Comparitive Analysis of an Automative Air Conditioning Systems Operating With CO2 and R134a.
Comparitive Analysis of an Automative Air Conditioning
Systems Operating With CO2 and R134a.
Brown, J. S.; Yana-Motta, S. F.; Domanski, P. A.
International Journal of Refirgeration, Vol. 25, No. 1,
automobiles; air conditioning; carbon dioxide
This paper evaluates performance merits of CO2 and R134a
automotive air conditioning systems using
semi-theoretical cycle models. The R134a system had a
current-production configuration, which consisted of a
compressor, condenser, expansion device, and evaporator.
The CO2 system was additionally equipped with a
liquid-line/suction-line heat exchanger. Using these two
systems, an effort was made to derive an equitable
comparison of performance; the components in both
systems were equivalent and differences in thermodynamic
and transport properties were accounted for in the
simulations. The analysis showed R134a having a better
COP than CO2 with the COP disparity being dependent on
compressor speed (system capacity) and ambient
temperature. For a compressor speed of 1000 RPM, the COP
of CO2 was lower by 21% at 32.2C and by 34% at 48.9 deg
C. At higher speeds and ambient temperatures, the COP
disparity was even greater. The entropy generation
calculations indicated that the large entropy generation
in the gas cooler was the primary cause for the lower
performance of CO2.