Heavy-Duty-, On- und Off-Highway-Motoren 2020

The utilization of hydrogen and hydrogen-based fuels is a promising option to reduce greenhouse gas emissions of heavy-duty vehicles. Here, the production of sustainable hydrogen plays a key role. Very promising is the production of hydrogen by means of water electrolysis that links fluctuating electricity production from renewable sources with sectors based on chemical energy carriers. Water electrolysis will be one of the key technologies to reduce the energy system transformation costs and to stabilize the electricity grid. Hydrogen can be used directly as a fuel in heavy-duty vehicles or converted with CO₂ to fuels like methanol or Fischer-Tropsch products. Methanol can be used both as a fuel and as feedstock for further upgrading to fuels like dimethyl ether (DME), oxymethylene ether (OME), methanol-to-gasoline (MtG) and methanol-to-jet fuel. Recently, also the conversion of hydrogen with nitrogen to ammonia as fuel gains increasing interest in combustion engines. Beyond CO2 reduction exhaust gas emissions have also to be reduced significantly. CatVap® is an innovative fuel processing technology that enables efficient exhaust gas treatment in order to achieve near-zero emission mobility. In addition, hydrogen can be used to operate fuel cell power trains, which is more and more discussed for heay-duty applications. Now it’s the time for a broader market introduction of hydrogen and hydrogen-based fuels in the mobility sector and thus, for cost reduction due the corresponding scale-effects.

Heavy-duty diesel engines will continue to play a major role in the heavy-duty truck business for years to come. Higher demands on exhaust emission requirements and challenging legislation in conjunction with relentless competition will push the technical development of diesel engines beyond what they currently represent. Regardless of alternative power units, the diesel engine will need to actively contribute to achieve future CO2 legislation goals and account for the overall accomplishment.

For this reason, in 2015 DAIMLER Truck AG decided to re-engineer and upgrade its heavyduty engine series as part of the so-called HDEP2020 project. HDEP (‘Heavy-Duty Engine Platform’) engines consist of inline-six engines brought to the market in 2008 and have been used ever since in trucks and buses of Daimler Truck AG and third-party applications around the globe. To this day, attributes such as high efficiency and technological leadership with respect to quality and fuel efficiency are inseparably associated with the HDEP engine platform.

As the first of its kind, the Detroit DD15 Gen 5 engine will be launched by end of 2020 to launch the new HDEP2020 generation. In early January 2021, it will be available in class 8 vehicles of DTNA (Daimler Trucks North America).

The DD15 HDEP2020 will be offered in a power range up to 505 hp with a maximum torque of 1,750 lb-ft.

The following article outlines the goals of the HDEP2020 engine project, describes the approach and explains the technical concept using the Detroit DD15 engine as an example.

MAN Engines, a subdivision of MAN Truck & Bus, develops and produces engines for on-road, off-road, power and marine applications. To meet the growing demand for alternative propulsion systems, MAN develops a diesel-electric hybrid system for a variety of marine applications, including commercial and pleasure boats. Goal is the development of a self-contained system, that can be customized and fully integrated in a large variety of vessel designs and applications.

This article presents the MAN technology concept, addressing the different demands of a marine hybrid system compared to conventional on-road solutions and gives an overview of the available operating modes along with a description of the incorporated components.

This paper focuses on the Total Cost of Ownership (TCO) impact of several propulsion system solutions applied to a heavy-duty long-haul truck for the European market sector, in 2020 and predictions for 2035. The research performed by Ricardo investigated Internal Combustion Engine propulsion systems with fossil and renewable fuels, but also a range of in-use zero-emission electric solutions. Battery Electric Vehicles and Fuel Cell Electric Vehicles, either as a prime move or range extender, were considered. A dedicated energy to motion transformation system, namely an Electric Drive Unit, was developed for Electrified Vehicles (xEVs), with high efficiency as the prime objective. A virtual product development process is described, which was applied to define the propulsion systems and to evaluate the vehicle energy consumption over a typical 24h mission profile, by means of system simulations. A presentation of the TCO model that was generated to compare the different propulsion system solutions in terms of €/(100km.t) is given, along with the assumptions it is based on. Results from the development of the Electric Drive Unit are provided and, suggestions are made for potential further work following this study.

