Comprehensive modeling study analyzing the insights of the NO–NO2 conversion process in current diesel engines

Abstract

Multiple researches have focused on reducing the NO x emissions and the greatest results have been achieved when lowering the combustion temperature by employing massive exhaust gas recirculation rates (LTC). Despite this benefit, a substantial increase in the NO 2 contribution to the NO x emissions has also been observed, which is the most harmful specie and is important for the design and positioning of the after-treatment devices. To understand how NO 2 behaves and how it contributes to the total NOx (NO 2 /NO x), not only under LTC but also for CDC conditions, a stepwise computational research study was performed with Chemkin Pro software, due to the complexity of isolating the different phenomena studied, to analyze: 1) general equilibrium conditions and 2) the influence of typical diesel engine phenomena (combustion and cooling effects) under non-equilibrium conditions.

New 0-D methodology for predicting NO formation under continuously varying temperature and mixture composition conditions

“…Considering exclusively NO will not influence significantly the results because as concluded in [40] the role of the combustion process in the NO 2 formation process is minor under current diesel engine conditions.…”

Computational assessment of combustion noise of automotive compression-ignited engines

“…In the framework of engine combustion simulations, the URANS approach has being employed for the majority of the applications. For example, URANS simulations have been used for enhancing the understanding of the flow motion during the gas exchange process [110] or the generation of pollutants [111], for optimizing the combustion system design [112,113] and for simulating the spray and flame structure, ignition delay and lift-off length [114].…”

Effect of H2 addition on combustion characteristics of dimethyl ether jet diffusion flame

“…It is of fundamental interest because it controls the mixing process of fuel and air, and consequently exerts a profound influence on the combustion process inside the reaction zone [50]. Hence, flame entrainment of turbulent diffusion flames is particularly important for all aspects of the combustor design, from the physical dimension to NOx and soot reductions [50][51][52].…”