction is cooled by the evaporator in the low temperature section, and the cooled liquefied gas is guided to the air / liquefied gas heat exchanger, The air in the freezer is cooled by heat exchange with heat.

Therefore, the present invention has the advantages that the cooling efficiency per unit area in the air / liquefied gas heat exchanger can be improved and that the structure of the heat exchanger can be simple and its mechanical strength can be small.

Further, in the present invention, liquefied gas is supplied to the defrosting re-evaporation coil to be vaporized, and this hot gas is guided to the frosted air / liquefied gas heat exchanger to be condensed and defrosted.

Therefore, in the present invention, since the frosted coil is heated from the inside by the hot gas method, the temperature rise in the freezer is small, and frost can be removed in a short time, and the refrigeration efficiency and the defrosting efficiency are significantly improved. .

(Application example) The present invention can also be applied to a defroster for a refrigerator utilizing the cooling capacity associated with the gasification of liquefied natural gas.

In this case, liquefied natural gas close to −100 ° C. is supplied to the evaporator to be gasified and then sent out. However, since the outside air comes into contact with the evaporator to cause frost, this evaporator is connected to the low temperature refrigerant side of the embodiment. Like the evaporator, the heat exchanger is connected to the heat receiver so that heat can be exchanged, and the air / liquefied gas heat exchanger connected to the heat receiver is used to cool the outside air.

By doing so, at the time of frost formation as in the above embodiment,
Compared to the method in which hot gas is supplied to the air / liquefied gas heat exchanger to defrost it, and the liquefied natural gas evaporator is heated and defrosted from the outside with a heater, etc. can do.

[Brief description of drawings]

FIG. 1 is a piping diagram of an embodiment of the present invention, and FIG. 2 is a piping diagram of a conventional device. A ... high temperature part, B ... low temperature part, 6 ... high temperature refrigerant side evaporator, 9 ...
Low temperature refrigerant side condenser, 12 ... Low temperature refrigerant side evaporator, 20 ... Liquefied gas circulation pump, 21 ... Cooling solenoid valve, 22 ... Heat receiver, 24 ... Air / liquefied gas heat exchanger, 25 ... Liquefied gas receiver , 26 ... Freezer, 27 ... Defrosting solenoid valve, 29 ... Defrosting re-evaporating coil, 30 ...
Heat storage tank.

Claims (1)

[Claims] 1. A binary cryogenic refrigerator using a high-temperature refrigerant having a high critical temperature and a low-temperature refrigerant having a low critical temperature, wherein a heat receiver is connected to a low-temperature refrigerant side evaporator so that heat can be exchanged, and a delivery side of a liquefied gas circulation pump. , Is switchably connected to the inlet of the heat receiver and the inlet of the defrosting re-evaporation coil to supply a liquefied gas having a critical temperature higher than that of the low-temperature refrigerant, and the outlet of the heat receiver is used for defrosting re-evaporation. The outlet of the coil is connected to the inlet of the air / liquefied gas heat exchanger, and the outlet of the air / liquefied gas heat exchanger is connected to the suction side of the liquefied gas circulation pump via the liquefied gas receiver. Therefore, the defrosting device is provided with a heating means attached to the defrosting re-evaporation coil.