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Technical Paper

A New Model Describing the Formation of Heat Cracks in Brake Discs for Commercial Vehicles

2018-10-05
2018-01-1882
During the development process of brake discs for commercial vehicles, heat cracks are a frequent problem. Since no profound model to forecast the occurrence of cracks has been presented yet, their prediction is hardly ever possible. The standardized heat crack test puts the brake disc under severe thermomechanical load and therefore forces it into cracking. In this paper, results from a series of heat crack tests on the dynamometer are presented, which provide insight into the hidden processes that accelerate or slow down the heat crack propagation in brake discs. This includes an extensive experimental setup using a thermographic camera, a set of capacitive displacement sensors, a pyrometer, and sliding thermocouples as well as a unique eddy-current heat crack detector that was developed at TU Darmstadt. Continuous monitoring of disc deformation, surface temperature and crack propagation at high sampling rates provides the base for a new, profound causal model.
Technical Paper

A Study on Safety Intelligent Driving System for Heavy Truck Downhill in Mountainous Area

2018-10-05
2018-01-1887
Mountainous area makes up more than half of the whole land area of China, the road of which is full of ups and downs. Heavy commercial vehicles as the main means of transport in mountainous areas, braking torque recession, even brake failure, often happens because of the overheating in long downhill journey, which seriously threats the safety of the driving. Therefore, this paper presents an intelligent assistant system based on Geographic Information System and vehicle dynamics. The main brake working time and heat generation can be effectively reduced through adjusting the speed at the ramp top, applying the engine auxiliary brake in the initial stage and choosing the brake time properly, in order to prolong the downhill driving distance and improve the safety of during continuous braking. In this paper, the characteristics of the road slopes have been analyzed and the effect of ramp characteristics on braking heat generation has been studied.
Technical Paper

Construction of a Multiple Driving Affective Scale

2018-10-05
2018-01-1888
Sensory evaluations of brake characteristics have been performed as solely based on the intuition of professional test drivers, because it was difficult to obtain a consistent response for how general drivers were feeling about brake characteristics. The problem is that there are no scales to measure such the feeling. In the current study, a psychological scale was constructed to measure the affective state of general automobile drivers, for the purpose of clarifying the effects of brake characteristics on the affective state. To construct the affective scale, two experiments were conducted. In the first experiment, a comparison of four types of vehicles was performed, and then an interview survey was performed to broadly collect the evaluation terminology of the affective state.
Technical Paper

Physical and Virtual Simulation of Light Weight Brake Drum Design for Heavy Duty Commercial Vehicles Using Alternate Material Technologies

2018-10-05
2018-01-1897
Brake drum in commercial vehicles is very important aggregate contributing towards major weight in brake system module. The main function of brake drum is to dissipate kinetic energy of vehicle into thermal energy, as a results in braking operation major load comes on brake drum. Hence this is very critical component for vehicle safety and stability. Objective of this paper is to increase the pay load, which is utmost important parameter for commercial vehicle end customers. To achieve the light weighing target, alternate materials such as Spheroidal graphite iron (SGI) and Forging Steel have been evaluated for development of brake drum. Many critical parameters in terms of reliability, safety and durability could be the cross section, thickness of hub, wheel loading, heat generation on drum, manufacturing and assembly process are taken into consideration. The sensitivity of these parameters is studied for optimum design, could be chosen complying each other's values.
Technical Paper

Simulation of Intake Manifold Water Injection in a Heavy Duty Natural Gas Engine for Performance and Emissions Enhancement

2018-09-10
2018-01-1653
The present work discusses the effects of intake manifold water injection in a six-cylinder heavy duty natural gas (NG) engine through one-dimensional simulation. The numerical study was carried out based on GT-Power under different engine working conditions. The established simulation model was firstly calibrated in detail through the whole engine speed sweep under full load conditions before the model of intake manifold water injector was involved, and the calibration was based on experimental data. The intake manifold water injection mass was controlled through adjustment of intake water/gas (water/natural gas) ratio, a water/gas ratio swept from 0 to 4 was selected to investigate the effects of intake manifold water injection on engine performance and emissions characteristics. On the other hand, the enhancement potential of intake manifold water injection in heavy duty NG engine under lean and stoichiometric condition was also investigated by the alteration of air-fuel ratio.
Technical Paper

Improving Combustion and Emission Characteristics in Heavy-Duty Natural-Gas Engine by Using Pistons Enhancing Turbulence

