Hi,

I have a refrigerant flow rate problem in liquid line. I recorded a video here: https://www.youtube.com/watch?v=3WkcFul2HvA. The refrigerant flowrate should be constant but you can see something happens (flash gas?).

Problem description: I have a stepper expansion valve which I think is properly sized for the evaporating temperatures I am working with. I also have a flowmeter in the liquid line (the one shown in the video), and I can control the ambient temperature at the condenser. I am working with R134a. I also have a condenser fan and a liquid receiver at the ouput of the condenser. In general, the refrigerant flowrate is not constant and fluctuates a lot. I even can hear a refrigerant sound similar to a boiling sound, though I do not see bubbles in the liquid line viewer. Can you tell me what can cause this problem?

I can of course provide more data since this is an experimental plant. I really would like to understand what causes this problem.

Best regards,

-Mario