A Novel Unitary Air Condition System Design for Flammable Refrigerants and Building Ventilation

摘要

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