Realizing low NOx emissions on a hydrogen-fuel spark ignition engine at the cold start period through excess air ratios control

• Published in: International journal of hydrogen energy 2018-11, Vol.43 (46), p.21617-21626
• Main Authors: Xu, Puyan, Ji, Changwei, Wang, Shuofeng, Bai, Xiaoxin, Cong, Xiaoyu, Su, Teng, Shi, Lei
• Format: Article
• Language: English
• Subjects: Cold start; Emission control; Excess air ratio; Hydrogen; Hydrogen-fueled engine
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2018.09.136

In this paper, the effects of excess air ratios (λ) on nitric oxide (NOx) emissions of a hydrogen-fueled spark ignition engine in the cold start period are studied. Cold start characteristics of hydrogen-fueled engine were investigated experimentally. The study was performed under different λ. The experimental results showed that, when λ declined from 1.6 to 0.7, the peak engine speed within the first 6 s increased and in-cylinder pressure in the first cycle raised firstly then decreased slightly while the flame development and propagation periods shortened, and the exhaust temperature at the 6th s raised from 329 K to 355 K. In addition, NOx emissions obviously decreased, whereas hydrocarbon (HC) and carbon monoxide (CO) emissions caused by the evaporated lubricant oil increased by decreasing λ within the first 6 s. •A hydrogen-fueled engine with low emissions in the cold start was realized.•Engine combustion and emission performances have been studied in this paper.•The flame development and propagation periods were shortened.•NOx emissions were decreased, HC and CO emissions were increased.