2018-09-10
2018-01-1685
Compressed Natural Gas (CNG), because of its low cost, high H/C ratio, and high octane number, has great potential in automotive industry, especially for heavy-duty commercial vehicles. However, relative slow flame speed of natural gas leads to long combustion duration and low thermal efficiency and tends to cause knock combustion at high load, which will aggravate engine thermal load and reliability. Enhancing turbulence intensity in combustion chamber is an effective way to accelerate flame propagation speed and improve combustion performance. In this study, the flow simulations of several piston bowls with different inner-convex forms were carried out using three-dimensional computational fluid dynamics (3D-CFD) software CONVERGE. The numerical results showed the piston bowls with inner-convex could disturb the charge swirl motion and enhance turbulence of different intensity. A hexagram geometry bowl was proved to have the best function in strengthening turbulence intensity.
Technical Paper

Heavy-Duty Diesel Engine Spray Combustion Processes: Experiments and Numerical Simulations

2018-09-10
2018-01-1689
A contemporary approach for improving and developing the understanding of heavy-duty Diesel engine combustion processes is to use a concerted effort between experiments at well-characterized boundary conditions and detailed, high-fidelity models. In this paper, combustion processes of n-dodecane fuel sprays under heavy-duty Diesel engine conditions are investigated using this approach. Reacting fuel sprays are studied in a constant-volume pre-burn vessel at an ambient temperature of 900 K with three reference cases having specific combinations of injection pressure, ambient density and ambient oxygen concentration (80, 150 & 160 MPa - 22.8 & 40 kg/m3-15 & 20.5% O2). In addition to a free jet, two different walls were placed inside the combustion vessel to study flame-wall interaction.
Technical Paper

Holistic Development of Future Low NOx Emission Concepts for Heavy-Duty Applications

2018-09-10
2018-01-1700
Further tightening of NOx emission standards as well as CO2 emission limits for commercial vehicles are currently under discussion. In the on-road market, lowering NOx emissions up to 90%, down to 0.02 g/bhp-hr, has been proposed by CARB and is evaluated by US EPA. Testing for in-service conformity using a portable emission measurement system (PEMS) is currently under review in the US. In Europe, CO2 emission limits are anticipated and a CO2 monitoring program is ongoing. PEMS legislation has been recently tightened and further restrictions can be expected. Stage V legislation has been introduced in Europe and it is foreseeable that further tightening of off-road standards will take place in the future. This study deals with virtual development and evaluation of future engine and exhaust aftertreatment (EAT) technology solutions to fulfill the diverse future emission requirements with emphasis on off-road applications.
Technical Paper

Development of Model Predictive Control Strategy of SCR System for Heavy-Duty Diesel Engines with a One-State Control-Oriented SCR Model

2018-09-10
2018-01-1763
Urea-based selective catalytic reduction (SCR) of nitric oxides (NOx) is a key technology for heavy-duty diesel engines to achieve the increasingly stringent NOx emission standards. The aqueous urea injection control is critical for urea-SCR systems in order to achieve high NOx conversion efficiency while restricting the tailpipe ammonia (NH3) slip. For Euro VI emission regulation, an advanced control strategy is essential for SCR systems since its NOx emission limits are tighter and test procedure are more stringent compared to Euro IV and Euro V. The complex chemical kinetics of the SCR process has motivated model-based control design approaches. However, the model is too complex to allow real-time implementation. Therefore, it is very important to have a reduced order model for SCR control system.
Technical Paper

A Simulation Study of Optimal Integration of a Rankine Cycle Based Waste Heat Recovery System into the Cooling System of a Long-Haul Heavy Duty Truck

2018-09-10
2018-01-1779
As a promising solution to improve fuel efficiency of a long-haul heavy duty truck with diesel engine, organic Rankine cycle (ORC) based waste heat recovery system (WHR) by utilizing the exhaust gas from internal combustion engine has continuously drawn attention from automobile industry in recent years. The most attractive concept of ORC-based WHR system is the conversion of the thermal energy of exhaust gas recirculation (EGR) and exhaust gas from Tailpipe (EGT) to kinetic energy which is provided to the engine crankshaft. Due to a shift of the operating point of the engine by applying WHR system, the efficiency of the overall system increases and the fuel consumption reduces respectively. However, the integration of WHR system in truck is challenging by using engine cooling system as heat sink for Rankine cycle. The coolant mass flow rate influences strongly on the exhaust gas bypass which ensures a defined subcooling after condenser to avoid cavitation of pump.
Technical Paper

