Performance comparison of R1234yf and R134a

In a recent study “A comparative study on the performance of HFO-1234yf and HFC-134a as an alternative in automotive air conditioning systems”, S. Daviran et al, have simulated an automotive air conditioning system and compared the performance of HFC-134a and HFO-1234yf as drop-in alternatives to HFC-134a. The simulated air conditioning system consists of a multi-louvered fin and flat-plate type evaporator, a wobble-plate type compressor, a mini-channel parallel-flow type condenser and a thermostatic expansion valve. Two different conditions have been considered in this program for the cycle analysis: for the first state, the cooling capacity is taken as constant, and for the second state the refrigerant mass flow rate is considered fixed. The performance characteristics of system including COP and cooling capacity have been studied with changing different parameters.

The results show that the refrigerant-side overall heat transfer coefficient of HFO-1234yf is 18-21% lower than that of HFC-134a, and the pressure drop is 24% and 20% smaller than HFC-134a during condensing and evaporating processes, respectively. Also, at constant cooling capacity, the COP of HFO-1234yf is lower than that of HFC-134a by 1.3-5%, and at constant mass flow rate, the COP of HFO-1234yf is about 18% higher than that of HFC-134a.