Influence of Pilot Fuel Injection Timing on Emissions from a Hydrogen Diesel Dual Fuel Engine

摘要

Diesel engines, over a period of time, have become indispensable to public transportationsector as well as mechanized agricultural sector. The problem of diesel fuel crisis has badlyaffected several activities in the developing countries. In this context is essential that a non-pollutingalternative fuel must be identified for use in existing diesel engines. Hydrogen, inview of its infinite source potential and clean-burning characteristics provides a readysolution to both these problems.This paper describes the tests carried out in the Engines and Unconventional Fuels Lab ofIndian Institute of Technology, Delhi on a multicylinder stationary diesel engine converted tohydrogen-diesel dual fuel mode of operation. The existing system hardware in the engine wasmodified to induct hydrogen into the engine system at an appropriate location so as to ensuresmooth engine operation without any undesirable combustion phenomena such as knockingand rapid rate of pressure rise.Significant performance and emission parameters of the system developed with hydrogen-dieseldual fuel were compared with neat diesel operation. Exhaust emission characteristicsof the engine were largely influenced by the Injection angle of the pilot fuel. Retarding thepilot fuel injection angle resulted in increased oxides of nitrogen emissions. Within aspecified range of pilot fuel injection retard angle a substantial reduction in both hydrocarbonand smoke opacity emissions were achieved. The injection angle was observed to be a verycritical parameter for engine performance and exhaust emission characteristics. Smokedensity exhibited an increasing trend with increase in injection retard angle. An increase ininjection retard angle had a glaring influence on the level of HC emissions. This study showsthat an optimum injection angle of the pilot fuel is extremely critical to the overall emissionbehaviour of the engine.