JPS5852147B2 - Two-stage compression refrigeration equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a two-stage compression refrigeration system equipped with a defrosting circuit.

First, a conventional two-stage compression refrigeration system will be explained with reference to FIG.

In the figure, 1 is a two-stage compression device equipped with a low-stage compressor 2 and a high-stage compressor 3, 4 is a condenser whose one end is connected to the discharge side of the high-stage compressor 3, and 5 is one end. A liquid reservoir 6 is connected to the other end of the condenser 4, and 6 is an intercooler, and one end of the cooling part is connected to the other end of the liquid reservoir 5 through a throttle device 7 of the intermediate circuit and an on-off valve 8 of the intermediate circuit. One end is connected to the suction side of the high-stage compressor 3, and one end of the cooled part is connected to the other end of the liquid reservoir 5 via an on-off valve 9 of the cooling circuit.

10 is a cooling circuit throttle device whose one end is connected to the other end of the cooled part of the intercooler 6; 11 is a cooler whose one end is connected to the other end of the cooling circuit throttle device 10; and 12 is a cooling circuit whose one end is connected to the other end of the cooling circuit. At the other end of the container 11, there is an accumulator whose other end is connected to the suction side of the low-stage compressor 2, 13 is an on-off valve of a defrosting circuit whose one end is connected to the discharge side of the high-stage compressor 3, and 14. 15 is a drain pan coil with one end connected to the other end of the defrosting circuit on-off valve 13 and the other end connected to one end of the cooler 11; 15 is a drain pan provided below the cooler 11 and equipped with the drain pan coil 14; 16 1 is a drain outlet of the drain pan 15, 17 is a condenser blower, and 18 is a cooler blower.

Reference numeral 100 denotes a cooling circuit, from the discharge side of the high-stage compressor 3 to a condenser 4, a liquid reservoir 5, a cooling circuit opening/closing valve 9, an intercooler 6, a cooling circuit throttling device 10, and a cooler 11. and a circuit that connects to the suction side of the low-stage compressor 2 via the accumulator 12.

Reference numeral 200 denotes an intermediate circuit, which branches off from the outlet side of the liquid reservoir 5 of the cooling circuit 100 and passes through the intermediate circuit on-off valve 8, the intermediate circuit throttling device 7, and the intercooler 6 to supply the suction to the high-stage compressor 3. It consists of a circuit that goes to the side.

300 is a defrosting circuit, which runs from the discharge side of the high-stage compressor 3 to the suction side of the low-stage compressor 2 via the defrosting circuit's on-off valve 13, drain pan coil 14, cooler 11, and assane muller 12. It is made up of circuits.

In the device configured in this way, during cooling operation, the cooling circuit on-off valve 9 and the intermediate circuit on-off valve 8 are opened, the defrosting circuit on-off valve 13 is closed, and the cooling circuit 100 and the intermediate circuit 200 are connected. supply refrigerant to.

That is, the refrigerant is circulated as shown by the solid line arrows in FIG.

Then, during defrosting operation, the on-off valve 9 of the cooling circuit is closed,
The defrosting circuit on-off valve 13 and the intermediate circuit on-off valve 8 are opened to supply refrigerant to the defrosting circuit 300 and the intermediate circuit 200.

That is, the refrigerant is circulated as indicated by the broken line arrows in FIG.

In this way, during normal cooling operation and defrosting operation, the refrigerant is also circulated in the intermediate circuit 200 to prevent the temperature of the refrigerant gas discharged from the high-stage compressor 3, the motor temperature, the oil temperature, etc. from rising. being done.

However, during defrosting operation, since the amount of refrigerant gas supplied to the condenser 4 is small, the condensing capacity of the condenser 4 becomes more than necessary relative to the amount of refrigerant gas. In the condensing device, the amount of refrigerant increases significantly when the outside temperature is low, so a large amount of refrigerant liquid accumulates in the liquid reservoir 5, and the amount of refrigerant circulating through the defrosting circuit 300 becomes insufficient, causing the cooling The amount of heating at 11 is reduced.

Therefore, the defrosting ability is extremely reduced, and the operating efficiency is deteriorated, such as requiring long hours of operation for defrosting.

