Take a sneak peek at the new NIST.gov and let us know what you think!
(Please note: some content may not be complete on the beta site.).

View the beta site
NIST logo

Publication Citation: Comparitive Analysis of an Automotive Air Conditioning Systems Operating with CO2 and R134a

NIST Authors in Bold

Author(s): J S. Brown; S F. Yana Motta; Piotr A. Domanski;
Title: Comparitive Analysis of an Automotive Air Conditioning Systems Operating with CO2 and R134a
Published: January 01, 2001
Abstract: 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 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 for CO2 was lower by 21% at 32.2 C and by 34 % at 48.9 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.
Citation: International Journal of Refrigeration-Revue Internationale Du Froid
Volume: 25
Issue: No. 1
Pages: pp. 19 - 32
Keywords: air conditioning,automotive,carbon dioxide,R134a,simulation,transcritical cycle,vapor compression cycle
Research Areas: Building and Fire Research
PDF version: PDF Document Click here to retrieve PDF version of paper (267KB)