Performance comparison of three refrigerants in a novel unitary air conditioning system.

Flammable refrigerants offer refrigerant alternatives for energy-efficient and environmentally-friendly refrigerating system. However, the flammability hinders their expanded utilization due to charge limits. The objective of this study is to design a novel unitary air conditioning system allowing the safe use of flammable refrigerants and economizer ventilation operation, and evaluate the performance of such a novel system. We simulated the performance and refrigerant charge of the novel system for three refrigerants, R-410A, R-290 and R-32. Reaching the same capacity, R-290 requires a lower refrigerant charge level than that of R-410A, which is the primary refrigerant used in traditional unitary air conditioning systems. The Annual Performance Factor could be increased by up to 59% as compared to the existing design for the same refrigerant. The refrigerant charge level can be reduced by 35% for R-290. Future work is needed to further reduce the refrigerant charge level while keeping the efficiency.