Air Side Heat Transfer Performance of Louver Fin and Multitube Heat Exchanger for Direct Methanol Fuel Cell Cooling Application

Abstract

The present work is performed to evaluate the heat transfer performance of a heat exchanger used in a direct methanol fuel cell. Because of material constraints and performance requirements, a louver fin heat exchanger is modified for use with conventional microchannel tubes and also with multiple smalldiameter tubes (called multitubes). Prototype heat exchangers are tested, and the airside heat transfer, pressure drop, and fan power are measured in a wind tunnel and simulated using a commercial code. The airside pressure drop and heat transfer coefficient of the multitubes show similar trends to those of the flattube heat exchanger if the contact resistance is negligible. The tube spacing of the prototype multitube heat exchangers has a small effect on the pressure drop and heat transfer, but it has a profound effect on the airside heat transfer performance because of the contact resistance between the tubes and louver fins. The airside pressure drop agrees well with an empirical correlation for flat tubes.