Assessment for Heat Transfer Enhancement in Heat Exchangers by Using Dimples geometry

Abstract

The pressure drop and heat transfer characteristics of a multi dimpled tubes heat exchanger were studied experimentally and numerically. Two different models of heat exchanger (plain and circular dimpled tubes) have been fabricated and tested. Instrumented heat exchangers were building up to cover the experiments for the selected range of Reynolds number (7000-18000). In the numerical study a software ANSYS (Fluent 14.5) with a Shear Stress Transport (SST) turbulent model have been used to calculate pressure drop and heat transfer coefficient for three models of heat exchangers(plain, circular dimpled and triangle dimpled tubes). The experimental results show that Average Nusselt number and the Pressure drop for the model of circular dimple tubes is higher than that for the plain tubes while the numerical results show that the triangular dimples have better results than the others. Comparisons between the experimental and numerical were done and show a good agreement between them