Matthias Thewes

Water injection for gasoline engines: Potentials, challenges, and solutions:

Further significant CO2 emission reduction beyond 2020 is mandatory in the United States and might also become mandatory in Europe, depending on the passenger car CO2 legislation, which is to be enacted. Hybrid and plug-in hybrid vehicles might account for a big portion of these CO2 reductions as a consequence of the favourable current legislative treatment which does not associate CO2 emissions from electric power generation with vehicle CO2 emissions. Nevertheless, these powertrains benefit from a highly efficient combustion engine. Exhaust heat recovery poses new synergetic possibilities for technologies to mitigate knock like cooled external exhaust gas recirculation and condensed water injection. The condensed water injection concept, which is proposed in this article, demonstrates a potential for efficiency increase of 3.3% – 3.8% in the region of the minimum specific fuel consumption on a stoichiometric combustion concept with Miller cycle and cooled external exhaust gas recirculation. Further improvement of the efficiency of up to 16% is possible at full-load operation. If water injection is used in addition to homogeneous lean combustion, an efficiency gain of 4.5% in the region of the minimum specific fuel consumption is achieved.

Tailor-made fuels for future engine concepts

Increasing carbon dioxide accumulation in earth’s atmosphere and the depletion of fossil resources pose huge challenges for our society and, in particular, for all stakeholders in the transportation sector. The Cluster of Excellence ‘Tailor-Made Fuels from Biomass’ at RWTH Aachen University establishes innovative and sustainable processes for the conversion of whole plants into molecularly well-defined fuels exhibiting tailored properties for low-temperature combustion engine processes, enabling high efficiency and low pollutant emissions. The concept of fuel design, that is, considering fuel’s molecular structure to be a design degree of freedom, aims for the simultaneous optimisation of fuel production and combustion systems. In the present contribution, three examples of tailor-made biofuels are presented. For spark ignition engines, both 2-methylfuran and 2-butanone show increased knock resistance compared to RON95 gasoline, thus enabling a higher compression ratio and an efficiency gain of up to 20% at full-load operation. Moreover, both fuels comprise a good mixture formation superior to the one of ethanol, especially under difficult boundary conditions. For compression ignition engines, 1-octanol enables a remarkable reduction in engine-out soot emissions compared to standard diesel fuel due to the high oxygen content and lower reactivity. This advantage is achieved without sacrificing the high indicated efficiency and low NOX emissions.

Road-to-rig-to-desktop: Virtual development using real-time engine modelling and powertrain co-simulation

By front-loading of the conventional vehicle testing to engine test bench or even further forward to offline simulations, it is possible to assess a large variation of powertrain design parameters and testing manoeuvres in the early development stages. This entails a substantial cost reduction compared to physical vehicle testing and hence an optimisation of the modern powertrain development process. This approach is often referred to as road-to-rig-to-desktop. To demonstrate the potential of this road-to-rig-to-desktop methodology as a seamless development process, a crank angle–resolved real-time engine model for a turbocharged gasoline engine was built with the simulation tool GT-POWER®. The model was validated with measurement data from an engine test bench and integrated into a vehicle co-simulation, which also includes a dual clutch transmission, the chassis, the environment and the automated driver. The most relevant functions of the engine and the transmission control systems were implemented in a Simulink-based software control unit. To verify the engine model in the transient vehicle simulation, two 900-s time windows from a 2-h real driving emission test, representing urban and motorway conditions, are simulated using the developed co-simulation platform. The simulation results are compared with the respective vehicle measurement data. The fuel consumption deviation caused by the combustion engine model is within 5%. The transient system behaviour and the dominant engine operation points could be predicted with a satisfying accuracy.

All lambda 1 gasoline powertrains

The introduction of new emission legislations in Europe (EU6d-TEMP) and China (CN6b) increases the pressure on the automotive industry to develop new and better exhaust gas aftertreatment and combustion systems. The fulfilment of PN and NOx targets in real world driving scenarios and increasingly electrified powertrains have led to the introduction of gasoline particulate filters (GPFs) and enlarged catalytic converters. Now, on top of these major upgrades, the monitoring of CO emissions according to Real Driving Emissions (RDE) legislation puts a potential ban on high load enrichment for thermal component protection into focus. Hence, new technologies which enable Lambda 1 operation in the entire map of a gasoline engine are urgently required. This paper presents technology packages for component protection at high load stoichiometric operation as well as operational strategies for ultra-low CO emissions in all real driving scenarios. Assessed solutions span from base engine modifications to water injection and vehicle cooling concepts as well as to control functions. Favorable combinations are identified taking into consideration costs and realistic integration in ongoing vehicle programs.

Extreme lean gasoline technology – best efficiency and lowest emission powertrains

Development of mobile propulsion technology is driven by fuel consumption and exhaust emission reduction. New gasoline powertrains currently developed at FEV address both these major trends using extreme lean combustion systems to combine best efficiency with lowest emission levels. This paper elaborates on the technology potentials and development methodologies used to handle challenges associated with gasoline lean burn.

Extreme downsizing for gasoline engines – fun to drive with extremely low emissions

This paper elaborates different boosting systems for extreme downsizing levels considering the target of optimal transient performance: