Air-Side Fin Geometry of a Tube-Strip Heat Exchanger for Fuel Cell Vehicles

Fuel cell vehicles (FCVs) are facing severe heat dissipation challenges because fuel cell stacks are required to operate at a narrower temperature range and higher heat dissipation than those in the internal combustion engine. This study conducts a numerical analysis of a tube-strip heat exchanger applied in a high-performance FCV. The typical unit cell of the tube-strip heat exchanger is selected to numerically optimize the cell-level thermal performance of the heat exchanger. Effects of structural parameters and operational conditions are investigated. The optimal structure is obtained by focusing on the heat transfer rate and fan power at the air side, where the overall heat transfer rate of heat exchanger is determined by the effectiveness number of transfer unit method and the theoretical framework of volume averaging. The results show that the heat exchanger with rectangular fins exhibits a greater heat transfer rate than those with trapezoidal and triangular fins at an inlet air velocity of 4 m/s. Compared with the fin without a louver, the heat exchangers equipped with louvers parallel and vertical with the air flow achieve heat transfer rates of 33.1 and 42.8 kW, respectively, which increase by 2.0 kW (6.4%) and 11.7 kW (37.5%) in heat transfer rate. For high-power heat dissipation, the louvered heat exchanger with a fin pitch of 2 mm shows the best thermal performance given the same fan power.