An experimental study on the thermal and hydraulic characteristics of open-cell nickel and copper foams for compact heat exchangers

High-porosity open-cell metal foams made of copper and nickel were inserted into a rectangular channel containing R245fa refrigerant with mass flux ranging from 76 to 391 kg/m(2) s. The single-phase heat transfer from the surrounding channels is driven by hot water in a closed cycle and ranges from 0.53 to 1.37 kW. The heat transfer and pressure drop across the embedded metal-foam samples were measured while maintaining constant conditions of the refrigerant inlet pressure and hot water supply. The heat transfer coefficient was calculated based on a modified Wilson-plot method. The results were compared with published correlations, and new correlations are proposed to take into account the characteristics of the foam geometry and material. In addition, three parameters are introduced to compare different types of metal foam samples. The results of the experiment show that the metal-foam-filled channel increases the Colburn j-factor by up to 6.3 times compared to an empty channel. As a result, the metal foams with higher pore density and higher thermal conductivity perform better than other samples in single-phase flow. (C) 2018 Elsevier Ltd. All rights reserved.