BOILING HEAT TRANSFER CHARACTERISTICS OF ECOFRIENDLY REFRIGERANTS INSIDE NARROW CHANNELS OF DOMESTIC REFRIGERATORS

Abstract

As CFC and HCFC refrigerants have been proved to cause ozone depletion and global warming, production and use of these refrigerants have been restricted as per Montreal protocol. Therefore new alternative refrigerants are being searched for the requirements of domestic and industrial cooling systems. Among these refrigerants HFC refrigerant R134a is currently used in many research work on domestic refrigerators. This work presents an experimental study of boiling heat transfer characteristics of ecofriendly refrigerants inside narrow channel of domestic refrigerator. A refrigerator, which was designed to work with R12 with gross capacity of 165 liter, is used in the experiment. Study is done on two diameter of evaporator tube, 4mm diameter (large channel)and 2mm diameter ( narrow channel). The cross section of channels was circular. The heat transfer characteristics for both the channel section have been studied for R12 and R134a and experimental results were compared with two standard-correlations too. In the study it was found that the heat transfer coefficient was higher for R12 as compared R12 as compared to R134a for both the channel sections. The cop was higher for R134a for both the sections. On comparison with standard correlation it was found that for large channel experimental results had good agreement with Bo Pierre's correlation, whereas for narrow channel it had good agreement with Black and Lazarek's correlation.