Future powertrain concepts for Off-Highway applications must meet very challenging requirements. In addition to compliance with ever more stringent pollutant emission targets, customers expect favorable performance and reliability characteristics at low total cost of ownership. In this context, the application of hybrid technologies derived from the automotive sector offers new possibilities. The paper discusses future legal boundary conditions and analyses different hybrid powertrain concepts for typical Off-Highway applications based on a comprehensive simulation study. The focus of this study is on a mild hybrid system with a cost optimized below 56 kW internal combustion engine and a simplified exhaust aftertreatment system. This hybrid powerpack is evaluated for different Off-Highway applications based on standard EPA nonroad cycles.

The European Commission has indicated that Euro VII emissions legislation should be the last round of emissions legislation and should aim to ensure vehicles are compliant under all conditions. Unlike previous rounds of legislation this will be set against the background of stringent CO₂ improvement requirements, so future technologies must serve to improve both emissions and fuel consumption. Ricardo examine what challenges this will introduce for engine manufacturers and what types of technologies might be adopted. A focus will be given to future exhaust aftertreatment solutions for improved real-world NO_x control with minimum fuel consumption penalty. Ricardo conclude it should be possible to meet an aggressive emissions target without EGR or expensive external heating solutions.

The currently discussed NOx limits reductions for commercial vehicles in Europe, as well as the recently published CARB regulation in the USA, will require a new approach for exhaust gas aftertreatment in order to keep greenhouse gas and CO₂ emissions within the limits.

In order to reach the required high conversion rates for nitric oxides in the SCR system it is essential to operate the exhaust aftertreatment in the optimal temperature window. Load points with low exhaust gas temperatures and especially cold starts will require (active) heating.

Increasing the exhaust temperature by “engine measures” cannot reach the high efficiency rates of energy-release compared to direct combustion of fuel in the exhaust system. A typical Particulate Filter regeneration in Heavy Duty applications is supported by fuel, which is injected into the exhaust system and combusted over the oxidation catalyst (DOC). For this the DOC must be within an appropriate temperature window which is not ensured in all engine load points. Utilizing electrical energy, the temperature of the Oxidation Catalyst (= electrically heated catalyst) can be increased, even in cold start, to the required level. This insures a safe combustion of the injected fuel with highly efficient heat release. With this setup it is possible to heat up (and keep warm) the exhaust system independently of engine operation. Thus, NO_x-conversion can start earlier and operate with higher efficiencies. With this configuration it is realistic to operate the engine a longer period of time, in more fuel-efficient load points, with no penalty for exhaust heating.

During low load engine operation, the temperature of the exhaust system can get very low, so that NO_x-conversion-efficiency is reduced. The exhaust system needs to be kept at operation temperature. Pure electrical heating might be sufficient for many low load points.

The measurement of tailpipe emissions using on-board exhaust sensors is widely discussed as one further solution to ensure the emission compliance over the vehicle lifetime and in real driving conditions. The information about the tailpipe emissions allows to adjust the control of the exhaust system to maintain low pollutant emissions. Additionally, the continuous measurement of tailpipe emissions helps to detect damaged or tampered systems quickly not only in the certification cycle but also in real driving conditions, thus extending the diagnostic coverage to a broad range of operating conditions. A typical example for exhaust sensors is the NO_x sensor, which is already installed in all modern Diesel engines to control the SCR and measures the tailpipe NO_x emissions continuously.

In the first section of this paper the different exhaust configurations and the heating strategies are described. The impact on the CO₂ emissions is analyzed in different driving cycles (FTP, low load cycle). In the second section, the measurements performance of NO_x sensors in the exhaust system is investigated. The investigation is based on the study about the different heating strategies. Therefore, the performance can be examined at various emission levels and operating conditions. The second section is concluded by a Monte Carlo Analysis, which addresses the influence of component tolerance on the system accuracy.

Today's challenge is to comply 100% with emission limits in Real Drive Emission (RDE) behavior, especially in the cold season, the so-called "cold city rides" that are characterized by the fact that during stop and go rides in the city, at no time a sufficient temperature for an efficient exhaust aftertreatment is reached [1]. The future Euro 6+ or certainly the expected new Euro 7 limit values will therefore only be achieved with suitable effective thermal heating, heat retention as well as DPF regeneration measures for the exhaust aftertreatment (EAT) system.

