PDA

View Full Version : Condensing temperature and outside air temperature



cjroos
20-04-2011, 06:06 PM
Does the condensing temperature change as outside air temperature changes? How are they related?

I would like to find curves of COP with outside air temperature, but I'm finding curves of COP with condensing temperature (at same evaporator temp.)

Thanks in advance for your help.

james10
20-04-2011, 06:16 PM
If it is an air cooled condensor then yes as the ambient increases the refrigerant will pick up the extra heat your condensing temp will always be around 10-15k above ambient

mad fridgie
20-04-2011, 10:15 PM
Is the system a simple on and off type
You have to start with you steady state state design, As the ambinet changes then the SCT changes, this changes the net cooling effect, you then need to recalculate the the evap duty to meet the new mass flow conditions, then you re calculate, the new heat of rejection, which then gives you a different mass flow, and changes the evap conditions again. You can keeping calculating until you get your required level accuracy. When satisifed with your data you then calculate your new COP.
If you have compressor displacement control (normally suction pressure) then evap duty remains constant, so then you need to calculate based upon the change of displacement at the different ambient