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Photo Credit: Peter Winandy | RWTH Aachen

04.03.2019

One third less consumption: Industry and research work together on fuel-efficient spark-ignition engines

In order to meet future CO2 limits, SI engine-driven vehicles must consume significantly less fuel. A new project of the Research Association for Internal Combustion Engines (FVV) is investigating how this can be achieved. The ambitious goal is to increase the efficiency of future spark-ignition engines to up to 50 per cent. At the same time, fuel consumption is to be reduced by around one third compared with today's fleet. The project is exploring new engine technologies in interaction with electrified powertrains and synthetic fuels.

Frankfurt/M. // The more chemical energy contained in the fuel can be converted into mechanical power, the better the efficiency and thus the fuel consumption rate of the vehicle. In the "ICE 2025+" research project financed from the FVV's own funds, four university institutes from Aachen, Braunschweig, Darmstadt and Stuttgart are investigating various measures aimed at significantly increasing engine efficiency. The aim of the project is to optimise the entire powertrain system in such a way as to achieve the lowest possible consumption in real world operation. In relation to the new WLTP cycle, this means achieving an average power efficiency of around 40 per cent, and even 50 per cent at specific operating points. New passenger car spark-ignition engines currently achieve an optimum performance of around 30 % per cent.

The researchers' methodological approach consists of combining various pre-selected technologies - such as higher compression ratios or water injection - and investigating their influence on system efficiency. In order to adapt the powertrain system to real world driving conditions, various vehicle classes as well as hybrid variants - from mild 48 volts to high-voltage hybrid powertrains - will be included in the study.

CO2 emissions from the transportation sector must fall significantly

The participating researchers work closely together. The first work package, which is carried out by the Institute for Internal Combustion Engines and Powertrain Systems (vkm) at Technische Universität Darmstadt, lays the foundations for vehicle simulation. This is important in order to be able to make exact statements about the CO2 emissions of the entire vehicle under realistic operating conditions with the engine data generated in the other work packages. It is also part of the job to find an operating strategy for the electric powertrain components that enables the combustion engine to work as efficiently as possible.

The second part of the project, engine simulation, which is being carried out at the Institute for Internal Combustion Engines and Automotive Engineering (IVK) at the University of Stuttgart, consists primarily of being able to make binding statements about increases in efficiency through various combinations of technologies with the aid of rapid calculation methods. In addition, a virtual engine is “designed“, which makes it possible to estimate the impact of external measures - such as exhaust heat recovery - on the engine.

Within "ICE 2025+", major measures to increase efficiency will not only be simulated, but also tested on a single-cylinder research engine. The Institute for Internal Combustion Engines (ivb) at Braunschweig Technical University is responsible for setting up and operating this test engine. The results obtained are not only used for technology evaluation but are also intended to improve existing simulation models.

The fourth work package, looks into the influence of carbon-neutral fuels on engine behaviour and is being carried out at the Chair of Internal Combustion Engines (vka) at RWTH Aachen University. Various synthetic fuels, both pure and blended, are being tested on a research engine for this purpose. In addition to assessing the potential of possible fuel alternatives in terms of efficiency and emissions, the results should also serve to improve existing simulation methods of the combustion process.

The results of the research project "ICE 2025+" will be available in spring 2020.

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