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Range Extenders for Electric Vehicles Land, Water & Air 2015-2025

Half the electric vehicle market value lies in larger road vehicles, notably cars, and here the legal restrictions are weaker or non-existent, and range anxiety compels most people to buy hybrids if they go electric at all. Over eight million hybrid cars will be made in 2025, each with a range extender, the additional power source that distinguishes them from pure electric cars. Add to that significant money spent on the same devices in buses, military vehicles, boats and so on and a major new market emerges. Whereas today's range extenders usually consist of little more than off- the- shelf internal combustion engines, these are rapidly being replaced by second- generation range extenders consisting of piston engines designed from scratch for fairly constant load. However, a more radical departure is the third- generation micro turbines and fuel cells that work at constant load.

Characterization and Potential of Dual Fuel Combustion in a Modern Diesel Engine

Diesel Dual Fuel, DDF, is a concept which promises the possibility to utilize CNG/biogas in a compression ignition engine maintaining a high compression ratio, made possible by the high knock resistance of methane, and the resulting benefits in thermal efficiency associated with Diesel combustion. Presenter Fredrik K�nigsson, AVL Sweden
Journal Article

An Analysis of Lubricating Gap Flow in Radial Piston Machines

Radial piston units find several applications in fluid power, offering benefits of low noise and high power density. The capability to generate high pressures makes radial piston pumps suitable for clamping function in machine tools and also to operate presses for sheet metal forming. This study is aimed at developing a comprehensive multidomain simulation tool to model the operation of a rotating cam type radial piston pump, with particular reference to the lubricating gap flow between the pistons and the cylinder block. The model consists of a first module which simulates the main flow through the unit according to a lumped parameter approach. This module evaluates the features of the displacing action accounting for the detailed evaluation of the machine kinematics and for the mechanical dynamics of the check valves used to control the timing for the connection of each piston chamber with the inlet and outlet port.
Technical Paper

Characterization of Cycle-by-Cycle Variations of an Optically Accessible Heavy-Duty Diesel Engine Retrofitted to Natural Gas Spark Ignition

The combustion process in spark-ignition engines can vary considerably cycle by cycle, which may result in unstable engine operation. The phenomena amplify in natural gas (NG) spark-ignition (SI) engines due to the lower NG laminar flame speed compared to gasoline, and more so under lean burn conditions. The main goal of this study was to investigate the main sources and the characteristics of the cycle-by-cycle variation in heavy-duty compression ignition (CI) engines converted to NG SI operation. The experiments were conducted in a single-cylinder optically-accessible CI engine with a flat bowl-in piston that was converted to NG SI. The engine was operated at medium load under lean operating conditions, using pure methane as a natural gas surrogate. The CI to SI conversion was made through the addition of a low-pressure NG injector in the intake manifold and of a NG spark plug in place of the diesel injector.
Technical Paper

Investigation on the Deformation of Injector Components and Its Influence on the Injection Process

The deformation of injector components cannot be disregarded as the pressure of the system increases. Deformation directly affects the characteristics of needle movement and injection quantity. In this study, structural deformation of the nozzle, the needle and the control plunger under different pressures is calculated by a simulation model. The value of the deformation of injector components is calculated and the maximum deformation location is also determined. Furthermore, the calculated results indicates that the deformation of the control plunger increases the control chamber volume and the cross-section area between the needle and the needle seat. A MATLAB model is established to The influence of structural deformation on needle movement characteristics and injection quantity is investigate by a numerical model. The results show that the characteristic points of needle movement are delayed and injection quantity increases due to the deformation.
Technical Paper

Optimizing the Piston/Bore Tribology: The Role of Surface Specifications, Ring Pack, and Lubricant

The present study looks into different possibilities for tribological optimization of the piston/bore system in heavy duty diesel engines. Both component rig tests and numerical simulations are used to understand the roles of surface specifications, ring pack, and lubricant in the piston/bore tribology. Run-in dynamics, friction, wear and combustion chamber sealing are considered. The performance of cylinder liners produced using a conventional plateau honing technology and a novel mechanochemical surface finishing process - ANS Triboconditioning® - is compared and the importance of in-design “pairing” of low-viscosity motor oils with the ring pack and the cylinder bore characteristics in order to achieve maximum improvement in fuel economy without sacrificing the endurance highlighted. A special emphasis is made on studying morphological changes in the cylinder bore surface during the honing, run-in and Triboconditioning® processes.
Journal Article

