Numerical analysis of conjugate heat transfer within internally channeled tubes

Abstract

A novel heat exchanger design concept to enhance heat transfer is presented. The exchanger geometry includes six channels arranged inside an insulated circular tube along its axis and forming the so-called internally channeled tube (ICT). The ICT concept offers an increase in the heat transfer surface area between cold and hot fluids. Two original channeled tube geometries are proposed and studied. Single-phase flow and conjugate heat transfer are captured by steady-state CFD simulations utilizing a new approach based on the fluid domain splitting. Heat transfer coefficients and pressure drop are determined under laminar and turbulent flow conditions using water as working fluid. The possibility to apply existing correlations to determine friction factors and Nusselt number in ICTs was explored based on the numerical results. Furthermore, an evaluation of the ICT designs is given in comparison with a traditional double-pipe heat exchanger (DPHE). The heat transfer rate in ICT heat exchangers was found to be up to 50% higher than that in the DPHE, yet with a pressure drop penalty of up to 70%.