Search Results

The trend towards renewable energy sources will continue under the pre-amble of greenhouse gas (GHG) emission reduction targets. The main question is how to harvest and store renewable energy properly. The challenge of intermittency of the renewable energy resources make the supply less predictable compared to the traditional energy sources. Chemical energy carriers like hydrogen and synthetic fuels (e-Fuels) seem to be at least a part of the solution for storing renewable energy. The usage of e-Fuels in the existing ICE-powered vehicle fleet has a big lever arm to reduce the GHG emissions of the transport sector in the short- and medium term. The paper covers the whole well-to-wheel (WtW) pathway by discussing the e-Fuel production from renewable sources, the storage and the usage in the vehicle. It will be summarized by scenarios on the impact of e-Fuel to the WtW CO2 fleet emissions.

India is the market with the highest sales of agricultural tractors and the market with the highest number of agricultural tractor park, as well. Even though taking into account the lower average power of Indian agricultural tractors compared to regions with considerably larger field sizes, their cumulated diesel fuel consumption reaches a significant size. The possible use of alternative powertrains like battery-electric, especially considering the lower power of the Indian tractor market, seems feasible, but might be struggling with challenges in terms of charging infrastructure and the possibly resulting lower productivity due to required charging times. Therefore AVL proposes to investigate the use of alternative fuels for internal combustion engines, a topic which is also being discussed by other global tractor OEMs. In that context the focus is typically on higher tractor powers due to current storage limitations of battery-electric systems and other alternatives.

In order to meet current and future emission and CO2 targets, an efficient vehicle thermal management system is one of the key factors in conventional as well as in electrified powertrains. Furthermore the increasing number of vehicle configurations leads to a high variability and degrees of freedom in possible system designs and the control thereof, which can only be handled by a comprehensive tool chain of vehicle system simulation and a generic control system architecture. The required model must comprise all relevant systems of the vehicle (control functionality, cooling system, lubrication system, engine, drive train, HV components etc.). For proper prediction with respect to energy consumption all interactions and interdependencies of those systems have to be taken into consideration, i.e. all energy fluxes (mechanical, hydraulically, electrical, thermal) have to be exchanged among the system boundaries accordingly.

The effect of “Start & Stop” and “Gear Shift Indicator” - two widespread fuel saving technologies - on fuel consumption and particle emissions of a Euro 5 passenger car is evaluated in this paper. The vehicle was subjected to a series of different driving cycles, including the current (NEDC) and future (WLTC) cycles implemented in the European type approval procedure at cold and hot start condition and particle number was measured with an AVL Particle Counter. In addition, we have utilized two Pegasor Particle Sensor units positioned in different locations along the sampling line to assess the impact of the sampling location on the particle characteristics measured during highly transient events. The results showed that the particle number emission levels over the WLTC were comparable to the NEDC ones, whereas NOx emissions were more than twofold higher. Both fuel saving technologies can lead to reduced fuel consumption and, subsequently CO2 emissions, in the order of 5%.

The Particle Measurement Programme (PMP) developed an exhaust particle number measurement protocol that has been adopted by current light duty vehicle emission regulations in Europe. This includes thermal treatment of the exhaust aerosol to isolate solid particles only and a number counting device with a lower cutpoint of 23 nm to avoid measurement of smaller particles that may affect the repeatability of the measurement. In this paper, we examine a potential alternative to the PMP system, where the thermal treatment is replaced by a catalytic stripper (CS). This offers oxidation and not just evaporation of the volatile components. Alternative sampling systems, either fulfilling the PMP recommendations or utilizing a CS, have been explored in terms of their volatile particle removal efficiency. Tests have been conducted on diesel exhaust, diesel equipped with DPF and gasoline direct injection emissions.

Most major regional automotive markets have stringent legislative targets for vehicle greenhouse gas emissions or fuel economy enforced by fiscal penalties. Large improvements in vehicle efficiency on mandated test cycles have already taken place in some markets through the widespread adoption of technologies such as downsizing or dieselization. There is now increased focus on approaches which give smaller but significant incremental efficiency benefits such as reducing parasitic losses due to engine friction. Fuel economy improvements which achieve this through the development of advanced engine lubricants are very attractive to vehicle manufacturers due to their favorable cost-benefit ratio. For an engine with components which operate predominantly in the hydrodynamic lubrication regime, the most significant lubricant parameter which can be changed to improve the tribological performance of the system is the lubricant viscosity.

Minimizing the lubricant volume in a transmission system reduces the churning losses and overall unit costs. However, lubricant volume reduction is also detrimental to the thermal stability of the system. Transmission overheating can result in significant issues in the region of loaded contacts, risking severe surface/sub-surface damage in bearings and gears, as well as reduction in the lubricant quality through advanced oxidation and shear degradation. The increasing trend of electrified transmission input speeds raises the importance of understanding the thermal limits of the system at the envelope of the performance to ensure quality and reliability can be maintained, as well as being a key factor in the development, effecting internal housing features for the promotion of lubrication. A nodal bearing thermal model will be shown which utilizes thermal resistances and smooth particle based CFD for determining bearing lubricant feed rates during operation.

