Study On Formaldehyde Emissions Characteristic Of Engine Running The Fuel Blended With Methanol

Methanol as alternative fuel for vehicles has a broad prospect in China because of its low producing cost and formed production technique. However, Formaldehyde emission of engine powered by methanol is known for strong carcinogenicity,and it can harm atmospheric environment and human health.Hence,generalize the methanol fuel so as to controlling the emission concentration of aldehyde is of great significance.A method is provided to determinate formaldehyde in the engine exhaust: Formaldehyde is absorbed by the acidic saturated solution of 2,4-dinitrophenyl hydrazine (DNPH) and converted to its hydrazone, the hydrazone is then extracted with CS2 and determinated using Gas Chromatography (GC). Based on theory mentioned above ,a sampling system is designed to measure formaldehyde emitted from engine.The measure method is applied to determine the formaldehyde emission from a DMCC engine, It is revealed by experiments that load,methanol proportion,methanol injection styles,catalytic converter,exhaust temperature affect formaldehyde emission characteristic from DMCC engine.The results showed as follows: the formaldehyde concentration from DMCC engine is about 10～30 times higher than that of diesel engine; the formaldehyde concentration is the highest at low-load, the lowest at medium-load at same rotate speed and methanol proportion; with the increasing of methanol proportion, the formaldehyde in exhaust is increasing in low load and middle load; the formaldehyde emission of Sequential Fuel Injection mode is less than that of Continuous Fuel Injection style at same work condition; the exhaust temperature is a key factor for the catalytic converter's effect. When the exhaust temperature is lower than 300℃or higher than 410℃, the formaldehyde emission is decreased by the catalyst, but it would increased if the exhaust temperature between 300℃to 410℃.Besides, this measure method determine the formaldehyde emission from a gasoline engine powered by M0,M10,M20,M30,respectively. The results showed as follows: the formaldehyde concentration of methanol/gasoline engine is 2~7 times higher than that of gasoline engine, but it is decreased by catalytic converter obviously to approach ultra-low emission.