JPH0694314A - Mixed refrigerant refrigerating circuit - Google Patents

Abstract

PURPOSE:To provide a mixed refrigerant refrigerating circuit which can reduce the load of a compressor at the time of start, can prevent an oil from being deteriorated, or prevent the compressor from being worn out by preventing a heating of the compressor from happening, and at the same time, of which the encapsulated refrigerant is less destructive to the ozone layer, for a mixed refrigerant refrigerating circuit to obtain a low temperature. CONSTITUTION:The title mixed refrigerant refrigerating circuit consists of a first refrigerant circuit A for which a compressor 1, condenser 2, flow divider 3, first intermediate heat-exchanger 4, capillary tube 5, and evaporator 6 are connected in order, and a second refrigerant circuit B which is branched from the flow divider 3 and connected to the piping between the evaporator 6 and compressor 1 of the first refrigerant circuit A by a capillary tube 9 and second intermediate heat-exchanger 10. Then, a cascade type heat-exchanger 11 is constituted of the first and second intermediate heat-exchangers 4, 10. At the same time, for a mixed refrigerant refrigerating circuit wherein a non-azeotropic mixed refrigerant is encapsulated in the first and second refrigerant circuit A, B, a solenoid valve 7 and tank 8 are provided between the flow divider 3 and capillary tube 9 of the second refrigerant circuit B.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mixed-refrigerant refrigeration circuit capable of reducing the load at the time of starting.

[0002]

2. Description of the Related Art Conventionally, a mixed refrigerant refrigerating circuit of this kind has been disclosed in Japanese Patent Laid-Open No. 3-88889, so that a compressor, a condenser, a flow divider, a first intermediate heat exchanger, and a pressure reducer. ,
A first refrigerant circuit in which an evaporator is sequentially connected and a branch from the flow divider, and a pipe between the evaporator and the compressor of the first refrigerant circuit via a pressure reducer and a second intermediate heat exchanger. A second refrigerant circuit connected to the first and second intermediate heat exchangers to form a cascade heat exchanger, and a non-azeotropic mixed refrigerant in the first and second refrigerant circuits. It is configured by enclosing it.

In such a circuit, the uncondensed refrigerant divided in the flow divider is evaporated in the cascade heat exchanger so that a lower temperature can be obtained in the evaporator.

Further, R12 (dichlorodifluoromethane) and R500 (an azeotropic mixture of R12 and R152a (1,1-difluoroethane)) are often used as refrigerants in refrigerators. The boiling point of R12 is about -3
At 0 ° C., the boiling point of R500 is about −33 ° C., which is suitable for ordinary refrigeration equipment. Further, even if the suction temperature to the compressor is relatively high, the discharge temperature does not become so high as to cause oil sludge in the compressor. Furthermore, R12 has good compatibility with the oil of the compressor, and also plays a role of returning the oil in the refrigerant circuit to the compressor.

[0005]

However, according to the above construction, the temperature of the evaporator reaches a considerably low temperature of minus several tens of degrees, so that the load of the compressor becomes large, and especially when the compressor is started up. There is a problem that heating causes deterioration of oil and wear due to poor lubrication.

Further, recently, it has become known that so-called specific CFCs may destroy the ozone layer, and their use has been regulated worldwide. Therefore, the above R12
There is an urgent need for research on refrigerants that can substitute for R500 and R500.

The present invention has been made in view of the above problems, and in a mixed refrigerant refrigeration circuit for obtaining a low temperature of minus several tens of degrees, the load of the compressor at the time of starting is reduced to prevent the compressor from being heated. An object of the present invention is to provide a mixed-refrigerant refrigeration circuit in which deterioration and wear of oil are prevented and the enclosed refrigerant hardly destroys the ozone layer.

[0008]

According to the present invention, there is provided a first refrigerant circuit in which a compressor, a condenser, a flow divider, a first intermediate heat exchanger, a pressure reducer and an evaporator are sequentially connected, and the flow divider is used. Branch,
A first refrigerant circuit and a second refrigerant circuit connected to a pipe between the evaporator and the compressor of the first refrigerant circuit via a pressure reducer and a second intermediate heat exchanger, In a mixed refrigerant refrigerating circuit in which a non-azeotropic mixed refrigerant is sealed in the first and second refrigerant circuits, the heat exchanger constitutes a cascade type heat exchanger, and a diverter of the second refrigerant circuit is provided. An on-off valve and a tank are provided between the pressure reducers.