Since the refrigerant liquid is accumulated in the liquid reservoir 5 one after another, the amount of refrigerant circulated through the intermediate circuit 200 during the defrosting operation also becomes insufficient.

Therefore, the discharge refrigerant gas temperature, motor temperature, oil temperature, etc. of the high-stage compressor 3 are increased, and various protection devices installed in the refrigerant circuit are activated to stop the defrosting operation, resulting in stable defrosting. There were drawbacks such as the inability to drive.

In addition, since the refrigerant gas discharged from the high-stage compressor 3 is supplied to the cooler 11 after heating the drain pan coil 14, the heating power in the cooler 11 is weak, and defrosting takes a long time. There is a drawback that frost operation is required, and if the heating order is reversed and the cooler 11 is heated first, the drain pan coil 14
There were disadvantages such as the heating power in the drain pan 15 becoming weaker and the drain falling into the drain pan 15 freezing and becoming impossible to drain.

This invention was made to eliminate the above-mentioned drawbacks, and during defrosting operation, without supplying refrigerant to the condenser, the defrosting circuit and the auxiliary heat exchanger are connected to the defrosting circuit, which is branched from the defrosting circuit. The refrigerant is supplied to the circuit that passes through the refrigerant and reaches the suction side of the high-stage compressor.

An embodiment of the present invention will be described below with reference to FIG.

In the figure, parts with the same reference numerals as in Figure 1 are numbered 1.
The part is the same as or corresponds to the figure.

Reference numeral 19 denotes a three-way valve which is an open-circuit switching device, and is provided at a branch part of a circuit that connects the discharge side of the high-stage compressor 3 to the condenser 4 and the cooler 11, respectively. It is configured to close the circuit.

20 is a drain pan coil which is an auxiliary heat exchanger,
One end is connected to a circuit connecting the three-way valve 19 and the cooler 11.

Reference numeral 21 is a throttle device having one end connected to the other end of the drain pan coil 20 and the other end connected to the suction side of the high stage compressor 3.

100 is a three-way valve 1 from the discharge side of the high-stage compressor 3.
9 and the condenser 4, etc., to the suction side of the low-stage compressor 2; 200, the intermediate circuit; A defrosting circuit 400 that connects to the suction side of the stage side compressor 2 branches from between the three-way valve 19 of the defrosting circuit 300 and the cooler 11, passes through the drain pan coil 20 and the throttling device 21, and then connects to the high stage compressor 3. This is an intermediate circuit for defrosting that leads to the suction side of the

Note that explanations of other parts will be omitted.

Next, the effect will be explained.

During cooling operation, the three-way valve 19 is controlled to close the cooling circuit 100.
side, and at the same time open the cooling circuit on-off valve 9 and the intermediate circuit on-off valve 8 to open the cooling circuit 100 and the intermediate circuit 200.
and supply refrigerant.

That is, the refrigerant is circulated as indicated by the solid line arrows in FIG.

Therefore, the refrigerant gas discharged from the discharge side of the high-stage compressor 3 is condensed in the condenser 4 and becomes a refrigerant liquid, which is accumulated in the liquid reservoir 5.

The water is then divided into the cooling circuit 100 and the intermediate circuit 200.

The refrigerant liquid flowing through the cooling circuit 100 is supercooled in the intercooler 6, and is depressurized in the cooling circuit throttling device 10.
The object to be cooled is cooled and evaporated in step 1, and
The air is drawn into the suction side of the low-stage compressor 2 and compressed.

On the other hand, the refrigerant liquid flowing through the intermediate circuit 200 is depressurized by the throttle device 7 of the intermediate circuit, and is evaporated by exchanging heat with the refrigerant liquid flowing through the cooling circuit 100 in the intercooler 6, and is then evaporated on the suction side of the high-stage compressor 3. This prevents increases in the temperature of the refrigerant gas discharged from the high-stage compressor 3, the motor temperature, the oil temperature, etc.

During defrosting operation, the three-way valve 19 is controlled to open the defrosting circuit 300 side, and at the same time, the cooling circuit on-off valve 9 and the intermediate circuit on-off valve 8 are closed, so that the defrosting circuit 300 and the defrosting circuit 300 are closed. Refrigerant is supplied to the frost intermediate circuit 400.

