JPS595817B2 - Defrost device - Google Patents

Description

[Detailed Description of the Invention] There are two methods for defrosting a cooler in a refrigeration system: a method called a thermobank type that uses heat storage water, and a method that uses hot gas from a compressor to be directly supplied to the cooler. There is.

In the former thermobank type, the components of the thermobank heat exchanger are tangential to water as the secondary heating medium, so
It has the disadvantage of being easily corroded and having a short product life.

In the latter hot gas direct supply type, the temperature difference between the refrigerant flowing through the cooling coil during defrosting and cooling is large, resulting in large expansion and contraction of the coil, which can cause distortion and sometimes cracks in the coil. It often happens.

The present invention makes it possible to provide a refrigeration system in which the above-mentioned conventional drawbacks are eliminated by supplying a minimum amount of heat of refrigerant necessary for defrosting to the cooler. The present invention will be explained below based on the drawings of the embodiments.

In the figure, reference numeral 1 denotes a compressor, the discharge port of which is connected to the inlet of a shell and tube type heat exchanger 2 through a discharge pipe 16 on the primary side to communicate with the inside of the shell which is the primary flow path 2a. The outlet of the shell is connected to one port a of a four-way switching valve 3, which is a switching valve device, with a discharge pipe 18 on the secondary side.

The four-way switching valve 3 is a freezing valve that switches the liquid supply from port A to port D during freezing and from port A to port C during defrosting).
3a and a defrosting port 3c, and a return port 3b for returning refrigerant vapor from the port C to the port during freezing.

Therefore, the port 3 for freezing in the four-way switching valve 3
The outlet d of a is connected to the condenser 5 via the check valve 4, and the liquid refrigerant from the condenser 5 is supplied to the cooler 8 via the liquid receiver 6, the liquid sending pipe 12, and the expansion valve γ. The refrigerant vapor from the cooler is sucked into the compressor 1 through the refrigerant return pipe 19, the return port 3b of the four-way switching valve 3, the suction pipe 20, and the liquid separator 9.

A branch pipe 13 having a defrosting valve 14 and a pressure reducing valve 17 is connected between the liquid receiver and the expansion valve in the liquid sending pipe 12 to the inlet of the tube 2b which is the secondary flow path of the heat exchanger 2. The outlet of the tube 2b is connected directly to the liquid separator 9 through the suction pipe 15 for defrosting, or through the suction pipe 20 as shown in the figure.
It is connected to.

Although the defrosting valve 14 is closed during freezing operation, it is opened during defrosting operation.

Further, a side passage 11 for defrosting is provided in parallel with the expansion valve 7, and a check valve 10 is provided in this side passage 11 for passing the defrosting refrigerant from the cooler.

Next, the operation of this device will be explained.

Cooling operation (flow indicated by solid line arrow) Gas from the compressor 1 flows through the discharge pipe 16, the shell which is the primary flow path 2a of the shell and tube type heat exchanger 2,
The refrigerant is condensed in the condenser 5 via the discharge pipe 18.4, the refrigerating port 3a of the switching valve 3, and the check valve 4. Kara cooler 8
The refrigerant vapor from the cooler 8 is sucked into the compressor 1 through the boat 3b of the switching valve 3 and the liquid separator 9.

Defrosting Operation (Flow of Broken Arrow) Hot gas from the compressor passes through the heat exchanger 2, reaches the switching valve 3, and is supplied to the cooler 8 through the port 3c, thereby defrosting the cooler.

The defrosted refrigerant passes through a side passage 11 with a check valve 10 that straddles the expansion valve 7 and flows back through the liquid supply pipe 12, but through an open drain in a branch pipe 13 that branches off from this liquid supply pipe. Frost valve 14
(closed during refrigeration operation), enters the tube 2b which is the secondary flow path of the heat exchanger 20, and is sucked into the compressor 1 from the suction pipe 15 for defrosting.

In the refrigeration system of the present invention having the above-described circuit, during defrosting operation, hot gas from the compressor 1 passes through the shell 2a, which is the primary flow path in the heat exchanger 2, and is heated by the same heat. Exchanger 2
The defrosted refrigerant passing through the tube 2b, which is the secondary flow path, removes heat and cools the tube.

Therefore, the saturated refrigerant gas having the minimum amount of heat necessary for defrosting is sent to the cooler, and the expansion of the cooling coil can be reduced, thereby protecting the coil.

The defrosted refrigerant is heated and vaporized by the hot gas while passing through the heat exchanger 2, so that it can be drawn into the compressor without any inconvenience. By providing the valve 17, vaporized low-temperature refrigerant gas can be supplied to the tube 2b of the heat exchanger, thereby making it possible to sufficiently cool the primary side hot gas of the heat exchanger.

Although the switching valve 3 is a four-way valve in Fig. 1, it may be composed of three valves Va, Vb, and Vc as shown in Fig. 2, or it may be composed of three valves Va, Vb, and Vc as shown in Fig. In some cases, Va and Vb are configured with one three-way valve.

[Brief explanation of the drawing]

Fig. 1 is a system diagram of a refrigeration circuit equipped with the device of the present invention;
The figure shows another example of the valve switching device, and FIG. 3 is an enlarged view of a four-way switching valve. In the figure, 1...Compressor, 2...Heat exchanger, Meter...Switching valve device, 4...Check valve, 5
...Condenser, 6...Liquid receiver, 7...
...Expansion valve, 8...Cooler, 9...
Liquid separator, 10... Check valve, 11...
Side channel, 12...Liquid feeding pipe, 13...Branch pipe, 14...Valve for defrosting, 15...
Suction pipe, 16... Discharge pipe, 17... Pressure reducing valve, 18... Discharge pipe, 19... Refrigerant return pipe, 20...・Suction pipe.

Claims (1)

[Claims] 1. A side passage is provided in the liquid sending pipe to the cooler, which has a check valve that straddles the expansion valve and allows the refrigerant to pass only in the opposite direction to that during refrigeration operation, and is closed during refrigeration operation.
A branch pipe with a defrost valve that opens during defrosting operation is provided, and this is connected to the secondary flow path of the heat exchanger, and the outlet of this secondary flow path is connected to the suction to the compressor. and the discharge pipe of the compressor is connected to the primary flow path of the heat exchanger, and its outlet is communicated with the condenser during refrigeration operation,
During defrosting operation, communication between the refrigerant return pipe from the cooler and the suction pipe to the compressor is cut off, and the refrigerant from the primary flow path is supplied to the cooler from the opposite direction to that during freezing operation. A defrosting device connected to a valve device.