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Experimental Investigation On The Effects Of Fuel Properties On Combustion And Emissions Of Diesel Engines

Posted on:2019-01-26Degree:MasterType:Thesis
Country:ChinaCandidate:J S MaFull Text:PDF
GTID:2392330623962252Subject:Power Machinery and Engineering
Abstract/Summary:PDF Full Text Request
New requirements have been placed on the physical and chemical properties of diesel because of increasingly strict emission regulations.Changes in fuel properties significantly affect engine performance and emissions.Therefore,it is necessary to further reveal the effects of fuel properties on the performance of diesel engines and provide some theoretical support for the formulation and development of fuel standards in China.In this paper,fuels with different physical and chemical properties,fuels with different distillation temperature and coal-to-liquids were selected.The ESC cycle was carried out on a high-pressure common rail heavy-duty diesel engine to study the effects of fuel properties on combustion characteristics,fuel economy and emissions characteristics.Firstly,for conventional diesel fuel that is not decoupled,fuel density is highly correlated with other physical and chemical properties.The weighted results of ESC show that when the density is less than 845kg/m~3,the emissions of NOx,soot,CO and HC are relatively low.Similarly,when the cetane number is higher than 48,PAH is less than 7.5%,and aromatic hydrocarbon is less than 25%,the weighted emissions are relatively low.Based on the research of not decoupled conventional diesel,the fuels with different distillation temperature and coal-to-liquids were further selected to decouple some of the physical and chemical properties of the fuel.The combined results of three tested fuels show that:As the load increases,the effects of fuel properties on the engine are gradually weakened.The ignition delay is mainly affected by cetane number and has little correlation with other fuel properties.CA50 is mainly related to the start of injection,and the effect of fuel properties on it is not obvious.When the CA50 is substantially equivalent,the Brake Thermal Efficiency(BTE)is mainly related to the kinematic viscosity,and the BTE of the fuel with low viscosity is relatively low.If increased aromatic hydrocarbon,extended combustion duration and reduced cetane number,it will increase NOx emissions.The effect of aromatic hydrocarbon on NOx emissions is dominant,and the effect of combustion duration is second.Decreased aromatic hydrocarbon,lower distillation temperature,lower kinematic viscosity and lower cetane number are beneficial to reduce soot emissions.The effect of cetane number on soot is less than other fuel properties.The decrease of distillation temperature,decrease of cetane number and decrease of kinematic viscosity will increase HC and CO emissions.The effect of distillation temperature on HC and CO emissions is the dominant factor,followed by cetane number.In addition,for coal-to-liquids,the BTE of both coal-to-liquids is lower than that of diesel.Compared to DCL(direct coal liquefaction),ICL(Indirect Coal Liquefaction)has lower NOx,HC and CO emissions.Soot emissions of ICL have been significantly lower than diesel.Therefore,ICL has the potential to replace diesel.
Keywords/Search Tags:Diesel, Diesel Engine, Fuel Properties, Combustion Characteristics, Emission Characteristics
PDF Full Text Request
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