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Book

Nonlinear and Hybrid Systems in Automotive Control

2003-05-01
A new generation of strategies for vehicle and engine control systems has become necessary because of increasing requirements for accuracy, ride, comfort, safety, complexity, and emission levels. In contrast with earlier systems, new control systems are based on dynamic physical models and the principles of advanced nonlinear control. With contributions from leading scientists in the field, this book presents an overview of research in this rapidly-expanding area. New approaches to solving theoretical problems, as well as numerous systems and control research issues, are covered.
Technical Paper

Simple linear feedback and extremum control of GDI engines

2000-06-12
2000-05-0056
A novel approach to the control of a GDI engine is presented. The controller consists of a combination of subcontrollers, where torque feedback is a central part. The subcontrollers are with a few exceptions designed using simple linear feedback and feedforward control design methods, in contrast to traditional table-based engine control. An extremum controller is used to minimize the fuel consumption in stratified mode. The controller has been evaluated with good results on the European driving cycle using a dynamic simulation model.
Technical Paper

Ultra-High Speed Fuel Tracer PLIF Imaging in a Heavy-Duty Optical PPC Engine

2018-04-03
2018-01-0904
In order to meet the requirements in the stringent emission regulations, more and more research work has been focused on homogeneous charge compression ignition (HCCI) and partially premixed combustion (PPC) or partially premixed compression ignition (PCCI) as they have the potential to produce low NOx and soot emissions without adverse effects on engine efficiency. The mixture formation and charge stratification influence the combustion behavior and emissions for PPC/PCCI, significantly. An ultra-high speed burst-mode laser is used to capture the mixture formation process from the start of injection until several CADs after the start of combustion in a single cycle. To the authors’ best knowledge, this is the first time that such a high temporal resolution, i.e. 0.2 CAD, PLIF could be accomplished for imaging of the in-cylinder mixing process. The capability of resolving single cycles allows for the influence of cycle-to-cycle variations to be eliminated.
Technical Paper

The Potential of SNCR Based NOx Reduction in a Double Compression Expansion Engine

2018-04-03
2018-01-1128
Selective Non-Catalytic Reduction (SNCR), used to reduce the emissions of nitrogen oxides (NOx), has been a well-established technology in the power plant industry for several decades. The SNCR technique is an aftertreatment strategy based on thermal reduction of NOx at high temperatures. In the compression ignition engine application, the technology has not been applicable due to low exhaust temperatures, which makes the SCR (Selective Catalytic Reduction) system essential for efficient nitrogen oxide reduction to fulfill the environment legislation. For a general Double Compression Expansion Engine (DCEE) the complete expansion cycle is split in two separate cycles, i.e. the engine is a split cycle engine. In the first cylinder the combustion occurs and in the second stage the combustion gas is introduced and further expanded in a low-pressure expansion cylinder. The combustion cylinder is connected with the expansion cylinder through a large insulated high-pressure tank.
Technical Paper

Sensitivity Analysis of Partially Premixed Combustion (PPC) for Control Purposes

2015-04-14
2015-01-0884
Partially Premixed Combustion (PPC) is a promising advanced combustion mode for future engines. In order to investigate the sensitivity of PPC to exhaust gas recirculation (EGR) rate, intake gas temperature, intake gas pressure, and injection timing, these parameters were swept individually at three different loads in a single cylinder diesel engine with gasoline-like fuel. A factor of sensitivity was defined to indicate the combustion's controllability and sensitivity to inlet gas parameters and injection timings. Through analysis of experimental results, a control window of inlet gas parameters and injection timings is obtained at different loads in PPC mode from 5 bar to 10 bar IMEPg load at 1200 rpm. To further study the PPC controllability with injection timing, main injection timing was adjusted to sustain steady combustion phasing subject to perturbation of inlet gas state.
Technical Paper

Effect of Pre-Chamber Volume and Nozzle Diameter on Pre-Chamber Ignition in Heavy Duty Natural Gas Engines

