| With the rapid development of global shipping industry,the pollutants emitted by Marine diesel engines are the main cause of air pollution in port cities.In recent years,more and more attention has been paid to the purification of particulate matter in Marine diesel engines.At present,diesel particulate filter(DPF)is the most effective method to reduce the exhaust particulate matter,while the shortcomings of the traditional DPF regeneration method limit the wide application of DPF.The purpose of this paper is to extend the regeneration method of DPF by combining with reciprocating combustion on the basis of traditional DPF regeneration.In this paper,the combustion experiment device of reciprocating flow DPF system is designed by ourselves,and the purpose of reciprocating flow regeneration is realized by adding propane fuel with low equivalent ratio to maintain high temperature field of DPF system.The simulation software is used to compare the simulated temperature field and the experimental temperature field of the reciprocating flow DPF system.The specific work and main conclusions of this paper are as follows:In this paper,under the condition of no-load operation of the diesel engine,propane gas is firstly injected into the DPF system to establish a high temperature field,and then the heat storage and heat release function of the reciprocating flow DPF system is utilized to maintain the high temperature area of the system under the condition of low equivalent ratio to achieve the continuous removal of most particles.The results show that:(1)This paper explores that when the mass flow rate of propane is 0.0915g/s and the reciprocating half cycle is 25s,the DPF system can not only maintain the high temperature field but also remove the particles well.Under this condition,the average conversion efficiency of particles removal is 94.7%and that of carbon monoxide removal is 95.5%.(2)With the increase of the reciprocating half period,the maximum temperature of DPF system is basically unchanged,but the temperature amplitude of the boundary of the high temperature region increases,and the combustion rate of particles decreases,resulting in the concentration of particles at the outlet of the system increases when the direction is reversed.(3)With the increase of the equivalent ratio,the maximum temperature of the DPF system increases,and the high temperature area becomes longer.Too high equivalent ratio will lead to the formation of secondary particles,resulting in the increase of the concentration of particles at the outlet of the system when the direction is reversed.(4)The reciprocating flow combustion can store more heat in DPF system than the unidirectional flow combustion,which is conducive to maintaining the high temperature of the system at a low equivalent ratio,which can not only save the amount of supplementary fuel,but also achieve regeneration effect of reciprocating flow DPF system.(5)The high temperature area maintained by the reciprocating flow combustion can be maintained for about 3 minutes after the propane fuel is cut off and the reciprocating flow continues.This is because the heat stored in the honeycomb ceramic body is fully utilized.In this paper,a two-dimensional pore model of DPF system with reciprocating flow is established by using simulation software,and the temperature field of the system is numerically simulated under the experimental conditions of propane mass flow rate of 0.0915g/s and reciprocating half cycle of 25s.Then,the variation law of temperature distribution,the law of heat storage and heat release and the influence of different half cycle on the temperature distribution of the system are discussed.They are basically consistent with the corresponding experimental data in the trend.The research content of this paper provides technical reference for further optimizing the DPF regeneration technology of reciprocating flow and engineering application reference for the purification of tail gas particles of marine diesel engine. |
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