Optimal distribution of metal foam inserts in a double-pipe heat exchanger

Abstract

PurposeIn the present research, a numerical investigation is carried out to study the fluid flow and heat transfer in a double-pipe, counter-flow heat exchanger exploiting metal foam inserts partially in both pipes. The purpose of this study is to achieve the optimal distribution of a fixed volume of metal foam throughout the pipes which provides the maximum heat transfer rate with the minimum pressure drop increase.Design/methodology/approachThe governing equations are solved using the finite volume method. The metal foams are divided into different number of parts and positioned at different locations. The number of metal foam parts, their placements and their volume ratios in each pipe are sought to reach the optimal conditions. The four-piece metal foam with optimized placement and partitioning volume ratios is selected as the best layout. The effects of the permeability of metal foam on the Nusselt number, the performance evaluation criteria (PEC) and the overall heat transfer coefficient are investigated.FindingsIt was observed that the heat transfer rate, the overall heat transfer coefficient and the effectiveness of the heat exchanger can be improved as high as 69, 124 and 9 per cent, respectively, while the highest value of PEC is 1.36.Practical implicationsPorous materials are widely used in thermo-fluid systems such as regenerators, heat sinks, solar collectors and heat exchangers.Originality/valueHaving less pressure drop than fully filled heat exchangers, partially filled heat exchangers with partitioned metal foams distributed optimally enhance heat transfer rate more economically.