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Hybrid electric vehicles (HEVs) are facing increased challenges of optimizing the energy flow through a vehicle system, to enhance both the fuel economy and emissions. Energy management of HEVs is a difficult task due to complexity of total system, considering the electrical, mechanical and thermal behavior. Innovative thermal management is one of the solutions for reaching these targets. In this paper, the potential of thermal management for a parallel HEV with a baseline control strategy under different driving cycles and ambient temperatures is presented. The focus of the investigations is on reducing fuel consumption and increasing comfort for passengers. In the first part of this paper, the developed HEV-model including the validation with measurements is presented. In the second part, the combined thermal management measures, for example the recuperation of exhaust-gas energy, engine compartment encapsulation and the effect on the target functions are discussed.

A model for the calculation of heat release in direct injection Diesel engines is presented. It needs only one engine-specific experimental parameter. In the form the model is presented here it is limited to the medium and upper load range, where Diesel combustion is mainly mixing controlled. The development of the model is based on data from medium speed engines. The applicability to automotive engines is shown in some examples. The model is based on the theory of single phase turbulent jets. Starting from the balance of momentum and fuel mass flow the stationary part of the jet can be calculated. The propagation of the front of the unsteady jet is determined from a continuity consideration. Heat release is calculated based on the assumptions of the Simple Chemically Reacting System (SCRS). Fuel that is mixed with air is assumed to be burnt instantaneously.

When comparing automotive and large-bore diesel engines, the latter usually show lower specific fuel consumption values, while automotive engines are subject to much stricter emission standards. Within an FVV (Research Association for Combustion Engines) project these differences were identified, quantified and assigned to individual design and operation parameters. The approach was split in three different phases: 1 Comparison of different-sized diesel engines 2 Correlation of differences in fuel consumption to design and operating parameters 3 Further investigations under automotive boundary conditions The comparison in the first phase was made on the basis of operating data and energy balances as well as the separation of losses based on the thermodynamic analysis. To also determine the quantitative effects of each design and operating parameter, a 1D process calculation model of the passenger car engine was transformed gradually to a large-bore engine in the second phase.

The EU recently decided to reduce CO2 emissions of commercial vehicle fleets by 30% until 2030. One possible way to achieve this target is to convert commercial vehicle diesel engines into stoichiometric natural gas engines. Based on this, a commercial vehicle single cylinder diesel engine with variable valve actuation and high-pressure EGR is converted into natural gas operation to increase efficiency and thus reduce CO2. Additionally, a water injection system is integrated. All three technologies are investigated on their own and in combination. To reduce longer combustion durations caused by Miller valve timing and charge dilution, a piston bowl with extra high turbulence generation is designed. Additionally, a swirl variation is carried out. The results show, that high swirl motion and high turbulence can lead to a disadvantage in efficiency despite faster combustion durations due to higher wall heat losses.

Catalyst fouling by deposit formation on components in the exhaust aftertreatment system is critical since RDE limits must be obtained at any time. Besides, uncontrolled oxidation of carbonaceous deposits might damage the affected exhaust aftertreatment component. To comply with current and future emission standards, diesel engines are usually operated with high EGR rates leading to increased soot and hydrocarbon emissions, which increases the likeliness of the formation of carbonaceous deposits on EAT components. With this background, a research project investigating the influencing parameters and mechanisms of deposit formation on DOCs was carried out. In a follow-up project, the results will be used in order to compare different deposit removal strategies. Within the scope of the presented project, a reference driving cycle was developed in order to create deposits within a short time.

The paper demonstrates the potentials of a high speed flap installed upstream of the intake valve of a HSDI diesel engine, to control the amount of fresh mixture and its composition. This switching device will not only enable the impulse charging or Miller-Cycle, but also a new method of external EGR.

Exhaust Gas Recirculation (EGR) is a proven method for in-cylinder NOx reduction. A multitude of scientific work has focused on the temperature-lowering effect of exhaust gases. The disadvantage of a turbocharged heavy duty diesel truck engine is a high positive pressure gradient between intake and exhaust which complicates a High Pressure Exhaust Gas Recirculation (HP-EGR). In this study, a new technology will be presented to introduce EGR in the high pressure loop of a turbocharged HD-Truck engine without penalty of fuel economy caused by the increase of pumping losses.

