Difference between flooded and dry type evaporator:
The major types of an evaporator are flooded type and dry type.
In a flooded type evaporator, the liquid refrigerant enters the evaporator through a flow‐control device,
which helps keep the liquid refrigerant at a consistent level in the evaporator. The heat exchanger of the
evaporator is immersed in liquid refrigerant. The mixture of liquid and gas contains large quantity of liquid
after evaporating process, so the “wet” vapor shall go through an accumulator before entering the
compressor.
In a dry type evaporator, liquid refrigerant flow into the evaporator is controlled by thermal expansion
valve or solenoid valve directly. The liquid evaporator turns into complete gas while the cooled medium is
flowing outside the exchanger.
Comparison:
1. Heat Ejection Efficiency
The Heat Exchanger of a flooded evaporator is immersed in liquid refrigerant, so it has a high heat ejection
co‐efficient.
The Heat Exchanger of a dry type evaporator is partially immersed in liquid refrigerant, so it has a slightly
lower heat ejection co‐efficient.
2. Refrigerant side resistance
Flooded evaporator is undergoing a higher rate of refrigerant side resistance than dry evaporator
3. Oil returning performance
In cases of miscible refrigeration oil and refrigerant, a flooded evaporator may undergo a situation of
unstable oil returning. And oil returning status has a direct impact on the working status of the
refrigeration unit.
Dry type evaporator has a convenient and stable oil return performance.
4. Refrigerant Charge
A flooded evaporator is filled full with liquid refrigerant, so it will take a much larger refrigerant charge
quantity. They are mostly going with an open type compressor which is more prone to leakage
A dry type evaporator has a refrigerant charge quantity as much as 1/2 – 1/3 of an flooded evaporator.