Optimal Calibration Strategy of a Hybrid Electric Vehicle Equipped with an Ultra-Lean Pre-Chamber SI Engine for the Minimization of CO2 and Pollutant Emissions

Abstract

The complexity of modern hybrid powertrains poses new challenges for the optimal control concerning, on one hand, the thermal engine to maximize its efficiency, and, on the other hand, the vehicle to minimize the noxious emissions and CO2. In this context, the engine calibration has to be conducted by considering simultaneously the powertrain management, the vehicle characteristics, and the driving mission. In this work, a calibration methodology for a two-stage boosted ultra-lean pre-chamber spark ignition (SI) engine is proposed, aiming at minimizing its CO2 and pollutant emissions. The engine features a flexible variable valve timing (VVT) control of the valves and an E-compressor, coupled in series to a turbocharger, to guarantee an adequate boost level needed for ultra-lean operation. The engine is simulated in a refined 1D model. A simplified methodology, based on a network of proportional integral derivative (PID) controllers, is presented for the calibration over the whole operating domain. Two calibration variants are proposed and compared, characterized by different fuel and electric consumptions: the first one aims to exclusively maximize the brake thermal efficiency, and the second one additionally considers the electric energy absorbed by the E-compressor and drained from the battery. After a verification against the outcomes of an automatic optimizer, the calibration strategies are assessed based on pollutant and CO2 emissions along representative driving cycles by vehicle simulations. The results highlight slightly lower CO2 emissions with the calibration approach that minimizes the E-compressor consumption, thus revealing the importance of considering the engine calibration phase, the powertrain management, the vehicle characteristics, and its mission.

Bicycle Traffic Model for Sustainable Urban Mobility Planning

“…New alternative fuel technologies (e.g., electricity, natural gas, and hydrogen) are ways to break the dependence on fossil fuels in order to reduce energy consumption and traffic-related emissions. However, it is important to look for ways to change transport behaviour in the short term, as long-term technological solutions have not yet been fully realised [43][44][45][46]. Another way to reduce energy consumption and GHG emissions is to reduce VKT (vehicle kilometres travelled) and vehicle ownership rates.…”

Simulation of the Performance of an Electrically Turbocharged Engine Over an Urban Driving Cycle

“…The turbocharger electrification technology, according to the study, increased fuel efficiency by 8%. In a study on a two-stage boosted ultra-lean sparkignition (SI) engine, Bozza et al [26] offer a calibration methodology with the aim of reducing CO2 emissions. The element that was considered when proposing two calibrated variants of a proportional integral derivative (PID) controller was different fuel and electric consumption.…”

Optimization of Pre-Chamber Geometry and Operating Parameters in a Turbulent Jet Ignition Engine

“…The application of lean burning mixtures can increase engine brake thermal efficiency up to 49%, especially when combined with an electric compressor [3], while reducing raw emissions of nitrogen oxides (NO X ) up to 92% [4] compared to conventional IC engines. There are several lean burn combustion concepts that can be adopted in IC engines, such as homogeneous charge compression ignition (HCCI) [5], spark assisted compression ignition (SACI), reactivity-controlled compression ignition (RCCI), jet-controlled compression ignition (JCCI) [6] and pre-chamber spark-ignited (PCSI) engines.…”

“…There are several lean burn combustion concepts that can be adopted in IC engines, such as homogeneous charge compression ignition (HCCI) [5], spark assisted compression ignition (SACI), reactivity-controlled compression ignition (RCCI), jet-controlled compression ignition (JCCI) [6] and pre-chamber spark-ignited (PCSI) engines. In the last few years, spark-ignited (SI) engines equipped with active or passive pre-chambers have attracted a lot of research work because this concept can easily be integrated into the existing engine architectures of conventional [7] or hybrid powertrains [3]. In such engines, the combustion process is initiated by the discharge of a spark in a small pre-chamber volume, and hot turbulent jets that are formed from the pre-chamber ignite the lean mixture in the main chamber.…”