Experimental Investigation of the Effect of Karanja Oil Biodiesel with Cerium Oxide Nano Particle Fuel Additive on Lubricating Oil Tribology and Engine Wear in a Heavy Duty 38.8L,780 HP Military CIDI Diesel Engine

2018-09-10
2018-01-1753
Biodiesel fuels are an alternative to diesel fuel. Biodiesel is an oxygenated, sulphur free, non-toxic, biogradable and renewable fuel. It is derived from vegetable oils. Since straight vegetable oils have quite high viscosity compared to mineral diesel, they have to be modified to bring their combustion-related properties and viscosity closer to mineral diesel. This is done by modifying their molecular structure through a transesterification process. In the present study, a military heavy duty 38.8 liter, 585 kW supercharged, compression ignition diesel injection (CIDI) engine was fuelled with diesel, Karanja oil methyl ester (KOME) biodiesel, and KOME biodiesel with cerium oxide fuel additive, respectively. These were subjected to 100 hours long term endurance tests. Lubricating oil samples, drawn from the engine fuelled with these fuels after a fixed interval of 20 hours, were subjected to elemental analysis.
Technical Paper

Real Driving NOx Emissions from Euro VI Diesel Buses

2018-09-10
2018-01-1815
Since 2013, Euro VI heavy-duty on-road vehicles have been on the market in the Europe. Regulated exhaust emissions, including nitrogen oxides and particulate matter, have been cut down to a very low level, independent of fuel (diesel or natural gas). Multiple research papers have shown that the regulated emissions from the Euro VI and US 2010 heavy-duty on-road vehicles tested on chassis dynamometers really deliver emission levels which correspond the type approval requirements, independent of the test cycle used. In-service conformity (ISC), which is included in the Euro VI legislation, requires heavy-duty on-road engine manufacturers to test and prove their engines to comply with the emission legislation during the engine in-use period. The measurements are carried out in the field using PEMS (Portable Emission Measurement System) equipment. This kind of testing, depicting real-world emissions is the final stage to confirm low real-life emissions.
Technical Paper

Heat Loss Analysis for Various Piston Geometries in a Heavy-Duty Methanol PPC Engine

2018-09-10
2018-01-1726
Partially premixed combustion (PPC) in internal combustion engine as a low temperature combustion strategy has shown great potential to achieve high thermodynamic efficiency. Methanol due to its unique properties is considered as a preferable PPC engine fuel. The injection timing to achieve methanol PPC conditions should be set very close to TDC, allowing to utilize spray-bowl interaction to further improve combustion process in terms of emissions and heat losses. In this study CFD simulations are performed to investigate spray-bowl interaction for a number of different piston designs and its impact on the heat transfer and the overall piston performance. The validation case is based on a single cylinder heavy-duty Scania D13 engine with a compression ratio 15. The operation point is set to low load 5.42 IMEPg bar with SOI -3 aTDC.
Technical Paper

Effects of Different Injection Strategies and EGR on Partially Premixed Combustion

2018-09-10
2018-01-1798
Premixed Charge Compression Ignition concepts are promising to reduce NOx and soot simultaneously and keeping a high thermal efficiency. Partially premixed combustion is a single fuel variant of this new combustion concepts applying a fuel with a low cetane number to achieve the necessary long ignition delay. In this study, multiple injection strategies are studied in the partially premixed combustion approach to reach stable combustion and ultra-low NOx and soot emission at 15.5 bar gross indicated mean effective pressure. Three different injection strategies (single injection, pilot-main injection, main-post injection) are experimentally investigated on a heavy duty compression ignition engine. A fuel blend (70 vol% n-butanol and 30 vol% n-heptane) was tested. The effects of different pilot and post-injection timing, as well as Exhaust-gas Recirculation rate on different injection strategies investigated.
Technical Paper

