Experimental Evaluation of an Automotive Heat Pump System with R1234yf as an Alternative to R134a.

In this study, performance characteristics of an automotive heat pump (AHP) system using R1234yf and R134a were investigated. Compressor speeds, air temperature and air flow velocity significantly influence the system performance parameters. Therefore, the effect of compressor speeds, air flow velocities and temperatures on the system performance characteristics were evaluated under various test conditions. Optimum experimental conditions were arranged to determine the performances of the AHP system. As a result, the heating performance of R1234yf is lower than R134a. The heating performance of AHP systems gets higher as air flow velocities drop. While the air flow velocities raised up from 1.2 to 4.5 m s−1, the heat capacity was decreased by 15%. Change in air velocities plays more role on the performance characteristics than the change in ambient temperature at low air flow velocities. Comparing the suction and discharge pressures of both the R134a and R1234yf, R1234yf is higher because of its vapour densities. Finally, R1234yf can be used in AHP systems for both cooling and heating applications. [ABSTRACT FROM AUTHOR]