Experimental investigation on flow boiling heat transfer of R245fa/R141b in horizontal smooth tube

An experimental investigation on the boiling heat transfer of a new mixture R245fa/R141 in a 10 mm horizontal smooth tube was conducted. The boiling heat transfer performances of R245fa, R141b and their mixture were investigated, and the prediction accuracy of four commonly used correlations was compared. The results show that the boiling heat transfer coefficients of pure and mixture increase with the increase of mass flow rate and heat flux, and decrease with the increase of saturation pressure. Besides, the boiling heat transfer coefficient of working fluids increases first and then decreases with the increase of vapor quality, which indicates that there is transitional vapor quality. What's more, the value of transitional vapor quality of R245fa/R141b is greater than that of R245fa and R141b. When the vapor quality is less than 0.55, the heat transfer coefficient of the mixture is lower than that of the pure working fluid. On the contrary, when the vapor quality is greater than 0.55, R245fa/R141b can achieve a higher heat transfer coefficient. The boiling heat transfer coefficient of R245fa/R141b increases with the increase of R245fa mass fraction. Among several selected correlations, the Gungor-Winterton correlation can predict the boiling heat transfer coefficient more accurately, and the average absolute error is 16.67%. © All Right Reserved.