Heat Transfer Through Metal-Foam Heat Exchanger at Higher Temperature

Abstract

Open pore metal foams are lightweight and offer high strength, rigidity, and a large heat transfer area per volume. They make efficient heat exchangers because of high thermal conductivity and high permeability. These heat exchangers made of nickel foam are suitable for high temperature application. They can be manufactured by shaping the foam into any desired configuration and depositing metal skins on it using thermal spray deposition method. Combustion based heating system that burns natural gas is designed to understand the heat transfer through metal foam heat exchanger at higher temperature. A test rig has been fabricated to perform heat transfer experiments. The rig is capable of generating hot combustion gases through methane-oxygen premixed combustion chamber. The design of the rig allows exposure of the thermally sprayed nickel foam to hot gases and finally, cooling the metal foam by circulating air through it. The experiments were performed on metal foam and hollow channel to measure the heat transfer enhancement of the metal foam. The surface temperature measurements were done for different flow rates of cooling air. A significant decrease in surface temperature of metal foam was observed.