Development of fuel cells for cogeneration and transportation applications.

摘要

This study has primarily been concerned with the experimental and theoretical development of the proton-exchange membrane fuel cell for cogeneration and transportation applications based on ethanol fuel. Ethanol is a desirable fuel by virtue of its renewability and smaller overall deleterious effect on the environment.; This research developed along the following two major themes: (1) Development of a novel fuel cell based on homogeneous catalysis for the cogeneration of electricity and value-added acetaldehyde using ethanol fuel directly in the fuel cell, and (2) Development of a fuel cell power generation system for mobile applications that utilizes ethanol fuel indirectly by reforming it on-board into hydrogen. The rationale for this is that although hydrogen is a superb fuel for fuel cells, its on-board storage and refueling problems make it impractical for transportation applications unless it can be generated on-board from a liquid fuel. Thus, the overall power plant involves reforming of ethanol into hydrogen and carbon dioxide on-board which is utilized in fuel cell stacks.; Since traces of CO are invariably produced during reforming, one of the objectives of this work was to develop and study a more CO tolerant Pt/Pd electrocatalyst for {dollar}rm Hsb2/Osb2{dollar} fuel cell. A further objective was to reduce the water dependence of proton-exchange membrane (PEM) fuel cells with a view to allow the operation of the fuel cell at a higher temperature than the conventional limit of 80-85{dollar}spcirc{dollar}C. This improves the performance as well as CO tolerance of the fuel cell. In order to realize this goal, a supported proton-exchange membrane for high temperature PEM fuel cell operations (120{dollar}spcirc{dollar}C) was tested. The efficacy of this idea was established by impregnating Nafion with heteropolyacids or with a mixture of heteropolyacid and a low melting molten salt.; Finally, a mathematical model using the reactor-separator approach with an analytical solution was developed to predict the effect of design parameters and operating conditions on the performance of the PEM fuel cell.