Automotive Powertrain Technologies
The Automotive Powertrains Technologies Laboratory is concerned with the reduction of pollutions and the climate gases by road vehicles. The focus is on advanced catalytic converters, increasing powertrain efficiency and the switch to renewable energy. The lab cooperates internally with various groups in the fields of materials research, battery systems and tribology and with research and industrial partners in the field of basic research and prototyping. It consists of the research groups Vehicle Systems, Powertrain Technologies, Exhaust Aftertreatment and Future Mobility Demonstrator.
Combustion process for gas engines
Commercially available natural gas/biogas engines for road vehicles are slightly modified gasoline or diesel engines. As a result, they do not fully use the potential of methane, a fuel very suitable for internal combustion engines. We are working on new low-emission and more efficient combustion processes, which are specially optimized for gas operation. This is achieved, for example, through high peak combustion pressures, high ignition energies, exhaust gas recirculation and adapted turbocharging and mixture formation. We are also optimizing combustion processes for gases with high hydrogen content.
ETHZ, Politecnico die Milano, Volkswagen AG Group Research, FPT Motorenforschung AG, Horizon2020/SBFI, BFE
Ignition spark spectroscopy
The ignition of different methane gas compositions is investigated in an optically accessible constant volume cell (a).
By means of spark induced plasma spectroscopy, atomic and molecular spectral characteristics in the spark plasma are determined (b), which allow conclusions to be drawn about the mixture composition, plasma temperature and electron density at the time of ignition.
This allows a detailed understanding of the processes involved in flame formation in gas engines.
Partner:ETHZ, Volkswagen AG Group Research, FOGA
Fluid mechanics investigations of AdBlue injection, gas entrainment and wall loading
The injection of reactants (AdBlue) into the exhaust gas of diesel engines is carried out in a high-temperature flow test rig with laser-optical measuring methods (a).
The impact of AdBlue droplets on the exhaust walls leads to strong local cooling. Measurements by infrared thermography and heat conduction calculations show local cooling rates in the order of MW/m2 (b). This cooling leads to liquid film formation. Persistent liquid films lead to the formation of solid deposits.Partner:
The nanostructure and size of the particles generated by internal combustion engines is revealing for their reactivity and toxicity. By means of TEM investigation and image processing, particle size and properties of the graphene layers are investigated. The investigations include particles from diesel, gasoline and gas vehicles. In addition, particles from aircraft turbines are investigated.
Another focus is micro- and nanoparticles from brake wear.
Real fuel consumption approach
The standard fuel consumption data of a vehicle contains only limited information about the energy demand of the vehicle in reality. The real fuel consumption and CO2 emissions, however, are decisive for the climate balance of a vehicle. A method was therefore developed with which the energy requirement and thus also the CO2 emissions of the real vehicle operation (including auxiliary consumers) can be determined. The aim is to be able to calculate real consumption to an accuracy of ±10% on the basis of a few usage parameters (proportions of city, out-of-town and motorway journeys, payload).Partner:
Fully variable valve train
A new electrohydraulic valve train for combustion engines was co-developed at Empa. The system allows the valve lift, opening and closing times of the inlet and outlet valves to be varied independently of each other. Activities include controlling engine load, optimizing engine efficiency at partial load, increasing efficiency and performance at full load, and reducing emissions at engine cold starts. Other operating modes such as cylinder deactivation and 2-stroke operation are also being investigated.
Wolfgang Schneider Ingenieurbüro
Additively prepared catalyst supports
Open-cell, polyhedral catalyst substrates (AM) were produced using additive manufacturing processes. The CFD simulations carried out for this purpose show a higher mass transfer (Sh number) from the gases to the solid, which compared to today's honeycomb catalyst supports (HC) leads to high pollutant conversions with low surface area and low precious metal coating. Experimental tests are currently being carried out in a modern vehicle.
The aim is to substitute precious metals with turbulence.
Future Mobility Demonstrator „move“
Using the optimization algorithm "Dynamic Programming", the ideal operating strategy was determined with regard to the electricity price and the demand at the plant filling station. In this way, the hydrogen production and compression units are operated at low electricity prices, while the filling station storage facilities always have sufficient fuel for refuelling.
Two demonstrator vehicles were set up to test new drive concepts.
A fuel cell electric drive was developed for a road sweeper (a). The vehicle was subsequently tested in practical use in various Swiss cities for a total of 3 years. By replacing the hydraulic power distribution system with an electric drive and the diesel engine with a fuel cell system, energy consumption (tank-to-wheel) could be reduced by up to 70%.
A van with a methane gas engine was equipped with an adapted fuel supply system in order to be able to use methane gas enriched with hydrogen up to 30 vol%. The vehicle was used for 1 year in a parcel delivery service with up to 200 engine start/stop per day. The engine start times could be greatly shortened with the addition of hydrogen. In addition, CO2 emissions are reduced according to the reduced carbon content.
Microscopic (stereomicroscopy, REM/EDX) images of used catalysts allow the analysis of damages in the coating or in the substrates as well as chemical aging in the form of catalyst poisons or surface layers of ash components. In addition, surface effects such as the sintering of precious metals can be quantified. Thus causes can be identified, such as different thermal expansion of substrate and coating, chemical interactions or high heat generation.
Exhaust gas investigations
The emission and energy consumption behaviour of modern vehicle technologies is analysed in detail with the aid of investigations in the exhaust gas laboratory (a) and on the road (b). Thanks to a modern infrastructure (all-wheel roller test bench in a climatic chamber with solar simulation), the study can be carried out under various climatic conditions.