A chemical factory
Terming the BSVI after-treatment system as a chemical factory, DICV sources informed that there are multiple chambers inside it. Describing it as a miniature of a typical chemical factory, the sources said that BSVI is met by either the use of an EGR or by the use of EGR and SCR. The use of the EGR system only for engines over a certain size would lead to an increase in NOx levels. These would then need to be reduced with an after-treatment system. The other way of achieving the desired emission levels, said sources, was to increase the particulate matter in the engine using the EGR system. This would warrant the use of a Diesel Particulate Filter (DPF) or Diesel Oxidation Catalysts (DOC).
Explaining that it would be difficult to meet the desired emission levels by using just the EGR or the SCR, sources mentioned that the use of multiple screens or filters, including SCR, DPF, and other catalysts is necessary.
It is these that make the BSVI aftertreatment system a chemical factory. The deployment of addition filters, the DPF especially, makes a BSVI system bigger and heavier. Needing precise thermal management, it also generates excess heat. Especially during regeneration. Calling for the safety of operators due to the temperatures it could reach, the BSVI system also leads to an increase in backpressure. It results in a drop in fuel efficiency. To compensate for any drop in fuel efficiency, DICV carried out several changes at the powertrain level. Without revealing the exact number of changes, sources said that the BSVI CVs will deliver better fuel efficiency if not on par with the BSIV ones.
Starting testing the mules as per Daimler’s standard protocol that is adhered to globally in 2018, the BSVI development involved the scanning of routes across the country. A programme was drafted to cover various duty cycles. To tap fuel efficiency, temperature and various other vitals as the mules operated in various regions of the country. Much work was carried out in the lab as well as on-field to ensure that the desired standards across several condition patterns were met. Attention was paid to get the thermal management right.