Proton exchange membrane fuel cell (PEMFC) is the most important system that converts chemical energy into electricity by using hydrogen oxidation and oxygen reduction reactions. With this approach, a 3-D (CFD) thermo-fluid model was studied using a commercial code ANSYS fluent for investigating the performance of the PEMFC system. The developed model can evaluate the distribution of gas species like the mass fraction of hydrogen, as well as the distribution of water in PEMFC. The results are used to investigate the influence of temperature and cell voltage on the consumption of hydrogen from inlet z= 0mm to outlet z=50 mm. The obtained polarization curve I-V is compared with the literature findings. The analysis shows a good agreement between our findings and the experimental results. The CFD simulation shows that the cell voltage affects considerably the hydrogen consumption; at 333 K, it can be seen that the hydrogen mass fraction decreases from 80% to 67% at 0.7 V and 80% to 73 % at 0.9 V. By comparing the hydrogen mass fractions; at a low cell voltage the hydrogen mass fraction dropped by only 7%, while at a high cell voltage the hydrogen mass fraction dropped by about 13% from the inlet to outlet. Consequently; our analyses show high consumption of hydrogen at low cell voltages.

The aim of this study is the search for new material for the manufacture of wind turbine blades in order to improve its performance and to reduce its cost. A composite material based on hemp natural fibres is studied. A numerical simulation using the finite element method is developed and a comparison of the performances of the new material with the usual composite of carbon fibres and glass is performed. The simulation allows us to calculate the proper values and the Eigenmodes of a wind turbine blade in the rotation. The results showed that the epoxy matrix allows to reduce the weight of composite hemp/epoxy relative to other matrix. It is almost 4.6% lighter than hemp/phenolic and 1.9% that hemp/polyester, so the blades hemp/epoxy has several advantages over the blades hemp/phenolic or over the blades hemp/polyester: this new material is characterised by lower weight and lower cost and has better mechanical features.   Keywords: Eigenmode, proper values, new material, blade, rotation.

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