PDA

View Full Version : design a condenser with 12 K subcooling







SkiLLet
27-02-2013, 10:31 AM
Hi All,

I am presently facing an engineering hurdle.

I am trying to design a system that gives an off coil of 5 Deg C, looking at refrigeration temp at -5 Deg C.

I am now trying to design the condenser. The refrigerant temp at discharge is 50 Deg C, RFRIGERANT used : R22/R423

I am looking at a subcooling of 12K which means after condeners I want the refrigerant temp to be 38 Deg C.

Ambient air : 35 Deg C / 5 Deg C

can anyone advice on how I should design the condenser ?

Please advice.

Warmest Regards
SkiLLet

Rob White
27-02-2013, 01:10 PM
.

Free subcooling can only be achieved at about 4 degsK maybe 6 degsK
and it is only possible to cool down to the ambient temperature.

In air conditioning systems they get round this problem with an over sized
condenser and fan speed control or they bring the liquid back to the bottom
of the condenser and make a few extra passes. This allows the liquid to reject
some heat to the ambient but it is only possible down to the ambient temps.

The over sized condenser also acts as a liquid receiver and stores the liquid
before use in the expansion device.

You could try designing a larger condenser with an extra subcooling section on
the bottom.

Another way is to use adiabatic cooling (water and air) if you spray water over
the condenser as you pass air over it the evaporation effect will lower the temperature
even further.

You could run your liquid line inside your suction and that will exchange the heat
to the suction gases.

Or you could pass your liquid line through a plate heat exchanger and then
increase the subcooling with a small refrigeration circuit built into your main system.
Using this subcooling method you may use 10% of the liquid refrigerant in the subcooling
process but if done properly it will increase your liquid quality up by as much as 30% or 40%.

Regards

Rob

.

TRASH101
27-02-2013, 01:37 PM
You are describing a temperature differential there aren't you ??? not subcooling unless you got liquid coming into the condenser.

You want to clarify?

TRASH101
27-02-2013, 01:38 PM
Well put there Rob btw