Abstract
The performances of refrigeration truck systems using R404A and R134a were investigated by experimental testing, and compared. The optimal COPs of the R404A and R134a systems were 2.96 and 3.42, when the refrigerant charge amount was 1.3 kg and 1.4 kg, respectively. When the indoor side air temperature increased from $5^{\circ}C$ to $9^{\circ}C$, the total exergy destruction rate of the R404A system was on average 39.1% higher than that of the R134a system. In addition, the exergy efficiency of the R404A system was 12.9% higher than that of R134a system, for various indoor air temperatures. When the outdoor side air temperature increased from $25^{\circ}C$ to $35^{\circ}C$, the total exergy destruction rate of the R404A and R134a systems decreased by 18.9% and 19.5%, respectively. In addition, the exergy efficiency of the R404A and R134a systems increased by 25.2% and 30.7%, respectively. As the compressor rotating speed increased, the COP of the R404A and R134a systems decreased by 23.6% and 18.4%. The total exergy destruction rate and exergy efficiency of the R404A system were 27.2% and 15.7% higher than those of R134a system, respectively. Compared to the R404A system, the R134a system showed a higher COP and a lower exergy destruction rate; thus it can be concluded that the R134a system has the better performance.