<div class="section abstract"><div class="htmlview paragraph">Air pollution in India and also global warming are two major concern in the country. To address this situation, India is moving from BS-IV to BS-VI for on-road applications with 90% reduction in NOx and 50% in PM with limit on particulate number. Also moving to Trem-IV and Trem-V for off-road applications subsequently. It needs higher efficiency after-treatment systems like SCR and DPF to achieve such lower emission levels. Addition of these complex after-treatment system, severely increase the cost of diesel power plant with heavy penalty on fuel economy. Hence, it is challenge to auto industry to reduce the complexity and cost, so that it requires an alternate solution to reduce NOx and PM emissions at source to reduce cost and system complexity. Low Temperature Combustion (LTC) is a potential concept to reduce the NOx and PM emissions simultaneously. LTC concept was experimentally demonstrated on engines of passenger car and light commercial segments, but not much work carried out for heavy duty engines.</div><div class="htmlview paragraph">The current research work focused on development of LTC concept to reduce both NOx and PM emissions to a required low levels with fuel efficiency improvement so that aftertreatment system cost and complexity will be reduced to a great extent for BS-VI norms. Extensive simulation work carried out in this research for selecting the combustion system including fuel injection system (nozzle configuration, injection pressures and multiple injection), air handling system (air-fuel ratio, EGR%, and swirl) and piston bowl (combustion bowl geometry, compression ratio) suitable to run the engine on both LTC and conventional modes. Engine was built with all modified features and experiments were performed as per BS-VI cycles (WHSC and WHTC).</div><div class="htmlview paragraph">Experiments carried out over entire engine operating zone with smooth transition between LTC modes in part loads and conventional combustion mode in high load zone. Cycle engine out emissions reduced up to 2.1 g/kWh NOx and ~0.03 g/kWh PM with ~5% overall cycle BSFC improvement in steady state WHSC cycle. Encouraging results have been achieved on transient WHTC cycle also. The lowest BSFC noticed during experiments was close to 191 g/kWh at optimized engine out NOx levels. Utmost important is reduced engine out emissions and improved fuel economy which reduces after-treatment system cost & complexity, operating, maintenance cost and improved field performance with increased regeneration intervals. This result in lower urea and fuel consumption. In summary, LTC is a cost effective solution for BS-VI.</div></div>
<div class="section abstract"><div class="htmlview paragraph">Development of future efficient and cleaner heavy duty engines are no longer limited to laboratory development under standard conditions. In order to address the global issues like climate change and poor air quality in its true sense, future advanced and existing heavy duty diesel engines should also be demonstrating emission conformity compliance as per legislations under real driving conditions using PEMS testing. In India starting from Apr 2023, heavy duty vehicles would be tested for in-service conformity and presently they are under monitoring phase. With the introduction of RDE (Real Driving Emission) the effort, cost and time requirements could be tremendous in order to meet conformity compliance over real driving conditions including the range of ambient conditions for the said period as per the norms. Hence, it would be of great importance if we can utilize virtual test bed (VTB) to off-load several initial field testing and calibration efforts by virtually running the vehicles over simulated cycles with various operating conditions that includes simulating payload, traffic, ambient condition change and predicting emissions and their conformity for these generated routes and operating conditions. However, this would indeed require a good correlation between the actual engine and vehicle behavior and the plant model. In this work an attempt has been made to understand how VTB can be used for this purpose. The PEMS testing data for the first heavy duty vehicle with GVW above 12 ton was used for one level of model validation were reasonable matching of various trip parameters, characteristics trends and emissions were observed for running the simulated cycle in VTB. Later we performed a parametric variations including payload, traffic and ambient conditions using a second vehicle with GVW above 12 ton category with different tonnage and application to understand their impact on trip characteristics, emissions and conformity factors and finally the results for one parameter was validated by conducting a PEMS test. With this approach, in contrast to conventional method we utilized virtual test bed with integration of engine ECU, plant model (engine +after treatment) and PUMA test system to investigate the possibility of generating drive cycle, performing parametric variations, simulating extreme conditions and understanding their impact on trip characteristics, emissions, and conformity factor moreover such findings will definitely help in understanding the scope of calibration work required to comply with real driving emission norms.</div></div>
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