Fully-Developed Convective Heat Transfer and Pressure Drop in a Square Duct With Baffle Inserts Using CFD Analysis

Abstract

The scope of this project is to investigate how the geometry of baffles affect heat transfer and pressure loss of a fluid flow at Re = 1000 through a square duct. For this purpose, Large Eddy Simulations are performed to investigate the effect of baffle height and baffle width. Focus is on the fully-developed flow that repeats itself at streamwise stations. The flow field predicted by Computational Fluid Dynamics simulations was validated using Particle Image Velocimetry. The different designs are evaluated in terms of Nusselt number, Nu and a loss coefficient, f, which are normalised using a reference geometry consisting of a square duct without baffles. The two parameters are additionally combined into a performance parameter eta η = (Nu/Nu0)/(f / f0)(1/3). It was found that adding baffles can result in a quadrupling of η. Reducing the height of baffles decreases heat transfer, while significantly reducing pressure loss and ultimately leading to a higher η. Reducing baffle height was also found to increase the temperature gradient at the upper wall and reduce it at the lower wall. Reducing baffle width resulted in the largest temperature gradient, but lead to poor heat transfer within the fluid.