Abstract
New simulation algorithm of soot oxidation in diesel particulate filter (DPF) is proposed. Two-dimensional finite differences scheme is used for calculation of the heat transfer in DPF (macro-scale). One dimensional model for treatment of the soot oxidation process in a separate filter channel (micro-scale) is based on a new expression for the oxidation reaction rate that is a modification of the known Bissett's equation. This expression allows consideration of the non-linear dependence of oxidation reaction rate on a reagent concentration. For cases of catalytic coating a modification of the known two-layer model is suggested. A fraction of soot that has been oxidized with the help of the catalyst is not invariable in the first layer, but it exponentially depends on the distance from a channel wall of the particle trap. Soot oxidation by O2 and/or NO2 in diesel particulate filters is investigated for various cases of non-catalytic and catalytic oxidation. The filter clogging propagation from its periphery to the center at critical temperature is described theoretically at first. A comparison between various types of DPF regeneration methods is performed by using the proposed simple simulation algorithm and appropriate computer code.
Highlights
Diesel particulate filters are the most effective option to control the particulate matter (PM) emissions[1,2,3,4]
A fraction of soot that has been oxidized with the help of a catalyst is not invariable in the first layer, but it exponentially depends on the distance from a channel wall of the particle trap
In recent works of Jeguirim et al.[32],[33] the kinetic coefficients are obtained for soot oxidation reactions by O2 andNO2 with and without coating by Ruthenium and Platinum on a channel wall of the trap
Summary
Diesel particulate filters are the most effective option to control the particulate matter (PM) emissions[1,2,3,4]. It is convenient to classify regeneration methods as active (applying external or engine measures of gas temperature control at DPF inlet) or passive (usually employing catalytic means)[2],[5],[6]. Between active regeneration methods utilizing engine measures of gas temperature control at DPF inlet the following means can be noted[2]: exhaust gas recirculation (EGR), injection timing retard, fuel post-injection, decrease of boost pressure, intercooler bypass. The NO2-carbon oxidation reaction follows the Langmuir-Hinshelwood mechanism and characterized by activation energy values far below those for C+O2 reactions and by non-linear dependence of the reaction rate, R, on NO2-concentration. Fino and Specchia[17] obtained activation energy of 123kJ/mol for catalytic O2-carbon oxidation by the development of a new soot combustion catalyst, PrCrO3 perovskite on CeO2. A comparative study of various DPFregeneration methods is performed using the developed model, corresponding computer code and based on the proposed new approach
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