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Technical Paper

Application of Electrically Driven Coolant Pumps on a Heavy-Duty Diesel Engine

2019-01-15
2019-01-0074
A reduction in CO2 emissions and consequently fuel consumption is essential in the context of future greenhouse gas limits. With respect to the thermodynamic loss analysis of an internal combustion engine, a gap between the net indicated thermal efficiency and the brake thermal efficiency is recognizable. This share is caused by friction losses, which are the focus of this research project. The parasitic loss reduction potential by replacing the mechanical water pump with an electric coolant pump is discussed in the course of this work. This is not a novel approach in light duty vehicles, whereas in commercial vehicles a rigid drive of all auxiliaries is standard. Taking into account an implementation of a 48-V power system in the short or medium term, an electrification of auxiliary components becomes feasible. The application of electric coolant pumps on an Euro VI certified 6-cylinder in-line heavy-duty diesel engine regarding fuel economy was thus performed.
Technical Paper

Technologies to Achieve Future Emission Legislations with Two Stroke Motorcycles

2018-10-30
2018-32-0042
Increasingly stringent emission regulations force manufacturers of two wheelers to develop low emission motorcycle concepts. Especially for small two-stroke engines with symmetrical port timing structure, causing high HC-emissions due to scavenge losses, this is a challenging demand that can only be met with alternative mixture formation strategies and by intensifying the use of modern development tools. Changing from EU4 to EU5, emission legislation will not only have an impact on the improvement of internal combustion but will also drastically change the after-treatment system. Nowadays, small two-stroke engines make use of a simple carburetor for external mixture preparation. The cylinders are scavenged by air/fuel mixtures. Equipped with exhaust gas after-treatment systems, such as secondary air with two or three catalytic converters, the emission limits for EURO 4 homologation can be achieved with carbureted engines.
Technical Paper

Overview of Different Gas Exchange Concepts for Two-Stroke Engines

2018-10-30
2018-32-0041
The concept of a loop scavenged two-stroke engine, controlling the intake and exhaust port by the moving piston, is a proven way to realize a simple and cheap combustion engine. But without any additional control elements for the gas exchange this concept quickly reaches its limits for current emission regulations. In order to fulfil more stringent emission and fuel consumption limits with a two-stroke engine, one of the most important measures is to avoid scavenging losses of fuel and oil. Additionally, it is necessary to follow a lambda = 1 concept for a 3-way exhaust gas after-treatment. Therefore, using internal mixture preparation systems in combination with different concepts to control the gas exchange process, the two-stroke engine could become a choice for automotive applications, especially as a Range Extender in a Plugin Hybrid Electric Vehicle (PHEV).
Technical Paper

Combustion Analysis with Residual Gas as a Design Parameter for Two-Stroke Engines

2018-10-30
2018-32-0045
In a variety of applications, two-stroke engines assert their usage as a propulsion unit, for examples in off-road vehicles, scooters, hand-held power tools and others. The outstanding power to weight ratio is the key advantage for two-stroke engines. Furthermore, two-stroke engines convince with high durability and low maintenance demand. However, an increasing environmental awareness, the protection of health and the shortage of fossil resources are the driving factors to further enhance the internal combustion process of two-stroke engines. The reduction of emissions and fuel consumption with a constant power level is focused on. Developments deal with the optimization of the combustion process itself or the enhancement of the exhaust gas aftertreatment. Especially in very small two-stroke engines an exhaust gas aftertreatment system is rarely applied, due to disadvantages regarding component temperatures and product costs.
Technical Paper

Influence of Ethanol and 2-Butanol Blended Fuels on Combustion and Emissions in a Small Displacement Two Stroke Engine

2018-10-30
2018-32-0044
Small displacement two-stroke engines are cheap and low-maintenance propulsion systems and commonly used in scooters, recreation vehicles and handheld power-tools. The restriction by emission legislation and the increasing environmental awareness of end users as well as decreasing energy resources cause a rethinking in the development of propulsion systems and fuels in these fields. Despite recent improvements of electric powertrains, two stroke engines are the challenged propulsion system in high performance handheld power tools at the moment. The reasons are the extraordinary high power to weight ratio of two-stroke engines, the high energy density of liquid fuels and the reliability of the product with respect to extreme ambient conditions. Nevertheless, further improvements on emissions and fuel consumption of small displacement two-stroke engines can be realized.
Technical Paper

