Simulation of hydrogen combustion in spark-ignition engines

Internal combustion engines (ICE) fuelled with hydrogen are highly efficient and have very clean emissions compared to polluting non-renewable fossil fuels such as diesel and gasoline. Extensive experimental studies have been conducted at the Laboratory for Transport Technology on the use of hydrogen in spark-ignition engines. Two engines, a GM 7.4 litre V8, and a one cylinder CFR engine have been converted to hydrogen. The objective was to better understand the combustion and injection characteristics and optimal set-up for propulsion of a hydrogen fuelled engine. The cost in both time and money were considered to be the greatest disadvantage. The research is now focussing on computer simulation because this can be done cheaply and give quicker results. Hydrogen is considered to be the fuel which eliminates harmful emissions (except NOx which is emitted at very low levels). A quasi-dimensional combustion model provided reasonable accuracy with fast computation. The greatest challenge for an accurate combustion model is the simulation of the large variation in air-fuel ratio seen in hydrogen fuelled engines. The key elements for the simulation of hydrogen combustion include laminar flame speed formula, heat transfer, and emissions. It was concluded that hydrogen fuel has a high flame speed and wide flammability limits, therefore a hydrogen engine is more efficient. 23 refs., 2 tabs., 5 figs.