How Thermostatic Expansion Valve Works?
During the normal working of the refrigeration plant the thermostatic expansion valve remains opened in certain position. When the refrigeration load increases, the temperature inside the evaporator also increases. In such cases there is need of the more refrigerant to take care of the increased load. The increased temperature in the evaporator is sensed by the feeler bulb of the thermostatic expansion valve. This leads to the expansion of the gas in the feeler bulb and also in the power element of the TEV leading to the increase in pressure P1. Due to this the diaphragm of the TEV moves down and tends to open the valve further to increase the flow of the refrigerant to the evaporator. At the same time the pressure P2 below the diaphragm also increases due to superheating of the refrigerant inside the evaporator. This pressure tends to close the valve. There is also spring pressure P3 below the diaphragm that opposes the opening of the valve. If the increase in the refrigeration load i
