| Methanol has many advantages as an alternative gasoline fuel. However, the unregulated emissions like formaldehyde from the methanol combustion will do great harm to human health and environment. This study was based on the national 863 project of"Development of methanol flexible fuel vehicle technologies", focusing on the combustion performance and unregulated emissions of methanol-gasoline fuels.First, the specific fuel consumption and emission performance of different methanol-gasoline fuels were tested on an engine test bench. The engine used was JL479QA and AVL SESAM-FTIR was used to measure the emissions. M5, M15 and M30 together with gasoline were tested on the unadjusted engine. The results show that for the same power output, the specific energy consumptions of the low-proportion methanol-gasoline fuels are a little bit lower than that of gasoline. But the power decreases in the engine speed characteristics because of the increase of A/F ratio. The gasoline needs to be adjusted with high proportion of methanol-gasoline blends like M85. The speed characteristics are similar to that of gaslone after being adjusted. THC gets lower with more methanols in the fuel, while NOX and CO are similar with gasoline. Methanol and formaldehyde emmsions get higher with the increase of methanols in the fuel. As long as the A/F ratio is near the stoichiometry, the TWC (Three Way Catalyst) has high conversion efficiency for all the emissions.Secondly, the cold start application with M10, M20 and M30 both under ambient temperature 25°C and low temperature -7°C was studied. The results show that the regular emissions of the methanol-gasoline fuels are similar to that of gasoline. Methanol and formaldehyde emmsions still get higher with the increase of methanols in the fuel. The initial cold start stage contributes the major of total emission. But once the catalyst is lit off, TWC has a high convertion efficiency of both regulated and unregulated emissions. |
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