Heavy-Duty (HD) diesel engines fulfill the current NOx limits by a sophisticated combination of in-cylinder technologies and an aftertreatment system. In the face of current testing cycles with low average load and efficiency/CO₂ demands measures for the provision of an adequate exhaust temperature become a development core. An alternative to common exhaust management strategies could be variable valve actuation (VVA). Hence a self-developed camless valve actuation system was implemented on a single-cylinder research engine to investigate potential strategies. As these investigations require an appropriate test bench setup the paper consists of two parts. The first part describes the design process of the test bench and focuses on the Rapid Prototyping Systems (RPS) that enabled its operation. The second part discusses the results of different VVA-based exhaust management strategies and gives an outlook to further investigations.

A vehicle thermal management system is required to increase the operating efficiency of components, to transfer the heat efficiently and to reduce the energy required for the vehicle. Vehicle thermal management technologies, such as engine compartment encapsulation together with grille shutter control, enable energy efficiency improvements through utilizing waste heat in the engine compartment for heating powertrain components as well as cabin heating and reducing the aerodynamic drag . In this work, a significant effort is put on recovering waste heat from the engine compartment to provide additional efficiency to the components using a motor compartment insulation technique and grille shutter. The tests are accelerated and the cost is reduced using a co-simulation tool based on high resolution, complex thermal and kinematics models. The results are validated with experimental values measured in a thermal wind tunnel, which provided satisfactory accuracy.

This study investigates the technical feasibility of onboard carbon capture in vehicles. In fact there are two different main concepts of hybrid electric vehicles with batteries and range extenders proposed. The first concept uses an Internal Combustion Engine as range extender. Carbon dioxide is separated from the flue gas of this Internal Combustion Engine by chemical or physical absorption. In the second concept a solid oxide fuel cell (SOFC) is used as a range extender. The CO remaining in the anode exhaust gas is not combusted as usual by mixing anode and cathode exhaust gases but shifted with water vapor, sufficient available in the anode exhaust gas flow, to H₂ and CO₂. The H₂ is separated by a membrane permeable only for H₂ and recycled by the methane flow to the SOFC stack. Carbon dioxide can then be separated by simply condensing the water vapor of the anode exhaust gas of the SOFC.

This paper describes the development process and the implementation of an electro-hydraulic variable valve actuation system to a HD single cylinder research Diesel engine. Because of the requirements of this special application the described development process deviates strongly from past publications. These requirements are directly derived from results of the combustion process development on a HD engine and their fulfillment by the VVA is simulated both for the mechanical design and the gas exchange. On the one hand the software AMESim is used on the other hand Ricardo Wave. Finally some experimental results of the prototype system are shown.

The tightening of the limit values for health-endangering exhaust-gas components, together with the current discussion of climate change caused by greenhouse-gas emissions, call for the use of new technologies to reduce fuel consumption and pollutant emissions. The main emphases in this respect are put on optimising air management, developing new combustion processes and improving process management, researching hybrid concepts and alternative fuels and designing the most possible consumption-neutral exhaust-gas treatment systems with high efficiency levels and conversion rates. In diesel engines, the use of a diesel particulate filter to reduce the particulate emissions after the engine is currently the most effective measure. A time-resolved determination of the particulate emissions in transient engine operation has not been called for by the legislators up to now. Likewise, the measurement technology, which is suitable for this purpose, has hitherto not been available.

In hybrid electric vehicles the combination of diesel engine and electric motor obviously provides lowest fuel consumption. However, compared with the Otto hybrid system, there are relatively high NOx and particulate matter emissions. This paper describes investigations of various strategies for a significant reduction of exhaust gas emissions in diesel hybrid electric vehicles. By reducing the dynamic operation of the combustion engine by supplementing the engine torque demand with an electric motor and limiting the maximum engine torque, the NOx emissions could be reduced by more than 30% and the particulate matter emissions by more than 20%, without influencing the fuel consumption compared to hybrid electric vehicles with conventional operation strategy.

In this paper, results from conventional, Homogeneous Charge Compression Ignition (HCCI) and Split Combustion (SC) combustion processes in combination with alternative fuels are discussed. First the results of the conventional combustion and Diesel fuel as reference are shown; thereafter the results of a blend of Diesel, Rapeseed Methyl Esther (RME) and ethanol and two blends of Diesel and butanol are described. Second the same fuel and blends are used with the (partially) homogeneous combustion systems to evaluate the possible reduction of emissions and fuel consumption. In addition to the limited emissions some measurements of the particle size distribution are carried out.

