Study of Basic Injection Configurations using a Direct-Injection Hydrogen Research Engine

The application of hydrogen (H-2) as an internal combustion (IC) engine fuel has been under investigation for several decades. The favorable physical properties of hydrogen make it an excellent alternative fuel for fuel cells as well as IC engines and hence it is widely regarded as the energy carrier of the future. The potential of hydrogen as an IC engine fuel can be optimized by direct injection (DI) as it provides multiple degrees of freedom to influence the in-cylinder combustion processes and consequently the engine efficiency and exhaust emissions. This paper studies a single-hole nozzle and examines the effects of injection strategy on engine efficiency, combustion behavior and NOx emissions. The experiments for this study are done on a 0.5 liter single-cylinder research engine which is specifically designed for combustion studies and equipped with a cylinder head that allows side as well as central injector location. A single-hole nozzle was placed in central location next to the spark plug and the fuel jets were oriented in a variety of different directions. Tests were conducted at different load points for all the injector orientations and the effects of varying the start of injection (SOl) timing on engine efficiency, combustion durations and NO) emissions were studied. The results show that the engine efficiency and NO) emissions are sensitive to the orientation of the fuel jets and the sensitivity varies with respect to different load conditions.