The BMW Group Forschung and Technik has joined forces with researchers from Graz and Vienna to develop a hydrogen combustion engine that achieves an efficiency level of up to 42 per cent – placing it on a par with the best turbo-diesel engines.
The so-called H2BVplus project was aimed at investigating the hydrogen self-ignition combustion process with current hydrogen combustion engines ignited by a spark. With the need for high efficiency on both economic and energy grounds, a hydrogen engine comes into its own due to its excellent ability for turbo-charging especially compared to spark-ignited engines as combustion anomalies such as backfiring and knocking can be ruled out. This increases the compression ratio.
With no particulate emission limit the hydrogen engine can produce effective pressure.
According to the researchers, the main challenge for combustion of hydrogen with self-ignition is the high auto-ignition temperature with other challenges including pressure increases, ignition pressures and the impact of high EGR rates and nitrogen oxide formation rates.
However, the newly developed system includes a new cylinder head for hydrogen operation based on a production diesel engine. It combines the strengths of diesel concepts with spark-ignition while utilising the combustion properties of hydrogen to achieve high efficiency values.
Test runs have shown that this combination followed by a diffusion style of combustion is ideal for engine efficiency.
