From 2021 on, the European Union fleet-wide average emission target for new cars will be 95 gCO2/km. A fine of €95 will be assigned to car manufacturers for each g/km of target exceedance for each car registered. As an example, Volkswagen sold 39861 cars in 2020 in Belgium which, with an average CO2 output of 114.5 gCO2/kg, would have resulted in a fine of 74 million euros (or almost 2000 EUR per car sold)! The development of a highly efficient and clean internal combustion engine (ICE) is thus a key requirement not only for Volkswagen but for all engine manufacturers.
There are 2 main pathways to improve the efficiency of current ICEs. The first one is to go away from fossil fuels, and move towards sustainable fuels. Methanol proves here to be an excellent candidate. It can be made in an environmental friendly way by combining green hydrogen with CO2. Additionally, due to its high octane number, high heat of vaporization and especially high flame speed, it serves as a great fuel specifically for spark ignition (SI) engines. Within the biomass limit, 2nd generation biofuels are also very interesting in the short term, as they allow formulating so-called “drop-in” fuel blends (fuels with reduced fossil content that work in the currently sold vehicles).
The second pathway involves the improvement of the technology used in the combustion engine. Variable valve timing, exhaust gas recirculation, lean combustion, variable compression ratio, water injection, cylinder deactivation etc. are all techniques used to improve the efficiency at part and/or full load of the engine. They can be used separately or combined depending on the load requirement. At some points, a combination of techniques might greatly improve efficiency while at other points might deteriorate it.
Within the research group “Transport Technology”, a turbocharged DISI engine – Volvo T3 was selected for this research. The engine itself is equipped with variable valve timing on both camshafts, direct injection, low pressure exhaust gas recirculation, a turbocharger and a backpressure valve. The engine is furthermore fully instrumented in terms of pressures, temperature and emissions.
The goal of this project will be to investigate the efficiency potential of all these techniques at low, medium and high loads. The influence of the different parameters on the combustion, performances and pollution emissions will be investigated and by optimizing the parameters at each load, the lowest average CO2 output in g/km can be found. This exploration focuses on methanol fuel but will also include drop-in fuels based on 2nd generation biofuels.