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Impact of Medium-pressure Direct Injection Engine Fueled by Hydrogen


In the automotive sector, hydrogen is being increasingly explored as an alternative fuel to replace conventional carbon-based fuels. Its combustion characteristics make it well-suited for adaptation to internal combustion engines. The wide flammability range of hydrogen allows for higher dilution conditions, resulting in enhanced combustion efficiency. When combined with lean combustion strategies, hydrogen significantly reduces environmental impact, virtually eliminating carbon dioxide and nitrogen oxide emissions while maintaining high thermal efficiency. This paper aims to assess the potential of using an outwardly opening poppet valve hydrogen direct injection (DI) system in a small engine for light-duty applications. To achieve this, a comparison of performance, emission levels, and combustion parameters is conducted on a single-cylinder spark-ignition (SI) research engine fueled by hydrogen, using both port fuel injection (PFI) and this new direct injection system. Two different engine loads are measured at multiple air dilution and injection timing conditions. The results demonstrate notable efficiency improvements, ranging from 0.6% to 1.1% when transitioning from PFI to DI. Accurate control of injection timing is essential for achieving optimal performance and low emissions. Delaying the start of injection results in a 7.6% reduction in compression work at low load and a 3.9% reduction at high load. This results in a 3.1-3.2% improvement in ISFC in both load conditions considered.

Funding source: This research has been partially funded by Agencia Estatal de Investigación of the Spanish Government through project TED2021- 130596B-C21 (BIOH2FUEL). M. Olcina-Girona is partly supported by the grant CIACIF/2021/437 of the ‘‘Subvenciones para la contratación de personal investigador predoctoral (ACIF)’’ of the Conselleria d’Innovació, Universitats, Ciència i Societat Digital de la Generalitat Valenciana. Funding for open access charge: CRUE-Universitat Politècnica de València
Related subjects: Applications & Pathways
Countries: Spain

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