Fuel Cell Systems Modelling for Heavy Duty Road Vehicles

The road transport sector is undergoing major transformations as a consequence of the compelling need of reducing carbon dioxide emissions, with many countries imposing limits to production and sale of fossil fuel vehicles in the near future. If produced through clean energy, hydrogen could represent a feasible solution for reducing emissions of long haul heavy duty road transport: one possible exploitation of hydrogen is in proton exchange membrane fuel cells (PEMFC), which can also provide an improvement in powertrain efficiency compared to internal combustion engines. Numerical simulations are a necessary tool in supporting the development of PEMFC systems, enabling their systematic analysis, fine-tuning, and optimization. This work focuses on fuel cell systems simulation, carried out with the commercial software GT-SUITE with the aim of calibrating the electrochemical model through a genetic algorithm and then optimizing the system components around the stack, understanding their behaviour in different operating conditions and finding optimal working parameters. The system performance has been analysed by means of a sensitivity analysis on pressure, air stoichiometric ratio and inlet air relative humidity, with a particular attention on water management in the fuel cell to avoid the phenomena of cathode flooding, associated with a major performance loss. Different results have been obtained based on operating temperatures and current density of the fuel cell, reaching efficiency values up to 47% at full power and over 55% at partial loads. At last, the liquid coolant circuit is analysed, which represent a critical aspect for fuel cell powered road vehicles since high amount of heat has to be rejected to the environment, forcing the use of big radiators to keep the system at an adequate working temperature.