The role of the engine in controlling regulated pollutants at the in-cylinder combustion level has been crucial, utilizing strategies such as Direct Injection, Common Rail System, and Exhaust Gas Recirculation until Bharat (CEV/Trem) Stage-III. With the implementation of stringent emission norms, specifically Bharat (CEV/Trem) Stage-IV and V, the significance of the Exhaust After Treatment (EAT) system in treating and controlling emissions outside the engine has increased substantially. The inclusion of Particulate Number (PN) in Bharat (CEV/Trem) Stage-V mandates the use of Diesel Particulate Filters (DPF). The soot particulates from the engine are filtered by the DPF and eventually need to be burned out via a process called regeneration.
Regeneration requires high exhaust temperatures, which are generated by exothermic reactions in the Diesel Oxidation Catalyst (DOC) with the addition of diesel fuel by an external dozer or in-cylinder late post injections. This study investigates the mechanisms of external dozer and late post injection strategies and selects the optimal system based on vehicle duty cycles.
During regeneration, post injections, especially with retarded injection timings and higher quantities, cause fuel dilution in oil, significantly impacting engine oil properties and oil drain intervals. The impact of post injection parameters on fuel burnt fraction, regeneration temperatures, and oil properties are experimentally investigated on an engine test bench, and optimal parameter values are derived.
Furthermore, real-world vehicle trials covering different terrains and duty cycles were conducted with optimized post injection parameters to evaluate the oil dilution impact on oil characteristics such as kinematic viscosity, Total Base Number (TBN), and Total Acid Number (TAN). The studies have shown that with optimal post-injection parameters, engine oil degradation remains within acceptable levels, meeting the target oil drain interval. Additionally, although wear element traces such as Fe, Si, and Cu increased, the overall values remained within the acceptable specifications of the oil.