Practicability and Influencing Factors of a Lean Burn Mode for Two-Stroke Engines in Hand-Held Powertools

2017-11-05
2017-32-0043
For many applications, such as scooters, hand-held power tools and many off-road vehicles, two-stroke engines are used as a preferred propulsion unit. These engines convince by a good power to weight ratio, a high durability and low maintenance technology and are therefore the first choice in this field of application. In general, already much development effort has been expended to improve those systems. However, an increasing environmental awareness, the protection of health and the shortage of fossil resources are the driving factors to further enhance the internal combustion process of those adapted two-stroke engines. The current focus here is on the reduction of emissions and fuel consumption with an at least constant power output. An approach to address an improvement of engine efficiency can be covered by applying a lean combustion burn mode.
Technical Paper

Thermodynamic Loss Analysis of a High Power Motorcycle Engine with Focus on Alcohol Blended Fuels

2017-11-05
2017-32-0070
The development of future internal combustion engines and fuels is influenced by decreasing energy resources, restriction of emission legislation and increasing environmental awareness of humanity itself. Alternative renewable fuels have, in dependency on their physical and chemical properties, on the production process and on the raw material, the potential to contribute a better well-to-wheel-CO2-emission-balance in automotive and nonautomotive applications. The focus of this research is the usage of alcohol fuels, like ethanol and 2-butanol, in motorcycle high power engines. The different propulsion systems and operation scenarios of motorcycle applications in comparison to automobile applications raise the need for specific research in this area.
Journal Article

Advanced Heat Transfer and Underhood Airflow Investigation with Focus on Continuously Variable Transmission (CVT) of Snowmobiles

2017-06-28
2017-01-9180
The presented paper focuses on the computation of heat transfer related to continuously variable transmissions (CVTs). High temperatures are critical for the highly loaded rubber belts and reduce their lifetime significantly. Hence, a sufficient cooling system is inevitable. A numerical tool which is capable of predicting surface heat transfer and maximum temperatures is of high importance for concept design studies. Computational Fluid Dynamics (CFD) is a suitable method to carry out this task. In this work, a time efficient and accurate simulation strategy is developed to model the complexity of a CVT. The validity of the technique used is underlined by field measurements. Tests have been carried out on a snowmobile CVT, where component temperatures, air temperatures in the CVT vicinity and engine data have been monitored. A corresponding CAD model has been created and the boundary conditions were set according to the testing conditions.
Journal Article

Improved Modeling of Near-Wall Heat Transport for Cooling of Electric and Hybrid Powertrain Components by High Prandtl Number Flow

2017-03-28
2017-01-0621
Reynolds-averaged Navier-Stokes (RANS) computations of heat transfer involving wall bounded flows at elevated Prandtl numbers typically suffer from a lack of accuracy and/or increased mesh dependency. This can be often attributed to an improper near-wall turbulence modeling and the deficiency of the wall heat transfer models (based on the so called P-functions) that do not properly account for the variation of the turbulent Prandtl number in the wall proximity (y+< 5). As the conductive sub-layer gets significantly thinner than the viscous velocity sub-layer (for Pr >1), treatment of the thermal buffer layer gains importance as well. Various hybrid strategies utilize blending functions dependent on the molecular Prandtl number, which do not necessarily provide a smooth transition from the viscous/conductive sub-layer to the logarithmic region.
Journal Article

Investigations and Analysis of Working Processes of Two-Stroke Engines with the Focus on Wall Heat Flux

2016-11-08
2016-32-0028
Small displacement two-stroke engines are widely used as affordable and low-maintenance propulsion systems for motorcycles, scooters, hand-held power tools and others. In recent years, considerable progress regarding emission reduction has been reached. Nevertheless, a further improvement of two-stroke engines is necessary to cover protection of health and environment. In addition, the shortage of fossil fuel resources and the anthropogenic climate change call for a sensual use of natural resources and therefore, the fuel consumption and engine efficiency needs to be improved. With the application of suitable analyses methods it is possible to find improving potential of the working processes of these engines. The thermodynamic loss analysis is a frequently applied method to examine the working process and is universally adaptable.
Technical Paper

Characterization of Different Injection Technologies for High Performance Two-Stroke Engines

