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Effective 1st April 2023, India's automotive emissions regulation has shifted from BS-VI Stage-1 to BS-VI Stage-2 standard the after-treatment systems need to demonstrate robust performance not just on the cycle, but also to demonstrate emissions for on-road Real Driving Emission (RDE) conditions. A stringent On-Board Diagnostics (OBD) strategy to monitor the real-time emission levels along with compliance Road Driving Emissions (RDEs) are focus areas for BS VI Stage-2 emission legislation. The maximum speed on MIDC is 90km/h in BS-VI Stage-1, Diesel Oxidation Catalyst (DOC)+Selective Catalyst Reduction Filter (SCRF®) was able to meet legislation at the lab, and now with the RDE cycle max speed of the vehicles under the M1 category <3.5 T will have the max permitted legal limit shall surpass 100 km/h for not around 3% of the span in the third phase of driving cycle for which max speed is up to 120 km/h.

The adoption of BSVI emission norms for Indian domestic market brought a very stringent window for pollutants. For CI engines, the major impact was in the reduction of NOx by 68% and PM by 82% from BSIV norms. Technologically advanced after treatment systems like SCR / DPF / LNT aid to meet the stringent emission norms. Implementation of high-end after treatment systems in vehicles, requires precise monitoring and fool proof feedback systems. On Board Diagnostics (OBD) makes this possible. OBD is used to monitor the performance of after treatment systems and warn the user in case of deterioration. The challenges in framing OBD strategy increases with more electronic hardware and complex algorithms taking control, to monitor precise information on system performance. For a fool proof OBD monitoring of the exhaust system, a complete understanding of the SCR system and its components in terms of hardware specifications and software functionality is critical.

Selective Catalytic Reduction is a key technology, used for NOx abatement. There are several models available for SCR system performance out of which most are experimentally verified only in flow reactors with simulated gaseous concentration and standard test conditions. But in the vehicle as well as in the engine test bench the conditions are very much dynamic compared to the simulated conditions of the lab. This transient behaviour emphasizes the need for a best fit model which accommodates the real-world dynamic conditions, thus reducing the overall effort in SCR catalyst selection for any given engine or vehicle application. The primary objective of this paper is to derive an empirical and mathematical efficiency model for SCR catalyst performance through a model-based design approach. The output from the model is compared with the experimental results from the vehicle and engine test bench, to validate the model accuracy.

In recent times diesel powered vehicles are becoming popular due to improved performance and reduced exhaust emission with this the market share of diesel passenger cars expected to approach 60 % over the next few years. In compliance with future emission standards for diesel powered vehicles, it is required to use diesel particulate filters (DPF) along with other exhaust emission control devices. There is a need for more optimized DPF cell structure to collect maximum soot load with low pressure drop and improved exhaust performance from diesel vehicles in Indian driving conditions. In this thesis paper a detailed parametric study have been carried out on different DPF cell structures like Square, Hexagonal and combined cell geometry. The performances of different cell structure has been evaluated for maximum soot loading capacity and regeneration rate, pressure drop, temperature distribution across cell structure.