The engine has played a pivotal role in controlling regulated pollutants at the in-cylinder combustion level through strategies such as Direct Injection, Common Rail Systems, and Exhaust Gas Recirculation up to Bharat (CEV/Trem) Stage-III. With the advent of more stringent emission norms, specifically Bharat (CEV/Trem) Stage-IV and V, the importance of Exhaust After-Treatment Systems (EATS) in managing emissions outside the engine has significantly increased. The inclusion of Particulate Number (PN) limits in Bharat (CEV/Trem) Stage-V necessitates the use of Diesel Particulate Filters (DPF), which trap soot particles that must be periodically removed through a process known as regeneration.
Regeneration requires elevated exhaust temperatures, typically achieved via exothermic reactions in the Diesel Oxidation Catalyst (DOC), facilitated by diesel fuel addition through external injection or in-cylinder injection strategies. This study investigates both external and in-cylinder injection mechanisms, proposing an optimal system tailored to the intended vehicle application. During regeneration, late post-injections, especially those with retarded timing and increased fuel quantities, can lead to fuel dilution in engine oil, adversely affecting the oil properties and oil drain intervals.
Experimental investigations were conducted on an engine test bench to evaluate the impact of post-injection parameters on fuel burn fraction, regeneration temperatures, and engine oil characteristics. Optimal parameter values were derived to balance regeneration efficiency and oil integrity. Additionally, real-world vehicle trials across different terrains and duty cycles were performed using the optimized post-injection parameters to assess the oil dilution effects on key oil properties such as kinematic viscosity, Total Base Number (TBN), and Total Acid Number (TAN). The results demonstrate that with optimized post-injection parameters, engine oil degradation remains within acceptable limits, supporting the target oil drain interval. Although wear element traces (e.g., Fe, Cu, Al) showed an increase, their concentrations remained within the oil specification thresholds.