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A full three-dimensional, nonisothermal computational fluid dynamics model of a proton exchange membrane (PEM) fuel cell with straight flow field channels has been developed to simulate the hygro and thermal stresses in polymer membrane, which are occurring in the cell during operation. The behavior of the membrane during the operation of a unit cell has been studied and investigated. This comprehensive model accounts for the major transport phenomena in a PEM fuel cell: convective and diffusive heat and mass transfer, electrode kinetics, transport and phase change mechanism of water, and potential fields. The model is shown to be able to realize the many interacting, complex electrochemical, transport phenomena, and stresses distribution that cannot be studied experimentally. This model is used to study the effect of operating parameters on fuel cell performance and hygro–thermal stresses in polymer membrane. Detailed analyses of the fuel cell performance under various operating conditions have been conducted and examined. The analysis helped identifying critical parameters and shed insight into the physical mechanisms leading to a fuel cell performance under various operating conditions.

The effect of the amount of hydrogen/ethyl alcohol addition on the performance and pollutant emission of a four-stroke spark ignition engine has been studied. The results of the study show that all engine performance parameters have been improved when operating the gasoline spark ignition engine with dual addition of hydrogen and ethyl alcohol. The important improvements of alcohol addition are to reduce the NOx emission with increase in the higher useful compression ratio and output power of hydrogen-supplemented engine. The addition of 8 mass% of hydrogen, with 30 vol% of ethyl alcohol into a gasoline engine operating at 9 compression ratio and 1500 rpm causes a 48.5% reduction in CO emission, 31.1% reduction in NOx emission and 58.5% reduction in specific fuel consumption. Moreover, the engine thermal efficiency and output power increased by 10.1 and 4.72%, respectively. When ethyl alcohol is increased over 30%, it causes unstable engine operation which can be related to the fact that the fuel is not vaporized, and this causes a reduction in both, the break power and efficiency.

Considering energy crises and pollution problems today, investigations have been concentrated on decreasing fuel consumption by using alternative fuels and on lowering the concentration of toxic components in combustion products. In the present work a quasi-dimensional model was developed to study the effect of hydrogen blending on fuel consumption and pollutant concentrations. The results of the study show that the maximum improvement in engine thermal efficiency occurs at 8% hydrogen blending. The results also show that 10%hydrogen blending reduces CO concentration by 73.8% but the NO concentration increases by100%. However the problem of increasing NO con- centration was solved by operating the engine with lean mixture. Hydrogen blending also reduces the specific fuel consumption until about 6%blending, then the effect becomes marginal. 1999 International Association for Hydrogen Energy. Published by Elsevier Science Ltd. All rights reserved.