[0009]

According to the mixed refrigerant refrigeration circuit of the present invention, when the compressor is started, if the open / close valve is opened, the tank functions as an expansion tank to lower the equilibrium pressure of the mixed refrigerant refrigeration circuit. Therefore, it is possible to reduce the load on the compressor and prevent the oil from being deteriorated or damaged due to wear. In addition, when the temperature of the cascade heat exchanger decreases after the start, the opening / closing valve is closed to circulate the low boiling point refrigerant in the first refrigerant circuit to obtain a desired evaporation temperature. When the temperature of the cascade heat exchanger rises and reaches a predetermined value, the on-off valve can be opened to introduce the liquid refrigerant into the cascade heat exchanger via the tank and the pressure reducer. The condensing temperature of the mold heat exchanger can be lowered to obtain a lower evaporation temperature.

[0010]

Embodiments Next, embodiments will be described with reference to the drawings. FIG. 1 shows a mixed refrigerant circuit of the present invention.

In this refrigerant circuit, for example, a non-azeotropic mixed refrigerant of difluoromethane (R32) and pentafluoroethane (R125), a non-azeotropic mixed refrigerant of R32, R125 and R134a, and a non-azeotropic mixed refrigerant of R32 and R134a. An azeotropic mixed refrigerant, a non-azeotropic mixed refrigerant of R32, R125 and R123,
Non-azeotropic mixed refrigerant of R32, R134a and R123, R
Non-azeotropic refrigerant mixture of 125 and R123, R32 and R12
3, a non-azeotropic mixed refrigerant of R32 and R124, a non-azeotropic mixed refrigerant of R32, R125 and R124, and a non-azeotropic mixed refrigerant of R125 and R124 are sealed.

Here, the evaporation temperature of R32 is -51.7.
C, the evaporation temperature of R125 is -48.5 ° C.

The circuit includes a first refrigerant circuit A in which a compressor 1, a condenser 2, a flow divider 3, a first intermediate heat exchanger 4, a capillary tube 5 and an evaporator 6 are sequentially connected, and the flow dividing is performed. Branching from the reactor 3 and passing through the solenoid valve 7, the tank 8, the capillary tube 9 and the second intermediate heat exchanger 10
The second refrigerant circuit B connected to the pipe between the evaporator 6 and the compressor 1 of the refrigerant circuit A of the above, and the first and second intermediate heat exchangers 4 and 10 are cascade type heat exchangers. 11 is formed. 1a is an accumulator.

Reference numeral 12 is a temperature sensor provided in the cascade heat exchanger 11. 13 is a temperature control device,
When the cascade heat exchanger 11 receives a signal from the temperature sensor 12 and the temperature exceeds a predetermined temperature, the solenoid valve 7 is opened, and when the temperature falls below the predetermined temperature, the solenoid valve 7 is closed.
That is, as shown in FIG. 2, the temperature control device 13 uses the power source 1
4, a temperature setting thermostat 15 connected in series to the compressor 1, and a solenoid driven thermostat 1 connected in parallel to a series circuit of the temperature setting thermostat 15 and the compressor 1.
6 and a solenoid valve 17, and a temperature sensor 12 connected to the solenoid driving thermostat 16. When the signal from the temperature sensor 12 is less than or equal to a predetermined value, the contact of the solenoid driving thermostat 16 is kept closed, the solenoid of the solenoid valve 7 is de-energized, and the solenoid valve 7 is closed. When the signal from 12 exceeds a predetermined value, the contact of the solenoid driving thermostat 16 is closed, and the solenoid of the solenoid valve 7 is energized to open the solenoid valve 7.

That is, the solenoid valve 7 is opened when the temperature of the cascade heat exchanger 11 becomes higher than the normal temperature of 25 to 30 ° C., and the temperature is at least 10 ° C. or lower, for example, 0.
Set to close at ℃.

Here, the temperature control device 13 includes the evaporator 6
It is set so that the cascade heat exchanger 11 can be maintained in a temperature range where forced cooling is not required as the cooling of the above-mentioned progresses and the heat absorption by the evaporator 6 decreases.

