Advise about pipe connection for air cooler

[mbc]

Hi
As you know the density of oil is a less than R22
So the oil will stay on top of R22
to remove that in wet Evaporator system is not easy
you have to feed hot gas from suction side and let goes to return pipe suction line or if you got own line for returning liquid line during defrost system
give more time for defrost to push R 22 and oil goes for return pipe and it become a little warm
your system has separator and feed by pump

All oil goes back to separator and you have to remove it with RECTIFIER VESSEL system

You need a rectifier vessel with either an electric heater or hot gas

[Tycho]

Some crude drawings of oil rectifier designs, I'm getting pretty good at MS Paint

oil rectifier.jpg
This is by far the easiest one to install and adjust.
One side is fed from the refrigerant pump discharge, through a solenoid (not on drawing) solenoid opens when 1 of the compressors start, liquid is fed through a TX valve into the heat exchanger, on the outlet I always put a Reg valve to adjust the flow during start up (it may be a bit exessive until the TX valve catches up), during normal operation there will be a nice and slow trickle of almost refrigerant free oil.

Warm side is fed by warm liquid from the HP receiver, doesn't matter if the liquid valve to the LP receiver is on/off or stepless.

oilrectifier1.jpg

This one is still fed by the refrigerant pumps, but can be a pain to adjust properly.
Liquid is fed from the refrigerant pump discharge through a Reg/needle valve (usually 1/2" pipe) into a balancing pipe the balancing pipe drains back to the bottom of the LP receiver.
The important part is to fill the rectifier to no more than 80%.
When warm liquid enters on the other side of the tubes, it will cause boiling on the cold side that in turn lifts the "oil rich" refrigerant up to the pipe feeding the compressor suction.

Reg valve and sight glass on the line to compressor suction is an absolute must

oilrectifier2.jpg

Same as the previous one, except this one does not have a balance pipe, the cold side is connected to the LP drum.

Main issue with this type is that you have to have a pretty stable level in the LP receiver, this type is almost exclusively used on Chillers where you have a very stable/fixed level.


My favourite is the fist one, because it's easiest to comission, and "it just works"