JPS6115978B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a refrigeration system that prevents an excessive rise in temperature and pressure within a cooler and sufficiently replenishes refrigerant to an intercooler at the end of a 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. A bypass pipe 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. Since the hot gas is liquefied, the amount of hot gas to the cooler decreases, and the pressure of the discharged gas decreases, which lowers the temperature of the discharged gas, 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 as low as possible, that is, the cooling water temperature 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.

From this point of view, it is conceivable to disconnect the refrigerant flow path between the compressor and the condenser during defrosting operation to prevent discharge gas from the compressor from entering the condenser. However, with this configuration,
The pressure and temperature of the refrigerant in the cooler increase excessively at the end of defrosting operation, and in two-stage compression refrigerators, the amount of refrigerant in the intercooler decreases, making it necessary to replenish the intercooler with refrigerant at the end of defrosting. The need arises.

In view of the above circumstances, an object of the present invention is to effectively and reliably defrost the cooler in a hot gas defrost type refrigeration system, contribute to energy saving, and reduce the pressure inside the cooler at the end of defrosting operation. ,
To provide a refrigeration system in which an excessive rise in temperature is suppressed, and in a two-stage compression refrigerator having an intercooler, there is no need to supply refrigerant to the intercooler at the end of defrosting operation. be.

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.

7 is a three-way solenoid valve as a switching solenoid valve device installed in the discharge gas refrigerant system of the compressor 1, and the discharge gas from the compressor 1 is passed through a pipe 8 and a check valve 9, and is passed through a pipe 10 during refrigeration operation. It is switched to flow into the condenser 2, and to flow into the cooling coil 12 of the cooler 4 through the bypass piping 11 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.

13 is a bleed pipe having a solenoid valve 14;
The bleed pipe 13 is provided between the inlet side of the three-way solenoid valve 7 and the condenser 2 (in the illustrated example, connected to the pipe 10). Reference numeral 15 denotes a sensor that operates to open the electromagnetic valve 14 when the pressure or temperature on the outlet side of the cooler 4 exceeds a set value.

16 is a liquid sending solenoid valve provided in the refrigerant liquid pipe 17 connecting the condenser 2 and the cooling coil 12; 18 is an expansion valve; 19 is a suction pressure regulating valve for the compressor 1; 20 is a suction gas solenoid valve; is a drain pan.

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 16 and the intake gas solenoid valve 20 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 16 and the suction gas solenoid valve 20 are switched.
is closed, so the flow of refrigerant is as shown by the dotted arrow. That is, the discharge gas from the compressor 1 flows from the solenoid valve 7 to the cooling coil 12 of the cooler 4 through the bypass pipe 11. cooling coil 1
The refrigerant exiting the refrigerant 2 is introduced into the heat exchanger 6 through the suction pressure regulating valve 19, and returns to the compressor 1 where it is vaporized by heat exchange with water stored in the heat exchanger.

At least in the first half of the defrosting operation, the pressure and temperature of the refrigerant flowing out from the cooling coil 12 are low, so the sensor 15 does not operate and the solenoid valve 14 remains closed, so the condenser 2 receives discharged gas. is not introduced, and even if the cooling water 3 continues to be supplied to the condenser 2, the temperature and pressure of the discharged gas will not drop, and defrosting will be performed effectively and reliably.

At the end of the defrosting operation, when the pressure and temperature of the refrigerant flowing out from the cooling coil 12 rise and exceed the set value of the sensor 15, the solenoid valve 14 opens and a part of the gas discharged from the compressor 1 is condensed through the bleed pipe 13. It is introduced into the vessel 2, and the rise in pressure and temperature is alleviated.

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 22. The intercooler 22
During defrosting operation, a part of the refrigerant liquid flowing out from the condenser 2 is guided through the electromagnetic valve 23 to the expansion valve 24, where it is vaporized to cool the refrigerant introduced into the cooler 4, and the refrigerant is introduced into the intercooler 22. The refrigerant gas flowing out is introduced into the high-stage compression section of the compressor 1 through the pipe 25.

In this embodiment as well, effects similar to those described above can be achieved. Furthermore, by providing the bleed pipe 13, a part of the discharged gas flows into the condenser 2 and is condensed at the end of the defrosting operation.
This makes it possible to replenish the refrigerant flowing to the compressor 1, and prevent the temperature of the high-stage suction gas from increasing through the pipe 25 to the compressor 1.

As described above, the refrigeration system of the present invention includes a switching solenoid valve device in the compressor discharge gas refrigerant system so that the discharge gas flows to the condenser during refrigerant operation and flows to the cooler side during defrosting operation. In addition, a bleed pipe with a solenoid valve that guides a portion of the discharged gas to the condenser when the cooler pressure and temperature rise at the end of defrosting operation is installed, so even when the cooling water temperature is low, such as during the cold season, the bleed pipe can be removed. It is possible to perform frosting effectively and reliably.

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 sometimes be passed through the condenser, the condensation temperature is lowered, the refrigeration system is operated at high operating efficiency, and energy savings are achieved. Further, an expensive water control valve is not required, and problems with its failure do not occur. In addition, excessive rise in temperature and pressure inside the cooler at the end of defrosting operation is prevented, and the safety of component equipment is not compromised. The refrigerant is refilled into the reactor, and the problem of excessive temperature rise in the high-stage intake gas is also resolved. Note that the present invention can also be applied to an air-cooled condensing type refrigeration system.

[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, 13
... Bleed pipe, 14 ... Solenoid valve, 15 ... Sensor.

Claims (1)

[Claims] 1. In a single-stage compression refrigerator or a two-stage compression refrigerator in which an intercooler is interposed between the condenser and the cooler, the discharge gas is passed through the refrigerant system of each compressor to the condenser during refrigeration operation, A switching solenoid valve device that switches the flow to the cooler during defrosting operation is installed in the bypass piping for defrosting, and a switching solenoid valve device is installed on the outlet side of the cooler between the inlet side of the switching solenoid valve device and the condenser. It is characterized by having a solenoid valve that is opened by a signal from a sensor provided when the pressure or temperature inside the cooler exceeds a set value, and further comprising a bleed pipe that straddles the switching solenoid valve. Refrigeration equipment.