Abstract
Late fuel post-injections are the most usual strategy to reach high exhaust temperature for the active regeneration of diesel particulate filters. However, it is important to optimise these strategies in order to mitigate their negative effect on the engine fuel consumption. This work aims at understanding the influence of the post-injection parameters, such as its start of injection and its fuel quantity, on the duration of the regeneration event and the fuel consumption along it. For this purpose, a set of computational models are employed to figure out in a holistic way the involved phenomena in the interaction between the engine and the exhaust gas aftertreatment system. Firstly, an engine model is implemented to evaluate the effect of the late fuel post-injection pattern on the gas properties at the exhaust aftertreatment system inlet in different steady-state operating conditions. These are selected to provide representative boundary conditions of the exhaust gas flow concerning dwell time, exhaust temperature and O 2 concentration. In this way, the results are later applied to the analysis of the diesel oxidation catalyst and wall-flow particulate filter responses. The dependence of the diesel particulate filter (DPF) inlet temperature is discussed based on the efficiency of each post-injection strategy to increase the exhaust gas temperature. Next, the influence on the dynamics of the regeneration of the post-injection parameters through the change in gas temperature and O 2 concentration is finally studied distinguishing the pre-heating, maximum reactivity and late soot oxidation stages as well as the required fuel consumption to complete the regeneration process.
Highlights
The regulation of pollutant emissions in internal combustion engines has continuously become more stringent in recent years
Defining the optimum regeneration strategy as the one leading to the minimum fuel consumption, i.e., the optimum combined impact of post-injection rate and regeneration duration, the current work analyses the efficiency of the timing and fuel mass rate of late fuel post-injection events in terms of exhaust gas temperature increase, change in specific fuel consumption and dynamics of the active regeneration
Once flow properties were defined at the aftertreatment systems (ATS) inlet, specific diesel oxidation catalyst (DOC) and diesel particulate filter (DPF) models were applied to assess the impact of the active regeneration strategy on the soot oxidation
Summary
The regulation of pollutant emissions in internal combustion engines has continuously become more stringent in recent years. Instead, when the exhaust temperature was higher it was more efficient to induce the oxidation in the catalyst so that the post-injection event should be delayed Another important aspect to define the regeneration strategy is related to the properties of the fuel, which determine the specific composition of the HC [25] and, the DOC response [26]. Defining the optimum regeneration strategy as the one leading to the minimum fuel consumption, i.e., the optimum combined impact of post-injection rate and regeneration duration, the current work analyses the efficiency of the timing and fuel mass rate of late fuel post-injection events in terms of exhaust gas temperature increase, change in specific fuel consumption and dynamics of the active regeneration. This way, the impact on the duration and the required fuel consumption of each stage is evaluated, making evident the variation in sensitivity to the post-injection timing and fuel mass rate of different engine operating conditions
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