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

Published

January 1, 2001

Author(s)

J S. Brown, S F. Yana Motta, Piotr A. Domanski

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

Pub Type

Journals

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Keywords

air conditioning, automotive, carbon dioxide, R134a, simulation, transcritical cycle, vapor compression cycle

Citation

Brown, J. , Yana Motta, S. and Domanski, P. (2001), Comparitive Analysis of an Automotive Air Conditioning Systems Operating with CO₂ and R134a, International Journal of Refrigeration-Revue Internationale Du Froid, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=860836 (Accessed October 13, 2025)