Hydrogen has been identified as a promising decarbonization fuel in internal combustion engine (ICE) applications in many areas including heavy-duty on and off road, power-generation, marine, etc. Hydrogen ICEs can achieve high power density and very low tailpipe emissions. However, there are challenges; designing systems for a gaseous fuel with its own specific mixing, burn rate and combustion control needs, which can differ from legacy products. Characterization and elimination of hot spots within the combustion are key to preventing unwanted pre-ignition.
The primary pollutant of concern for Hydrogen ICEs is NOX and this can be addressed by running the engine at very lean equivalence ratios and the use of Exhaust Gas Recirculation (EGR). Computation Fluid Dynamics (CFD) is a valuable tool to model the combustion characteristics under different conditions and can also be used to predict thermal loading.
Being able to determine thermal distribution and temperatures of the power cylinder components has always been critical to the design and development of ICE programmes. This remains a key requirement when considering hydrogen as an alternative fuel for both clean sheet hydrogen ICE designs and implementation of fuel conversions. Significant improvements have been made in recent years in the speed and accuracy of CFD tools for combustion and thermal prediction, but these still present lead times that can preclude their use in early concept work or parametric studies.
A recently developed thermal Finite Element (FE) tool helps to reduce CFD and thermal survey costs, complementing these approaches to make the engine development cycle more efficient. This new FE based tool meets the current and future challenges of ICE design and development, to accurately predict the thermal loading and temperatures of an ICE quickly under multiple full-load and part-load conditions, relevant for hydrogen combustion development.
This paper presents how both CFD and the FE analytical tools are applied to a Euro VI HD engine converted to operate on hydrogen gas using direct injection. A CFD model is presented that accurately predicts the trends in engine performance and correctly captures the flame acceleration driven by thermo-diffusive effects. In addition, CFD combustion and FE temperature results are presented at low-, part and full-load conditions including a lambda swing to investigate the effect of different equivalence ratios on structural temperature. These data are compared with measurements taken from a single-cylinder engine tested at the Ricardo hydrogen test facility.
