Performance evaluation of tubular aluminum foam heat exchangers in single row arrays

Abstract

Two sets of three tubular heat exchangers, constructed by wrapping aluminum foam of different thickness around cylindrical tubes, are being tested for heat transfer performance and pressure drop characteristics. Each set of heat exchangers is mounted such that it forms an array of a single, vertical row inside a low airflow wind tunnel. The tests are carried out under cross-flowing air velocity between 0.5 and 5.0 m/s at 0.5 m/s interval. The effects of foam thickness and transversal pitch distance are discussed and thermo-hydraulic results are benchmarking against those of a conventional finned tube array. It is found that within the designated range of airflow and the same level of compactness, the heat exchanger array with thicker foam layer enhances heat transfer 1.5 to 1.8 times compared with the one having thinner foam. In an array with fixed foam thickness, heat transfer improves at narrower pitches. At a discussion of the results, two empirical correlations to predict friction factor and thermal resistance are presented.