Hydrogen Fuel Cell Cold Operation

Abstract

The purpose of this project is to model the operation of a proton exchange membrane (PEM) fuel cell during operation in weather as cold as -40 °C. The fuel cell must be kept above the freezing point of water, and it is hypothesized this can be done by utilizing the heat produced in the system. The system is being designed to provide off-grid power for operation of various scientific sensors requiring power output of 20 W at a potential of 12 V. A fuel cell combines hydrogen and oxygen to form water, heat, and electricity. Process steps include generating hydrogen from the alcoholysis and/or hydrolysis of sodium borohydride, creating electricity from the fuel cell to charge a battery, and preheating feed air to provide oxygen to the fuel cell. The project explores 1) modeling of the reaction kinetics for hydrogen production, 2) modeling the efficiency and kinetics of the catalytic reaction between the generated hydrogen and oxygen from air within the fuel cell, and 3) modeling heat flow within the system to preheat the incoming air and maintain good fuel cell temperature. The reaction kinetics show sufficient hydrogen production to keep the fuel cell running as specified. The modeled efficiency gives an average efficiency just above 50% for the conversion of chemical potential energy to usable power. The heat flow, assumed to be 1-dimensional, shows sufficient heat transfer to keep the area around the fuel cell above the freezing point of water as modeled.