Using Ethanol/Diesel Mixtures in a Compression Ignition Engine with Ignition Improver Additives

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. Higher order alcohols were used as additional surfactants in order to achieve phase stability comparable to commercial gasohol with water contamination. A final preferred Diesohol (i.e. diesel/alcohol) blend containing approximately 67.93% D-2 diesel fuel, 25% ethanol, 5% butanol, 2% ignition improver additive, and 0.07% Lubrizol additive was further tested including gaseous emissions. The blend showed a reduction in NOx, CO2 and soot emissions. HC emissions were increased. CO emissions were reduced at high load but increased at low load.