Effects Of Diesel-kerosene Wide Distillation Blended Fuels On Combustion And Performances Of Diesel Engines

The physical and chemical characteristics of fuels have important impacts on combustion process and performances of diesel engines.Relevant researches showed that it is an effective way to improve the combustion process and reduce the engine emissions by designing and optimizing the fuel properties.This paper uses diesel-kerosene wide distillation blended fuels,aims to investigate the influence of diesel-kerosene wide distillation blended fuels on combustion process and performances(power output,fuel economy,exhaust gas temperature and emissions)of diesel engines through the engine bench test.The research could provide a new thinking and technical reference for achieving high-efficient and clean combustion of diesel engines.The main research work and conclusions are as follows:Three kinds of wide distillation blended fuels with different physical and chemical properties were prepared,that were D80K20(80% diesel and 20% aviation kerosene(rocket propellant,RP3)by volume),D60K40 and D40K60 in this research.The calculated results showed that with the increase of RP3 ratios in the diesel-RP3 blends,the density,cetane number,kinematic viscosity and surface tension decreased,the lower heating value increased,the T10,T50 and T90(10%,50% and 90% distil-off temperature)decreased.The engine bench test platform based on KM195 diesel engine was established.The engine speed was controlled to be 3600,2700 and 2000r/min,while the engine load was respectively 100%,50% and 10% of the full loads at different speeds(respectively represented the heavy,medium and light load conditions).The in-cylinder pressure,effective power,fuel consumption,exhaust gas temperature,particulate concentrations and size distribution,soot and NOX emissions,as well as CO and THC emissions for D100,D80K20,D60K40 and D40K60 were experimentally measured and calculated to investigate the influence on engine combustion process and performances.The results indicated that with the increase of RP3 ratios in the diesel-RP3 blended fuels,the maximum in-cylinder pressure values for D100,D80K20,D60K40 and D40K60 at the same working conditions were almost the same,the maximum rise rate of in-cylinder pressure slightly increased,the peak heat release rate of premixed combustion became higher,the peak heat release rate of diffusion combustion was lower,and the crank angle corresponding to the maximum in-cylinder pressure,peak heat release rate of premixed and diffusion combustion was delayed.Besides,the ignition delay was prolonged,the combustion duration decreased,the cumulative heat released percentage of premixed combustion increased,the cumulative heat released percentage of diffusion combustion decreased,and the crank angle corresponding to the 50% cumulative heat release of the whole combustion phase was delayed.While the maximum in-cylinder combustion temperature remained almost the same,the cyclic variations represented by the coefficient of variation(COV)of indicated mean effective pressure(IMEP)became larger especially at low speed and light load conditions.In terms of engine performances,the values of effective power and brake thermal efficiency(BTE)for the diesel-kerosene wide distillation blended fuels remained almost the same with that of the D100,while the exhaust gas temperature gradually decreased with the increase of RP3 ratios.Besides,as the RP3 ratios increased,the number concentration,surface area concentration,volume concentration,mass concentration for nucleation-mode particulates at different test conditions increased,while the number concentration,surface area concentration,volume concentration,as well as mass concentration for accumulation-mode particulates decreased.The total number concentration,total surface area concentration,total volume concentration,as well as total mass concentration for particulates decreased.The measured and calculated results also indicated that the diesel-RP3 wide distillation blended fuels could reduce the soot emissions remarkably,together with a slightly increased trend for nitrogen oxides(NOX)emissions,and the improvements on soot emissions were more obvious with the increase of RP3 ratios.While the total hydrocarbon(THC)emissions showed an increased trend,the carbon monoxide(CO)emissions increased at light loads and decreased at heavy loads.To sum up,the diesel-RP3 wide distillation blended fuels could greatly reduce the particulate emissions of diesel engines without affecting the combustion thermal efficiency and power output,and benefited in improving the “trade-off” relationship between soot and NOX emissions,which means that the diesel-RP3 wide distillation blended fuels had advantages on achieving high-efficient and clean combustion of diesel engines.