Experimental Study On Emissions, Detergency And Lubricity For Methanol Gasoline Engines

Methanol gasoline vehicles, which are partially used and demonstrated in China, have low fuel costs and high potential of energy saving and emissions reduction. But the harmful emissions, detergency and lubricity of methanol gasoline engines still get widespread attention. This paper first investigates the fuel quality of methanol gasoline in China market. And then engine bench tests and lubricant tribology tests are conducted to study the effects of methanol fuels on the emissions, detergency and lubricity of a port fuel injection gasoline engine. One kind of port fuel injection methanol gasoline engine is tested on the engine test bench, using 93# gasoline(M0), low proportion methanol gasoline(M15) and pure methanol fuel(M100) from China market. Regulated and unregulated emissions are measured under specific operating conditions, and the effects of M15 and M100 on engine-out emissions are comparatively analyzed. The endurance tests of 100-hour are carried out on a designed cycle, and intake valve deposit(IVD) and combustion chamber deposit(CCD) are collected and weighed to study the effects of different proportion methanol fuel on engine IVD and CCD. Lubricants in different test phases are sampled, and then their components and main characteristics as well as tribology test results are analyzed to study the influence of different proportion methanol fuels on lubricant performance.Fuel market investigation shows that, there are many phenomena of false identity in China methanol gasoline market. Low proportion methanol gasoline has problems of poor oxidation stability, and higher sulphur and manganese content than the limit values of standards. Among the organic components of low proportion methanol gasoline, paraffins take the largest proportion in volume percent, followed by aromatics, methanol, olefins, naphthenes and ethers.Emission test results show that, with the increase of methanol proportion, HC and CO emissions decrease, while methanol and formaldehyde emissions increase. The effects of methanol fuel on NOX emissions are complex and not directly related to the methanol proportion.Deposit test results indicate that, methanol gives low potential for the formation of deposits. Compared with gasoline, low proportion methanol gasoline can significantly reduce IVD and CCD. When using pure methanol fuel, there is almost no deposit generated both on the intake valves and in the combustion chambers.Lubricant test results show that, there is almost no methanol found in used lubricant, probably because of the high volatility of methanol. Methanol gasoline appears no influence on the lubricant viscosity and the acid/base number, but it can make engine wear and corrosion more serious, and increase iron, copper, aluminum contents in lubricant. Methanol may also cause more leakage of coolants, and make sodium and potassium contents in lubricant increased.Tribology test results show that, the used lubricant has a lower friction coefficient than the fresh lubricant, perhaps attributed to comprehensive effects of the lubricant viscosity, fuel dilution and phosphorus content, or because of some antifriction products generated in the using process of lubricant.