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Abstract
Several researches and development activities proved that R22 has bad effects on the environment such that global warming. The near azeotropic refrigerant mixture of R410A has been considered as one of the primary replacements for R22 in the air-conditioning system applications. Local heat transfer coefficients of R22 and R410A are determined in asmooth horizontal copper tube with inner diameter of 9.525 mm and length of 1m during convective boiling Experiments are carried out varying: the vapor quality (0.1:0.8), the heat flux (6:29) kW/m2 and the evaporation temperature (-5:5ºC) at mass flux of 100 kg/m2s. Experimental results showed that the local heat transfer coefficients increase with vapor quality, heat flux and evaporation pressure. The heat transfer coefficients of R410A are better than those of R22 by about 17% and 14% during the lower and higher value of evaporating pressures and heat flux, respectively. The modified Kattan model results are found to be well agreement with the experimental results. Pressure DROP for R410A is lower than that for R22 by about 26% The effect of the heat flux on frictional pressure DROP is seen to be of only minor importance at vapor qualities. It’s observed that frictional pressure gradients rise with the reduction of evaporation temperature. It can be noted that Muller method works the best, where its deviation ranges by 20% to -30% in a comparison to experimental pressure DROP results.