View Full Version : Need help in designing flooded evaporator

30-08-2016, 12:51 AM
We need some help in designing a flooded evaporator with R404A. Cooling capacity of 3-5 T. Specifically need help with oil management and return of oil to the compressor.

Anyone has experience with such a system? Any pointers will be appreciated.


30-08-2016, 03:47 AM
Hi infi.
I inherited a low temp R22 gravity fed evaporator and surge vessel system, a raging/ constant problem recovering oil floating on top of refrigerant, particularly at -40SST the oil turned to honey consistency. the system had hot gas driven skimmers from operating level, giant waste of time.
The system should of had several stages of oil separators after compressor to eliminate any oil carry over.
The only way I could clear oil out was a total pump out, allow time time get oil fluid then drain it off manually. R22 and R404a have similar characteristics. magoo.

Glenn Moore
31-08-2016, 08:47 PM
Hi infi
Firstly don't use R404A in a flooded system, use R507 . Fit oil separator ,and an Oil Rectifier .
The Rectifier samples refrigerant from the evaporator , this refrigerant/ oil is then lead into a rectifier pot which has a small heater inside. The heater then boils the refrigerant out of the oil and is vented to suction leaving pure oil in the pot. the oil is then fed to the compressor via a float valve on the compressor sump

01-09-2016, 03:16 PM
could you draw the diagram please ?

05-09-2016, 11:33 PM

I have commissioned a few freezing system with R-404a in south america where we used an oil rectifier.
these were liquid overfeed systems where we used pumps to pump liquid from a LP receiver to the evaporators.

You don't give us too much information on how the system around the evaporator is designed, if it's liquid overfeed with pumps, I can give you two ways to get very good oil return