Experimental study of the effect of brazed compact metal-foam evaporator in an organic Rankine cycle performance: Toward a compact ORC

Compact-sized organic Rankine cycle (ORC) power generators require small-scale heat exchangers to achieve high power density. The objective of this study is to investigate the effect of a Brazed Metal-foam Plate Heat Exchanger (BMPHE) in an Organic Rankine Cycle (ORC) performance parameters. This evaporator is one of the first industrial full BMPHE which is composed by Nickle-foam with 25 PPI (pore per inch). In addition, a series of the experiments have been done using conventional Brazed Plate Heat Exchanger (BPHE) to make a comprehensive comparison for both cycles. Two parameters of power density and pressure gradient are introduced to make a clear comparison in addition to ORC performance parameters. Experimental data are presented for a 1-kW scroll expander and heat source temperatures between 80 and 120 °C. The results show that although the compact evaporator (BMPHE) increases the pressure drop by factors of 1.4-2.6, the overall performance of the ORC is not adversely affected, and the power density is increased by a factor of 2.5 in maximum.