Experimental study on confined metal foam flow passage as compact heat exchanger surface

摘要

This work focuses on forced convection through asymmetrically heated rectangular confined porous flow passage of aspect ratio of 50 (width/height = 150/3). Heat transfer characteristics of the porous flow passage were investigated with four different open-cell aluminium metal foams (MF) as porous media. Two sets (four samples) of aluminium foams of 20 ppi and 40 ppi pore densities with each set had two different relative densities (RD) of 9-11% and 12-16% (as per supplier's specification). One set of MFs was uncompressed (9-11% relative density) while another set was obtained by unidirectional compressing the MFs of 6-8% RD and 6 mm height flow passages. The study was systemically conducted with constant heat flux at the bottom surface of the flow passage, and on the basis of compact heat transfer surface analogy. Steady state condition was achieved before acquiring data. Temperature distribution along flow direction was investigated to study thermal development of air flow through it. It was found that thermally developed flow exists in such confined flow passages. Moreover, as a case study of a potential application, a systematic method was followed to obtain performance curves for all the flow passages as compact heat transfer surfaces for use in a Polymer Electrolyte Membrane Fuel Cell (PEMFC). The performance curves were utilised to obtain the best compact heat transfer surface for its possible use in a PEMFC.