The CatVap system is an important key enabler for near zero-emission internal combustion (IC) engines that need to be realized in the near future. Our paper from last year showed the basic function of the CatVap system as well as the new heat-up and temperature control system for exhaust aftertreatment systems [2]. We are now presenting the first engine tests, focusing on the CatVap system for commercial vehicle applications which has now been significantly enhanced. Our newly developed system has shown great potential in dynamic component tests and advanced engine testing, i.e. on a modern medium-duty commercial vehicle engine test bench; it also produced impressive results in comparison with other technologies such as an HC dosing system. CatVap is showing decisive advantages in such direct comparisons, e.g. in terms of heating speed, dynamics, even temperature distribution and efficiency at significantly lower light-off temperatures (e.g. for the DOC). This enables a significantly earlier start of urea dosing for the SCR system. Last but not least, our new technology shows significantly lower additional fuel consumption, especially compared to HC dosing technology. These impressive new results will be presented and discussed in detail in this article.

When used as a fuel, natural gas exhibits considerable potential for reducing CO2 emissions. Further significant reductions can be achieved by using bio-methane produced either from electricity generated from renewable sources or from biomass. In order to demonstrate the potential of an engine designed from scratch to run on natural gas, DEUTZ AG initiated and carried out the 'HoLeGaMo' (high-performance natural gas engine) project. The target of this project, supported by the Federal German Ministry for Economic Affairs and Energy through Project Management Jülich (PTJ), is to develop a test stand demonstrator of a monovalent industrial engine, powered by natural gas, that is capable of delivering a level of performance comparable to that of a corresponding diesel engine with, at the same time, the lowest possible fuel consumption. With four cylinders and a displacement of 5.0 litres, it easily fits into the range of medium-sized industrial engines. In order to achieve the project's aims, a new cylinder head was designed for an existing rugged basic diesel drive unit; the engine was equipped with a VGT turbocharger and, in addition, for each cylinder, a charge dosing valve, operating synchronously to the engine speed, was installed. These dosing valves represent the core feature of the research project: they are intended to de-throttle the stoichiometrically operated and spark ignited engine at partial load and, at high loads, to facilitate internal cooling of the mixture by applying the 'Miller' process. This presentation will illustrate the engine's stationary and dynamic performance compared with a corresponding diesel engine. The benefits and the downsides, in particular of the rapid-acting charge dosing valves employed, and how the necessary modelbased engine management system was implemented will be explained in detail.

It is generally accepted that for some heavy-duty transport primemover or energy-converter applications, battery-electrification is unlikely to meet the required balance of product attributes. This is particularly the case with the attributes of autonomy (range), mass, package volume and cost. In this regard, chemical fuels still have the advantage despite storage challenges for some. Ricardo expects that heavy-duty commercial vehicles will include combustion engines for some time to come, whilst transitioning from fossil diesel to a variety of renewable bio- and electrofuels such as bio-diesel, HVO, ethanol, methane, methanol and hydrogen

Many of these fuels require a spark-ignited (or other positive ignition) combustion system. This will drive changes to the optimal heavy-duty base engine architecture. In this paper, the future fuels that are expected to be most prevalent are discussed, along with efficiency expectations in various vehicle classes. Further, some of the measures recommended to fully optimise a heavy-duty engine for operation on renewable, spark-ignited fuels are presented.

Electrification of vehicles is important to reduce greenhouse gas (CO2) emissions and stop global warming, but electrification will not be enough. Use of alternative and renewable fuels in SI-ICE will be an important complement to electrification in the heavy-duty segment, motivated by their ability to efficiently use the large potential of renewable fuels with low cetane numbers which are not suitable for diesel-like combustion. However, the property of alternative and renewable fuels may vary considerably, with a significant decrease in engine performance and total cost of ownership (TCO) as result. There is a need to compensate for a varying combustion phase and assure robust ignition while keeping the spark plug wear to a minimum, despite such variations.

The peak pressure location (PPL) can accurately be estimated using ion sense and the ignition timing adapted in a closed loop to compensate for variations in the fuel combustion property. The spark design and requirements are discussed when using different and/or varying fuel. Preliminary results on ignitability and electrode wear indicate that the electrode wear can be reduced considerably. The TCO can be reduced by approximately $1100 per year for fuel and spark plugs alone, hereby making SI-ICE fueled by alternative and renewable fuels an even more attractive solution to reduce the GHG-emissions.

