Theoretical And Experimental Study On Purification Of Diesel Exhaust Particulates

Based on fluid mechanics,this thesis uses ANSYS to simulate the exhaust gas flow process of diesel engines,and designs an exhaust purification device on this basis,and verifies the purification effect of the device through simulation experiments and bench experiments.Based on heat transfer theory and heat transfer methods,a spiral-tube exhaust gas purification model is established,and the trapping efficiency of the spiral outer tube on particulate matter is analyzed,and the influence of the structural parameter changes of the spiral tube on the cooling effect of the exhaust gas is explored,and finally the fitting is obtained.The relational expression of heat transfer coefficient.Based on the two-phase flow theory,a dynamic model of the exhaust particles in the straight channel and the curved channel is established.The theory and method of the water film on the curved plate surface to purify the diesel particulate matter are proposed.The vertical water film and the horizontal water film adsorption model are established.The influence of the structure parameters of the curved plate on the particle collection efficiency is discussed.A simulation experiment and a bench experiment platform were built to verify the effectiveness and feasibility of the device.The main contents are as follows:First of all,the thesis analyzes the filtration mechanism of the particle trap,analyzes the force of the particles in the pipeline movement based on the gas-solid two-phase flow theory,establishes the corresponding dynamic model,and establishes the corresponding dynamic model for the particles in the straight channel and the curved channel device.Compare the movement conditions inside and optimize the relevant parameters to achieve a higher trapping efficiency of particulate matter.Secondly,the thesis builds a heat transfer model of the spiral casing sandwich.Aiming at the high temperature problem of diesel engine exhaust exhaust gas,a spiral-tube heat exchanger is used to cool the exhaust gas during its flow.By simulating the flow and heat transfer process of the interlayer exhaust gas flow channel and the cold fluid channel in the inner tube,the velocity and temperature distribution of the interlayer exhaust gas channel and its change characteristics are obtained,and the distribution cloud map of the exhaust particles in the spiral outer tube is simulated.Comparative analysis of the influence of structural parameters on exhaust gas cooling,and finally fitting the relationship of the heat transfer coefficient of the spiral casing.Third,the thesis constructs a water film box model on the curved plate surface.Micropores are designed on the surface of the curved plate.Water seeps from the micropores to form a water film.The exhaust particles will collide with the wall during the flow of the box and be adsorbed by the water film covering the top.Study the formation of a vertical water film conditions of.At the same time,the particles and air flow field when passing through the curved plate box were simulated,and the distribution characteristics of the particles in the curved plate box were obtained.According to the simulation results,the effect of different bending angles,spacing,length and other structural parameters on the gas-solid The effect of separation efficiency,and finally the structural design of the box body is optimized.Finally,the dissertation developed a diesel engine exhaust particulate matter treatment device.This device mainly uses the method of the exhaust particulate matter to collide with the curved plate and be adsorbed by the water film covering the surface to separate and collect the exhaust particulate matter.The feasibility of this device is verified by simulation test and bench test.The test results show that the device has an obvious purification effect on diesel engine exhaust particles.