Thermal performance of a 10-kW phase-change plate heat exchanger with metal foam filled channels

Compact-sized organic Rankine cycle (ORC) power generators call for small-scale heat exchangers to work with them. Since the heat transfer area plays a direct role in the performance of heat exchangers, micro-cellular structures such as metal foams are proposed to increase the heat duty of heat exchangers by increasing the surface area while maintaining their small size. In this experimental study, the performance of a 10-kW heat exchanger with channels filled with copper metal foam was investigated. A hot water loop was designed for heat input. The cold side of the heat exchanger works with R245fa as the working fluid. Single-phase and two-phase experiments were performed with different mass fluxes ranging from 180 to 600 kg/m2s. The effect of the pores per inch (PPI), working pressure, and different arrangements of metal foams was also investigated. Although the metal foam increases the pressure drop in the channel, it increases the recovered waste heat from the heat source and overall heat transfer coefficient of the heat exchanger by up to 2.3 times compared to a conventional heat exchanger without metal foams.