View Full Version : Transcritical CO2 Gas cooler/Compressor relationships

15-06-2014, 05:45 PM
Hello all,

I've been wondering about the performance data given by :
Bitzer transcritical compressor (http://www.bitzer.de/eng/productservice/p4d/KP-130)

In the performance data, above the critical pressure 70bars, it uses T(gc for gas coolers) instead of T(condensing). How is one supposed to relate the gas cooler and compressor performances using the graphical* method?

* Conventional ways use Tc (X axis) and Qo(Y axis). With the introduction of T(gc), should the corresponding values of Qo be plotted on the same graph? or should the graph enter a new "transcritical performance region?"

Or can anyone here point me to a good gas cooler manufacturer which provide performance data?

Rob White
16-06-2014, 08:44 AM

On the R744 Ph chart, you draw the graph in the transcritical position,
that way the amount of heat rejected in the gas cooler can be calculated
but it the cooler gas does not turn to liquid until you drop the pressure
of the liquid.

R744 works in transcritical when the condensing temp is about 32 degC and
subcritical when the condensing temp is below 32 degC (if I remember correctly)