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The usage of ethanol and two different mixtures of ethanol and gasoline (E85 and E65) wаs investigated on a modified diesel engine designed to work in a dual-fuel combustion mode with intake manifold alcohol injection. The maximum ratio of alcohol to diesel fuel was limited by irregular combustion phenomena like degrading combustion quality and poor process controllability at low load and knock as well as auto-ignition at high load. With rising alcohol amount, a significant reduction of soot mass and particle number was observed. At some testing points, substituting diesel with ethanol, E65 or E85 led to a reduction of NOx emissions; however, the real benefit concerning the nitrogen oxides was introduced by the mitigation of the soot-NOx trade-off. The indicated engine efficiency in dual-fuel mode showed an extended tolerance against high EGR rates. It was significantly improved with enhanced substitution ratios at high loads, whereas it dropped at low loads.

Fuel cells as alternative propulsion systems in vehicles can achieve higher driving ranges and shorter refueling times compared to pure battery-electric vehicles, while maintaining the local zero-emission status. However, to take advantage of pure battery electric driving, an externally rechargeable battery can be combined with a fuel cell range extender. As part of a research project, an efficient air supply system for a fuel cell range extender was developed. To this end, a 25 kW PEM fuel cell system test bench was set up. The different parameter influences of the test bench, in particular of the air supply system, were analyzed and evaluated in terms of stack/system efficiency and functionality. The control software of the test bench was specifically developed for the flexible operating parameter variation. All adjustable variables of the system (air ratio, stack temperature, pressure, etc.) were varied and evaluated at steady-state operating points.

As a consequence of the global warming, more strict maritime emission regulations are globally in force or will become applicable in the near future (e.g. NOX and SOX emission control areas). The tough competition puts economic pressure on the maritime transport industry. Therefore, the demand for efficient and mostly environmental neutral propulsion systems that meet the environmental legislations and minimize the cargo costs are immense. Medium speed dual fuel engines are in accordance with the strict maritime emissions legislation IMO Tier III. They do not require any exhaust gas aftertreatment, are economically competitive, and allow fuel flexibility. These engines deliver the highest efficiency in high load operation. A valuable approach to improve the efficiency and reduce the environmental impact in low and part load is represented by the electronic cylinder cut-out. Thereby, the natural gas admission is deactivated and the valves are kept activated.

In recent years a new combustion phenomenon called Low-Speed Pre-Ignition (LSPI) occurred, which is the most important limiting factor to exploit further downsizing potential due to the associated peak pressures and thus the huge damage potential. In the past there were already several triggers for pre-ignitions identified, whereat engine oil seems to have an important influence. Other studies have reported that detached oil droplets from the piston crevice volume lead to auto-ignition prior to spark ignition. However, wall wetting and subsequently oil dilution and changes in the oil properties by impinging fuel on the cylinder wall seem to have a significant influence in terms of accumulation and detachment of oil-fuel droplets in the combustion chamber. For this reason, the influence of test fuels with different volatility were investigated in order to verify their influence on wall wetting, detachment and pre-ignition tendency.

One promising application in the emission control is the Selective Catalytic Reduction (SCR) system for the reduction of nitric oxides from exhaust emissions. Previous works at the institute have highlighted the importance of accurate CFD turbulence modeling with respect to the turbulent mixing of ammonia vapor [1]. With the help of Laser Doppler Anemometry (LDA) measurements it was confirmed that RANS approaches are capable of predicting the velocity field adequately. In contrast, the turbulence level was underestimated for all RANS approaches [2]. Based on this work the paper at hand presents CFD results using Large Eddy Simulation (LES). The sensitivity of the solution with respect to spatial and temporal resolution as well as the boundary conditions is demonstrated. In accordance with the Kolmogorov theory grid sizes ranging from 3.2 to 20 million cells were investigated using LES methodology.

This paper focuses on the potentials of a Belt-Starter-Generator (BSG) in the context of an ultra-light vehicle prototype with a target curb weight of only 600 kg. Therefore, two hybrid approaches with a voltage level below 60 V are described and their potentials regarding electrical driving and CO2 reduction are analysed in detail. Introducing the ‘Cars Ultra-Light Technology’ (CULT) project, the holistic lightweight approach is described as a main requirement for the further hybrid investigations. In addition, a P2-hybrid structure with a 12 V BSG on the transmission input shaft enabled unique features despite the low voltage level and limited electrical power resources. The CO2 reduction for this powertrain combination is described and compared to a conventional stop start configuration. The validation process on a dynamic test rig is presented as well.

Current commercial vehicles' engines are complex systems with multiple degrees of freedom. In conjunction with current emissions regulations manufacturers are forced to combine highly developed engines with complex aftertreatment systems. A comprehensive simulation model including the engine and aftertreatment system has been set up in order to study and optimize the overall system. The model uses a phenomenological spray combustion model to predict fuel consumption and NO emissions. In addition physical models for the material temperatures and the reaction kinetics were generated for the aftertreatment system. Steady state and transient measurements were used to calibrate the engine as well as the aftertreatment model. The aim for a system-level optimization was a reduction of fuel consumption while meeting emission standards.

The Selective Catalytic Reduction (SCR) is a promising approach to meet future legislation regarding the nitric oxide emissions of diesel engines. In automotive applications a liquid urea-water solution (UWS) is injected into the hot exhaust gas. It evaporates and decomposes to ammonia vapor acting as the reducing agent. Significant criteria for an efficient SCR system are a fast mixture preparation of the UWS and a high ammonia uniformity at the SCR catalyst. Multiphase CFD simulation is capable to support the development of this process. However, major challenges are the correct description of the liquid phase behavior and the simulation of the ammonia vapor mixing in the turbulent exhaust gas upstream of the SCR catalyst. This paper presents a systematic study of the impact of the turbulence model and the numerical spatial discretization scheme on the prediction of the turbulent mixing process of the gaseous ammonia.

