Evaluation of Different Methodologies of Soot Mass Estimation for Optimum Regeneration Interval of Diesel Particulate Filter (DPF) 2021-26-0208

Diesel engines have always been popular for their low end torque and lugging abilities. With their higher thermal efficiencies through technical advancements, diesel engines are preferred powertrains in mass transportation of goods as well as people [14] [15]. A diesel engine always banks on excess air, which is subjected to higher compression ratios so as to achieve temperatures, enough to facilitate auto-ignition of diesel. With the advent of turbocharging and intercooling, the air availability is further enhanced, ensuring better combustion efficiency, lesser HC, CO and particulate matter (PM) emissions together with improved fuel efficiencies [2] [15]. Higher air availability also has its own shortcomings in the form of higher NOx (Nitrogen oxides) emissions. With stringent emission norms in place, reduction of NOx as well as PM, without sacrificing performance and fuel economy, is of utmost importance. A Diesel Particulate Filter (DPF) essentially traps particulate emissions and hence reduces their outflow into the surrounding atmosphere. With the usage of Exhaust Gas Recirculation (EGR), particulate emissions are higher. Regeneration of DPF is a process where the accumulated particulates are burned at high temperatures, actively or passively [14]. This accumulation will otherwise lead to significantly higher back- pressures and DPF choking which will impede engine performance. However, frequent regeneration also contributes to higher dilution of engine oil, leading to shorter oil change intervals and under extreme circumstances, an engine failure due to improper lubrication. This emphasizes the need to estimate the amount of soot in the DPF. Two methods to estimate soot are explored. One of the methods uses important flow parameters (temperature & mass/volume flow) to estimate particulate emissions from the engine. Further, corrections based on temperature, NO2/ NOx ratio and mass/volume flow are used to estimate the amount of soot getting oxidized passively [12]. The second method monitors the differential pressure across the DPF to determine the amount of loading. A 4 cylinder, turbocharged, intercooled, direct injection (DI) diesel engine for LMDCV, certified for BS-VI emission norms is made use of to achieve the same. The soot model arrived is capable of predicting the accumulated soot in the DPF to ± 15% over different duty cycles (City, Extra Urban and Highway).