A study has been performed with two fuel blends, both allowing the principal usage of up to 33 vol. % CO₂ neutral fuel in a EURO 5 engine. The intention has been to understand, if those fuels can be applied as drop in fuels without any calibration changes and still meeting the emission limits the engine has been certified to. This would offer a significant CO₂ reduction potential with the engine fleet, already in the market. The vehicle emission tests showed, that for both fuel blends the emission are very close to those, measured with standard B5 fuel and well within the limits. Also the tank-to-wheel CO₂ emissions were close or even slightly reduced, thus offering the full well-to-wheel CO₂ reduction potential of the fuel blends. However, the stationary measurement on the engine test bench revealed the risk that under non-cycle conditions the NO_x emissions are increased, in case no calibration adjustment will be done. So far both fuel blends have not been tested with regard to wear and compatibility with the fuel hoses and engine oil.

Most current forecasts show a world with an increasing replacement of fossil energy by regeneratively produced electric energy. In this future world E-Fuels will play an important role for the operation of large engines for example in maritime transport and power generation.

Woodward L’Orange developed an injection system which is suitable to manage a variety of „advanced“ E-fuels which may replace todays well known carbon based long-chain fuels and give additional advantages. This concept is prepared to inject Methane, Propane, Methanol or Ammonia in a DI concept and allows to design combustion engines with high power density, good operability and low greenhouse gas critical emissions.

The basic injector concept will be discussed and some basic results from Gas combustion development will be shown. In addition the „scaling“ to the other E-fuels and different engine sizes will be demonstrated. This is mainly a scaling in nozzle size and some hydraulic details dependent on the thermodynamic phase state of the fuel at injection.

In addition to the injector the required type of HP pumps or compressor will be shown, which are all different in design and efficiency, dependent on the used E-Fuel.

Finally the complete system chains will be evaluated against each other to give an indication on the suitability for different applications.

The reduction of greenhouse gases in the transport sector is fundamental for reaching the European climate goals. Shipping is responsible for about 2-3 percent of the global CO₂ emissions, depending on the world trade with an increasing trend. Hence, the International Maritime Organization (IMO) is forcing an emission reduction until year 2050 of at least 50% based on emissions from year 2008.

One solution to this problem could be the use of CO₂-neutral fuels in conventional internal combustion engines (ICE). Especially synthetic fuels based on hydrogen from renewable energy and carbon dioxide are attractive for a use in ICEs due to their unlimited availability and customizable properties. In the framework of the public founded research project “ISystem4EFuel” such “e-fuels” were tested with respect to their usability in large ship engines at Rostock University and FVTR GmbH.

Two promising e-fuels were chosen and investigated as blend components with reference EN 590 diesel in injection chamber and single-cylinder engine tests: oxymethylenether (OME) and paraffinic diesel (HVO). A prototype injector from Woodward L’Orange GmbH that is able to measure control chamber pressure was used to get additional information about fuel impacts on needle dynamic.

Results showed drop-in quality of HVO-blends with negligible impact on injection control and positive effects in terms of decreased ignition delay and reduced soot emission. OME-blends were significantly affecting the injection control and the needle dynamic due to their lower heating values. OME-blends showed superior soot emission behavior at slightly increased NO_x emissions.

The growing concern with environmental impact is a major drive in the search of alternatives to conventional fossil fuels. In this context, the blending of some quantity of biodiesel in diesel as a mean of reducing CO₂ emission levels is being increasingly adopted. Brazil, for example, has determined a steady increase from 2% (2008) up to 12% (2020) in blend rate with no signs of stop or reversion on the tendency. Nevertheless, the expected impact of this fuel evolution on engine pollutant emissions raises questions on how an ageing Diesel fleet will react and how new calibrations may be efficiently developed.

A promising approach to tackle this challenge in a cost-effective way is the adoption of Gaussian process regression (GPR) in the context of model-based calibration, using virtual, use-case specific, driving cycles. The aim of this paper is to evaluate this methodology on São Paulo context by selecting a four cylinder, Euro V diesel engine, representative of the city bus fleet, and combining it with a São Paulo’s urban bus driving cycle and 10% biodiesel blend rate.

