Experiment Study And Numerical Simulation On The Electrospray And Combustion Characteristics Of Biodiesel-ethanol Blends

In the face of the over-exploitation of global resources and the depletion of fossil energy reserves,it is necessary to find alternative fuels,so the development of biofuels has been attached importance to.Biodiesel has also attracted much attention due to its good ignitability,low pollution and renewable combustion products,However,biodiesel is difficult to mix with air due to its high density and viscosity,while ethanol with low density and low viscosity mixed into biodiesel,mixing fuel can improve the atomization characteristics of the fuel,optimize the combustion process and reduce the emission of pollutants.Atomized liquid fuel can improve fuel efficiency.However,electrostatic atomization technology has attracted attention due to its advantages such as small and uniform particle size of atomized droplets,easy control of droplet motion,and difficulty in aggregation of homopolar charge.Based on the good solubility of ethanol and biodiesel,in order to better combine the advantages of both,Meanwhile,the problem of poor atomization effect caused by high viscosity of biodiesel was solved.In this paper,the ethanol/biodiesel blended fuel was studied.The atomization combustion of ethanol-biodiesel was combined with the electrostatic atomization technology.The atomization and combustion characteristics of ethanol and ethanol-biodiesel blended fuel in the electrostatic atomization field were analyzed through experiments and numerical simulation.The electrostatic atomization of ethanol-biodiesel with different mixing ratios was studied,the specific charge of the droplets increases with the nozzle voltage and the blending ratio of ethanol.the fuel droplets with higher blending ration of ethanol have bigger electrostatic Weber number and are more likely to breakup.According to the electrostatic Weber number,a criterion is obtained for the charged liquid droplets.Based on the present experimental conditions,the critical electrostatic Weber number is 19.Compared to ethanol in single,double electrode burner atomization combustion simulation results,found that inside the double electrodes burner droplet axial velocity and the particle size less than inside the single electrode burner droplet axial velocity and the particle size,The mass fraction of carbon dioxide in double electrode burners was significantly greater than that in single electrode burners,The mass fraction of carbon monoxide in the double electrode burner wassignificantly lower than that in the single electrode burner,The results show that the combustion reaction in the double electrode burner is more sufficient,and it is fully proved that adding ring electrode can improve the combustion effect.by numerical simulation results of electrostatic atomization combustion of ethanol-biodiesel blended fuel,it is found that the mixed fuel with large proportion of ethanol has smaller particle size and shorter spray length,blended fuels with a smaller proportion of ethanol produce a smaller mass fraction of oxygen,a smaller mass fraction of carbon dioxide and a larger mass fraction of carbon monoxide.It not only proves that the mixed fuel can improve the atomization effect but also reduce the CO emission,it also reflects the interaction between atomization effect and combustion effect.