Numerical investigation of heat transfer and pressure drop of heat transfer oil in smooth and micro-finned tubes

The laminar, non-isothermal flow of the heat transfer oil in horizontal smooth and micro-finned tubes with different fin heights and helical angles are investigated numerically for the constant wall temperature boundary condition. Simulations have been performed for the Reynolds number ranging from 100 to 1000, the fin height varying from 0.2 to 0.5 mm, and the fin helix angle between 5 and 45°. The results are presented in the form of streamlines, temperature contours, relative Nusselt number, and friction factor. The numerical procedure is validated by comparing the simulation results for the flow and heat transfer of the oil through the micro-finned and smooth tubes with the corresponding experimental results from the literature. The comparisons demonstrate good agreements between the simulation and the experimental results for both the smooth and micro-finned tubes. The results indicate maximum heat transfer enhancement of 44 percent and friction factor increase of 69 percent for the flow of heat transfer oil through the micro-finned tubes in comparison with heat transfer and friction factor of the fluid flow through the corresponding smooth tube at the Reynolds number of 10³.