Study On Influence Of Molecular Properties Of Oxygenate/Diesel Blended Fuels On Sooting Tendency

In recent years,air pollution has posed a big threat to the environment of our human beings.The soot particles produced by combustion of the fossil fuels are the main source of air pollution,while clean alternative fuels can address this serious problem.Oxygenated fuel has attracted attention in the research field of clean candidates,which emission reduction ability is mainly determined by its molecular structure and properties.Therefore,it is of great significance to investigate the affecting mechanism of molecular properties of the oxygenated blended fuels upon the sooting tendency.This study will provide a guide for the evaluation of the sooting tendency of blended fuels and development of the efficient selection and preparation of clean alternative fuels.In this paper,firstly,diesel fuel and eight kinds of oxygenated compounds were selected,and the smoke-point measurement device were designed and used to obtain the smoke-point values of oxygenated compounds blended with diesel fuel at different blending volume percentages.Normalized Oxygen Extended Sooting Index(OESI)was introduced to quantify the sooting tendency of fuel.The index values incorporating the smoke-point values were established to decrease with increasing blending volume percentage of the oxygenated additives in blends,following an exponential fitting relationship.Then the resulting exponents were used to quantify the sooting tendencies of the blended fuels,which were shown to increase in the order:ethanol/diesel<dimethyl carbonate/diesel<dimethoxy methane/diesel<methyl butanoate/diesel<n-butanol/diesel<methyl tertiary-butyl ether/diesel<methyl decanoate/diesel<dibutyl maleate/diesel.Furthermore,based on the molecular property factors of oxygen content,oxygenated functional group,carbon number,and H/C ratio which affect the sooting tendency of the blended fuels,three affecting indicators were proposed,taking into account the molecular structure of oxygenates and the combustion mechanism of blended fuels.So-called indicators were termed the affecting oxygen content,affecting carbon number and affecting H/C ratio.A calculation algorithm of three affecting indicators was established by the functional numbers of oxygen and carbon atoms of blended fuel molecules on the sooting tendency.Additionally,priority order of three affecting indicators on the sooting tendency of the tested blended fuels(except dibutyl maleate/diesel blend)should follow the results by Relative Weight Analysis,that decreased in the order of affecting carbon number>affecting oxygen content>affecting H/C ratio.Finally,comprehensive combination of three affecting indicator value and their priority order was shown to be able to evaluate the sooting tendency of most of the tested blended fuels effectively,especially that of diesel blended fuels with the same type of oxygenated additives could be reasonably interpreted by this evaluation method.