Evaluation of flow boiling heat transfer in horizontal circular trapezoidal-shaped microfin tube

Experimental investigations were conducted to analyze the evaporation heat transfer of R407c inside a horizontal microfin (trapezoidal-shaped) Cu-tube. The experiments were performed in equipment specifically designed and fabricated for phase change analysis, with a test section consisting of a 1m long Cu-tube with an outer diameter of 9.52 mm and a recirculating water heating system. The following test parameters were used: a heat flux of 5-85 kW center dot m(-2), mass flux of 20-350 kg center dot m(-2)center dot s(-1), vapor quality range of 0.03-0.667, and saturation temperature of 283.15-313.15 K. The novel aspect of this study is the newly designed microfin tube with helix and apex angles of 22 degrees and 48 degrees, fin height of 0.22 mm, and a total of 60 fins. Following experimental analysis, flow boiling heat transfer coefficients rise with mass flux, vapor quality, lower saturation temperature, hydraulic diameter, and heat flux. The experimental outcomes were also compared with established correlations. The error range for the experimental data was found to be within +/- 25%, which shows that the data are accurate to a high level of 95%. Besides that, correlations of evaporation heat transfer through a 9.52 mm horizontal round microfin tube were established by using the interpolation technique in LINGO software to anticipate the internal evaporator heat transfer coefficient as a consequence of saturation temperature. At saturation temperatures of 283.15 K and 293.15 K, the new correlation can predict most of the previous experimental results within +/- 20% the error margin.