Applying Advanced CFD Analysis Tools to Study Differences between Start-of-Main and Start-of-Post Injection Flow, Temperature and Chemistry Fields Due to Combustion of Main-Injected Fuel

This paper is part of a larger body of experimental and computational work devoted to studying the role of close-coupled post injections on soot reduction in a heavy-duty optical engine. It is a continuation of an earlier computational paper. The goals of the current work are to develop new CFD analysis tools and methods and apply them to gain a more in depth understanding of the different in-cylinder environments into which fuel from main- and post-injections are injected and to study how the in-cylinder flow, thermal and chemical fields are transformed between start of injection timings. The engine represented in this computational study is a single-cylinder, direct-injection, heavy-duty, low-swirl engine with optical components. It is based on the Cummins N14, has a cylindrical shaped piston bowl and an eight-hole injector that are both centered on the cylinder axis. The fuel used was n-heptane and the engine operating condition was light load at 1200 RPM.
Journal Article

Piston Cooling Nozzle Oil Jet Evaluation Using CFD and a High Speed Camera

Piston cooling nozzles/jets play several crucial roles in the power cylinder of an internal combustion engine. Primarily, they help with the thermal management of the piston and provide lubrication to the cylinder liner and the piston’s wrist pin. In order to evaluate the oil jet characteristics from various piston cooling nozzle (PCN) designs, a quantitative and objective process was developed. The PCN characterization began with a computational fluid dynamics (CFD) turbulent model to analyze the mean oil velocity and flow distribution at the nozzle exit/tip. Subsequently, the PCN was tested on a rig for a given oil temperature and pressure. A high-speed camera captured images at 2500 frames per second to observe the evolution of the oil stream as a function of distance from the nozzle exit. An algorithm comprised of standard digital image processing techniques was created to calculate the oil jet width and density.
Journal Article

New MAHLE Steel Piston and Pin Coating System for Reduced TCO of CV Engines

Total cost of ownership is requiring further improvements to piston friction reduction as well as additional gains in thermal efficiency. A piston compression height reduction in combination with carbon based piston pin coatings is enabling advancements in both demands. MAHLE implemented a new innovative metal joining technology by using laser welding to generate a cooling gallery. The MonoLite concept offers design flexibility which cannot be matched by any other welding process. Especially an optimum design and position of the cooling gallery as well as durability for very high peak cylinder pressures can be matched. This is particularly advantageous for complex combustion bowl geometries that are needed in modern diesel engines to meet fuel economy and emission requirements. The MonoLite steel piston technology offers a superior compression height reduction potential compared to typical friction welded designs.
Journal Article

A New Piston Insulation Concept for Heavy-Duty Diesel Engines to Reduce Heat Loss from the Wall

To reduce heat transfer between hot gas and cavity wall, thin Zirconia (ZrO2) layer (0.5mm) on the cavity surface of a forged steel piston was firstly formed by thermal spray coating aiming higher surface temperature swing precisely synchronized with flame temperature near the wall resulting in the reduction of temperature difference. However, no apparent difference in the heat loss was analyzed. To find out the reason why the heat loss was not so improved, direct observation of flame impingement to the cavity wall was carried out with the top view visualization technique, for which one of the exhaust valves was modified to a sapphire window. Local flame behavior very close to the wall was compared by macrophotography. Numerical analysis by utilizing a three-dimensional simulation was also carried out to investigate the effect of several parameters on the heat transfer coefficient.
Journal Article

Optimization of an Advanced Combustion Strategy Towards 55% BTE for the Volvo SuperTruck Program

