HYDROGEN DIRECT INJECTION IN RECIPROCATING ENGINES USING COMMERCIAL INJECTORS

Several techniques are being developed to solve the problem of urban pollution. Among other solutions (improvements in engine control and combustion, electrical propulsion) one of the possibility is the employment of low carbon content fuels. A nearly zero emission vehicle may be propelled by hydrogen, in this case the only polluting agents are nitrogen oxides when using internal combustion engines. Though fuel cells are considered to be the most promising solution in the long term, they are still in the prototypical phase, while the internal combustion engine continues to be a relevant topic. Hydrogen used as a fuel, combined with hybridization was considered to be a very effective solution for urban vehicles such as small buses or light duty vehicles. In particular, series hybrid vehicles can use very small displacement engines as range extenders resulting in a noticeable fuel economy when considering urban cycles. This document is the Doctor of Philosophy course thesis in Land Vehicles and Transport System. The object of the thesis is the study of a hydrogen direct injection system for reciprocating engines using commercial injectors. In particular, this study is applied to a $505cm^3$ single-cylinder engine. This is a typical unit displacement and consequently it will be possible to extend the results to multi-cylinder engines for automotive purpose. This activity is a part of a project funded by the Tuscan region and carried out in cooperation with several Departments of the University of Pisa.