Fuel cell systems with evaporative cooling and methods for humidifying and adjusting the temperature of the reactant streams

Abstract

A fuel cell using fuel and oxidant resulting in the production of water and heat in addition to electrical power. The fuel cell employs an evaporative cooler and has methods to adjust the moisture and temperature for the fuel and oxidant flows to improve the fuel cell efficiency. The water produced by the fuel cell is used to provide the water for wet channels of the evaporative cooler. The evaporative cooler has separate product channels and dry working channels that are cooled by heat transfer across a heat exchanger plate. The heat exchanger plate forms part of each wet working channel on the wet side of the heat exchanger plate and part of the product channel and the dry working channel on the dry side. The fuel passes first through the dry working channel then the wet working channel becoming humidified by the evaporation therein and cooling the heat exchanger plate before going to the anode of the fuel cell. The oxidant is cooled by passing through the product channel before being directed to the cathode. In another embodiment, the evaporative cooler is incorporated with the fuel cell and is formed by an anode separator, with the fuel flowing by a dry side of the heat exchanger plate of the anode separator that is being cooled by the evaporation on the wet side. The evaporation adding moisture to the fuel as it passes by the wet side and the heat exchanger plate cooling the fuel on the dry side.