Study of single phase flow heat transfer and friction pressure drop in a spiral internally ribbed tube

The experimental results of single-phase flow heat transfer and pressure drop experiments in the turbulent flow regime in a spirally ribbed tube and a smooth tube are presented in this paper. The ribbed tube has an outside diameter of 22 mm and an inside diameter of 11 mm (an equivalent inside diameter of 11.6 mm) and the smooth tube has an outside diameter of 19 mm and an inside diameter of 15 mm. Both tubes were uniformly heated by passing an electrical current along the tubes with a heated length of 2500 mm. The working fluids are water and kerosene, respectively. The experimental Reynolds number is in the range of 10(4)-5.10(4) for water and is in the range of 10(4)-2.2.10(4) for kerosene. The experimental results of the ribbed tube are compared with those of the smooth tube. The heat transfer coefficients of the ribbed tube are 1.2-1.6 fold greater than those in the smooth tube and the pressure drop in the ribbed tube is also increased by a factor of 1.4-1.7 as compared with those in the smooth tube for water. The corresponding values for kerosene are 2-2.7 and 1.5-2, respectively. The heat-transfer enhancement characteristics of the ribbed tube are assessed. This tube is especially suitable for augmenting single-phase flow heat transfer of kerosene. Correlations for the heat transfer and the pressure drop for the spirally ribbed tube are proposed, according to the experimental data.