Why the expansion valve of the freezer must be after the condenser and before the evaporator?

This is determined by its function. Since the expansion valve is a valve, whether its opening and closing degree and timing are appropriate, and whether the evaporator can complete the evaporation work normally, has a very important and direct connection. If the refrigerator expands The valve is installed before the condenser of the refrigerator, and its function must be to control the size of the condenser’s air supply, but in fact, the condenser does not require a restriction on the size of the gaseous refrigerant supply.

On the other hand, if the expansion valve is installed after the evaporator, its role must be to control the amount of gaseous refrigerant entering the suction end of the compressor. This is also meaningless. In the entire refrigerator cycle system, it is necessary to control the flow of refrigerant. There is only the evaporator. By controlling the amount of liquid supplied to the evaporator, the condenser can work in an “appropriate amount”, which can affect the normal operation of the compressor.

But don’t forget that the expansion valve is not an independent component. It is a “system”, a system placed in the refrigeration system. Its main function is to detect the temperature of the gaseous refrigerant discharged from the evaporator, and then use this data to determine the expansion. The size of the “quantity” of the liquid refrigerant supplied by the valve to the evaporator can be said to be indispensable and the position of each component in the entire refrigerator system is indispensable.