Reduced-order model to estimate safe flammable refrigerant charge limits for a one-room air conditioner

摘要

The Heating, Ventilation, Air-Conditioning and Refrigeration (HVAC&R) industry is currentlytransitioning away from high global warming potential (GWP) hydrofluorocarbon (HFC) refrigerants.However, many lower-GWP alternatives are flammable. Current safety codes restrict use of allflammable refrigerants; revision of the codes is needed to facilitate wider use of flammablealternatives. Hence, information is needed to enable reliable estimates of safe charge limits forflammable refrigerant options for different HVAC&R applications. A reduced-order model (ROM) wasdeveloped and validated to help estimate safe charge limits based on computational fluid dynamics(CFD) simulations of refrigerant releases in a single room for a range of parameters. Validation ofthe ROM vs. the CFD results showed good general agreement for mean refrigerant concentration.The normalized mean bias error (NMBE) was 0.67% with a maximum error of 15%.