Comprehensive experimental and numerical investigation on a dedicated hydrogen combustion system for heavy duty application

Abstract

In the critical context of global warming, the diversification of the energy sources is urgently required. Regarding mobility, in addition to vehicles electrification and advanced biofuels, hydrogen holds the potential to address significant emission reduction for internal combustion engines. This approach preserves the advantages of current fossil fuel engines, such as established and proven technology, long lifespan, controlled costs, and an ultra-low carbon footprint. Hydrogen is convenient for heavy-duty and off-road applications for which battery capacity is challenging. Currently, two approaches cohabit in the engineering of hydrogen internal combustion engines: the adaptation of a Diesel-based engine or the design of a brand-new engine dedicated to hydrogen. The presented study focuses on a dedicated combustion chamber for hydrogen combustion for heavy-duty applications with a pent-roof cylinder head and a specific piston shape. The key features of the combustion system have been defined through numerical analysis, focusing on the main challenges of hydrogen combustion engine: fuel/air mixing quality, combustion process, and resistance to abnormal combustions. A heavy-duty single-cylinder engine equipped with this optimized combustion system has been tested on a test bench using hydrogen with realistic conditions for the air loop. The test campaign has been focused on the injection strategy and the identification of the optimal settings. A new methodology for characterization of abnormal combustion has been developed to precisely detect pre-ignition or knock at high load. The main limitations have been identified to operate the engine at full load. Finally, the engine has been tuned in the whole operating range with optimal settings and the performances have been benchmarked by comparing with current engines fueled with Diesel or natural gas. 3D simulation feedback has been done also through the test campaign to assess the validity of the numerical approach used to design this hydrogen combustion system.