Cycle performance of alternative refrigerants for domestic air-conditioning system based on a small finned tube heat exchanger

• Comparisons are made in the air conditioner system based on 5 mm tube fin heat exchanger.
• The R22 system has a similar performance to others in heating mode while a huge difference in cooling mode.
• The optimal charge of R290 is reduced with nearly no decline in the capacity and COP.
• SLHX is attached to the system of R290 and successfully promote safety and capacity.
• Heat loads are taken into account to evaluate the advantages and disadvantages of R290 and R32.

In order to find alternative refrigerants which exhibit both favorable cycle performance and environmental friendliness, R32 and R290 were utilized to contrast to R22 and R410A as substitutes in the present study. The experiments were conducted with a 5 mm finned tube heat exchanger based on the enthalpy method in a small split household air conditioner. The results showed that in nominal cooling conditions, the COPR of R32 and R290 were 26.8% and 20.4% higher than R22, 7.3% and 2.1% higher than R410A. And in nominal heating conditions, the COPHR of R32 and R290 were both 11.0% higher than R22, 5.3% higher than R410A. The systems with R290 and R32 have similar capacities to that with R22 and R410A in heating mode, but a relatively huge difference of capacities in cooling mode. In consideration of charge amount, R290 could be considered as the most superior alternative refrigerant in air conditioners with the small finned tube heat exchanger.