Use of peripheral fins for R-290 charge reduction in split-type residential air-conditioners

Abstract

The use of hydrocarbons as refrigerants has increased substantially in the past decades due to more severe regulations on direct and indirect carbon dioxide emissions. However, safety standards related to flammable fluids limit the amount of propane (R-290) used in air-conditioning (AC) systems. In this study, an experimentally validated numerical model for a split-type AC system is employed and, for the first time, an air-side peripheral fin geometry is used in the condenser in an attempt to reduce the refrigerant charge for a given system cooling capacity. To establish a fair basis for comparison, plain, wavy and louvered fins were also investigated in the model. A more realistic assessment of the system performance was achieved by considering the POE ISO 22 oil circulation ratio (OCR) in the computation of the physical properties of the mixture. The results have shown that, for the simulated range, heat exchangers with peripheral fins provided higher values of thermal conductance (UA) and cooling capacity than other types of fins. A substantial decrease in the R-290 mass (as high as 12.13%) was observed when peripheral fin condensers were employed.