A performance analysis of porous graphite foam heat exchangers in vehicles

Due to the increasing cooling power and space limitation in vehicles, a new compact heat exchanger – graphite foam heat exchanger is proposed for vehicle cooling application. The graphite foam has high thermal conductivity (the effective thermal conductivity is 40–150 W/m K) and low density (0.2–0.6 g/cm3), but it has high flow resistance which is a problem in heat exchanger applications. In order to find a graphite foam heat exchanger with low flow resistance, four different configurations (baffle, pin-finned, corrugated, and wavy corrugated) of graphite foam fins are analyzed in terms of thermal performance and pressure drop by using a computational fluid dynamics approach. The simulation results show that the wavy corrugated foam presents high thermal performance and low pressure drop. Moreover, a comparative study between the wavy corrugated foam heat exchanger and a conventional aluminum louver fin heat exchanger is carried out to evaluate the performance of graphite foam heat exchangers in terms of coefficient of performance (removed heat/air pumping loss), power density (removed heat/mass of heat exchangers), and compactness factor (removed heat/volume of heat exchangers). Finally, this paper concludes that graphite foam heat exchangers should be further developed in vehicles, and presents several recommendations for how such development can be promoted.