Investigation of domestic air conditioner with a novel low charge microchannel condenser suitable for hydrocarbon refrigerant

For environmental protection, flammable hydrocarbon refrigerants have been applied to domestic refrigerator and air conditioners. How to reduce refrigerant charge is the main problem for the safety use of hydrocarbons. A novel low charge microchannel condenser was proposed and investigated experimentally and numerically in domestic air conditioner system. Experimental results show that in comparison with normal microchannel condenser, cooling capacity of the novel condenser system increased by 1.6%, system refrigerant charge decreased by 28.3%. The optimum charge for R290 was reduced to 190 g, which meet the safety requirement of China National Standard GB 4706.32-2012. A numerical model of domestic air conditioning system (3.2 kW) with this new condenser was established. Parametric analysis of the new condenser and its impact on the system performance was studied. It was found that the reasonably reducing header inner diameter and flat tube hole diameter can cause more refrigerant charge reduction in condenser (−6.9% and −45.5% respectively) and almost no energy efficiency attenuation. Flow pass arrangement and its impact on refrigerant charge were also studied in this paper. If the novel condenser are fully optimized or other components of the air conditioning system (like compressor) are improved, the system charge may be reduced to 150 g, so as to meet IEC safety charge requirement.