Calibration and parametric investigations on Lean NOx Trap and Particulate Filter models for a light-duty diesel engine 2020-01-0657
To comply with the stringent future emission mandates of light duty diesel engines, it is essential to deploy a suitable combination of emission control devices like diesel oxidation catalyst (DOC), diesel particulate filter (DPF) and DeNOx converter (LNT or SCR). Arriving at an optimum size and layout of these emission control devices for a particular engine through experiments is both time and cost intensive. Thus, it becomes important to develop suitable well-tuned simulation models that can be helpful to optimize individual emission control devices as well as arrive at an optimal layout for achieving higher conversion efficiency at minimal cost.
Towards this objective, the present work intends to develop a one dimensional Exhaust After Treatment Devices (EATD) model using a commercial code. The model parameters are fine-tuned based on experimental data. The EATD model is then validated with experiments data that are not used for tuning the model. Subsequently, the model was used for studying the effects of geometrical parameters of the after-treatment devices like diameter and length on the conversion efficiency and the pressure drop. The experimental investigations are done in a single cylinder light duty diesel engine fitted with a Lean NOx Trap (LNT), Diesel Oxidation Catalyst (DOC) and Diesel Particulate Filter (DPF). From the IDC cycle, 8 representative operating conditions were chosen and experiments were conducted at steady state at these conditions. The chemical kinetic parameters, friction loss and heat transfer coefficient of one dimensional model was tuned using five of the 8 experimental data sets. The remaining three data sets were used to validate the predictions with no further tuning. The model could predict the conversion efficiency, pressure drop and outlet temperature. The calibrated model was then used to predict the effect of geometrical parameters. The effect of length and diameter changes of EATD was studied with this calibrated model. The results indicated that increasing the diameter is more effective than increasing the length for enhanced conversion efficiency and reduced pressure drop across LNT. For LNT increase the diameter by 5% and reduction in length by 10% gave a 1% reduction in volume, 15% reduction in pressure drop while the conversion efficiency increased max 1.6%. For cDPF, increase in the diameter by 10% and reduction in length by 10% gave an 8% increase in volume, 27% reduction in pressure drop while the conversion efficiency increased max 1.5% thus the current model and methodology can be used for optimizing the size of EATD.
S. Suresh Bagavathy, A Ramesh, Anand Krishnasamy, Senthur Pandian
Mahindra & Mahindra, Ltd., IIT Madras, Mahindra Research Valley