A naturally aspirated SI engine with port fuel injection was investigated at the Institute for Powertrains and Automotive Technology of the Vienna University of Technology to analyze the impact of the ethanol blend E85 on the full load performance. Measurements and numerical studies with a predictive wall film model have been carried out to explain the mixture cooling, the calorific fluid properties after inlet valve closing and the volumetric efficiency with conventional fuel and E85. It could be shown that only with a detailed modelling of the wall film formation in the inlet port an accurate prediction of the engine's full load performance is possible when studying different fuels with varying fluid properties. Anyway, an integrated approach that includes measurements and numerical investigations is necessary to analyse the mixture preparation and the engine process correctly.

In this study the performance of a monofuel compressed natural gas articulated truck was investigated under real-world conditions. To analyze the CNG vehicle due to fuel consumption and exhaust emissions a representative road-test route was conducted, including sections with significantly different driving conditions. Moreover, driving tests on freeway under higher load were carried out. As experimental equipment, a new ultra compact on-board system measured the in-car exhaust mass emissions in real time. Every second, a full dataset of CO₂, CO, HC and NOx emission rates was provided. The real-world emission measurements are based on a modal analysis of the emission concentrations in the tailpipe of the vehicle. The exhaust gas mass flow is calculated from the air mass flow and the gas components with a real-time reaction model. In combination with the vehicle speed, the emission rates in g/s are then calculated in gram per kilometer.

Future legislations claim further reduction of all restricted emissions as well as the limitation of soot emissions in diesel engines. Special alternative diesel fuels that do not contain aromatic compounds, therefore, promise great potential for further reduction of HC, CO and particulate emissions. During a research project carried out at the Institute for Powertrains and Automotive Technology at the Vienna University of Technology, the potential of alternative diesel fuels was investigated using a state-of-the-art diesel engine with common rail direct injection. The testing took part using an engine test rig as well as on the chassis dynamometer test bench to demonstrate the emission levels in real life conditions. As real biofuel, pure HVO (Hydrogenated Vegetable Oil) was investigated and additionally in different blends with fossil diesel fuel.

The piston ring and cylinder liner tribosystem is very sensitive. It is a heavily loaded system with high temperature and force exposure. High demands are made on the components in this area. These facts concern not only system components, but also the engine oil which can reach up to 300°C at the inner cylinder walls. High temperatures and force cause oil aging. As a part of the combustion chamber, the piston ring-cylinder liner tribosystem is in close contact with combustion constituents. If alternative fuels like ethanol are used, the influences to this tribosystem have to be investigated. In particular, the impacts of oil aging have to be considered to avoid higher wear and damage to the engine, to assure low fuel consumption, and to extend oil change intervals. Research work on abrasion of the ring-cylinder system was aimed to gain detailed information about the effects on this tribosystem.

Turbocharged diesel engines are popular propulsion systems for automotive applications like trucks or passenger cars because of their high efficiency and advantageous torque characteristic. The high NOx emissions due to their combustion process and missing three-way catalyst are, however, a disadvantage. Consequently, to satisfy future emission legislations, NOx emissions must be reduced. In addition, growing environmental awareness requires reduction of CO2 emissions, respectively, consumption. Hybridization is an effective method to achieve these multiple goals. The general tendency in direction of electrification of the powertrain leads to a diversity of drive concepts. In this context, the study of the entire system is as important as the analysis and evaluation of the interaction of the system components.

An optimized monofuel CNG light duty vehicle based on the Opel Zafira was investigated under real-world conditions and the results are presented in this study. To analyze the real-world performance of the monofuel CNG vehicle due to fuel consumption and exhaust emissions representative experimental test on road-test routes were performed, including sections with significantly different driving conditions. Furthermore, driving tests at different constant speeds on freeway were carried out. A benchmarking to the same vehicle with diesel powertrain was done as well. The test vehicles were equipped with a new compact on-board measurement system and additionally GPS tracking to link the received geographic information of the road-test routes with the measured exhaust mass emission data. The measurement results were validated with Matlab Simulink models of the powertrain and vehicle.

The objective of the project was to compare the exhaust gas emissions and fuel consumption of a test vehicle, which was on a one hand operating with premium gasoline 95 RON (RON 95) and a mixture of 90% by volume premium gasoline 95 RON and 10% by volume of high purity bio ethanol (E10) on the other hand. As a test vehicle a Skoda Octavia station wagon was used. The engine of the tested vehicle corresponded to the Euro 4 emission standard. The investigations were conducted under the real world conditions, and also at the chassis dynamometer test bench. The tested vehicle was equipped with a new On-board measurement System (OBM) to determine the mass emissions on real world driving routes. The measurement method is based on modal analysis of the emission concentrations in the tailpipe of the vehicle, and real time exhaust mass flow determination.

The goal of this project was to determine the exhaust mass emissions of light duty trucks (LDT) with three different engine concepts under real world conditions in the urban area of Vienna. Therefore three identical GM Opel Combo LDT with 1.6 liter monovalent CNG S.I. engine, 1.7 liter common rail turbo charged diesel engine and 1.4 liter Ecotec gasoline S.I. engine were tested systematically on representative urban routes and in parcel service. All engines corresponded to the new Euro IV emission standard and were within the same power range.