Numerical analysis of heat convection through a double-pipe heat exchanger: Dimpled influence

In this study, the heat convection through a double-pipe heat exchanger using a dimpled tube is numerically investigated at different values of Reynolds numbers. The main objective of this study is to investigate the effect of geometrical parameters of inner dimpled tube on the hydrothermal characteristics of water flow. The geo-metrical parameters include, the dimple arrangements (inline and staggered), the distribution angle of dimples and pitch ratio. The heat transfer of inner dimpled tube is investigated and compared with the results of con-ventional smooth tube. Also, the thermal performance factor TPF is presented. In order to describe the me-chanisms that promote increased heat transfer, the temperature and pressure contours are presented. The nu-merical simulation appears the inner dimpled tube with staggered arrangement improves about 50% as Nusselt number than that dimpled tube with inline arrangements and deduces, the highest heat transfer performance is obtained at distribution angle of 60o. The TPF values varied from (1.67-5.22) for dimpled tubes with inline arrangement while varied from (4.91-8.633) for dimpled tubes with a staggered arrangement. In addition, the results show, the TPF values under geometrical parameters considered dimple diameter (D=6 mm), pitch (P = 8 mm) and Reynolds number (Re=10,000) with staggered arrangement obtained the largest significant TPF value which is 9.07.