ATEX Volume & Water Cooling Modeling at Swiss Solar Boat

Following Swiss Solar Boat’s participation in the Monaco Energy Boat Challenge (MEBC) in 2021 and 2022, the team recognized the crucial need to improve the boat’s autonomy. This reflection led to the development of the Renewable Energy Foiler (REF), a three-seater solar–hydrogen hybrid foiling boat.

In this context, I was first responsible for translating the MEBC hydrogen safety rules and applying them to the REF in order to determine the ventilation system specifications. This involved the modeling of hydrogen (H₂) diffusion inside the boat compartments in the event of a small crack in the piping.

Since hydrogen is stored at very high pressure, the gas would escape at supersonic velocity in the event of a leak. Classical fluid mechanics is therefore not applicable in this region, so a compressible fluid dynamics model was first used to describe the jet behavior at the leak, before switching to classical fluid mechanics and to a diffusion model for the rest of the compartment.

This approach made it possible to determine the required ventilation flow rate needed to keep the H₂ concentration below the lower flammability limit.

In addition, since the fuel cell requires water cooling, I contributed to the modeling of different cooling systems by evaluating the pressure losses and heat flux evacuated for different designs, in order to identify the most efficient configuration compatible with the boat’s constraints.

Skills Used

• Modeling high-pressure H₂ flow (compressible regime and diffusion)
• Design of the ventilation system for ATEX safety
• Analysis of pressure losses, flow rates, and thermal transfers in cooling systems
• MATLAB, Microsoft Excel, compressible/incompressible fluid mechanics, heat and mass transfer