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Ethanol-Diesel Fumigation in a Multi-Cylinder Engine

SAE International Journal of Fuels and Lubricants

Lund University-Kent Ekholm, Maria Karlsson, Per Tunestål, Rolf Johansson, Bengt Johansson
Volvo Powertrain-Petter Strandh
  • Journal Article
  • 2008-01-0033
Published 2008-04-14 by SAE International in United States
Fumigation was studied in a 12 L six-cylinder heavy-duty engine. Port-injected ethanol was ignited with a small amount of diesel injected into the cylinder. The setup left much freedom for influencing the combustion process, and the aim of this study was to find operation modes that result in a combustion resembling that of a homogeneous charge compression ignition (HCCI) engine with high efficiency and low NOx emissions. Igniting the ethanol-air mixture using direct-injected diesel has attractive properties compared to traditional HCCI operation where the ethanol is ignited by pressure alone. No preheating of the mixture is required, and the amount of diesel injected can be used to control the heat release rate. The two fuel injection systems provide a larger flexibility in extending the HCCI operating range to low and high loads.It was shown that cylinder-to-cylinder variations present a challenge for this type of combustion. By using closed-loop cylinder-individual control of pressure derivatives and IMEP with the amounts of fuels injected, combustion was successfully harmonized between the cylinders.Successful fumigation operation was verified up to 18.4…
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Multi-Output Control of a Heavy Duty HCCI Engine Using Variable Valve Actuation and Model Predictive Control

Lund Institute of Technology-Rolf Johansson, Per Tunestål, Bengt Johansson
Volvo Powertrain Corporation-Johan Bengtsson, Petter Strandh
Published 2006-04-03 by SAE International in United States
Autoignition of a homogeneous mixture is very sensitive to operating conditions, therefore fast control is necessary for reliable operation. There exists several means to control the combustion phasing of an Homogeneous Charge Compression Ignition (HCCI) engine, but most of the presented controlled HCCI result has been performed with single-input single-output controllers. In order to fully operate an HCCI engine several output variables need to be controlled simultaneously, for example, load, combustion phasing, cylinder pressure and emissions. As these output variables have an effect on each other, the controller should be of a structure which includes the cross-couplings between the output variables. A Model Predictive Control (MPC) controller is proposed as a solution to the problem of load-torque control with simultaneous minimization of the fuel consumption and emissions, while satisfying the constraints on cylinder pressure. One of the major motivations for using MPC is that it explicitly takes the constraints into account. When operating an HCCI engine there are several contraints present, for example on the cylinder pressure and on the emissions. A drawback of MPC…
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Variable Valve Actuation for Timing Control of a Homogeneous Charge Compression Ignition Engine

Lund Institute of Technology-Petter Strandh, Johan Bengtsson, Rolf Johansson, Per Tunestål, Bengt Johansson
Published 2005-04-11 by SAE International in United States
Autoignition of a homogeneous mixture is very sensitive to operating conditions. Therefore fast combustion phasing control is necessary for reliable operation. There are several means to control the combustion phasing of a Homogeneous Charge Compression Ignition (HCCI) engine. This paper presents cycle-to-cycle cylinder individual control results from a six-cylinder HCCI engine using a Variable Valve Actuation (VVA) system. As feedback signal, the crank angle for 50% burned, based on cylinder pressure, is used. Three control structures are evaluated, Model Predictive Control (MPC), Linear Quadratic Gaussian control (LQG) and PID control. In the control design of the MPC and LQG controller, dynamic models obtained by system identification were used. Successful experiments were performed on a port-injected six-cylinder heavy-duty Diesel engine operating in HCCI mode.
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System Identification of Homogeneous Charge Compression Ignition (HCCI) Engine Dynamics

Lund Univ.-Johan Bengtsson, Petter Strandh, Rolf Johansson, Per Tunestål, Bengt Johansson
  • Technical Paper
  • 2004-35-0135
Published 2004-04-19 by University of Salerno in Italy
Homogeneous Charge Compression Ignition (HCCI) combustion lacks direct ignition timing control, instead the autoignition depends on the operating condition. Since autoignition of a homogeneous mixture is very sensitive to operating condition a fast combustion timing control is necessary for reliable operation, the ignition timing control design requiring appropriate models and system output variables for its feedback design. This paper demonstrates the use of system modelling and identification as a means to find models relevant to the engine control. The identification methods used were various subspace-based methods. An LQG controller was designed based on the estimated models and tested on a six-cylinder, heavy-duty engine running in HCCI operation.
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Cycle-to-Cycle Control of a Dual-Fuel HCCI Engine

