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The purpose of this study is to reduce cooling loss in gas engines using hydrogen. In this report, the effect of different hydrogen-CNG supply methods on combustion and exhaust characteristics of SI engine were investigated. As a result, the 13A-port-injection caused sharp heat release at hydrogen addition ratio (RH) of 20 %, with a maximum brake thermal efficiency of 27.5 %. Also, the hydrogen-port-injection promotes combustion above RH=40 % and reduces cooling loss, resulting in a maximum brake thermal efficiency of 31.0 % at RH=80 %, 1.8 pt higher than that of the 13A-port-injection.

In recent years, internal combustion engine using hydrogen gas, has attracted attention as one solution to the problem of global warming. Hydrogen gas has excellent combustion characteristics such as wide limits of inflammability and fast burning velocity because of high diffusion rate. Therefore, it has been made to obtain stable ignition and combustion by adding hydrogen with lean mixture in spark ignition engines using hydrocarbon fuels and to be attempted efficient operation by engine researchers. The purpose of this study is to reduce cooling loss in a gas engine using hydrogen gas and hydrogen Mixer system (Mixer) engine was remodeled to hydrogen Port Injection (PI) system engine. In this report, the heterogeneity of hydrogen mixture is clarified by comparing the combustion characteristics of the Mixer and the PI, and the effect of the difference in hydrogen supply systems on cooling loss is system. Ignition delay of the PI system is shorter than that of the Mixer.

In recent years, depletion of energy resources and increasing CO2 emission have been concerned. As this solution, the use of biofuels from garbage is focused. In this research, higher efficiency and lower emissions in the gas engine for power generation using biomass gas are aimed. However, the biomass gas is low caloric value and the output is low and the combustion is unstable. Therefore, a turbocharged spark ignition gas engine is used as the test institution. As a result, it is found that combustion stability and high efficiency of biomass gas can be realized.

Bio-mass fuel gas is very important because bio-mass gas is renewable and carbon free. Especially, woody chips are very popular and are not used efficiently. Gasifier makes the producer gas from woody chips. Conventionally, dual fuel engines are used to generate electricity by producer gas and light oil. As the dual fuel engine can run under the low heating value gas, dual fuel engine is very useful. As light oil is fossil oil, it is not carbon free. If bio-mass gas engine can run only by producer gas, this power unit is carbon free. As the heat value of producer gas is very low and fluctuates always, bio-mass gas engine should be controlled A/F precisely. As the producer gas contains of hydrogen from 15 to 18%, NOx should be higher on concentration of 15 % hydrogen. Output of bio-mass gas engine should be low because of low heat value of producer gas. The three way catalyst can reduce NOx and CO. Stoichiometric mixture can make output higher than lean burn.

To control natural-gas HCCI combustion, internal exhaust gas recirculation (EGR) by exhaust valve reopening (EVRO) during the induction stroke was applied to a single-cylinder test engine. The results demonstrate that combustion phasing can be controlled successfully by adjusting the EGR ratio, and so improvement of thermal efficiency and reduction in unburned exhaust emissions are feasible. In addition, the results of the EVRO method were compared to those of intake-valve pilot opening (IVPO) during the exhaust stroke. It was shown that EVRO is more useful than IVPO as a heat-recovery method for HCCI combustion.