In the mixed-refrigerant refrigeration circuit thus constructed, the high-temperature and high-pressure gaseous refrigerant mixture (mixed refrigerant of R32 and R125) discharged from the compressor 1 flows into the condenser 2 to radiate heat, and then split. Flows into the vessel 3. At this time, when the temperature of the cascade heat exchanger 11 is still low, such as when the compressor is started, the solenoid valve 7 is open without operating, and the liquefied refrigerant (R125) in the flow divider 3 is used. Is introduced into the tank 8. As a result, at the time of starting the compressor 1, the tank 8 functions as an expansion tank, and in the first refrigerant circuit A that is the main refrigerant circuit, only the refrigerant (R32) having a low boiling point circulates, and the equilibrium pressure of the mixed refrigerant refrigeration circuit. It is possible to reduce the load on the compressor and prevent the oil from being deteriorated or damaged due to wear.

After that, when the temperature of the cascade heat exchanger 11 rises to a predetermined value or more, the electromagnetic valve 7 is closed and the liquid refrigerant (R125) stored in the tank 8 is passed through the capillary tube 9. It is introduced into the cascade heat exchanger 11 to further lower the condensation temperature of the cascade heat exchanger 11. As a result, by circulating the refrigerant (R32) having a low boiling point in the first refrigerant circuit A, a desired evaporation temperature can be obtained. Further after this, the cascade heat exchanger 11
When the temperature rises and reaches a predetermined value, the solenoid valve 7 is opened again and the refrigerant in the tank 8 can be introduced into the cascade heat exchanger 11 via the tank 8 and the capillary tube 9. By lowering the condensation temperature of the cascade heat exchanger 11, a lower evaporation temperature can be obtained.

[0019]

As described above, according to the present invention, when the on-off valve is opened at the time of starting the compressor, the tank can function as an expansion tank to reduce the equilibrium pressure of the mixed refrigerant refrigeration circuit. It is possible to reduce the load on the compressor and prevent the oil from being deteriorated or damaged due to wear. When the temperature of the cascade heat exchanger decreases after the start, the on-off valve is closed and the refrigerant having a low boiling point is circulated in the first refrigerant circuit to obtain the desired evaporation temperature. When the temperature of the cascade heat exchanger rises and reaches a predetermined value, the on-off valve can be opened to introduce the liquid refrigerant into the cascade heat exchanger through the tank and the pressure reducer. The condensing temperature of the mold heat exchanger can be lowered to obtain a lower evaporation temperature.

Further, since the liquefied refrigerant is diverted by the second refrigerant circuit, the oil can be diverted together with the liquid refrigerant, and the oil return can be improved.

Further, according to the mixed-refrigerant refrigeration circuit of the present invention, since the refrigerant enclosed in the circuit is out of regulation, it is possible to suppress the destruction of the ozone layer, and to keep the environment favorable and to obtain a desired value. It is possible to provide a mixed-refrigerant refrigeration circuit which has a high refrigerating capacity, has a good oil return, and can be used as a substitute for R500 and R502, and has excellent practicability.

Thus, the mixed refrigerant refrigeration circuit of the present invention is
It is effective for a device that achieves a low temperature of -40 ° C.

[Brief description of drawings]

FIG. 1 is a refrigerant circuit diagram showing a mixed refrigerant refrigeration circuit of the present invention.

FIG. 2 is an electric circuit diagram of a temperature control device.

[Explanation of symbols]

 1 Compressor 2 Condenser 3 Divider 4 First Intermediate Heat Exchanger 5 Capillary Tube 6 Evaporator 7 Solenoid Valve 8 Tank 9 Capillary Tube 10 Second Intermediate Heat Exchanger 11 Cascade Heat Exchanger

Claims (1)

[Claims] 1. A first refrigerant circuit in which a compressor, a condenser, a flow divider, a first intermediate heat exchanger, a pressure reducer, and an evaporator are sequentially connected, and a pressure reducer and a second refrigerant branching from the flow divider. A second refrigerant circuit connected to a pipe between the evaporator and the compressor of the first refrigerant circuit via an intermediate heat exchanger of
In the mixed refrigerant refrigeration circuit in which a non-azeotropic mixed refrigerant is sealed in the first and second refrigerant circuits, the second refrigerant is formed while the cascade type heat exchanger is composed of the second intermediate heat exchanger and the second intermediate heat exchanger. A mixed-refrigerant refrigeration circuit characterized in that an on-off valve and a tank are provided between a shunt and a pressure reducer of the circuit.