Forced Convective Liquid Cooling of Arrays of Protruding Heated Elements Mounted in a Rectangular Duct

Abstract

Experiments are performed to study forced convection water cooling of arrays of protruding heat sources with specified heat input. Each array has four rows, with three elements in each row. The arrays are mounted at the top or at the bottom of a rectangular channel. The Reynolds number, based on channel height, is varied from around 2500 to 9000. Flow visualization and temperature measurements revealed that the flow over the arrays was fully turbulent, even at the smallest Reynolds number. Different channel heights (ranging from 3 to 4 times the height of each element), different heat inputs to the modules, and different streamwise spacings between the elements are employed. The spanwise spacing between the elements is kept constant. It is found that the average Nusselt number is higher for smaller channel heights and streamwise spacing, at constant Reynolds number. The effect of buoyancy on the average heat transfer rate from the arrays is found to be small over the parametric ranges considered here. A small variation in the heat transfer coefficient is found in the spanwise direction. The observed trends are considered in terms of the underlying transport processes. The heat transfer data are also correlated in terms of algebraic equations. High correlation coefficients attest to the consistency of results. The data are compared with previous air and water cooling studies, wherever possible, and a good agreement is obtained.