That is, the refrigerant is circulated as indicated by the broken line arrow in FIG.

Therefore, the refrigerant gas discharged from the discharge side of the high-stage compressor 3 is divided into the defrosting circuit 300 and the intermediate circuit 400 for defrosting.

The refrigerant gas flowing through the defrosting circuit 300 heats the cooler 11 to defrost it, passes through the accumulator 12, is sucked into the suction side of the low-stage compressor 2, and is compressed.

On the other hand, the refrigerant gas flowing through the intermediate circuit 400 for defrosting heats the drain pan 15 with the drain pan coil 20, and part of it becomes a refrigerant liquid, which is reduced in pressure by the expansion device 21 and evaporated, and is then evaporated on the suction side of the high-stage compressor 3. This prevents increases in the discharge gas temperature, motor temperature, oil temperature, etc. of the high-stage compressor 3.

In this way, in the embodiment described above (9), an intermediate circuit 400 for defrosting is provided which branches from the defrosting circuit 300 and reaches the low pressure side of the high-stage compressor 3 via the drain pan coil 20, and during defrosting operation, Since refrigerant gas is supplied to each of the defrosting circuit 300 and the defrosting intermediate circuit 400,
The cooler 11 is heated and defrosted by the refrigerant gas flowing through the defrosting circuit 300, and the drain pan coil 20 is heated by the refrigerant gas flowing through the intermediate circuit 400 for defrosting.

Therefore, the heating power of the cooler 11 and the drain pan coil 20 can be ensured, the cooler 11 can be defrosted in a relatively short time, and the drain pan 15 does not freeze.

In the above embodiment, an air-cooled condensing device using the condenser blower 17 was described as the condensing device, but other types of condensing devices such as a water-cooling condensing device may be used.

As described above, according to the present invention, the cooling circuit, the defrosting circuit, and the intermediate circuit for defrosting are provided, and during the defrosting operation, the defrosting circuit and the intermediate circuit for defrosting are provided without supplying refrigerant to the cooling circuit. Since the refrigerant is supplied to the intermediate circuit, refrigerant liquid does not accumulate in the liquid reservoir during defrosting operation.

Therefore, the amount of refrigerant circulated through the defrosting circuit can be maintained appropriately, and defrosting performance can be maintained without deterioration and defrosting operation with high operational efficiency can be performed.

Since refrigerant is supplied to the high-stage compressor via the auxiliary heat exchanger in the intermediate circuit for defrosting, increases in the discharge gas temperature, motor temperature, oil temperature, etc. of the high-stage compressor are prevented. This allows for stable defrosting operation and other effects.

[Brief explanation of drawings]

FIG. 1 is a refrigerant circuit diagram showing a conventional two-stage compression refrigeration system, and FIG. 2 is a refrigerant circuit diagram of a two-stage compression refrigeration system showing an embodiment of the present invention. In the figure, 1 is a two-stage compression device, 4 is a condenser, 11 is a cooler,
14, 20 are drain pan coils, 19 is a three-way valve, 100
300 is a cooling circuit, 300 is a defrosting circuit, and 400 is an intermediate circuit for defrosting. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A two-stage compression device having a low-stage compressor and a high-stage compressor, a circuit switching device that switches and controls a refrigerant circuit between a cooling operation circuit and a defrosting operation circuit, a condenser, and a liquid compressor. A cooling circuit in which a reservoir, a throttling device, and a cooler are connected in sequence; a defrosting circuit in which the two-stage compression device, the circuit switching device, and the cooler are connected in sequence; and the circuit switching of the defrosting circuit. An intermediate circuit for defrosting is provided, which branches off between the device and the cooler, passes through an auxiliary heat exchanger, and reaches the suction side of the high-stage compressor, and during defrosting operation, the circuit switching device is switched on. A two-stage compression refrigeration system, characterized in that the refrigerant is supplied to the defrosting circuit and the defrosting intermediate circuit through switching control. 2. The two-stage compression refrigeration system according to claim 1, wherein the auxiliary heat exchanger is a drain pan coil provided below the cooler.