The working principle of refrigeration is that the compressor compresses the lower pressure steam into higher pressure steam,so that the volume of the steam is reduced and the pressure is increased.The compressor sucks the lower-pressure working fluid vapor from the evaporator, raises its pressure,and sends it to the condenser,where it is condensed into a liquid with a higher pressure.After being throttled by a throttle valve,it becomes a lower pressure. After the low liquid, it is sent to the evaporator,where it absorbs heat and evaporates to become a steam with lower pressure,and then it is sent to the inlet of the compressor to complete the refrigeration cycle.