Hello All,

Not been on this forum for a while as have been working on other things.
I'm building a small water-to-water heat pump which uses a brazed plate heat exchanger as the evaporator.
I would like to know if anybody has had problems with oil return to the compressor when using a brazed plate heat exchanger, or can offer any guidance on the required refrigerant velocity within the heat exchanger?
The evaporator will be operating with at least 11K of superheat at the outlet so a reasonable proportion of the upper part of the evaporator will contain vapour, the velocity of which is likely to be quite low (less than 0.5m/s). This would too low for a suction line.
Given that the channels in a brazed plate heat exchanger are much smaller than the suction line, does this mean I can get away with lower velocities?

Any help much appreciated.

James.