Performance Study For Electronic Controlled Engine Fuelled With Natural Gas-Hydrogen Mixtures

Fossil fuel reserves all over the world are diminishing at an alarming rate and a shortage of crude oil is expected at the early decades of this century. These factors have lead researchers to introduce more clean alternatives used to power ICEs.The merits of H₂ as a fuel make it more popular. HCNG (natural gas-hydrogen blends) is one kind of transitional fuel which has very large potential before the technologies of H₂ engine are well developed. Therefore, performance study for HCNG engine is necessary and valuable.This paper is a part of project 50676008 supported by National Natural Science Foundation of China.In this study, an electronic controlled multi-cylinder CNG engine is rebuilt to be a HCNG engine. The control strategy of ECU for HCNG engine is studied. CNG/H₂ double multipoint injection control system is developed. Application of Bayesian networks for engine fault diagnosis is analyzed and the troubleshooting function in ECU is realized.One single-cylinder HCNG engine is used for the investigations. By the orthogonal tests method, the individual influences of different factors to HCNG engine are obtained. Further more, the survey for the effects of air excess factor and spark advance angle is conducted. Result shows that when the hydrogen fraction is in the range of 15%～25%, engine power and efficiency increase and the HC,CO,CO₂ emissions decrease with the increase of hydrogen fraction in HCNG fuel. When blending H₂ into CNG, lean burn limit is extended. Using HCNG at relatively leaner fuel-air mixtures and retarded spark timing can totally improve the engine emissions without lower the thermal efficiency.