This paper describes a novel design and verification process for analytical methods used in the development of advanced combustion strategies in internal combustion engines (ICE). The objective was to improve brake thermal efficiency (BTE) as part of the US Department of Energy SuperTruck program. The tools and methods herein discussed consider spray formation and injection schedule along with piston bowl design to optimize combustion efficiency, air utilization, heat transfer, emission, and BTE. The methodology uses a suite of tools to optimize engine performance, including 1D engine simulation, high-fidelity CFD, and lab-scale fluid mechanic experiments. First, a wide range of engine operating conditions are analyzed using 1-D engine simulations in GT Power to thoroughly define a baseline for the chosen advanced engine concept; secondly, an optimization and down-select step is completed where further improvements in engine geometries and spray configurations are considered.
Journal Article

Heat Loss Analysis of a Steel Piston and a YSZ Coated Piston in a Heavy-Duty Diesel Engine Using Phosphor Thermometry Measurements

Diesel engine manufacturers strive towards further efficiency improvements. Thus, reducing in-cylinder heat losses is becoming increasingly important. Understanding how location, thermal insulation, and engine operating conditions affect the heat transfer to the combustion chamber walls is fundamental for the future reduction of in-cylinder heat losses. This study investigates the effect of a 1mm-thick plasma-sprayed yttria-stabilized zirconia (YSZ) coating on a piston. Such a coated piston and a similar steel piston are compared to each other based on experimental data for the heat release, the heat transfer rate to the oil in the piston cooling gallery, the local instantaneous surface temperature, and the local instantaneous surface heat flux. The surface temperature was measured for different crank angle positions using phosphor thermometry.
Technical Paper

Methane Conversion and Ammonia Formation Model over a Pd-Rh Three-Way Catalyst for CNG Heavy-Duty Engines

Research activities in the development of reliable computational models for aftertreatment systems are constantly increasing in the automotive field. These investigations are essential in order to get a complete understanding of the main catalytic processes which clearly have a great impact on tailpipe emissions. In this work, a 1D chemical reaction model to simulate the catalytic activity of a Pd/Rh Three-Way Catalyst (TWC) for a Natural Gas heavy-duty engine is presented. An extensive database of tests carried out with the use of a Synthetic Gas Bench (SGB) has been collected to investigate the methane abatement pathways, linked to the lambda variation and oxide formation on palladium surface. Specific steady-state tests have shown a dynamics of the methane conversion even at fixed λ and temperature conditions, essentially due to the Pd/PdO ratio.
Journal Article

IEA Technology Network Cooperation: Fuel and Technology Alternatives for Buses: Overall Energy Efficiency and Emissions

In 2009 - 2011, a comprehensive project on urban buses was carried out in cooperation with IEA's Implementing Agreements on Alternative Motor Fuels and Bioenergy, with input from additional IEA Implementing Agreements. The objective of the project was to generate unbiased and solid data for use by policy- and decision-makers responsible for public transport using buses. The project comprised four major parts: (1) a well-to-tank (WTT) assessment of alternative fuel pathways, (2) an assessment of bus end-use (tank-to-wheel, TTW) performance, (3) combining WTT and TTW data into well-to-wheel (WTW) data and (4) a cost assessment, including indirect as well as direct costs. Experts at Argonne National Laboratory, Natural Resources Canada and VTT worked on the WTT part. In the TTW part, Environment Canada and VTT generated emission and fuel consumption data by running 21 different buses on chassis dynamometers, generating data for some 180 combinations of vehicle, fuel and driving cycle.
Journal Article

Numerical Simulation Study of Carbon Build-up and Oil Consumption in a Heavy Duty Diesel Engine

Nowadays, the use of numerical simulations is an important tool in order to optimize the engine and components behaviors, directly contributing to the emissions and lead-time development project reduction. With the increase of engine thermal specific loading, excessive piston carbon build-up may be an issue, eventually causing liner polishing and excessive Lube Oil Consumption (OC). During the development of a Cummins heavy duty 8.9L engine, preliminary engine test results indicated excessive OC levels, above the engine specification limits. Also, a considerable carbon build-up, mainly in the second ring groove, was observed. This paper presents the application of piston rings numerical simulation to predict the piston ring pack behavior and evaluate potential sources of OC which may explain the excessive values obtained in engine tests.
Journal Article

