JPS6152904B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hot gas defrost type refrigeration system, and particularly to a configuration for effectively performing defrosting operation.

Conventional hot gas defrost refrigeration equipment uses piping from the compressor to the condenser and the cooling coil of the cooler to directly supply the hot gas discharged from the compressor to the cooling coil of the cooler during defrosting operation. Bypass piping is provided with a solenoid valve connecting the. However, according to this conventional configuration, when defrosting operation is performed when the temperature of the cooling water supplied to the condenser is low, such as during a cold season, a portion of the gas discharged from the compressor also flows to the condenser and is condensed. To liquefy,
As the amount of hot gas to the cooler decreases and the pressure of the discharged gas decreases, the temperature of the discharged gas decreases, causing insufficient heating of the cooler and incomplete defrosting. To prevent this, conventionally, during defrosting operation, the supply of cooling water to the condenser is often stopped, or the cooling water temperature is often adjusted so that the cooling water temperature does not become too low.

However, from the viewpoint of energy saving, during refrigeration operation, the pressure of the discharged gas should be kept as low as possible, that is, the temperature of the cooling water should be kept as low as possible.

Further, when defrosting operation is performed while adjusting the cooling water temperature, there are problems such as failure of the water control valve for adjusting the water control valve and increase in price.

In addition, conventional refrigerators have the disadvantage that the suction gas pressure of the compressor decreases at the beginning of defrosting operation, causing the compressor to temporarily stop, resulting in a low pressure cut and prolonging the defrosting operation time. be.

In view of the above-mentioned circumstances, it is an object of the present invention to effectively and reliably defrost a hot gas defrost type refrigeration system, prevent the occurrence of low cuts at the initial stage of defrosting operation, and shorten the defrosting time. The purpose of the present invention is to provide a refrigeration system having the following configurations.

The details of the present invention will be explained below with reference to embodiments shown in the drawings. Figure 1 shows an embodiment in which the present invention is applied to a single-stage compression type refrigerator, where 1 is a compressor, 2 is a condenser that condenses the gas discharged from the compressor 1 using cooling water 3, and 4 is a cooling device. 5 is a fan for circulating cold air, 6
is a heat exchanger that vaporizes the refrigerant liquid flowing out from the cooler 4 during defrosting operation.

Reference numeral 7 designates a three-way solenoid valve as a switching solenoid valve device installed in the discharge gas refrigerant system of the compressor 1, which controls the gas discharged from the compressor 1 through the discharge pipe 8 and the check valve 9 during refrigeration operation. It flows into the condenser 2 through the piping 10, and is switched so that it flows through the bypass piping 11 to the cooling coil 20 of the cooler 4 during defrosting operation. Instead of this three-way solenoid valve 7, for example, two two-way solenoid valves or the like can be used as the switching solenoid valve device.

12 is a low pressure compensation pipe that connects the refrigerant liquid pipe 13 between the condenser 2 and the cooling coil 20 of the cooler 4 and the inlet side pipe 14 of the heat exchanger 6; 15 is provided in the low pressure compensation pipe 12; The solenoid valve 15 opens when a low pressure detector 17 that detects a decrease in the pressure or temperature of the suction gas in the suction gas pipe 16 of the compressor 1 is activated.

18 is a bleed pipe connecting between the inlet side of the three-way solenoid valve 7 and the condenser 2; 19 is the bleed pipe 18;
This is a solenoid valve provided in the cooler 4.
The sensor 21 is activated when the refrigerant pressure or temperature on the outlet side of the cooling coil 20 exceeds a set value.

22 is a liquid sending electromagnetic valve provided in the refrigerant liquid pipe 13, 23 is an expansion valve, 24 is a drain pan of the cooler,
25 is a suction gas solenoid valve, and 26 is a suction pressure adjustment valve that adjusts the suction pressure of the compressor during defrosting operation.

In this refrigeration system, during refrigeration operation, the three-way solenoid valve 7 is in a switching position that communicates the pipe 8 and the pipe 10, and the liquid feeding solenoid valve 22 and the intake gas solenoid valve 25 are opened. Therefore, during refrigeration operation, the refrigerant flow is as shown by the solid arrow, and the flow of the refrigerant is as shown by the solid line arrow.
The gas discharged from the condenser 2 is led to the condenser 2 through a pipe 8, a check valve 9, a three-way solenoid valve 7, and a pipe 10.

On the other hand, during defrosting operation, the three-way solenoid valve 7 is switched, and the liquid feeding solenoid valve 22 and the suction gas solenoid valve 25 are switched.
is closed, so the flow of refrigerant is as shown by the dashed arrow. That is, the discharge gas from the compressor 1 is
It flows from the three-way solenoid valve 7 through the bypass pipe 11 to the cooling coil 20 of the cooler 4. cooling coil 2
The refrigerant that has exited the air is introduced into the heat exchanger 6 through the suction pressure regulating valve 26, where it is vaporized by heat exchange with water stored in the heat exchanger and returned to the compressor 1.

