Thermal characteristics in square channel with 45° staggered baffle inserts

Abstract

The paper presents a study of heat transfer in a heat exchanger channel inserted with staggered inclined baffles. The channel has a square section with uniform wall heat flux conditions. The fluid flow and heat transfer characteristics are presented for Reynolds numbers based on the hydraulic diameter of the channel ranging from 4000 to 25,000. The inclined baffles with an axial pitch equal to three times of channel height and with the attack angle of 45° are mounted in tandem and staggered arrangement on the lower and upper walls of the test channel. Effects of four baffle-to-channel height ratios (e/H = 0.1, 0.2, 0.3 and 0.4) on heat transfer in terms of Nusselt number and pressure loss in the form of friction factor are experimentally investigated. The experimental result shows that the insertion of staggered inclined baffles with the e/H=0.4 provides higher heat transfer and friction factor values than others. This is caused by higher baffle-to-channel height ratios of using e/H = 0.4 interrupting the flow and diverting its direction thus promoting high levels of mixing over others.