Performance of diesel oxidation catalysts in RCCI combustion

What is it about?

This paper investigates the performance of a diesel oxidation catalyst (DOC) when used in reactivity-controlled compression ignition (RCCI) combustion. RCCI is a promising combustion strategy that offers high thermal efficiency and low emissions of NOx and particulate matter. However, it also produces high levels of unburned hydrocarbons (UHCs) and carbon monoxide (CO), which can challenge the effectiveness of the DOC. The authors performed experimental tests using a single-cylinder engine fueled with a mixture of diesel and gasoline. They measured the catalyst conversion efficiency (the percentage of UHCs and CO converted by the catalyst) under a variety of conditions, including different mass flows and temperatures. They also developed a lumped DOC model that was able to reproduce the experimental results and predict the light-off temperatures for UHCs and CO. The authors concluded that the performance of a DOC in RCCI combustion is highly damaged and must be improved by optimizing the catalyst size and cell geometry. Additionally, the use of reactors with high catalyst loading should improve the light-off temperature and make the catalyst more tolerant to high pollutant concentrations.

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Why is it important?

This paper contributes to provide new insights into the performance of diesel oxidation catalysts (DOCs) under reactivity-controlled compression ignition (RCCI) combustion conditions. RCCI is a promising combustion strategy for reducing emissions of soot and NOx, but it also produces high levels of unburned hydrocarbons (UHCs) and carbon monoxide (CO). The authors of this paper found that the conversion efficiency of a DOC under RCCI conditions is very sensitive to the mass flow and temperature of the exhaust gases due to the UHCs and CO high concentrations, thus increasing their light-off temperature. They also found that the performance of the DOC might be improved by increasing the residence time and using high catalyst loading. These findings are important for the development and optimization of DOCs for use in RCCI engines. In addition to its technical significance, this paper is also important for societal reasons. RCCI combustion has the potential to significantly reduce emissions of soot and NOx, which are two of the most harmful pollutants emitted from diesel engines. By understanding the performance of DOCs under RCCI combustion conditions, we can develop more effective aftertreatment systems that can help to make future engines cleaner and more environmentally friendly.

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