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An experimental screening of non-nitrogen containing ignition improvers was conducted to investigate the possible use of diesel/alcohol fuel blends in an unmodified CI engine. The five non-nitrogen containing ignition improvers were: Di-Tertiary Butyl Peroxide; O,O-t-Amyl-O (2-Ethyl hexyl) monoperoxycarbonate; 1,1 Bis-(t-butylperoxy)-3,3,5-trimethylcyclohexane; Tertiary Butyl Hydroperoxide; and t-Amyl Perbenzoate. Alcohol content tested ranged from 10% to 100% by volume. For diesel/alcohol fuel blends containing more than 10% alcohol, BTEs similar to pure diesel could only be achieved with the addition of an ignition improver additive. Since diesel/alcohol blends separate with water addition, additives to improve water addition phase stability were also investigated. The blend employing the preferred ignition improver additive was found to have a greater ability to stay in solution than a control diesel blend without the additive.

The objective of the project reflected in this summary paper is to document an experimental design data-base on hydrogen-fueled automotive engines. The effort, sponsored by the U.S. Department of Energy, is directed toward possible future designs of airbreathing piston engines using hydrogen. To this end, pertinent performance and emissions (NOx only) characteristics of 16 engine configurations are presented graphically. Configurational variations of a 1600 cc automotive test engine included: throttled and unthrottled operation (i.e., quantity and quality power level control); central manifold, port, direct cylinder injection [not included]; single and divided combustion chambers; exhaust gas recirculation (EGR), water induction and air injection; and certain other features.

Present research efforts are pursuing the development of complex fuel delivery systems in an effort to successfully incorporate existing combustion chambers and coolant systems designed for hydrocarbon fuels into a hydrogen-fueled engine design. This paper presents the hypothesis that fundamental redesign of the combustion chamber shape and coolant passages can solve the hydrogen engine design problems more economically than redesign of the fuel delivery system. The differences in knock with hydrogen fuel and with hydrocarbon fuel are discussed. It is concluded that the combustion chamber shapes designed to reduce knock with hydrocarbon fuel actually promote knock with hydrogen fuel.