Study On The Effect Of Emission Characteristics Of Explosion Proof Diesel Engine By DOC+CDPF After-treatment Device

On account of its characteristics of high efficiency,safety in coal mine machinery,Explosion-proof diesel engine is widely used,but it is a serious threat for underground staff’s life safety and body health because of high CO and soot emissions.Diesel oxidation catalytic(DOC)and catalytic diesel particulate filter(CDPF)are the mainstream means to reduce the emission of CO and particulate matter on account of its high conversion,capture efficiency and low exhaust pressure drop.Therefore,they are applied to the explosion-proof diesel engine,and their working characteristics and effects on the emission performance of the explosion-proof diesel engine are discussed,which is of great theoretical significance and engineering application value for the matching of the explosion-proof diesel engine and DOC+CDPF device.Based on a certain type of explosion-proof diesel experimental prototype,firstly,carry out the explosion-proof diesel engine bench and analyze how the after-treatment device(DOC+CDPF)affect the performance of explosion-proof diesel engine.Meanwhile,the purification efficiency of after-treatment equipment is quantified;In order to make full use of the utilization rate and improve the service life of the carrier,by using FLUENT to analyze the fluid simulation of DOC+CDPF,the pros and cons of the device are measured by flow uniformity,and the optimization schemes are put forward to provide reference for the application of the after-treatment device in the explosion-proof diesel engine.1)The structure and working principle of DOC and DPF are briefly introduced,and the selection method of post-treatment device is provided.Carried out different types of after-treatment equipments and explosion-proof units engine bench test,the results show that the DOC+CDPF can reduce fuel consumption,no significant influence on engine performance,improve the thermal efficiency of the engine,and cannot produce larger exhaust back pressure.The addition of PY03 DOC+CDPF has no significant effect on the emission of explosion-proof diesel engine and the device has high trapping and conversion efficiency for CO and particulate matter,a small amount of reduction in NO_X.2)Aimed at the phenomenon of burned carrier and inhomogeneous radial deposition of particulate matter in the test process,the numerical simulation of DOC+CDPF internal flow field is conducted by using FLUENT fluid simulation software.Analysing the internal pressure,velocity distribution,the pros and cons of the device is evaluated through the flow uniformity index.3)in order to explore the relationship between DOC internal component transportation and flow velocity,chemical reaction rate to combustible gas CO under the catalysis of the precious metal catalyst platinum(Pt)on the surface of the DOC simulation analysis is simulated via the FLUENT software,and the feasibility of using DOC at the level of CO emission is demonstrated.Through the discrete model,the deposition characteristics of particulate matter on the porous wall are investigated.The results show that the larger inlet velocity causes the particles to deposit in the rear wall of the channel,resulting in an increase in the exhaust pressure.4)Combined the use requirements and research status at home and abroad of the after-treatment device,the optimized design schemes of DOC+CDPF are put forward,which optimize the design of the unreasonably structured region of DOC+CDPF.The modified DOC+CDPF structure are verified and analyzed by fluid simulation.The results show that the maximum flow velocity of the optimized schemes decreases and the outlet mass flow increases,which is beneficial to reduce the exhaust back pressure,less energy consumption,increase effective air flow area,improve the utilization rate of the carrier,reduce the heat load carrier,and thus enhance the conversion efficiency and service life of catalysts.