Investigation of Conjugate Heat Transfer in a Fin-and-Tube Heat Exchanger

Abstract

A numerical study was achieved on a realistic fin-and-tube heat exchanger in order to investigate its heat transfer and friction characteristics. The computations assume a steady-state heat transfer and fluid flow. Nusselt number and friction factor characteristics of the heat exchanger are determined for various values of Reynolds numbers. Conjugate convection-conduction energy conservation equations in 3 dimensions have been solved along with mass and momentum conservation equations in order to determine these characteristics. Both laminar and turbulent flow regimes are considered. The effect of turbulence modeling was investigated using three different models (the one equation Spalart-Allmaras turbulence model, the standard k-ε model and the RSM model). The computations allowed the determination of the dynamic and thermal fields. Model validation was carried out by comparing the calculated friction factor f and Colburn j-factor to experimental results found in the literature. The plotted results showed a qualitatively good agreement between numerical results and experimental data. The results obtained also showed that the simplest of the three turbulence models tested (i.e. Spalart-Allmaras) gives the closest values to the experimental data.