Christophe Josset

Global energy optimization of a light-duty fuel-cell vehicle

In this paper, an analytic tank to wheel model of a light-duty fuel-cell vehicle is presented. This model takes into account all the elements of the vehicle along with their interactions. It is used to optimize the velocity profile of the vehicle in order to minimize the energy consumption per kilometer.

Multiphysics Modeling and Driving Strategy Optimization of an Urban-Concept Vehicle

This paper is dedicated to the optimization of the driving strategy of a high efficiency fuel cell based power train. This power train is developed to equip an urban-concept vehicle that runs energetic races where the objectives are to go the furthest with the lowest quantity of fuel (Shell Eco Marathon). Through a comprehensive dynamical model, including the mechanical requirement, the thermal behavior of the fuel cell stack and the various losses and consumption of the power train devices. This model is then integrated into a global optimization algorithm, to determine the best race strategy to be adopted (velocity profile, motor current, gearbox ratio).

Change of Preferential Liquid Breakthrough Pathways in PEMFC Gas Diffusion Layers: Evidence of Pressure-Induced Dynamic Transport

In this work, the change of liquid water preferential pathways through PEM fuel cell Gas Diffusion Layers (GDL) with ex situ devices is investigated. A capillary network constituted of two connected micro channels is first developed. It is shown that once the larger channel has been invaded, the pressure variation due to the growth of the water droplets at the channel tip enables the liquid water to invade the smaller capillary channel. At the end, the liquid preferential path is modified. This result is then generalized considering a real GDL. Liquid water is injected through the GDL to a micro channel, and changes in liquid water pathways are observed after several hours of operations. The reported experimental observations show that pressure-induced dynamic transport due the water droplet eruption in the channel has to be taken into account to predict the preferential pathway after long time of fuel cell operation.

Fluid dynamic breakthrough in two connected capillaries: From stationary to oscillating state

In this paper, we investigate the pore structure and the impacts of Haines jumps on the change in preferential pathways (called the dynamic breakthrough) during fluid percolation through thin porous media. Two capillaries connected in parallel are used to represent a thin porous medium, and Haines jumps are observed through the formation of droplets. Using a droplet growth model and experimental visualisations, the change in preferential pathways is shown to be strongly influenced by the pore lengths, pore radii ratios, and droplet detachment volumes. This work provides a better understanding of the redevelopment of continuous fluid paths observed through thin porous media in electrochemical systems.