Condensation Characteristics of HFC refrigerants in horizontal tubes

The author did his PhD from IIT Delhi, India in 2010 and is currently working as Associate Professor at NIT Jalandhar. He is teaching courses related to thermal engineering such as design of heat exchangers and Design & simulation of thermal systems both at undergraduate and graduate level. He is currently guiding research in multiphase flow.

Chlorofluorocarbons (CFCs) and hydro chlorofluorocarbons (HCFCs) had been in commanding position, as ideal refrigerants, until their effect on the ozone depletion layer was discovered in year1974. The process of ozone layer depletion in the stratospheric layer of atmosphere, involves the catalytic destruction of ozone by the atoms of halogens such as chlorine and bromine. A variety of pure and mixtures of HFC refrigerants such R134a, R404A (R125/R134a/R143a, 44%/4%/52%), R410A (R-32/R-125, 50%/50%) are being used as substitutes for the conventional CFC/HCFC refrigerants. These refrigerants have zero Ozone depleting potential (ODP) and similar thermodynamic and transport properties as that of conventional CFC/HCFC refrigerants. But,the major limitation of these refrigerants has been, that, these have lower value of heat transfer coefficients compared to CFCs. In order to augment their heat transfer characteristics, the micro finned horizontal tubes are replacing the earlier smooth horizontal tubes. The present work has focused on evaluating condensation characteristics of pure and mixtures of HFC based refrigerants in practical air-conditioning systems using micro-fin tubes.