2015-04-14
2015-01-0867
It has previously been shown by the authors that the pre-chamber ignition technique operating with fuel-rich pre-chamber combustion strategy is a very effective means of extending the lean limit of combustion with excess air in heavy duty natural gas engines in order to improve indicated efficiency and reduce emissions. This article presents a study of the influence of pre-chamber volume and nozzle diameter on the resultant ignition characteristics. The two parameters varied are the ratio of pre-chamber volume to engine's clearance volume and the ratio of total area of connecting nozzle to the pre-chamber volume. Each parameter is varied in 3 steps hence forming a 3 by 3 test matrix. The experiments are performed on a single cylinder 2L engine fitted with a custom made pre-chamber capable of spark ignition, fuel injection and pressure measurement.
Technical Paper

An Advanced Internal Combustion Engine Concept for Low Emissions and High Efficiency from Idle to Max Load Using Gasoline Partially Premixed Combustion

2010-10-25
2010-01-2198
A Scania 13 1 engine modified for single cylinder operations was run using nine fuels in the boiling point range of gasoline, but very different octane number, together with PRF20 and MK1-diesel. The eleven fuels were tested in a load sweep between 5 and 26 bar gross IMEP at 1250 rpm and also at idle (2.5 bar IMEP, 600 rpm). The boost level was proportional to the load while the inlet temperature was held constant at 303 K. For each fuel the load sweep was terminated if the ignitibility limit was reached. A lower load limit of 15 and 10 bar gross IMEP was found with fuels having an octane number range of 93-100 and 80-89 respectively, while fuels with an octane number below 70 were able to run through the whole load range including idle. A careful selection of boost pressure and EGR in the previously specified load range allowed achieving a gross indicated efficiency between 52 and 55% while NOx ranged between 0.1 and 0.5 g/kWh.
Technical Paper

Effects of Negative Valve Overlap on the Auto-ignition Process of Lean Ethanol/Air Mixture in HCCI-Engines

2010-10-25
2010-01-2235
This paper presents a computational study of the effects of fuel and thermal stratifications on homogenous charge compression ignition (HCCI) combustion process in a personal car sized internal combustion engine. Stratified HCCI conditions are generated using a negative valve overlap (NVO) technique. The aims of this study are to improve the understanding of the flow dynamics, the heat and mass transfer process and the onset of auto-ignition in stratified charges under different internal EGR rate and NVO conditions. The fuel is ethanol supplied through port-fuel injection; the fuel/air mixture is assumed to be homogenous before discharging to the cylinder. Large eddy simulation (LES) is used to resolve in detailed level the flow structures, and the mixing and heat transfer between the residual gas and fresh fuel/air mixtures in the intake and compression strokes.
Technical Paper

Flow and Temperature Distribution in an Experimental Engine: LES Studies and Thermographic Imaging

2010-10-25
2010-01-2237
Temperature stratification plays an important role in HCCI combustion. The onsets of auto-ignition and combustion duration are sensitive to the temperature field in the engine cylinder. Numerical simulations of HCCI engine combustion are affected by the use of wall boundary conditions, especially the temperature condition at the cylinder and piston walls. This paper reports on numerical studies and experiments of the temperature field in an optical experimental engine in motored run conditions aiming at improved understanding of the evolution of temperature stratification in the cylinder. The simulations were based on Large-Eddy-Simulation approach which resolves the unsteady energetic large eddy and large scale swirl and tumble structures. Two dimensional temperature experiments were carried out using laser induced phosphorescence with thermographic phosphors seeded to the gas in the cylinder.
Technical Paper

HCCI Gas Engine: Evaluation of Engine Performance, Efficiency and Emissions - Comparing Producer Gas and Natural Gas

2011-04-12
2011-01-1196
The Technical University of Denmark, DTU, has constructed, built and tested a gasifier [1, 11] that is fueled with wood chips and achieves a 93% conversion efficiency from wood to producer gas. By combining the gasifier with an internal combustion engine and a generator, a co-generative system can be realized that produces electricity and heat. The gasifier uses the waste heat from the engine for drying and pyrolysis of the wood chips while the produced gas is used to fuel the engine. To achieve high efficiency in converting biomass to electricity it necessitates an engine that is adapted to high efficiency operation using the specific producer gas from the DTU gasifier. So far the majority of gas engines of today are designed and optimized for SI-operation on natural gas.
Technical Paper

HCCI Heat Release Data for Combustion Simulation, Based on Results from a Turbocharged Multi Cylinder Engine

