The environmental potential of hydrogen addition as complementation for diesel and biodiesel: A comprehensive review and perspectives

At present, the world petroleum resources are very scarce, and environmental pollution is very serious, which is closely related to the wide application of diesel engines. It encourages researchers to explore more environmentally friendly fuels. In recent years, the research on hydrogen as an alternative fuel has been deepened. Previous studies mostly focused on the influence of hydrogenation on combustion, performance and emission characteristics of internal combustion engines when operating parameters were changed or some technologies were adopted. However, few people have reviewed the combined effects of hydrogen and other alternative fuels on diesel engines. This paper makes an in-depth analysis of the research on the field of alternative fuels in recent years. Firstly, this paper introduces alternative fuels, hydrogen production technology and dual fuel technology. It also highlights the application of hydrogen as an alternative fuel in internal combustion engines. Secondly, the performance, combustion and emission characteristics of diesel engine are analyzed emphatically under dual-fuel mode. Then, the problems of high NOx emission and limited hydrogen energy share in the current dual-fuel engine research are also discussed. In addition, this paper also expounds the technology of homogeneous charge compression ignition (HCCI) strategy, water injection strategy and compression ignition to alleviate the shortcomings of diesel-hydrogen dual fuel engine. The purpose of this paper is to provide information for engineers and researchers interested in hydrogen. This paper summarizes a large number of high-quality journal literature, including the latest publications.