A Methodology to Assess Road Tankers Rollover Trend During Turning

An experimental methodology is proposed to measure the rollover propensity of road tankers when subjected to lateral perturbations derived from steering manoeuvers. The testing principle involves subjecting a scaled down sprung tank to the elimination of a lateral acceleration, to analyze its rollover propensity as a function of various vehicle's operational and design parameters. Initial acceleration is generated through putting the scaled tank on a tilt table supported by a hydraulic piston. The controlled release of the fluid in the hydraulic system generates a perturbation situation for the tank, similar to the one that a vehicle experiences when leaving a curved section of the road and going to a straight segment. Durations for the maneuver and initial tilt angles characterize both the corresponding intensities of the steering maneuver.
Journal Article

Design of Hydraulically Interconnected Suspension Systems for Tri-axle Straight Trucks with Rear Tandem Axle Bogie Suspensions

This study has proposed a new roll-resistant hydraulically interconnected suspension (HIS) system for a tri-axle straight truck with rear tandem axle bogie suspension to suppress the roll motion of truck body. The equations of motion of the mechanical and hydraulic coupling system are established by incorporating the hydraulic forces as external forces into the mechanical subsystem, in which the hydraulic forces are derived using impedance transfer matrix method and related to the state vectors of mechanical subsystem at the boundaries. Based on the derived equations of the coupling system, modal analysis method is employed to investigate the dynamic characteristics, including natural frequencies, mode shapes and dynamic responses. The results indicate that the proposed HIS system can effectively enhance the natural frequencies of truck body pitch and roll modes, and significantly increase the mode damping. The mode shapes of truck body are also changed.
Technical Paper

Real Driving Emissions of Diesel and LNG Euro VI Heavy-Duty Vehicles Measured with FTIR-PEMS

To replace conventional Diesel and to make the transport sector CO2 neutral, liquid bio methane or liquefied biogas (LBG) is one possible solution to replace conventional fuel. Due to the ongoing development of methane engines for trucks and the possible perspective of realizing closed CO2 cycles, a pilot project "Use of LBG (Liquefied Biogas) for Swiss heavy-duty transportation" has been launched in Switzerland. This project is intended to demonstrate the performance of LBG trucks as well as their environmental benefits. The emission behavior of the vehicles is a critical point in the evaluation of the idea of using methane as a fuel. In the present paper the conducted real drive emission measurements of two different methane gas and one Diesel powered truck, as reference, with the parallel use of a standard and FTIR-PEMS are presented. The configuration of both PEMS systems mounted on a trailer is shown, as well as the real drive scenario.
Journal Article

Modelling and Numerical Simulation of Dual Fuel Lean Flames Using Local Burning Velocity and Critical Chemical Timescale

Abstract Addition of hydrogen to hydrocarbons in premixed turbulent combustion is of technological interest due to their increased reactivity, flame stability and extended lean extinction limits. However, such flames are a challenge to reaction modelling, especially as the strong preferential diffusion effects modify the physical processes, which are of importance even for highly turbulent high-pressure conditions. In the present work, Reynolds-averaged Navier-Stokes (RANS) modelling is carried out to investigate pressure and hydrogen content on methane/hydrogen/air flames.
Journal Article

An Investigation of the Effects of the Piston Bowl Geometries of a Heavy-Duty Engine on Performance and Emissions Using Direct Dual Fuel Stratification Strategy, and Proposing Two New Piston Profiles

Abstract Direct dual fuel stratification (DDFS) strategy benefits the advantages of the RCCI and PPC strategies simultaneously. DDFS has improved control over the heat release rate, by injecting a considerable amount of fuel near TDC, compared to RCCI. In addition, the third injection (near TDC) is diffusion-limited. Consequently, piston bowl geometry directly affects the formation of emissions. The modified piston geometry was developed and optimized for RCCI by previous scholars. Since all DDFS experimental tests were performed with the modified piston profile, the other piston profiles need to be investigated for this strategy. In this article, first, a comparative study between the three conventional piston profiles, including the modified, stock, and scaled pistons, was performed. Afterward, the gasoline injector position was shifted to the head cylinder center for the stock piston. NOX emissions were improved; however, soot was increased slightly.