PERFORMANCE SIMULATION OF SINGLE-EVAPORATOR DOMESTIC REFRIGERATORS CHARGED WITH PURE AND MIXED REFRIGERANTS

A computer simulation of single-evaporator domestic refrigerators charged with pure and mixed refrigerants has been performed in an attempt to screen out the best substitutes for R12. In simulating a steady-state thermal system, both successive substitution and the Newton-Raphson methods were employed independently and yielded the same results without any significant difference in their performance. An extensive screening was carried out for 15 pure and 21 mixed refrigerants. The results indicate that few pure fluids may be drop-in replacements for R12 due to mismatch of volumetric capacity, even if some fluids such as R22, R152a, R142b and R141b have a comparable coefficient of performance (COP) to that of R12. Only R22-R142b and R32-R142b mixtures yielded increases in COP of up to 3% with the same capacity as that of R12. In the short run, these mixtures may be substituted for R12, thus helping to solve the ozone layer depletion problem without a significant change in energy efficiency. More efficient heat exchangers are recommended as one of the means of increasing energy efficiency.