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The influence of preheat temperature on methane-air laminar burning velocity was investigated with a burner tube technique. The measurements were made by varying preheat temperature from 30°C to 600°C, pressure from 0.1MPa to 0.3MPa and equivalence ratio from 1.0 to the fuel-lean measurable limit(>0.5). The laminar burning velocity was determined using the area method visualized with schlieren photography. It shows a strong dependence on preheat temperature and increases proportionally to the approximate square of the preheat temperature at constant pressure. While the increase of pressure decreases the burning velocity, the dependence is relatively small.

In order to reduce smoke exhaust from diesel engines, experimental research was conducted on the forced mixing and dissolving of air into diesel fuel and on operation of diesel engines with such fuel. First, an air-fuel mixing system was made, which could be mounted and operated on existing diesel engines with minimum alteration to the fuel injection system, and the performance of the mixing system was investigated. Then, the system was applied to a single-cylinder test engine which could be operated both as a prechamber type and as a direct injection type engine; it was test operated with these two combustion methods, and an effective reduction in the density of exhaust smoke was confirmed.

A hydrogen-fueled engine system with spark ignition, low pressure direct gas injection and metal hydride as the hydrogen storage medium was developed. Although it is known that direct injection effectively increase power and prevent backfiring of spark ignited hydrogen engine and that metal hydride is promising as the hydrogen fuel source, no engine system has been made which combines those two features. It is because that the hydrogen gas pressure generated from the metal hydride is generally not high enough for direct injection into the cylinder. This paper reports the features of the newly developed hydrogen engine system together with the experimental vehicle which carries the engine system, and the on board test results.