The hydrogen-fuelled internal combustion engine (ICE) is a promising zero-carbon fuel powertrain for heavy-duty applications. Hydrogen engines have attracted increasing interest because they use robust and cost-effective technology to deliver de-fossilization along with competitive performance and very low NOx emissions.

This paper reports the development of a dedicated spark-ignition hydrogen combustion system. The combustion system employs a pent-roof four-valve layout with tumble intake ports and direct fuel injection in a cylinder size of 2.2 litres. Design, 1-D gas-dynamics and 3-D computational fluid-dynamics (CFD) simulation results are used to compare the characteristics of this second-generation engine to the converted flat head combustion systems previous developed by the authors. In-cylinder air motion and turbulence, air-fuel mixing, and combustion are all reviewed.

A single-cylinder research engine incorporating this dedicated SI combustion system has been manufactured and prepared for testing. Experimental results from the engine will be reported in future publications.

IMechE-74222-H2-ICE-07
Presented by Ricardo at the IMechE Powertrain Systems for a Sustainable Future Conference, October 21-22, 2025.