Driven by societal challenges on CO2 emissions and energy security, new pre-mixed combustion concepts, Reactivity Controlled Compression Ignition (RCCI) and Partially Premixed Combustion (PPC), are studied in CI engines as they are ultra clean, have very high indicated thermal efficiencies (57-59% reported in literature), and enable the usage of (combination of) a wide range of (bio-)fuels (fuel flexibility). These concepts are characterized by controlled auto-ignition of a pre-mixed mixture of higher octane fuels, air and exhaust gas.. Compared to classical diesel combustion, they lack direct control of combustion phasing and of rate of heat release and in general do not reach the same fuel conversion efficiency. Focus of this research is on maximizing efficiency and load range, specifying the best practical fuel (mix), and making the concepts robust for varying operating conditions. Given the sensitivity of these new concepts to operating conditions, advanced numerical combustion models will be developed based on single cylinder data and employed to optimize the fueling strategy and pin point the sources of the emissions and reduced fuel conversion efficiency. This will guide the development of improved hardware (pistons) and software (control models, virtual sensors). The latter is essential for the envisioned closed-loop combustion control concept, which enhances robust performance by cycle-to-cycle control and cylinder balancing. We explicitly aim to bridge the gap between single cylinder research and a full six cylinder by performing full system studies to define the hardware and software demands for a successful implementation on a six-cylinder engine. The research proposal combines the internationally recognized strengths of both participating groups, CT with their state-of-the-art combustion FGM models and world class experimental facilities and CST with their state-of-the-art model-based engine control strategies (QANU report 2014)The proposed combustion concepts imply an enormous societal impact. An increase in thermal efficiency towards 57-59% means roughly a decrease of 20% in GHG emissions from our main propulsion source for long-haul transport. This goes along with the corresponding reduction in operational costs. The concurrent decrease in NOx and Soot emissions will lead to a lower demands for after treatment systems which will also further decrease the vehicle fuel consumption associated with that. A secondary benefit is related to the fuel itself. These new concepts allow also the usage of a wide range of gasoline like fuels with a lower demand on the fuel quality. The current fuel mix in Europe is maximized towards high quality diesel and a shortage of diesel is eminent in the future. Application of low-quality gasoline like fuels in diesel engines will lead to a more balanced fuel mix in Europe, and possibly lower costs for refineries. Similarly, more bio-fuels are applicable (e.g. alcohols). All in all the energy dependency is reduced.
People involved in this project: Bart Somers, Robbert Willems, Theo de Groot, Bart van Pinxten & Lyon Hegh