The Combustion Characteristcs And Performance For SI Engine Fueled With Methanol/Gasoline

With the rapid development of the automobile industry, oil resource has been consumed more and more by the vehicles, and that leads to relative shortage of energy and the increasing dependence on overseas oil in our country. According to the latest data, China's dependence on imported oil will be close to 60% in 2011. So, the implementation of energy diversification strategy is imperative. As a fuel, methanol is high oxygen content and can be full combustion. And it can be produced by coal. China has abundant coal resources, and the technology of producing methanol by coal is perfect and cost is low. So the methanol can be one of the effective alternatives to petroleum resources.In the experiment, the engine is controlled respectively by the original electronic control unit (ECU) and the special ECU for the methanol to burn the various proportions of methanol-gasoline., and all of the combustion characteristics in the cylinders, power, fuel economy, regulated emissions and non-regulated emissions, are compared and analyzed. And the sensor for detecting the volume concentration of methanol-gasoline is studied and developed.The results show that the sensor for detecting the relative volume concentration of methanol-gasoline can give the corresponding the voltage signals quickly and accurately on the basis of the different concentrations. Compared to the original engine, the engine burning the low proportion of methanol-gasoline makes that the maximum combustion pressure and the pressure rising rate has increased, and the ignition delay and rapid burning duration shorten , also the heat release is in advance, the pressure cyclic variation increases slightly as well when full load. When controlled by methanol ECU, the maximum combustion pressure and pressure rising rate are both higher than that of gasoline and low proportion methanol-gasoline, and the ignition delay and rapid burning duration are both shorter significantly, also the pressure cyclic variation are decreased evidently. When fueled with moderate proportion of methanol-gasoline, the engine combustion is deteriorated in the control of either gasoline ECU or methanol ECU. In the control of methanol ECU the engine fueled with high proportion methanol-gasoline, the engine's power is higher than that of the gasoline and low proportion methanol-gasoline. When fueled with low proportion methanol-gasoline in the control of gasoline ECU, the engine's power is almost the same as the original engine. The engine's fuel economy is better than that of gasoline when fueled with methanol and low proportion methanol-gasoline. But the methanol mixing ratio is larger, and the fuel economy is worse. With the increasing of methanol proportion, when fueled with the high proportion methanol-gasoline, the engine's NOx and THC emissions are lower than that of low proportion methanol-gasoline, but CO emission is relative higher. Considering the non-regulated emissions, when fueled with containing methanol, the engine's methanol and formaldehyde emissions are higher than that of gasoline. The mixing proportion is larger, and the emissions are higher. Owing to the gasoline contained the ethylene etc, the engine's acetaldehyde emission is higher than the fuel contained the methanol.