Single phase heat transfer and flow friction correlations for microfin tubes

Abstract

Single-phase heat transfer as well as pressure drop characteristics for microfin tubes with nominal diameter of 9.52, 7.94, and 7.0 mm are reported in the present investigation. In this study, seven commercially available microfin tubes and a smooth tube were tested using water as the test fluid. The heat transfer coefficients were obtained using the Wilson plot technique. It was found that the microfin tube exhibits a rough tube characteristics, and the enhancement levels increase with the Reynolds number and eventually reach a maximum value at a critical Reynolds number. The Dittus-Boelter type Wilson plot function cannot correlate the heat transfer data when the Reynolds number is less than the critical Reynolds number. Using the heat-momentum transfer analogy, a better correlation of the present mirocfin heat transfer data is achieved. In addition, the present correlations can predict 85.2% of the experimental data within 10% and 95.8% of the friction factor within 10%.