Heat Exchanger Design ConsiderationsUsing Carbon Foam Materials

摘要

Research efforts have been conducted for the Air Force and Navy to develop improved primaryenvironmental control system (ECS) heat exchangers used on various aircraft platforms. Designconditions for these types of heat exchangers range in heat duties of 50-425 kW and peak operatingtemperatures of 500-1200 F. These air to air heat exchangers typically involve single pass cross-flowdesigns currently using a plate-fin configuration. To date, the materials of choice have been metals(aluminum, stainless steels and super alloys) depending on the peak temperatures. However, advances inthe processing of carbon materials have improved their cost and have significantly improved their thermalconductivity. Applying carbon materials to advanced heat exchangers will have advantages in bothsaving weight and improving thermal performance. In particular, the advanced open cell-graphite foamswhich possess very high thermal conductivity are of significant interest for improved heat exchangerperformance and lower mass. Only limited heat transfer and pressure drop characteristic data has beenavailable to date on the specific carbon foams on which to base the thermal design. As part of thedevelopment effort fundamental thermal performance testing has been conducted to establish theconvective heat transfer and the pressure drop characteristics of several different types of carbon open cellfoams. This paper presents the both the heat exchanger thermal design considerations and provides someheat transfer and pressure drop performance data for a open cell foam heat exchanger.