30 May 2005

PERFORMANCE OF HCFC22 ALTERNATIVE NATURAL REFRIGERANTS FOR AIR-CONDITIONING AND HEAT-PUMPING APPLICATIONS


In this study, performance of 2 pure hydrocarbons and 7 mixtures was measured in an attempt to
substitute HCFC22. The mixtures were composed of propylene (R1270), propane (R290), HFC152a, and
dimethylether (RE170, DME). The pure and mixed refrigerants tested have GWPs of 3-58 as compared to
that of CO2 and the mixtures are all near-azeotropic showing the gliding temperature difference (GTD) of
less than 0.6?. Thermodynamic cycle analysis was carried out to determine the optimum compositions
and actual tests were performed in a breadboard type laboratory heat pump/air-conditioner at the
evaporation and condensation temperatures of 7 and 45? respectively. Test results show that the
coefficient of performance (COP) of these mixtures is up to 5.7% higher than that of HCFC22. While
propane showed 11.5% reduction in capacity, most of the fluids had the similar capacity to that of
HCFC22. Compressor discharge temperatures were reduced by 11-17? with these fluids. There was no
problem with mineral oil since the mixtures were mainly composed of hydrocarbons. The amount of
charge was reduced up to 55% as compared to HCFC22. Overall, these fluids provide good performance
with reasonable energy savings without any environmental problem and thus can be used as long term
alternatives for residential air-conditioning and heat pumping applications.