2010-05-05
2010-01-1490
When simulating homogenous charge compression ignition or HCCI using one-dimensional models it is important to have the right combustion parameters. When operating in HCCI the heat release parameters will have a high influence on the simulation result due to the rapid combustion rate, especially if the engine is turbocharged. In this paper an extensive testing data base is used for showing the combustion data from a turbocharged engine operating in HCCI mode. The experimental data cover a wide range, which span from 1000 rpm to 3000 rpm and engine loads between 100 kPa up to over 600 kPa indicated mean effective pressure in this engine speed range. The combustion data presented are: used combustion timing, combustion duration and heat release rate. The combustion timing follows the load and a trend line is presented that is used for engine simulation. The combustion duration in time is fairly constant at different load and engine speeds for the chosen combustion timings here.
Technical Paper

Force Feedback for Assembly of Aircraft Structures

2010-09-28
2010-01-1872
Variability in composite manufacture and the limitations in positional accuracy of common industrial robots have hampered automation of assembly tasks within aircraft manufacturing. One way to handle geometry variations and robot compliancy is to use force control. Force control technology utilizes a sensor mounted on the robot to feedback force data to the controller system so instead of being position driven, i.e. programmed to achieve a certain position with the tool, the robot can be programmed to achieve a certain force. This paper presents an experimental case where a compliant rib is aligned to multiple surfaces using force feedback and an industrial robot system from ABB. Two types of ribs where used, one full size carbon fiber rib, and one smaller metal replica for evaluation purposes. The alignment sequence consisted of several iterative steps and a search procedure was implemented within the robot control system.
Technical Paper

Unburned Hydro Carbon (HC) Estimation Using a Self-Tuned Heat Release Method

2010-10-25
2010-01-2128
An estimation model which uses the gross heat release data and the fuel energy to estimate the total amount of emissions and unburned Hydro Carbon (HC) is developed. Gross heat release data is calculated from a self-tuned heat release method which uses in-cylinder pressure data for computing the energy released during combustion. The method takes all heat and mass losses into account. The method estimates the polytropic exponent and pressure offset during compression and expansion using a nonlinear least square method. Linear interpolation of polytropic exponent and pressure offset is then performed during combustion to calculate the gross heat release during combustion. Moreover the relations between the emissions specifically HC and Carbon Monoxide (CO) are investigated. The model was validated with experimental data and promising results were achieved.
Technical Paper

Influence of Spray-Target and Squish Height on Sources of CO and UHC in a HSDI Diesel Engine During PPCI Low-Temperature Combustion

2009-11-02
2009-01-2810
Laser induced fluorescence (LIF) imaging during the expansion stroke, exhaust gas emissions, and cylinder pressure measurements were used to investigate the influence on combustion and CO/UHC emissions of variations in squish height and fuel spray targeting on the piston. The engine was operated in a highly dilute, partially premixed, low-temperature combustion mode. A small squish height and spray targeting low on the piston gave the lowest exhaust emissions and most rapid heat release. The LIF data show that both the near-nozzle region and the squish volume are important sources of UHC emissions, while CO is dominated by the squish region and is more abundant near the piston top. Emissions from the squish volume originate primarily from overly lean mixture. At the 3 bar load investigated, CO and UHC levels in mixture leaving the bowl and ring-land crevice are low.
Technical Paper

HCCI Combustion of Natural Gas and Hydrogen Enriched Natural Gas Combustion Control by Early Direct Injection of Diesel Oil and RME

2008-06-23
2008-01-1657
Natural gas and hydrogen enriched natural gas has been tested as fuels together with diesel oil and RME in a single cylinder Scania research engine. The gas was introduced as port injection while the diesel was introduced as early direct injection. Because the gas was premixed with air before combustion and the diesel was injected early in the compression stroke, the engine ran close to HCCI mode. However, a more precise description of the combustion would be PPC (Partially Premixed Combustion) as the diesel oil was not expected to be totally premixed. The experiments revealed that the combustion phasing could successfully be controlled by the amount of diesel oil injected for loads between 3.5 and 7.5 bar IMEPg at 1200 rpm. For a given combustion phasing, the hydrogen was not found to influence the required amount of diesel noticeable. However, a large difference between the RME and diesel oil could be seen by the necessity to inject more RME to obtain the same combustion phasing.
Technical Paper

Combustion Chamber Geometry Effects on the Performance of an Ethanol Fueled HCCI Engine