In 2023, the European Union set more ambitious targets for reducing greenhouse gas emissions from passenger cars: the new fleet-wide average targets became 93.6 g/km for 2025, 49.5 g/km in 2030, going to 0 in 2035. One year away from the 2025 target, this study evaluates what contribution to CO2 reduction was achieved from new conventional vehicles and how to interpret forecasts for future efficiency gains. The European Commission’s vehicle efficiency cost-curves suggest that optimal technology adoption can guarantee up to 50% CO2 reduction by 2025 for conventional vehicles. Official registration data between 2013 and 2022, however, reveal only an average 14% increase in fuel efficiency in standard combustion vehicles, although reaching almost 23% for standard hybrids. The smallest gap between certified emissions and best-case scenarios is of 14 g/km, suggesting that some manufacturers’ declared values are approaching the optimum.

Recent turbocharged Gasoline engines based on MPFI offer excellent power output and high nominal torque, however, also some disadvantages. The most significant restrictions of TC-engines - like poor fuel economy, limited emission capability and delayed transient response (turbo lag) - can be improved dramatically by a refined GDI application. The synergy effects of GDI, which are also partly used at naturally aspirated engines, are even more significant with turbocharging. The low emission capability of GDI enables turbocharged SULEV concepts within moderate cost of the emission / aftertreatment system. The outstanding low-end-torque, the high specific power and torque output of refined GDI-Turbo concepts enable high fuel efficiency combined with excellent fun to drive. Thus such GDI-Turbo concepts will become the most attractive technology to fulfill highest fuel economy-, emission- and performance requirements simultaneously.

The upcoming Euro 7 regulation introduces the concept of continuous On-Board (emission) Monitoring (OBM), while On-Board Fuel/Energy Consumption Monitoring (OBFCM) is already an integral part of modern vehicles. The current work aims to assess whether on-board data could provide sufficient information to characterize real-world vehicle performance and emissions. Nine Euro 6d-ISC-FCM passenger cars were used, covering a wide range of powertrain technologies, from conventional gasoline and diesel to hybrid (HEV) and plug-in hybrid (PHEV) electric vehicles. Three vehicles were thoroughly tested in the laboratory and on the road, aiming at evaluating in detail the on-board data monitoring system. The evaluation concerned OBFCM device recordings of fuel consumed and distance travelled, as well as tailpipe NOx emissions and exhaust mass flow rate.

In this study, engine performances and exhaust emissions characteristics of compression ignition engine fueled with GTL were investigated by comparison with diesel fuel. Diesel engine could be operated fueled with GTL without any special modify for the test engine. With the high cetane number of GTL, the ignition lag was shorter, and the combustion started earlier than that of diesel fuel. Brake thermal efficiency operated with GTL increased at middle load conditions due to incomplete combustion emission such as CO and THC were lower than that of diesel fuel operation. NOx emission with GTL was comparable to diesel fuel, and there was a little decrease at high load. With GTL, soot emission was lower than with diesel fuel at above middle load condition. It seemed to be a reason of soot reduction that there was little sulphur contained in GTL.

Despite the increasingly stringent emissions legislation, users and owners of commercial diesel vehicles are continually demanding that each new engine generation is more economical than the previous one. This is especially important for commercial vehicles where the majority of engines are in the 1-2ltr./cyl. class. The demands are being reflected in new engine designs with lower friction and improved structural stiffness, together with fuel systems having increased pressure capability, higher spill rates, injection rate shaping and advanced control features. These fuel system requirements have led to a variety of new fuel injection systems and in the search for increased injection pressure these fuel systems have placed greater demands on the engine, especially in areas such as the cylinder head and fuel system drive, sometimes with adverse effects on the combustion and fuel injection system induced mechanical noise.

Increasingly stringent greenhouse gas and emission limits demand for powertrain electrification throughout all vehicle applications. Beside fully electric powertrains different configurations of hybrid powertrains will have an important role in upcoming and future vehicle generations. As already discussed in previous papers, the requirements on the combustion engine in hybrid powertrains are different to those in a conventional powertrain solution, heading for brake thermal efficiency targets of 45% and above within the product lifecycle for conventional fuels. Focus on product cost and production and assembly facility investment drives reuse of technology packages within modular powertrain technology platforms, with different combinations of internal combustion engines (ICE), transmissions, and e-drive-layouts. The goal of zero carbon operation requires compatibility of ICE for sustainable fuels.

