refrigerant velocity

[PaulLag]

Hi there

hope everybody is fine !
Please, I am facing to following question.
Can anybody help me in order to determine which is the minimum refrigerant velocity we need to have in an heat exchanger in order to allow oil return to compressor ?
I am referring specifically to an evaporator.

I assume this will be function of evaporating temperature.

Please, can anybody give me an hint or suggest me some specific literature ?
thanks in advance !

 

[berkshire]

The problem as a general rule is not in the evaporator coil/coils, they should be designed to allow the oil to drain by gravity to the suction tube.
However the suction line itself should be designed to get the oil from the evaporator to the compressor without slugging the oil. Suggested gas velocities are in the 500fpm range for horizontal lines, and in the 1500 fpm range for vertical up lines.
B.E.

You are judged not by what you know, but by what you can do.