The Role of Common Valve Machines in Refrigeration Systems

The Role of Common Valve Machines in Refrigeration Systems

1. The role of the evaporation pressure regulating valve

The evaporating pressure regulating valve is generally used in a refrigeration compressor, which is responsible for both high-temperature cold storage and low-temperature cold storage in a one-machine multi-storage refrigeration system. The evaporating pressure regulating valve is generally installed on the outlet pipe of the evaporator of the high and low temperature cold storage to maintain the stability of the evaporating pressure in the evaporator of different temperatures and working pressures in the system. The evaporating pressure regulating valve is divided into two types: direct acting and control.

2. The function of the condensing pressure regulating valve

When the condensing pressure regulating valve refrigeration system is running, the condensing pressure must be maintained within the normal range. If the condensing pressure is too high, it will cause damage to the refrigeration equipment and increase power consumption. If the condensing pressure is too low, it will cause the liquefaction process of the refrigerant and the work of the expansion valve, so that the refrigeration system cannot work normally, resulting in a significant drop in cooling capacity.

The condensing pressure adjustment of the water-cooled condenser is realized by adjusting the flow of cooling water. According to different working principles, the condensing pressure regulating valve is divided into temperature-controlled water regulating valve and pressure-controlled water regulating valve.

Most of the condensing pressure regulating valves used in small and medium-sized cold storage refrigeration systems are pressure-controlled water volume regulating valves. The pressure-controlled water volume regulating valve directly uses the condensing pressure as the control signal to control the opening of the valve, and its working principle is the same as that of the temperature-controlled water volume regulating valve. Structurally, the pressure-controlled water volume regulating valve also has a direct-acting type.

3. The function of the safety valve

In the refrigeration system of small and medium-sized refrigerators, in order to prevent the high pressure of the refrigeration system from exceeding the limit value and cause the pipeline to burst, it is necessary to install a safety valve on the pipeline of the refrigeration system. In this way, when the high pressure in the system exceeds the limit value, the safety valve is automatically activated to release the refrigerant to the low pressure system or to the atmosphere.

It is mainly composed of valve body, spool adjustment spring, adjustment screw and so on. The inlet end of the safety valve is connected to the high pressure system, and the outlet end is connected to the low pressure system. The working principle of the safety valve is that when the high pressure in the system exceeds the safety limit value, the high pressure gas will automatically open the valve core and discharge into the low pressure system from the outlet. Usually the opening pressure limit of the safety valve is 2.0-2.1MPa for R22 refrigeration system.

4. Function of fusible plug

Fusible plugs are often used in small and medium-sized cold storage refrigeration systems using Freon as the refrigerant to ensure the safety of the high-pressure liquid receiver. A fusible alloy is cast in the fusible plug, and the melting temperature of the fusible alloy is very low, generally below 75°C. The composition of fusible alloy is different, and its melting temperature is also different. Fusible alloy melting temperature parameters When used in a refrigeration system, fusible plugs with different melting temperatures and compositions of fusible alloys can be selected according to the pressure to be controlled in the system.

When the refrigeration system is working, if the pressure in the accumulator suddenly rises, the temperature of the refrigerant in it will also rise accordingly. When the temperature rises to the melting temperature of the fusible alloy, the fusible alloy melts immediately to form a void, and the refrigerant in the liquid receiver is released into the atmosphere, thus protecting the safety of people and equipment. After the fusible plug is melted, the fusible alloy must be recast, and it can be used after leak detection. Generally, replacement is often used in the maintenance process.

5. Check valve

Check valve is also called non-return valve, check valve, one-way valve or check valve. Its function is to ensure the directional flow of the medium in the pipeline without backflow. The check valve is installed on the exhaust pipe of the refrigeration compressor and the outlet pipe of the liquid pump. When installing, pay attention to the direction marked on the valve body to be consistent with the allowable refrigerant flow direction.