Difference between Open and Closed Air Refrigeration System

Open System	Closed System
Air is directly led to the space to be cooled.	Dense air passed through pipes all the time.
Since air is supplied to the refrigerator at atmospheric pressure, the volume of air handled by the compressor is large.	Suction pressure is higher than atmospheric pressure so a smaller volume of air is to be handled by the compressor.
Moisture leads to the formation of frost at the end of expansion thus drier is used.	Pressure ratio can be reduced which results in higher COP.