At the beginning of this defrosting operation, the amount of heat exchanged in the discharged gas in the cooling coil 20 is large. Therefore, in the conventional system, the temperature and pressure of the refrigerant flowing out from the cooling coil 20 are small, and the compressor will stop for small loads. This is a so-called low pressure cut.

However, in this embodiment, the low pressure detector 17 detects the suction gas pressure to the compressor 1 and the solenoid valve 15
In order to open the refrigerant, the refrigerant liquid stored in the condenser 2 is introduced into the heat exchanger 6 through the low pressure compensation piping 12 and the piping 14, where it is vaporized.
The suction gas pressure increases, and low pressure cut of the compressor at the initial stage of defrosting operation is prevented. In addition, since the discharge gas of the compressor 1 is not introduced into the condenser 2, even if cooling water is kept being supplied to the condenser 2, the temperature and pressure of the discharge gas will not decrease, and defrosting will not occur. be carried out effectively and reliably.

Furthermore, in this embodiment, when the pressure and temperature of the cooling coil 20 rise at the end of the defrosting operation, the sensor 21 is activated to open the solenoid valve 19, and a part of the gas discharged from the compressor 1 is passed through the bleed pipe 18. Since it is introduced into the condenser 2, excessive increases in cooler pressure and temperature are prevented and safety is ensured.

FIG. 2 shows another embodiment of the present invention, in which the present invention is applied to a two-stage compression refrigerator having an intercooler 28.

The intercooler 28 is connected to the condenser 2 during refrigeration operation.
A part of the refrigerant liquid flowing out from the intercooler 28 is guided through the electromagnetic valve 29 to the expansion valve 30 and vaporized there to cool the refrigerant introduced into the cooler 4. It is introduced into the high-stage compression section of the compressor 1.

In this embodiment as well, the same effects as described above can be achieved. Furthermore, by providing the bleed pipe 18, a part of the discharged gas bleeds into the condenser 2 and condenses at the end of the defrosting operation, so it becomes possible to replenish the refrigerant flowing to the intercooler, and the refrigerant flows to the compressor 1. This can prevent the temperature of the high-stage intake gas from increasing through the pipe 31.

In the above embodiments, the solenoid valve 15 is opened by the output of the low pressure detector 17, but in a refrigeration system equipped with a liquid receiver, the refrigerant liquid in the liquid receiver is introduced into the heat exchanger 6. This may be done to prevent low pressure cuts.

As described above, the refrigeration system of the present invention is provided with a switching solenoid valve device so that the discharge gas of the compressor flows to the condenser during refrigeration operation and to the cooler side during defrosting operation, and also includes A low-pressure compensating pipe with a solenoid valve connecting the liquid outlet side of the liquid container and the inlet side of the cooler defrosting heat exchanger is provided, as well as a low-pressure detector for the compressor intake gas that operates the solenoid valve. Regardless of the pressure inside the condenser, all the hot gas from the compressor is supplied to the cooling coil, which shortens the defrosting time. Since refrigerant liquid is supplied from the compressor and the pressure is kept constant, low cut of the compressor is prevented. Even when the cooling water temperature is low, such as during the cold season, defrosting can be performed effectively, reliably, and quickly. In addition, when performing defrosting operation during the cold season, there is no need to adjust the cooling water temperature to a high temperature, and defrosting can be performed while low-temperature cooling water is flowing through the condenser. Since cooling water at a low temperature can be passed through the condenser during operation, the condensation temperature is lowered, the refrigeration system is operated with high operating efficiency, and energy savings are achieved. Also, there is no need for expensive water control valves.
There is no problem of its failure.

[Brief explanation of the drawing]

FIG. 1 is a refrigeration cycle diagram showing one embodiment of the invention, and FIG. 2 is a refrigeration cycle diagram showing another embodiment of the invention. In the figure, 1... Compressor, 2... Condenser, 4... Cooler, 6... Heat exchanger, 7... Three-way solenoid valve, 12
...Low pressure compensation piping, 15 ... Solenoid valve, 17 ... Low pressure detector, 18 ... Bleed pipe, 19 ... Solenoid valve, 21 ... Sensor.

Claims (1)

[Claims] 1. A switching solenoid valve device that allows the discharge gas of the compressor to flow to the condenser during refrigeration operation and to the cooler during defrosting operation, and the liquid outlet side of the condenser or liquid receiver and the cooler during defrosting operation. A low pressure compensation pipe having a solenoid valve connected to the inlet side of a heat exchanger that vaporizes refrigerant liquid flowing out from the low pressure compensation pipe, and a pressure detector that opens the solenoid valve of the low pressure compensation pipe when the compressor suction pressure decreases. , and a bleed pipe having a solenoid valve that is opened when the pressure or temperature on the outlet side of the cooler rises above a preset value is provided between the inlet side of the switching solenoid valve device and the condenser. A refrigeration device characterized by: