Abstract: The optimal charge amounts of R-410A and R-454B in Air Handler Unit (AHU) were compared through experimental studies, and the differences in various performance parameters under A_full and B_full conditions were analyzed. The feasibility of replacing R-410A with R-454B in AHU was also assessed. The results indicated that the optimal charge amounts for R-410A and R-454B are 3 kg and 3.65 kg, respectively. Compared to R-410A, R-454B showed a capacity reduction of 2.22% and 2.64% under A_full and B_full conditions, respectively, with an EER2 increase of 2.76% and 1.41%. Additionally, the discharge temperature decreased by 3.9 °C and 4.7 °C, the suction temperature decreased by 6.0 °C and 5.2 °C, the condensing pressure decreased by 6.35% and 5.70%, and the evaporating pressure decreased by 2.10% and 2.14% under the same conditions. These results suggest that R-454B can generally meet the capacity and energy efficiency requirements of current R-410A systems. Moreover, R-454B imposes lower high-temperature protection and strength requirements on system components compared to R-410A, indicating that R-454B can be directly used in existing R-410A systems, a reference for the mass transition of refrigerants in AHU was provided.

Key words: R-410A, R-454B, GWP, Performance, Refrigerant, EER2