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Proton Exchange Membrane (PEM) Fuel Cell (FC) presents itself as a promising technology in view of zero-tailpipe emission vehicles. In addition, the constant development of renewable energy sources will lead to an increase in green hydrogen availability, and thus completely eliminate emissions for devices that use H2 as an energy vector. However, PEM FCs are still far from being fully developed as a technology: thermal and water management are the main issues that researchers are studying through experiments and Computational Fluid Dynamics (CFD) simulations. For the numerical approach, H2O removal models often consider a simplified flat surface, but the microgeometry of the Gas Diffusion Layer (GDL) has a leading role in determining the critical dimension for droplet detachment and how much resistance the surface poses to water sliding. The aim of this paper is to investigate the influence of droplets number on a GDL.

In a previous paper, the authors assessed the potential of CFD modeling in developing a new intake system for a small spark-ignition engine. The effect of the intake port and valve design on the charge motion within the cylinder was illustrated [1]. In this paper, a detailed analysis of the influence of the intake port geometry on the combustion process, therefore on the performance, of a MPI spark-ignition engine has been carried out. The purpose of such a theoretical analysis is to provide some guidelines, in developing new intake solutions, aimed to improve the combustion quality of a production engine on the market since the early 80's. A 3-D computer code has been used to model the intake, compression and combustion processes of the engine. The model has been validated comparing the computational results to the data, relative to the normal production engine, provided by the manufacturer.

Hydrogen and gasoline can be burned together in internal combustion engines in a wide range of mixtures. In fact, the addition of small hydrogen quantities increases the flame speed at all gasoline equivalence ratios, so the engine operation at very lean air-gasoline mixtures is possible. In this paper, the performance of a spark-ignition engine, fuelled by hydrogen enriched gasoline, has been evaluated by using a numerical model. A hybrid combustion model for a dual fuel, according to two one-step overall reactions, has been implemented in the KIVA-3V code. The indicated mean pressure and the fuel consumption have been evaluated at part load operating points of a S.I. engine designed for gasoline fuelling. In particular, the possibility of operating at wide-open throttle, varying the equivalence ratio of air-gasoline mixture at fixed quantities of the supplemented hydrogen, has been studied.