Performance evaluation of alternative refrigerants for R134a in automotive air conditioning system

Aiming to explore environmentally friendly working fluids replace R134a for automotive air conditioning applications, seven potential pure refrigerants were analyzed first in terms of safety, environmental characteristics, and cycle performances. It was found that the pure refrigerants have some defects when applied individually. However, using the principle of complementary advantages, the mixtures employed in automotive air conditioning can make up for the shortcomings existing in the pure refrigerants. On this basis, the thermophysical models of vapor-liquid equilibrium, enthalpy, entropy, and critical properties of binary mixtures were established. Also, the properties and cycle performances of 14 blends were investigated, and the results indicated that the predicted models of vapor-liquid equilibrium have high accuracy, where the average absolute relative deviations of pressures and the average absolute deviations of vapor-phase mole fractions were less than 2% and 0.005, respectively. M1 (R13I1/R152a [30/70]) and M11 (R13I1/R290 [40.3/59.7]) showed superiorities in cycle performances and environmental and safety characteristics. Moreover, the operating pressures of which were close to that of R134a, and they were expected to become the substitutes for R134a in automotive air conditioners.