Simulation Research On The Partial-Flow Dilution Sampling System Of Particulate Measurement

Diesel exhaust particles are easily inhaled due to their fine size, which will cause respiratory and lung disease, and the particles have carcinogenic substances adsorption, which is harmful to people's health. Particle pollution has become a problem needed to be solved urgently. First, we must have a better system for particulate emissions measurement to research of diesel particulate emission control technology. In this paper, many works have been done on the partial flow dilution sampling system for diesel particulate measurement based on the principles of computational fluid dynamics.The mixed-ability of the partial flow dilution sampling system is studied by FLUENT software. Diesel exhaust and air mixing quality are analyzed under different experimental conditions. Due to air and diesel exhaust enter the dilution channel by different entry, Species Model was used to analyze their mixing quality, and Energy Equation was used to analyze their energy exchange, Turbulent Model was used to analyze turbulent effects.Distribution characteristics and variation regularity in the pipeline is studied by FLUENT software. The distribution characteristics and variation regularity of both temperature gradient field of near-wall and turbulent kinetic energy field of pipeline are analyzed under different conditions of inlet velocity and temperature based on Energy Equation, Viscous Model.Influence factors and its variation regularity of diesel particulates deposition rate in the transport pipe are studied. Combine the distribution characteristics and variation regularity of flow field in the transport pipe, particulates thermophoresis deposition, turbulent deposition and the total deposition under thermophoretic force and turbulence are researched, under different conditions of inlet velocity and temperature using Energy Equation, Viscous Model and Radiation Model, Discrete Phase Model. During the course of researching on particulates deposition, influence of turbulent edd is also taken into account enough, also. particulates thermophoresis deposition, turbulent deposition and the total deposition are compared. Radiation Model was used to analyze radiation heat transfer between air and particulates in this paper.After the research work above, the mixed-ability of the particulate measurement system with partial flow dilution sampling system and diesel particulates deposition rate in the pipeline are concluded. Theoretical basis and research foundation of further optimizing this system are supplied by the research results.