FIRE Software Based Simulation And Experimental Investigation Of Lean-NO_x Trap

Lean burn technology is a promising way to achieve the purpose of energyconservation and emission reduction of gasoline engine, NOx emission is the mainproblem that hinders its extensive application. LNT (Lean-NOx Trap) can efficientlyeliminate NOx emission of lean burn gasoline engine in a wide temperature range,thus it is important for lean burn gasoline to make a good use of LNT. This paper builtan LNT numerical simulation model, and verified the model by experimental data.Numerous of flow field information can be obtained from the simulation, it canprovide theoretical basis for the optimization of LNT.The temperature, velocity, pressure and concentration fields of adsorption periodwere simulated and the influence of temperature, CPSI, NOx concentration onadsorption was analyzed. The results show that: The center of LNT carrier gets morethermal impact, and when the inlet temperature is different it is found that lowtemperature is benefit to NO adsorption while high temperature is benefit to NO2adsorption; The velocity and pressure fields are uniform, and when the CPSI increasesthe pressure drop increases significantly while the velocity field changes very little,moreover, high CPSI is benefit to NOx adsorption; Reduce the inlet concentration ofNOx can improve the efficiency of LNT.The concentration field of reduction phase was simulated and the influence ofconcentration of reductive gas was analyzed. The results show that: In the beginningof reduction phase, there is a NO peak, this peak must be eliminated rapidly or it willmake a great NO leak; The increase of CO concentration reduces the reductionduration, but the effect is slight; the increase of C3H6concentration does not influencethe reduction duration; H2concentration has a great influence on reduction duration,when H2concentration increases the reduction duration decreases significantly, so inorder to improve fuel consumption and reduce emissions, the recommendation is toincrease the H2concentration in reduction phase in practical application to cut downthe reduction duration.