Firstly, a space-filling test plan was constructed aiming to explore parameter combinations on the neighborhood of the original calibration. The proposed test cases were measured on an engine dynamometer and then fed to ETAS ASCMO (Advanced Simulation for Calibration, Modeling and optimization). The tool generated a virtual engine model based on Gaussian process regression with which the calibration was optimized for each different cycle

As the world’s largest manufacturer of commercial vehicles above 6 tons, the Daimler Truck AG is the reference for the national and international heavy-duty transport. In order to offer a tailor-fit powertrain for optimum performance, Daimler Truck AG develops its own turbochargers for heavy-duty truck engines. This work presents a novel development procedure at Daimler Truck AG and its application on the design optimization of the turbocharger’s compressor and turbine stage.

The key idea of this novel development procedure is to conduct the design optimization systematically. Numerical optimization approaches, mathematical algorithms and in-house developed tool chains are applied to enable a systematic and automatized design optimization process. Further, parameterized CAD models are used for all stages’ components.

Lastly, the development procedure is applied to a baseline turbocharger for a 10.7 l heavy-duty engine in an exemplary prototype project. Within a relatively short development time and few iterations, an efficiency benefit of around 1-1.5 percentage points is measured for the optimized compressor stage and of around 2-3 percentage points on the turbine side.

Improving fuel economy and reducing tailpipe emissions are persistent challenges for the diesel engine industry. Dynamic Skip Fire (DSF®) for diesel engines (dDSF) has the potential to reduce both fuel consumption and tailpipe emissions simultaneously. An analytical model was created by Tula and FEV using FEV’s Complete Powertrain Simulation Platform to conduct a dedicated simulation to study the benefits of dDSF over various characteristic test cycles. In addition, together Cummins and Tula have been collaborating to evaluate dDSF in a heavy-duty application for both real world driving and performance assessments. Results demonstrate that dDSF can achieve significant fuel economy benefit, while realizing marked reduction in tailpipe NO_x emissions.

In order to fulfill present and future emission standards in-service conformity gains in importance. Furthermore, it increases the necessity to understand the evolution of catalysts and their performance while aging. In this context, the Institute for Internal Combustion Engines and Powertrain Systems of the Technische Universität Darmstadt is monitoring a vehicle of a logistic company equipped with a data-logging-system during its daily delivery mission over a period of three years. This setup records environment, driver behavior, vehicle, engine and exhaust-aftertreatment data during daily usage. Unlike test bench measurements, the comparison and rating of different systems in real-life requires new methods as the always changing boundary conditions create a lack of reproducibility.

Therefore the goal of the presented methodology is the assessment of the catalyst state during its real-life use. It is relying on the data provided by the vehicle ECU and does not require further sensors. The main gain of the methodology described in this study is the continuous evaluation of the catalyst performance and the mission profile independent rating of the catalyst state. It is therefore usable within the development process of a catalyst as part of the field validation as well as a monitoring tool for pre-fail recognition during regular vehicle use.

In order to reduce greenhouse gas emissions from the transport sector, the EU has agreed on new regulations to limit the CO₂ emissions of new heavy-duty vehicles over 16 tons by 15% from 2025 onwards and by 30% from 2030 onwards compared to the 2019 reference. These CO₂ targets pose a major challenge, especially for the heavy-duty sector. The increase in freight traffic and vehicle size as well as weight restrictions limit the reduction potential of energy consumption. Moreover, the total costs of ownership (TCO) play a decisive role in which technologies find their way into this competitive market. Recent studies show that new energy sources from renewable energies will have a noticeable effect on reducing CO₂ emissions in the transport sector until 2030.

In this transition, a significant portion will be achieved by vehicle measures, like e.g. aerodynamic and rolling resistance improvements, as well as intelligent mobility vehicle functionalities. To reduce CO₂ emissions of long-haul trucks, the focus during the next decade will continue to be on optimizing the efficiency of the powertrain driven by an internal combustion engine. The improvement of the combustion efficiency is one part of the possible and necessary measures.

An additional potential is to recycle a part of the engine’s waste energy generated during operation wherever and whenever it can be used efficiently. Because of region-specific legislations, applications and market demands prior to 2025, a short-term flexible integration is crucial and therefore requires a modular architecture. It consists of four major systems:

The presentation describes the concept of such a modular electrified HD long haul Truck. Based on driving cycle simulations, the potential of the various modules, different configurations and applications are determined.

In addition, it is analyzed how the use of alternative fuels (e.g. H₂, Methanol, CNG, LNG, etc.) can further reduce CO₂ emissions. As further initiative in this paper, intelligent mobility vehicle functionalities will be presented, which use information about truck and cloud connectivity and are adapted to the customer-specific truck operation requirements.