ABSTRACT
Diesel (or compression-ignition) engines are the most efficient energy con verters among all reciprocating engines. They are also among the best che mical to mechanical energy converters, with an efficiency that can be higher than 50%. This is due to a thermodynamic cycle with a high compression ratio, reduced pumping losses during the intake cycle (throttleless opera tion), and a capability to burn very lean mixture. Moreover, diesel fuel is more energetic than gasoline, providing compactness of energy storage. Diesel combustion, at least up to now, is straified and lean. This allows for very low emission levels of CO and HC. Since part of the mixture burns in a rich regime, soot can occur, and a tradeoff as always is to be found with NO emission depending on peak pressure timing.
