Experimental and numerical studies of heat transfer and friction factor of therminol liquid phase heat transfer fluid in a ribbed tube

Experiments and numerical simulations on heat transfer coefficient and friction factor of Therminol 55 liquid phase heat transfer fluid have been conducted in a ribbed tube with outer diameter and inner diameter of 19.0 and 15.0 mm, and pitch and rib height of 4.5 and 1.0 mm, respectively. Experimental results show that the heat transfer and thermal performance of Therminol 55 liquid phase heat transfer fluid in the ribbed tube are considerably improved compared to those of the smooth tube when the Reynolds number ranges from 500 to 11,500. Compared to the heat transfer in the smooth tube, the heat transfer in the ribbed tube increases by 33-4.6 times for the laminar flow and by 1.9-3.8 times for the turbulent flow. In addition, the measured pressure drop results reveal that the average friction factor in the ribbed tube, as compared to that in the smooth tube, increases by 2.0-3.1 times for the laminar flow and by 3.0-3.9 times for the turbulent flow. Numerical simulations of three-dimensional flow behavior of Therminol 55 liquid phase heat transfer fluid are carried out using FLUENT code in the ribbed tube. The numerical results show that the heat transfer of ribbed tube is improved because vortices are generated behind ribs, which produce some disruptions to fluid flow and enhance heat transfer compared with smooth tube. The studies of three-dimensional flow structure including distributions of velocity, temperature and turbulent kinetic energy and dissipation rate are carried out. The numerical results prove that the ribbed tube can improve heat transfer and fluid flow performances of Therminol liquid phase heat transfer fluid. (C) 2015 Elsevier Ltd. All rights reserved.