ALTERNATE FUELS FOR ON-ROAD ENGINES AND IMPACT ON REDUCING CARBON FOOTPRINT
thesisposted on 02.08.2021, 13:11 authored by Vrushali Satish DeshmukhVrushali Satish Deshmukh
Variable valve actuation remains one of the most studied technologies for diesel engines for fuel benefits, efficiency improvements and emission control. The same can be implemented on natural gas engines however presence of throttle valve in the spark ignited natural gas engine leads to different set of challenges and outcomes. In this document, focus is on GT power led analyses for a mid-range natural gas engine and the VVA strategy applied is modulation of intake valve closure timing. The simulations are run for early intake valve closure and late intake valve closure, both applied independently and run for steady state conditions. The focus is on the low torque range to study the impact of IVC modulation on throttling losses for low torque region. The simulation studies showed that IVC strategies both early as well as late IVC do benefit in terms of thermal efficiency improvements by up to 3% and reduction in brake specific fuel efficiency by up to 13%.It also showed considerable reduction in pumping loop and increase in open cycle efficiency when IVC modulation is applied. Validating the model further with real on-engine data and then calibrating the existing GT power with the on-engine data to validate the conclusions drawn would be the next set of goals for this project.
Second part of this document is focused on real life testing of soy biodiesel fueled heavy duty on-road engine with modern exhaust aftertreatment system with SCR. Soybean based biodiesel remains one of the most sought-after alternate fuel and biofuel to be used in on-road engines. Burning biodiesel leads to a cleaner exhaust compared to conventional diesel as the biofuel is oxygenated fuel leading to more complete combustion and lower amount of emission species such as CO, CO2and PM in the exhaust. The experiments discussed in this document consisted of developing torque curve envelopes and steady state tests (RMC set points). Three soy biodiesel blends were studied which included B20-20% biodiesel, B50 –50% biodiesel and B100 –100% biodiesel. NOx emissions were observed to be considerably higher for B100 at engine outlet by up to80% as well as at tailpipe outlet increased by up to380%, compared to that of conventional diesel which is attributed to the thermal mechanism of NO production. The exhaust gas temperatures were observed to be lower by up to40-degreeC while the urea dosing was considerably higher by up to83% when using biodiesel blend B100.Thisresearch paves the way to testing further using varying biodiesel blends for regulation certification trials, for tuning the diesel engines for different biodiesel blends and for developing the control strategy for the existing diesel engines to accommodate biodiesel.