Louver fin, Fuel cell, Heat transfer, Pressure drop, Brazing
The present work is performed to evaluate the heat transfer performance of a heat exchanger used in a fuel cell. Because of material constraints and performance requirements, a louver fin heat exchanger is modified for use with conventional micro-channel tubes and with multiple small-diameter tubes (a so-called multi-tube). Prototype heat exchangers are tested, and the air-side heat transfer, pressure drop, and fan power are measured in a wind tunnel and simulated using a commercial code. The air-side pressure drop and heat transfer coefficient of the multi-tubes show similar trends to those of the flat-tube heat exchanger if the contact resistance is negligible. The tube spacing of the prototype multi-tube heat exchangers has a small effect on the pressure drop and heat transfer, but it has a profound effect on air-side heat transfer performance because of the contact resistance between the tubes and louver fins. The air-side pressure drop agrees well with an empirical correlation for flat tubes.