Hydrothermal Characteristics of Water Flow Into a Dimpled Tube Heat Exchanger: A Parametric Study

Abstract

In this study, the hydrothermal water flow characteristics using a dimpled inner tube heat exchanger are investigated experimentally and numerically.A numerical analysis has performed on two types of dimpled tubes (In-lined and staggered distributions) for two distribution angles 60 o and 90 o , and two dimple diameters (4 mm and 6 mm) with constant pitch ratio (X/d=8). In experimental part, a staggered arrangement dimpled inner tube distribution with angle 60 o , dimple diameter of 6 mm and constant pitch ratio (X/d=8)is used as well as plain tube. The results illustrate that the heat transfer as Nusselt number for case of staggered dimpled inner tube improved between 7.55 and 11.2 times than plain tube. The numerical results demonstrate that staggered distribution of dimpled inner tube improve the Nusselt number nearly with 50% bigger than that the in-line distribution dimpled tube. The thermal performance factor (TPF) varied from 1.67 to 5.22 for tubes with in-line arrangement while from 4.91 to 8.633 for dimple tubes with a staggered arrangement.