A novel unitary air conditioning system design for flammable refrigerants and building ventilation.

Abstract

Flammable refrigerants like R32 and R290 can be used as alternative refrigerants for energy efficient and environmentally friendly air conditioning systems. Nevertheless, the safety issue of such flammable refrigerants limits their market expansion. Moreover, enhancements in building envelop insulation have resulted in significant reduction in buildings’ thermal loads and increased demands for ventilation. The objective of this study is to propose and develop a novel unitary air conditioning system design enabling flammable refrigerants usage and building ventilation. In this novel design, we minimized the refrigerant charge by using microchannel heat exchanger designs and reducing the liquid line length. In addition, advanced hybrid options were applied such as two-stage cycles and economizers. Moreover, the return air and condensate water from the evaporator were used to cool down the condenser. We investigated the performance of the new unitary system design and found that the annual performance factor can be increased up to 45%. This device can be used for building air conditioning and ventilation with high efficiency in a safe manner with environmentally friendly refrigerants.