申論題

The expansion valve is the regular through which the refrigerant passes from the high pressure side of the system to the low pressure side. The pressure drop causes the evaporating temperature of the refrigerant to fall below that of the evaporator. Thus, for example, the refrigerant can be boiled off by an evaporator temperature of -18 ℃ because the pressure drop brings the evaporating temperature of the refrigerant down to say -24℃.