This paper investigated the flow and thermal characterization of parallel-plate heat exchangers partially filled with metal foams analytically. Firstly, the velocity and temperature distributions in partially filled symmetrical channel have been plotted and the effect of key parameters (e.g. porosity, pore density, height of metal foams, flow ratio in metal-foam filled region) on its flow and heat transfer performance have been analyzed. Then, the results have been applied for combined heat exchangers with symmetrical and asymmetrical channels to have optimized heat transfer performance and relatively low and identical pressure drop for each channel. (C) 2017 Elsevier Ltd. All rights reserved.