The goal of this research is to reduce nitrous oxide (NOx) and carbon monoxide (CO) emissions and to retain the performance characteristics of a diesel engine by modifying the in-cylinder combustion process. To accomplish this goal, a direct-injected diesel engine was converted to a homogeneous charge, catalytic compression ignition (HCCI). The engine runs on aqueous ethanol supplied by an electronic fuel injection system.
Central to this engine conversion is a catalytic igniter consisting of a platinum catalyst element enclosed in a small pre-chamber adjacent to the main combustion chamber. The catalytic igniter failed in initial tests with the high compression engine, forcing a redesign of the igniter core. Over 50 hours of engine testing were completed with the new igniter design. The testing was conducted with a mixture of 30 percent water and 70 percent ethanol. A tenfold decrease in nitrous oxide (NOx) emissions, a 10 percent increase in maximum power output, and a one percent improvement in specific fuel consumption were observed compared to the original engine configuration. Even more significant performance improvements are likely to occur in future engine testing when ignition timing is optimized. The results to date show promise for adding this technology to turbo-charged diesel engines.