Properties and Cycle Performance of Refrigerant Blends Operating Near and Above the Refrigerant Critical Point
Piotr A. Domanski, William V. Payne
Performance of R22 and R410A split air conditioners was evaluated experimentally at the ambient temperature range from 82 F to 135 F. Capacity and EER decreased as the outdoor temperature increased. The capacity of the R410A system relative to the capacity of the R22 system was within 8 %. EER of the R410A system relative to the R22 system decreased as the outdoor temperature increased. Over the outdoor temperature range from 82 F to 135 F, the EER ratio of the R410A system to that of the R22 system varied from 1.05 to approximately 0.8. Additional tests were performed for the R410A system at ambient temperatures up to 155 F, which resulted in transcritical operation. No noticeable changes in noise level or operation of the system was noted.The modeling part of the study effort included development of EVAP-COND, a windows-based software package for simulation of finned-tube evaporators and condensers. Both models were validated with laboratory test results obtained for the R22 and R410A systems. Additionally, a model for a TXV-equipped air conditioner was developed, validated with laboratory data, and used for comparative evaluation of R22, R410A, R404A, and R134a systems. The simulation results are consistent with the test results obtained for R22 and R410A systems and can be explained in terms of refrigerant thermophysical properties and their impact on performance in a system with non-optimized heat exchangers.
Air Conditioning and Refrigeration Technology Institute - 21st Century Research