Hydrogen-fuelled internal combustion engines (ICEs) offer a zero-carbon fuel option for many applications. As part of the global effort to study hydrogen ICEs Ricardo has developed single-cylinder and multi-cylinder heavy-duty engines.

The engines are representative of a 13 litre Euro VI heavy-duty production application converted to run on hydrogen fuel with limited changes. The engine is fitted with direct hydrogen injectors which enable flexible injection strategies and reduce hydrogen in the intake system. Steady-state testing was carried out over an array of speed and load points covering a typical heavy-duty drive-cycle area.

Engine test results are presented and analysed in this paper. The combustion system can run to values exceeding lambda 5 and 40% exhaust gas recirculation (EGR) can be tolerated. The impact of lambda, EGR, injection and ignition timing variations are presented and demonstrate how the system responds to the corresponding changes in specific heat capacity, mixture preparation, and combustion phasing.

Abnormal combustion events present a sizeable challenge for hydrogen ICEs due to very large knocking pressures and pre-ignition risks. These events are analysed and mitigation measures presented.