Browse Publications Technical Papers 2022-37-0018
2022-06-14

Virtual Development of a Single-Cylinder Engine for High Efficiency by the Adoption of eFuels, Methanol, Pre-Chamber and Millerization 2022-37-0018

The new CO2 and emissions limits imposed to European manufacturers require the adoption of different innovative solutions, such as the use of potentially CO2-neutral synthetic fuels alongside a tailored development of the internal combustion engine, as an excellent solution to accompany the hybridization of vehicles.
Dr.Ing. h.c. F. Porsche AG and FKFS, already partners for the development of engines with eFuels, propose a new study carried out on a research engine, investigating the combination of Porsche synthetic gasoline (POSYN) with an engine with millerization and passive pre-chamber. The use of CO2-neutral fuels allow for an immediate reduction in CO2 emissions from all cars already on the market, particularly since Porsche is one of the manufacturers whose cars remain in use for the longest time.
The data collected on a single-cylinder engine test bench, for different fuels, with conventional spark plug are used as input for the calibration of 3D-CFD simulations. The numerical study shows in detail the mixture formation, the turbulence in the cylinder and how to take advantage of the fuel cooling power by evaporation. Abnormal combustion is also studied by varying the ignition timing and evaluating the location of knock and its time-characteristics for the new engine concept.
A new pre-chamber design with asymmetrical holes is proposed and virtually tested in combination with synthetic fuel and methanol, for three high-load operating points. The injection strategy is optimized to support the turbulence at the electrode. Early intake valve closing timings are tested to increase knock resistance. Once methanol as a fuel is used, some optimizations in hardware are needed, in comparison to the adoption of regular gasoline. Particularly, a direct injector with higher mass flow and optionally a port fuel injector can be used to speed up the evaporation of methanol and mixture preparation.
The virtual development using different combination of fuels and hardware modifications led to a rise of engine indicated efficiency at high load from 39 % to 42 %, with constant engine compression ratio and stoichiometric combustion.

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