We know that the four major components of the industrial water chiller include: compressor, evaporator, condenser and expansion valve. Today, the East Star Xiaobian want to join us to see what the role of thermal expansion valve in industrial chillers.
Thermal expansion valve, which can control the amount of liquid supply of the evaporator, but also throttling saturated liquid refrigerant. According to the structure of thermal expansion valve, divided into two types of internal balance and external balance. Taking into account the refrigerant flows through the evaporator pressure loss, to reduce the opening superheat, improve the utilization rate of the heat transfer area of the evaporator, the general self expanding valve outlet to the outlet of the evaporator, the refrigerant pressure drop evaporation temperature corresponding to the drop of more than 2~3 DEG C, should be used outside the balanced thermal expansion valve.
External balance thermal expansion valve is based on the principle of force balance. When working, the upper part of the elastic metal diaphragm is acted by the pressure P3 of the working medium in the temperature sensing package, and the following is influenced by the pressure of the outlet of the evaporator and the force of the spring force P2 P1. The diaphragm is raised up or down under the action of three forces, so that the valve hole is closed or opened to adjust the amount of liquid supplied by the evaporator. When the amount of fluid into the evaporator, the evaporator heat load is less than, then the evaporator superheat steam export increases, diaphragm at the top of the pressure is greater than the bottom pressure, forcing the diaphragm downward bulge through the mandrel compression spring, and the valve pin to open the top of the valve, Kong Kaida, liquid supply increased. On the contrary when the need for liquid amount is greater than the evaporator heat load, then exit vapor superheat decreases, temperature in the system pressure is reduced, the force force is less than the bottom of the top of the diaphragm, the diaphragm bulge upward, the elongation of the spring, ejector valve on the move and make a small hole off of the evaporator for the liquid volume also be reduced. Overheating of thermal expansion valve is composed of opening superheat and effective superheat. The overheating is related to the pretightening force of the spring, and the effective superheat is related to the strength of the spring and the travel of the valve needle.
From this we know, regardless of which chiller, it needs thermal expansion valve, which can be summarized as follows:
1, expansion valve can play a throttling effect on the water cooler: high temperature and high pressure liquid refrigerant through the expansion valve throttle hole flow, become low temperature, low pressure fog like hydraulic refrigerant, for refrigerant evaporation create conditions
2, expansion valve can control the flow of refrigerant: into the evaporator liquid refrigerant, through the evaporator, refrigerant by liquid evaporation into the gas, absorb heat, reduce the temperature inside the car. Expansion valve controls the flow of refrigerant, ensure the outlet of the evaporator is completely gaseous refrigerant, if the flow is too large, export containing liquid refrigerant enters the compressor may produce liquid hammer; if the refrigerant flow is too small, early evaporation is completed, caused by lack of refrigeration.