3557 -- Investigation of R-22/R-142b Mixture as a Substitute for R-12 in Single-Evaporator Domestic Refrigerators

Describes the investigation in a single-evaporator domestic refrigerator of an R22/R142b refrigerant mixture as a substitute for R12. Notes that a steady-state thermodynamic cycle analysis indicated an increase in the coefficient of performance 3% to 5% with R22/R142b in the composition range of 0.3 to 0.6 mass fraction R22 compared to R12. For the tests, a countercurrent evaporator and condenser were used in an attempt to obtain the best performance with the mixture. The refrigerator was fully instrumented with more than 70 thermocouples, two pressure transducers and digital watt and watt-hour meters. Experimental results indicate that the R22/R142b mixture at 0.52 mass fraction R22 performs up to 3% better than R12 with countercurrent heat exchangers and synthetic oil (alkyl benzene). A further study indicates that with a properly matched motor and compressor, the R22/R142b mixture at 0.4 to 0.45 mass fraction R22 would show even better performance at the same compressor on-time and a lower compressor dome temperature than R12.

KEYWORDS: Refrigerants, refrigeration, refrigerators, domestic, experiment, R12, R22, R142b, performance, mixtures, efficiency