Upcoming, increasingly stringent greenhouse gas (GHG) as well as emission limits demand for powertrain electrification throughout all vehicle applications. Increasing complexity of electrified powertrain architectures require an overall system approach combining component technology with integration and industrialization requirements when heading for further significant efficiency optimization of the subsystem internal combustion engine. The requirements on the combustion engine in hybrid powertrains are quite different to those in a conventional powertrain solution. Next-generation hybrid engines, with brake thermal efficiency (BTE) targets starting from 42-43% and aiming for 45% and above within the product lifecycle, require a re-thinking of the base engine architecture of current modular engine platforms. At the same time focus on the product cost and minimized additional investment demand reuse of current production, machining and assembly facilities as far as possible.

Knocking combustion places a major limit on the performance and efficiency of spark ignition engines. Spontaneous ignition of the unburned air-fuel mixture ahead of the flame front leads to a rapid release of energy, which produces pressure waves that cause the engine structure to vibrate at its natural frequencies and produce an audible ‘pinging’ sound. In extreme cases of knock, increased temperatures and pressures in the cylinder can cause severe engine damage. Damage is thought to be caused by thermal strain effects that are directly related to the heat flux. Since it will be the maximum values that are potentially the most damaging, then the heat flux needs to be measured on a cycle-by-cycle basis. Previous work has correlated heat flux with the pressure fluctuations on an average basis, but the work here shows a correlation on a cycle-by-cycle basis. The in-cylinder pressure and surface temperature were measured using a pressure transducer and eroding-type thermocouple.

Variable Compression Systems (VCS) for Internal Combustion Engines (ICE) will become increasingly more important in the future to meet stringent global fuel economy and CO2 standards. A Dual Mode VCS is in development at AVL and the basic functionality and potential were described in a technical paper which was presented at the SAE WCX 2017 [1]. The system is based on a hydraulically switched and locked conrod with telescopic shank. The AVL Dual Mode VCS was designed and virtually optimized with CAE simulation methods for the boundary conditions of a typical 2.0 L Inline (I) 4 Turbocharged Gasoline Direct Injection (TGDI) engine representing state-of-the-art gasoline engine technology for the next years to come.

In order to achieve future CO2 targets - in particular under real driving conditions - different powertrain technologies will have to be introduced. Beside the increasing electrification of the powertrain, it will be essential to utilize the full potential of the internal combustion engine. In addition to further optimization of the combustion processes and the reduction of mechanical losses in the thermal- and energetic systems, the introduction of Variable Compression Ratio (VCR) is probably the measure with the highest potential for fuel economy improvement. VCR systems are expected to be introduced to a considerable number of next generation turbocharged Spark Ignited (SI) engines in certain vehicle classes. The basic principle of the AVL VCR system described in this paper is a 2-stage variation of the conrod length and thus the Compression Ratio (CR).

The paper focuses on an optimization methodology, which uses Design of Experiments (DoE) methods to define component parameters of parallel hybrid powertrains such as number of gears, transmission spread, gear ratios, progression factor, electric motor power, electric motor nominal speed, battery voltage and cell capacity. Target is to find the optimal configuration based on specific customer targets (e.g. fuel consumption, performance targets). In the method developed here, the hybrid drive train configuration and the combustion engine are considered as fixed components. The introduced methodology is able to reduce development time and to increase output quality of the early system definition phase. The output parameters are used as a first hint for subsequently performed detailed component development. The methodology integrates existing software tools like AVL CRUISE [5] and AVL CAMEO [1].

Biofuels are a promising alternative to fossil fuels as their availability has been reduced during the last decades and they are the main sources of greenhouse gases emissions. Moreover, the targets of the international regulations include reduction of fossil fuels consumption, and improvement of the sustainability of the vehicle fleet. Blending gasoline with biofuels will result in changes in fuel blending procedures and combustion process especially for the gasoline direct injection (GDI) engines. In this article, flame visualization using chemiluminescence techniques in a Single Cylinder Optical Research Engine (SCORE) is presented, with an adjusted intake pressure of 850 mbar and early intake single injection (280 CAD BTDC), by using 100% hydrocarbon-based gasoline, E10 (90% gasoline - 10% ethanol) and ETBE20 (80% gasoline - 20% ethyl tert-butyl ether). ETBE20 is a potential alternative for E10, as it contains the same amount of renewable fuel and has low water solubility.

In this study, spray images of LPG Blended Fuels (LBF) for DI diesel engines were observed using a constant volume chamber at high ambient temperature and pressure, and the spray characteristics of the fuel were investigated. The LBF spray started to vaporize at the injector tip and the outer downstream regions of the spray, like diesel fuel, because of the high temperature at these areas. There were more vaporized areas compared to diesel fuel. Sufficient fuel injection volume and volatility of LBF resulted in good fuel-air mixture, then, THC emissions decreased compared to diesel fuel at high load engine test conditions. Butane spray image could not be observed at the injector tip. It seems that the high temperature of the injector tip caused the butane spray to vaporize rapidly. Spray tip penetration with LBF and butane were equal or greater than with diesel fuel. The high volatility of LBF and butane had no noticeable effect on spray penetration.