An Evaluation of Unthrottled Combustion System Options for Future Fuels

Demand upon finite petroleum crude reserves is forcing various countries to examine alternatives. Within the USA liquid hydrocarbon fuels manufactured from coal and oil shale are envisaged. When considering such alternatives, the trade-offs between the production costs, fuel specifications and the technical implications in use must be studied.

This paper describes a programme of work examining the interaction between several fuel/light duty engine combinations. Com-bustion systems covered indirect and direct injection diesel and spark ignited stratified charge. Fuels primarily covered D-2 diesel, naphtha and intermediate broad-cut blends. Low ignition quality diesel fuels were also addressed.

The data obtained assists in the selection of candidate combustion systems for future fuel groups based upon baseline performance characteristics. Performance and environmental penalties as appropriate are also highlighted relative to each candidate. Further work areas for a fuller understanding are also reviewed.