2016-11-08
2016-32-0001
High performance engines are used in many different powersports applications. In several of these applications 2-stroke engines play an important role. The direct injection technology is a key technology for 2-stroke engines to fulfill both the customers’ request for high power and the environmental requirements concerning emissions and efficiency. As the load spectrum differs from one application to the other, it was interesting to find out if different injection technologies can answer the needs for different applications more efficiently regarding performance but also economic targets. Therefore, the results of the BRP Rotax 600 cm3 E-TEC (direct injection system) engine are compared to the same base engine but adopted with the LPDI (low pressure direct injection) technology developed by IVT at Graz University of Technology. The systems were compared on the engine testbench over 17 rpm / load points representing different product usage profiles.
Technical Paper

Thermodynamic Limits of Efficiency Enhancement of Small Displacement Single-Cylinder Engines

2015-11-17
2015-32-0817
Millions of small displacement single-cylinder engines are used for the propulsion of scooters, motorcycles, small boats and others. These SI-engines represent the basis of an affordable mobility in many countries, but at the same time their efficiency is quite low. Today, the limited fossil fuel resources and the anthropogenic climate require a sustainable development of combustion engines, the reduction of fuel consumption being an important factor. A variety of different strategies (turbo-charging, cylinder deactivation, direct injection, etc.) are investigated here to increase the efficiency of multi-cylinder engines. In the case of small displacement single-cylinder engines, other strategies are required because of their special design and the high pressure on costs. In the context of this paper different layout parameters which have an influence on the working process are investigated, with the aim of increasing the efficiency of small displacement single-cylinder engines.
Technical Paper

Layout and Development of a 300 cm3 High Performance 2S-LPDI Engine

2015-11-17
2015-32-0832
In consideration of the fact that in extreme Enduro competitions two-stroke motorcycles are still dominating, the Institute of Internal Combustion Engines and Thermodynamics, Graz University of Technology, with a long tradition in two-stroke technology, has developed a new 300 cm3 two-stroke motorcycle engine. The 2-stroke LPDI (Low Pressure Direct Injection) technology was originally developed for the 50 cm3 Scooter and moped market in Europe. In 50 cm3 applications the LPDI technology fulfils the EURO 4 emission standard (2017) [1]. In a next step the LPDI technology was applied to a 250 cm3 Enduro engine demonstrator vehicle. Based on the results of the demonstrator, a complete new high performance 300 cm3 engine was developed. The development of this new engine will be described in this publication. Some interesting aspects of the layout with 3D-CFD methods and also 1D-CFD simulation to optimize the exhaust system by DoE methods are discussed in the paper.
Journal Article

Advantages and Challenges of Lean Operation of Two-Stroke Engines for Hand-Held Power Tools

2014-11-11
2014-32-0009
One of the most significant current discussions worldwide is the anthropogenic climate change accompanying fossil fuel consumption. Sustainable development in all fields of combustion engines is required with the principal objective to enhance efficiency. This certainly concerns the field of hand-held power tools as well. Today, two-stroke SI engines equipped with a carburetor are the most widely used propulsion technology in hand-held power tools like chain saws and grass trimmers. To date, research tended to focus on two-stroke engines with rich mixture setting. In this paper the advantages and challenges of leaner and/or lean operation are discussed. Experimental investigations regarding the influence of equivalence ratio on emissions, fuel consumption and power have been performed. Accompanying 3D-CFD simulations support the experiments in order to gain insight into these complex processes. The investigations concentrate on two different mixture formation processes, i.e.
Technical Paper

Control of a Low Cost Range Extender for L1e Class PHEV Two-Wheelers

2014-11-11
2014-32-0014
Due to the small number of two wheelers in Europe and their seasonal use, their contribution to the total emissions has been underestimated for a long time. With the implementation of the new emission regulation 168/2013 [3] for type approval coming into force 2016, the two wheeler sector is facing major changes. The need to fulfil more stringent emission limits and the high demand on the durability of after treatment systems result in an engine control system that is getting more complex and therewith more expensive. Especially the low cost two wheelers with small engine capacities will be affected by increasing costs which cannot be covered by the actual competitive product price. Therefore, new vehicle concepts have to be introduced on the market. A vehicle concept of a plug in hybrid electric city scooter with range extender as well as the range extender itself have already been published in SAE Papers 2011-32-0592 [1] and 2012-32-0083 [2].
Technical Paper

