Study On Charged Characteristics Of Diesel Micro-nano Particulate Matter Under Corona Discharged In The Wire-cylinder Device

Modern diesel engines are widely used because they are excellent in economic,power and reliable.However,micro-nano particles of diesel engines have large specific surface area which can absorb heavy metal and other harmful substances,which would pose a threat to natural environment and human health.Therefore,how to reduce the amount of fine particles of diesel engines has been a challenging and urgent problem.With the application of particle oxidation catalyst and other after-treatment technology,the emissions of diesel particles have been greatly reduced,but it is difficult to control the number of micro-nano particles.And in the particulate emission standard of stage ?,the requirements of particulate number of diesel particles are added.Electrical agglomeration(EA)technology is a kind of preprocessing methods to promote the growth of particulate matter,reduce the number of particulate matter and improve the collection efficiency of diesel particulate filter,which is more and more attention in the field of controlling the number of micro-nano particles of diesel engines.The aim of this article is to carry out the fundamental work of charged characteristics of diesel particles.A diesel particle electric charging wire-cylinder device was designed and the charged electric quantity measuring system which was applied to engine test bench was set up.The electric quantity of charged particles was measured by using the homemade Faraday cylinder and the high precision digital charge meter.The influence of different working and structure parameters on the characteristics of charged diesel particles was studied.Base on FLUENT software,the diesel particle's motion trail under the electrical field environment in the line-cylinder charged reactor was numerically simulated.The main research contents are as follow:(1)Based on the charging theory of diesel particles under the direct current electric field,the diesel particles charged and electric quantity measuring test platform was set up.On the test platform,diesel particles were charged under corona discharged and the electric quantity were measured by homemade Faraday cylinder and digital charge meter.(2)The influence factors of charge-mass ratio of diesel particles was investigated on engine test bench,such as electrode materials?electrode diameter?charged voltage?partial exhaust flow rate and the internal temperature of discharge area.Meanwhile negative voltage?partial exhaust flow rate?the internal temperature of discharge area were optimized and the results showed that the influence on charge-mass ratio of diesel particles was in the order of charged voltage>partial exhaust flow rate>the internal temperature of discharge area.(3)According to the force analysis on a charged particle,a mathematical model of charged reactor was built?solved and calculated by FLUENT for the diesel particle's motion trail under different conditions,which would optimize the charged reactor and provide the micro-theoretical foundation for the later agglomeration of charged particles.