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A premixed charge compression ignition methanol engine targeting a drastic decrease in NOx emissions and a brake specific energy consumption equivalent to that of a DI diesel engine has been developed (1). The problems of this combustion system are that the brake thermal efficiency decreases, and CO and THC emissions increase due to a deterioration of high load combustion. The purpose of this study is to improve the high load combustion of a premixed charge compression ignition methanol engine using a flash boiling fuel injection technique. The results of this study have shown that the premixed charge compression ignition methanol combustion system using a flash boiling fuel injection technique increases the brake thermal efficiency, decreases CO and THC emissions, while maintaining low NOx emissions in the high load region.

A new combustion system targeting a drastic decrease in NOx emission and a brake specific energy consumption equivalent to that of a DI diesel engine has been developed. In this new combustion system, a lean burn system using early injection was employed to reduce NOx emission and an auto-ignition DI engine system was employed to achieve the low energy consumption. Methanol was used as the fuel for reducing NOx emission. The objective of this study is to clarify the possibility of the system for the auto-ignition of a premixed lean mixture of methanol fuel. This study shows that the gas temperature at ignition, Tig, is the predominant factor affecting auto-ignition. Auto-ignition occurs when Tig exceeds approximately 1000K. The methanol lean burn system in an auto-ignition DI engine drastically decreased NOx emission with almost the same brake specific energy consumption as a diesel engine in the middle load region.

An autoignition DI methanol engine has been developed to improve the thermal efficiency under low load conditions. The engine was compared with glow-assisted and spark-assisted DI methanol engines, and with conventional DI diesel engines. The results show that the autoignition occurs when the gas temperature in the cylinder exceeds approximately 900K. In the autoignition DI methanol engine, combustion proceeds rapidly, which results in high peak of heat release and short combustion duration. The thermal efficiency of the autoignition DI methanol engine, therefore, is higher than that of other type methanol engines and almost the same as that of diesel engines under low load conditions. NOx of the autoignition DI methanol engine is the lowest since it has the highest EGR.

Although the exhaust gas in a heavy-duty methanol engine is an oxygen rich atmosphere, there is some unburned methanol in the exhaust gas. Then, NOx control concept using lean NOx catalyst with unburned methanol as the reducing agent is considered. The purpose of this study is to verify the capability of lean NOx catalyst to reduce NOx in actual methanol engine exhaust. It was found through synthetic gas tests that alumina catalysts are effective for NOx removal. It was also found through engine tests that the catalyst temperature range between 500 °C and 600 °C and space velocity of less than 20,000 1/hr are requirements for a high NOx conversion efficiency. Although NOx conversion efficiency decreased at full load engine condition, it could substantially promote NOx conversion efficiency to add methanol into the exhaust gas before the catalyst bed.

In order to investigate the impact of the Ethanol content on existing domestic Gasoline vehicles, we conducted an exhaust gases test, a fuel evaporative emissions test, a high-temperature driveability test, and a material impact test. As a result, no safety problems occurred in the metal material impact test at an Ethanol content of 3% or less. In the exhaust gases test, the fuel evaporative emissions test, and the high-temperature driveability test, no problems occurred at an Ethanol content of 3% or less. Based on these results and discussions conducted by the fuel policy subcommittee of the advisory committee for natural resources and energy survey, it was concluded that the Ethanol content in Gasoline must be 3% or less and the oxygenate (alcohol etc.) content must be limited to a value corresponding to a total oxygen content of 1.3% or less. The results obtained by this study were reflected in the Japanese Gasoline compulsory quality regulations.

In 1999, some Japanese fuel suppliers sold highly concentrated alcohol fuels, which are mixtures of gasoline and oxygenates, such as alcohol or ether, in amounts of 50% or more. In August 2001, it was reported that some vehicle models using the highly concentrated alcohol fuels encountered fuel leakage and vehicle fires due to corrosion of the aluminum used for the fuel-system parts. The Ministry of Economy, Trade and Industry (METI) and the Ministry of Land, Infrastructure and Transport Government of Japan (MLIT) jointly established the committee on safety for highly concentrated alcohol fuels in September 2001. The committee consisted of automotive technology and metal corrosion experts knowledgeable about preventing such accidents and ensuring user safety. Immersion tests were conducted on metals and other materials used for the fuel-supply system parts to determine the corrosion resistance to each alcohol component contained in the highly concentrated alcohol fuels.