2008-06-23
2008-01-1656
Homogeneous Charge Compression Ignition (HCCI) combustion is limited in maximum load due to high peak pressures and excessive combustion rate. If the rate of combustion can be decreased the load range can be extended. From previous studies it has been shown that by using a deep square bowl in piston geometry the load range can be extended due to decreased heat release rates, pressure rise rates and longer combustion duration compared to a disc shaped combustion chamber. The explanation for the slower combustion was found in the turbulent flow field in the early stages of the intake stroke causing temperature stratifications throughout the charge. With larger temperature differences the combustion will be longer compared to a perfectly mixed charge with less temperature variations. The methods used for finding this explanation were high-speed cycle-resolved chemiluminescence imaging and fuel tracer planar laser induced fluorescence (PLIF), together with large eddy simulations (LES).
Technical Paper

Evaluation of the Operating Range of Partially Premixed Combustion in a Multi Cylinder Heavy Duty Engine with Extensive EGR

2009-04-20
2009-01-1127
Partially Premixed Combustion (PPC) is a combustion concept by which it is possible to get low smoke and NOx emissions simultaneously. PPC requires high EGR levels and injection timings sufficiently early or late to extend the ignition delay so that air and fuel mix extensively prior to combustion. This paper investigates the operating region of single injection diesel PPC in a multi cylinder heavy duty engine resembling a standard build production engine. Limits in emissions and fuel consumption are defined and the highest load that fulfills these requirements is determined. Experiments are carried out at different engine speeds and a comparison of open and closed loop combustion control are made as well as evaluation of an extended EGR-cooling system designed to reduce the EGR temperature. In this study the PPC operating range proved to be limited.
Technical Paper

Partially Premixed Combustion at High Load using Gasoline and Ethanol, a Comparison with Diesel

2009-04-20
2009-01-0944
This paper is the follow up of a previous work and its target is to demonstrate that the best fuel for a Compression Ignition engine has to be with high Octane Number. An advanced injection strategy was designed in order to run Gasoline in a CI engine. At high load it consisted in injecting 54 % of the fuel very early in the pilot and the remaining around TDC; the second injection is used as ignition trigger and an appropriate amount of cool EGR has to be used in order to avoid pre-ignition of the pilot. Substantially lower NOx, soot and specific fuel consumption were achieved at 16.56 bar gross IMEP as compared to Diesel. The pressure rise rate did not constitute any problem thanks to the stratification created by the main injection and a partial overlap between start of the combustion and main injection. Ethanol gave excellent results too; with this fuel the maximum load was limited at 14.80 bar gross IMEP because of hardware issues.
Technical Paper

HCCI Operating Range in a Turbo-charged Multi Cylinder Engine with VVT and Spray-Guided DI

2009-04-20
2009-01-0494
Homogenous charge compression ignition (HCCI) has been identified as a promising way to increase the efficiency of the spark-ignited engine, while maintaining low emissions. The challenge with HCCI combustion is excessive pressure rise rate, quantified here with Ringing Intensity. Turbocharging enables increased dilution of the charge and thus a reduction of the Ringing Intensity. The engine used is an SI four cylinder base with 2.2L displacement and is equipped with a turbocharger. Combustion phasing control is achieved with individual intake/ exhaust cam phasing. Fuel injection with spray guided design is used. Cycle resolved combustion state is monitored and used for controlling the engine either in closed or open loop where balancing of cylinder to cylinder variations has to be done to run the engine at high HCCI load. When load is increased the NOx levels rise, the engine is then run in stoichiometric HCCI mode to be able to use a simple three-way catalyst.
Technical Paper

Studying the potential efficiency of low heat rejection HCCI engines with a Stochastic Reactor Model

2009-09-13
2009-24-0032
The main losses in internal combustion engines are the heat losses to the cylinder walls and to the exhaust gases. Adiabatic, or low heat rejection engines, have received interest and been studied in several periods in history. Typically, however, these attempts have had to be abandoned when problems with lubrication and overheating components could not be solved satisfactorily. The latest years have seen the emerging of low temperature combustion in engines as well as computational powers that provide new options for highly efficient engines with low heat rejection. Stochastic Reactor Models (SRM) are highly efficient in modeling the kinetics decided low temperature combustion in HCCI and PPC engines. Containing the means to define the variations within the cylinder while employing detailed chemistry, micro mixing and heat transfer modeling, the interaction between heat transfer, exhaust gas energy and the combustion process can be studied with the SRM.
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