Correlations development for Nusselt number and friction factor in a dimpled surface heat exchanger tube

The present experimental investigation is focused on the study of heat transfer and pressure drop of heat exchanger tube fitted with dimpled ribs on the inner wall. The effect of geometrical parameters, predominantly the streamwise spacing, spanwise spacing, and dimpled depth to print diameter has been investigated. The heat exchanger tube has streamwise spacing () in range of 15-35, spanwise spacing () in range of 15-35, ratio of dimpled depth to print diameter () of 0.5-1.5, and Reynolds number () ranges from 5,000 to 27,000. Experimental results show that the heat transfer and thermal hydraulic performance enhances by 4.19 times and 2.53 times, respectively, for of of 15, of 15, and of 1.0. The experimental data collected are utilized for the development of the statistical correlations for and for selected values of roughness parameters and flow Reynolds number.