Environmental and economical reasons have led to an increased interest in the usage of alternative fuels for combustion engines. To clarify the influence of these so-called future fuels on engine performance and emissions it is mandatory to understand their effect on spray formation. Usually this is done by performing various spray experiments with potential future fuels which are available for research purposes today. Due to the multitude of possible future fuels and therefore the uncertainty of their properties and their influence on spray formation a more general approach was chosen in the present study. The possible range of physical properties of future fuels for diesel engines was identified and more than twenty different fluids with representative properties, mostly one-component chemicals, were chosen by means of design of experiment (DoE).

The supercharging of small-displacement gasoline engines requires high pressure ratios combined with a wide range of air flow rate. To resolve this conflict, two-stage turbo charging with two turbochargers or the combination of a turbocharger and a mechanical compressor is used. But this is associated with an increase in complexity. The highest potential for avoiding a multi-stage system is provided by the systematic modification of the turbo-machinery operating maps, e.g. on the turbine side by using variable turbine geometry. An additional promising approach is the implementation on the compressor side of a variable guide vane. The shape of the compressor map is directly affected and the requirements for highly boosted engines can thus be fulfilled. The present paper provides an assessment of the potential of a variable compressor in combination with a variable geometry turbine (VTG) and additional wastegate on a small-volume gasoline engine.

There are numerous methods for accelerated ash loading of particulate traps known from literature. However, it is largely unknown if a combination of these methods is possible and which one generates the most similar ash compared to ash from real particulate filters. Since the influencing variables on the ash formation are not yet fully understood, ashing processes are carried out under carefully controlled laboratory conditions on an engine test bench. The first ashing takes place with low sulfated ash phosphorus and sulfur oil without any methods to increase the quantity of produced ash. The obtained ash is used as a reference and is compared hereinafter with the process examined. Four methods to increase the ash production ratio are investigated. The first one is an increase of the ash content of the lubrication oil through an increase of the additives in the oil. The second one is the additional generation of ash with a burner system where oil is injected into the flame.

In view of the rapidly increasing complexity of conventional as well as hybrid powertrains, a systematic composition platform seeking for the global optimum powertrain is presented in this paper. The platform can be mainly divided into three parts: the synthesis of the transmission, the synthesis of the internal combustion engine (ICE) and the optimization and evaluation of the entire powertrain. In regard to the synthesis of transmission concepts, a systematical and computer-aided tool suitable both for conventional und hybrid transmissions is developed. With this tool, all the potential transmission concepts, which can realize the desired driving modes or ratios, can be synthesized based on the vehicle data and requirements.

This work is based on calculations about extreme mean effective and maximum pressures which were published earlier by the author and colleagues. The motivation for the work presented in this paper is to reduce the maximum pressure while keeping a high mep without sacrificing efficiency. It is investigated in a theoretical study in how far this can be accomplished via turbocompounding. The basis is a 320 mm bore four stroke medium speed engine. It is equipped with a state-of-the-art two stage turbocharging system. As a first step turbocompounding is investigated for mean effective pressures from 22 to 80 bar. The bsfc of the turbocharged engine is in the range of 175 to 185 g/kWh depending on mep. With turbocompounding the exhaust pressure before turbine is optimised and figures between 160 and 165 g/kWh are reached. Thermal loading of the engine increases. In the second step strategies to reduce maximum pressure are investigated for an mep of ca. 50 bar.

Variable valve trains offer the opportunity to apply advanced combustion process strategies such as the Miller cycle. As is well known, applying Miller timing for CI engines is an effective way to reduce NOX emissions and can lead to an increase in engine efficiency. Because of the intended future NOX and GHG limits for on-road HD CI engines, the use of variable valve trains become more and more inevitable. Previous studies of the authors have shown that the improvement potential highly depends on the achievable cylinder charge level. Increasing this (through additional increase in boost pressure) results in a significant decrease in ISFC as well as in an improved NOX-PM trade-off. However, in these considerations the pressure difference of the charge air and the exhaust back pressure was kept on the same level. The present paper investigates the improvement potentials for heavy duty CI engines taking a two-stage turbocharging group into account.