Kinetic Parameter Estimation of a Diesel Oxidation Catalyst under Actual Vehicle Operating Conditions

Abstract

A realistic numerical model of a commercial diesel oxidation catalyst (DOC) was developed under an actual vehicle operating condition. To provide the material data as well as to examine the performance characteristics, conversion experiments through the DOC were performed with a 2.0 liter EGR-mounted diesel engine on a dynamometer test bench. Then, on the basis of the currently developed in-house computational code, kinetic parameters of the model reactions were calibrated through a numerical fit to the experimental data. To cover a wide range of operating temperatures, the experiments and modeling were conducted under low engine speeds (i.e., 1000 and 1500 rpm). Main objectives of this study are to develop not only a numerical model based on real-world experiments but also a methodology of how to construct it. Details of the procedure are described step-by-step in this article. Also, on the basis of the experimental results currently observed, it is proposed that additional models considering the NO2 reaction to produce NO are further required than the generally adopted DOC models to capture the negative efficiency behavior in NO oxidation at low temperatures. Because the present DOC model does not take these reactions into account, its prediction performance with experimental results at 1000 rpm is poor for NO and NO2 emissions at low temperatures but is fairly good for CO and HC emissions. On the other hand, the prediction performance at 1500 rpm is good for all of the species as well as over all of the operating temperature ranges.

The pollutant emissions from diesel-engine vehicles and exhaust aftertreatment systems

“…Besides, DOCs play a role in decreasing the mass of diesel particulate emissions by oxidizing some of the hydrocarbons that are adsorbed onto the carbon particles (Chen and Schirmer 2003;Wang et al 2008). DOCs may also be used in conjunction with SCR catalysts to oxidize NO into NO 2 and increase the NO 2 :NO x ratio.…”

“…The loading is approximately 50-90 g/ft 3 . Currently, DOC containing Pt and Pd is most commonly used for oxidation and many studies conducted by researchers focused on these precious metal-based catalysts (Kolli et al 2010;Kim et al 2003;Wiebenga et al 2012;Wang et al 2008;Haneda et al 2011).…”

Impact of biodiesel fuel on engine emissions and Aftertreatment System operation

“…The analysis of the downstream ratio first highlights that below 190°C the NO-NO 2 conversion efficiency is negative for both the fuels [53,[58][59][60]. The last cited studies [59,60] observed this NO 2 depletion even with degreened DOC attributing this result to a NO 2 -NO reduction by HC, with a weaker effect due to CO [59].…”

Low Temperature Activity of Euro4 Diesel Oxidation Catalysts: Comprehensive Material Analyses and Experimental Evaluation of a Representative Panel

“…Thus, if such HC evolution is expected, due to the zeolite, contained in every DOC, that first traps HC at low temperatures then releases those HC with temperature and/ or GHSV rising up, CO concentration evolution downstream of the DOC appears more surprising [5]. Concerning NO 2 , adsorption and desorption is presumed even if no usual adsorption oxide, such as BaO or MgO, is found in the wash-coats.…”