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An experimental investigation was carried out to assess the effect on engine operation of the addition of 20% hydrogen by volume to natural gas. Blends of hydrogen and natural gas are referred to as hythane in this report. Three groups of testing were conducted. All the tests were conducted at light loads similar to those in urban driving. The first group of tests were conducted using a 2.0 liter Nissan four cylinder engine to measure the increase in flame front propagation rate when fueled with hythane as compared to pure methane (simulating natural gas). The second group of tests were conducted with a 1.6 liter Toyota four cylinder engine to measure the changes in emissions and thermal efficiency comparing hythane operation to pure methane operation.

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 following report covers the design, and testing of a dedicated hydrogen-fueled engine. Subsequent modifications to the design are also covered. Both part-load and full-load data were taken under laboratory conditions. The engine design included a billet aluminum single combustion chamber cylinder-head with one intake valve, two sodium cooled exhaust valves, and two spark plugs. The cylinder-head design also included drilled cooling passages. The fuel-delivery system initially employed two modified Siemens electrically actuated fuel injectors. Subsequent modifications allowed operation with a premixed hydrogen-air mixture. The exhaust system included two separate headers, one for each exhaust port. The piston/ring combination was designed specifically for hydrogen operation.