Air Cooled 50cm3 Scooter Euro 4 Application of the Two-Stroke LPDI Technology

2014-11-11
2014-32-0008
The Institute for Internal Combustion Engines and Thermodynamics, Graz University of Technology, has presented several applications of its 2-stroke LPDI (low pressure direct injection) technology in the previous years ([1], [2], [3]). In order to improve the competitiveness of the 2-stroke LPDI technology, an air cooled 50cm3 scooter application has been developed. All previous applications have been liquid cooled. This air cooled application demonstrates the EURO 4 (2017) ability of the technology and shows that the 2S-LPDI technology can also be applied to low cost air-cooled engines. Hence, the complete scooter and moped fleet can be equipped with this technology in order to fulfil both the emission standards and the COP (conformity of production) requirements of Euro 4 emission stage. The paper presents the Euro 4 Scooter results and describes the efficient conversion process of the existing carburetor engine to the LPDI version.
Technical Paper

Engine Operating Parameter-based Heat Transfer Simulation to Predict Engine Warm-up

2014-04-01
2014-01-1103
Optimization of engine warm-up behavior has traditionally made use of experimental investigations. However, thermal engine models are a more cost-effective alternative and allow evaluation of the fuel saving potential of thermal management measures in different driving cycles. To simulate the thermal behavior of engines in general and engine warm-up in particular, knowledge of heat distribution throughout all engine components is essential. To this end, gas-side heat transfer inside the combustion chamber and in the exhaust port must be modeled as accurately as possible. Up to now, map-based models have been used to simulate heat transfer and fuel consumption; these two values are calculated as a function of engine speed and load. To extend the scope of these models, it is increasingly desirable to calculate gas-side heat transfer and fuel consumption as a function of engine operating parameters in order to evaluate different ECU databases.
Technical Paper

Expansion to Higher Efficiency - Investigations of the Atkinson Cycle in Small Combustion Engines

2012-10-23
2012-32-0059
Small combustion engines can be found in various applications in daily use (e.g. as propulsion of boats, scooters, motorbikes, power-tools, mobile power units, etc.) and have predominated these markets for a long time. Today some upcoming competitive technologies in the field of electrification can be observed and have already shown great technical advances. Therefore, small combustion engines have to keep their present advantages while concurrently minimizing their disadvantages in order to remain the predominant technology in the future. Whereas large combustion engines are most efficient thermal engines, small engines still suffer from significantly lower efficiencies caused by a disadvantageous surface to volume ratio. Thus, the enhancement of efficiency will play a key role in the development of future small combustion engines. One promising possibility to improve efficiency is the use of a longer expansion than compression stroke.
Technical Paper

Low Cost Range Extender Technology for Hybrid Electric City Scooters

2012-10-23
2012-32-0083
Electric driving is generally limited to short distances in an emission sensible urban environment. In the present situation with high cost electric storage and long charging duration hybridization is the key to enable electric driving. In comparison to the passenger car segment, where numerous manufacturers are already producing and offering different hybrid configurations for their premium class models, the two wheeler sector is not yet affected by this trend. The main reason for the retarded implementation of this new hybrid technology is its high system costs, as they cannot be covered by a reasonable product price. Especially for the two wheeler class L1e, with a maximum speed of 45 km/h and an engine displacement of less than 50 cm₃, the cost factor is highly important and decisive for its market acceptance, because the majority of vehicles are still low-cost products equipped with simple carbureted 2-stroke engines.
Journal Article

Future Engine Technology in Hand-Held Power Tools

2012-10-23
2012-32-0111
Today mankind is using highly sophisticated tools which contribute to maintain the standard of living. Nevertheless, these tools have to be further improved in the near future in order to protect health and environment as well as to ensure prosperity. Two-stroke engines equipped with a carburettor are the most used propulsion technology in hand-held power tools like chain saws and grass trimmers. The shortage of fossil resources and the necessary reduction of carbon dioxide emissions ask for improved engine efficiency. Concurrently, customers demand for an easy usage with high performance at all operating conditions, e.g. varying ambient temperature and pressure and different fuels. Moreover, world-wide emission limits will be even stricter in future. The improvement of the emission level, fuel consumption and customer benefits, while keeping the present advantages of two-stroke engines, like high specific power and simplicity, are the goals of this research work.
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