Heat transfer simulation of annular elliptical fin-and-tube heat exchanger by transition SST model

Abstract

In this study, thermo-fluid characteristics of elliptical annular finned tube heat exchanger were numerically studied in detail. Transition SST model was utilized to simulate turbulent flow. Effects of air velocities, horizontal to vertical fin diameter ratios, and fin densities were examined in detail. The simulations indicate superior performance of elliptical fin layout. It was shown that pressure drop of annular elliptical fin can be only one half of that of a circular annular fin while containing comparable heat transfer performance. The vertical elliptical annular fin may even contain a higher heat transfer performance over circular fin. Correlations are proposed to estimate the Nu number and pressure drop based on the annular circular fin. The maximum deviations between the proposed correlations and simulations regarding pressure drop and heat transfer coefficient are 5.6% and 3.2%, respectively. For further elaboration of the superiority of the elliptical layout from the second law perspective, normalized entropy generation was also studied. In all cases, the entropy generation rate in circular fin was higher than that of an elliptical fin.