Lund Institute of Technology-Petter Strandh, Johan Bengtsson, Rolf Johansson, Per Tunestål, Bengt Johansson
Published 2004-03-08 by SAE International in United States
A known problem of the HCCI engine is its lack of direct control and its requirements of feedback control. Today there exists several different means to control an HCCI engine, such as dual fuels, variable valve actuation, inlet temperature and compression ratio. Independent of actuation method a sensor is needed. In this paper we perform closed-loop control based on two different sensors, pressure and ion current sensor. Results showing that they give similar control performance within their operating range are presented.Also a comparison of two methods of designing HCCI timing controller, manual tuning and model based design is presented. A PID controller is used as an example of a manually tuned controller. A Linear Quadratic Gaussian controller exemplifies model based controller design. The models used in the design were estimated using system identification methods.The system used in this paper performs control on cycle-to-cycle basis. This leads to fast and robust control. Dual fuels with different octane numbers were used to control the combustion timing.The engine was a 12 liter 6 cylinder heavy-duty diesel engine modified…
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Multiple Point Ion Current Diagnostics in an HCCI Engine

Division of Combustion Engines, Lund Institute of Technology-Andreas Vressner, Petter Strandh, Anders Hultqvist, Per Tunestål, Bengt Johansson
Published 2004-03-08 by SAE International in United States
Interest in ion current sensing for HCCI combustion arises when a feedback signal from some sort of combustion sensor is needed in order to determine the state of the combustion process. A previous study has revealed that ion current sensors in the form of spark plugs can be used instead of expensive piezoelectric transducers for HCCI combustion sensing. Sufficiently high ion current levels were achieved when using relatively rich mixtures diluted with EGR. The study also shows that it is not the actual dilution per se but the actual air/fuel equivalence ratio which is important for the signal level. Conclusions were made that it is possible to obtain information on combustion timing and oscillating wave phenomena from the measurements. However, the study showed that the ion current is local compared to the pressure which is global in the combustion chamber. This observation triggered the present study where the aim is to investigate the ion current at different locations in the combustion chamber. The ion current was measured simultaneously at seven locations in the combustion chamber.…
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Ion Current Sensing for HCCI Combustion Feedback

Dept. of Automatic Control, Lund Institute of Technology-Johan Bengtsson, Rolf Johansson
Div. of Combustion Engines, Lund Institute of Technology-Andreas Vressner, Per Tunestål, Bengt Johansson
Published 2003-10-27 by SAE International in United States
Measurement of ion current signal from HCCI combustion was performed. The aim of the work was to investigate if a measurable ion current signal exists and if it is possible to obtain useful information about the combustion process. Furthermore, influence of mixture quality in terms of air/fuel ratio and EGR on the ion current signal was studied. A conventional spark plug was used as ionization sensor. A DC voltage (85 Volt) was applied across the electrode gap. By measuring the current through the gap the state of the gas can be probed. A comparison between measured pressure and ion current signal was performed, and dynamic models were estimated by using system identification methods.The study shows that an ion current signal can be obtained from HCCI combustion and that the signal level is very sensitive to the fuel/air equivalence ratio. The most important result from this study is that the ion current signal proved to be an excellent indicator of the actual combustion timing which is crucial piece of information for HCCI control.
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Modeling SI-engines for Hybrid Vehicles

Lund Institute of Technology, Sweden-Petter Strandh, Rolf Egnell
Published 2001-03-05 by SAE International in United States
One of the most attractive features of hybrid vehicles powered by SI-engines with three way catalysts is the potential of reaching extremely low emissions. In conventional drive trains, limitations in the air/fuel control result in lambda excursions during transients. These deviations from the ideal lambda result in increased emissions.In a hybrid vehicle, rapid load and speed changes of the SI-engine could be limited to an acceptable level as the battery acts as a power buffer. However, the efficiency of charging and discharging the battery is rather low, which means that excessive power buffering will increase the fuel consumption of the vehicle. Thus it is of great importance to know what degree of speed and load changes the air/fuel control system could cope with without an increase in emissions.Most SI-engine models for hybrid vehicles are quasi stationary, which means that data achieved at stationary load conditions are assumed to be representative for transient operation as well. In this paper a concept is presented in which stationary engine data is used, but corrected for the effects of…
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Fuel and Additive Influence on the Ion Current

Combustion Engines, Dept. of Heat and Power Engrg., Lund Institute of Technology, Sweden-Bengt Lassesson, Petter Strandh
Combustion Physics, Dept. of Physics, Lund Institute of Technology, Sweden-Raymond Reinmann, André Saitzkoff
Published 1998-02-01 by SAE International in United States
The influence on the ion current from a variety of fuels and additives has been investigated. The ion current has been measured in an engine as well as in a continuous atmospheric burner. The acquired ion current data has been statistically treated in order to find general trends and behaviors. The measurements were found to be in agreement with established theories for the ion current formation. This work indicates that the use of alternative fuels will not endanger the large engine control potential supplied by the ion current technique, since the changes induced by the fuel variety can be accounted for, when using the different fuel types of today.
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