Evaluation of Injector Location and Nozzle Design in a Direct-Injection Hydrogen Research Engine

The favorable physical properties of hydrogen (H₂) make it an excellent alternative fuel for internal combustion (IC) engines and hence it is widely regarded as the energy carrier of the future. Hydrogen direct injection provides multiple degrees of freedom for engine optimization and influencing the in-cylinder combustion processes. This paper compares the results in the mixture formation and combustion behavior of a hydrogen direct-injected single-cylinder research engine using two different injector locations as well as various injector nozzle designs.

For this study the research engine was equipped with a specially designed cylinder head that allows accommodating a hydrogen injector in a side location between the intake valves as well as in the center location adjacent to the spark plug. Indicated efficiency, emissions as well as in-cylinder pressure data and endoscopic images are used to evaluate the effects of injector location on the mixture formation and consequently the combustion process. In addition to the injector location, different nozzle designs specifically designed for either location are being investigated. The results showed significant differences in combustion and emissions performance between the central injector location and the side location.