Experimental and numerical investigation on heat transfer of Therminol heat transfer fluid in an internally four-head ribbed tube

This paper describes the thermo-hydraulic performance of an internally four-head ribbed tube. The convective heat transfer coefficient and pressure drop of Therminol 55 heat transfer fluid are measured and simulated in an internally four-head ribbed tube. Experimental results show that the increase in heat transfer rate of the internally four-head ribbed tube is 1.05-1.35 times higher compared to that of the smooth tube. Also, the average friction factor of the internally four-head ribbed tube is 1.3-1.5 times higher than the smooth tube. In addition, correlations of the Nusselt number and friction factor in terms of Reynolds number and Prandtl number are determined, based on the curve fitting of the experimental data. Numerical simulations of three-dimensional flow of Therminol 55 heat transfer fluid show that the heat transfer is improved because the rib valley give a high heat transfer rate by ribs based on Renormalization-group (RNG) k-ε turbulent model and Realizable k-ε turbulent model in the internally four-head ribbed tube.