Spray Forming of Metal Foam Heat Exchangers
Hamid R. Salimi Jazi, Javad Mostaghimi, Larry Pershin, Sanjeev Chandra and Thomas W. Coyle
Open pore metal foams make efficient heat exchangers because of their high thermal conductivity and permeability. This study describes a novel method to form sandwich structure by using wire-arc spraying to deposit Inconel 625 skins on the surface of sheets of 10 and 20 pores per linear inch (PPI) nickel foam. The skins adhere strongly to the foam struts, giving high heat transfer rates. Tests were done to characterize the skin/foam interface and to determine the hydraulic and thermal characteristics of the heat exchangers and correlations developed to calculate Fanning friction factor and Nusselt number as a function of Reynolds number for airflow through the sandwich structure. Measured heat transfer coefficients for the foam heat exchangers far exceed those of straight flow channels at the same flow rate.
Keywords: Thermal spray, metal foams, high temperature heat exchanger, wire-arc spraying, plasma spray, heat transfer measurements, heat recovery system