Farm Tractor Efficiency Gains through Optimized Heavy-Duty Diesel Engine Oils

2018-09-10
2018-01-1752
Modern agriculture has evolved dramatically over the past half century. To be profitable, farms need to significantly increase their crop yields, and thus there are amplified demands on farming equipment. Equipment duty cycles have been raised in scope and duration, as the required output of the agricultural industry to sustain a growing population has stimulated the need for further advances in effective productivity gains on the farm. The mainstay mechanical assistant to the farmer, the tractor, has also evolved with the changes in modern agriculture to meet the requirements of these newer tasks. Larger, more capable vehicles have been introduced to help farmers efficiently meet these demands. At the same time, the current generation of tractor diesel engine lubricants has facilitated high levels of performance in the agricultural equipment market for many years. This is a testament to the role modern lubricants play in productivity in such a critical industry.
Technical Paper

The Complex Application of Monitoring and Express Diagnosing for Searching Failures on Common Rail System Units

2018-09-10
2018-01-1773
The article deals with experimental and theoretical researches of hydraulic processes in a system of accumulator fuel supplying (Common Rail) during the diagnosing while the vehicle idling and during the acceleration. The aim of the work is to assess the efficiency of the offered diagnosing technique as the point of view of cutting-down time for troubleshooting and as the point of view of increasing reliability of failure localization. Feature of the presented approach is that it uses the analysis of fuel pressure fluctuations in the high pressure hydroaccumulator, synchronously with the analysis of rotary speed of an engine crankshaft and the steering signals on electromagnetic magnets (or piezoelements) of injectors. The technique uniting preliminary diagnosing of Electronic Engine Control (EEC) and components of the vehicle fuel units during the constant remote monitoring process, and deep, detailed diagnosing at a service station is described.
Technical Paper

Effects of Environmental Parameters on Real-World NOx Emissions and Fuel Consumption for Heavy-Duty Diesel Trucks Using an OBD Approach

2018-09-10
2018-01-1817
OBD (On-Board Diagnostic) test system is applied to research influences of environmental parameters (altitude and environment temperature) on real-world NOx emission and fuel consumption for heavy-duty diesel trucks in this paper. The research results indicate that altitude and environment temperature have great influence on NOx emission rate and fuel consumption. High altitude in range of 3000~4000 m results in NOx emission rate is lower than low and moderate temperature because of air intake amount decreasing. However the fuel consumption rate is higher than lower altitude because altitude influences real-time changes of air inflow and combustion conditions in the cylinder of the engine. NOx emission rate and fuel consumption is more stable at different vehicle speed, VSP and RPM at high altitude, and NOx emission rate fluctuate dramatically at low and moderate altitude. The fuel consumption rate is higher at 10~20 °C than that at lower and higher temperature.
Technical Paper

The Effect of Cerium Oxide Nano Particles Fuel Additive on Performance and Emission of Karanja Biodiesel Fueled Compression Ignition Military 585kW Heavy Duty Diesel Engine

2018-09-10
2018-01-1818
Global warming with stringent emission legislation along with the depletion of fossil fuel has given us an opportunity to find biodiesel as alternative to diesel fuel. Biodiesel has been widely accepted as comparable fuel to diesel in diesel engine. This is due to its renewable property, better lubricity, along with lesser gaseous emission as compared to diesel fuel. However, there is a major disadvantage in the use of biodiesel as it increases NOx emission. Fuel additive becomes one of the essential tools to overcome the drawback of biodiesel required to meet the international standard of performance and emission. In this study, the performance, combustion, and gaseous emission of CO, CO2, HC, NOx and PM including particle size number distribution characteristics, were compared for diesel, Karanja oil biodiesel, and Karanja oil biodiesel with Cerium Oxide Nano particles fuel additive, in a 12 cylinder, 585 kW, CIDI military diesel engine.
Technical Paper

Developmental Driver Model for Long Vehicles Based on Preview-Follower Theory

2018-08-07
2018-01-1629
A long vehicle is more difficult to drive than a short one, but the mechanism of this phenomenon is still ambiguous. This paper will devote main effort to elaborate this phenomenon based on the theory of preview-follower driver model. Drivers always hope that the vehicle center can travel according to a predetermined trajectory. However, there is often a deviation between the vehicle center predicted by the driver and the actual center. As for this phenomenon, a conception of driver preview eccentricity is proposed. In order to analyze the influence of the proposed conception on vehicle driving track, a multi-axle steering vehicle model is built and some basic expressions of important parameters are deduced from this model firstly. Then, the developmental driver model with the factor of preview eccentricity based on preview-follower theory is established in the state of low velocity quasi-static. Subsequently, this model for long vehicles is extended to a dynamic driver model.
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