Evaluation of carbon dioxide as R-22 substitute for residential air-conditioning

J. Steven Brown, Yong Chan Kim, Piotr A. Domanski

Research output: Chapter in Book/Report/Conference proceedingConference contribution

19 Citations (Scopus)


This paper compares the performance of CO 2 and R-22 in residential air-conditioning applications using semi-theoretical vapor compression and transcritical cycle models. The simulated R-22 system had a conventional component configuration, while the CO 2 system also included a liquid-line/suction-line heat exchanger. The CO 2 evaporator and gas cooler were microchannel heat exchangers originally designed for CO 2. The R-22 heat exchangers employed the same microchannel heat exchangers as CO 2 with the difference that we modified the refrigerant passages to obtain reasonable pressure drops. The study covers several heat exchanger sizes. The R-22 system had a significantly better coefficient of performance (COP) than the CO 2 system when equivalent heat exchangers were used in the CO 2 and R-22 systems, which indicates that the better transport properties and compressor isentropic efficiency of CO 2 did not compensate for the thermodynamic disadvantage of the transcritical cycle in comfort cooling applications. An entropy generation analysis showed that the CO 2 evaporator operated with fewer irreversibilities than did the R-22 evaporator. However, the CO 2 gas cooler and expansion device generated more entropy than their R-22 counterparts and were mainly responsible for the low COP of the CO 2 system.

Original languageEnglish
Title of host publicationASHRAE Transactions
Number of pages10
Volume108 PART 2
Publication statusPublished - 2002
EventASHRAE Transactions 2002 - Honolulu, HI, United States
Duration: 2002 Jun 222002 Jun 26


OtherASHRAE Transactions 2002
CountryUnited States
CityHonolulu, HI


ASJC Scopus subject areas

  • Fluid Flow and Transfer Processes

Cite this

Brown, J. S., Kim, Y. C., & Domanski, P. A. (2002). Evaluation of carbon dioxide as R-22 substitute for residential air-conditioning. In ASHRAE Transactions (Vol. 108 PART 2, pp. 954-963)