View Full Version : Refrigerant velocity limitation in evaporator ?

07-02-2015, 08:56 PM
Hello, I have found that,in suction line refrigerant velocity must be higher than 8-10 m/s for proper oil return.
I wonder about is there any highest velocity limitation value for the evaporator inlet ? for refrigerant R744

26-02-2015, 06:14 PM
Oil return in a (dry?) riser very dependent on viscosity and temperature....and in the case of 744, the means and flows associated with defrosting, where applicable.

As to inlet side: effective distribution says there is a lowest velocity for a flashing refrigerant feeding multiple cap tubes; with velocity increasing, material erosion is the next effect of consequence; and neglecting very low temperature and pressure effects, the next portion of the envelope is established at high velocities associated with near-sonic 2-phase flows. Doubt you will be working near that last limitation.

09-03-2015, 06:27 AM
Thank you sterl