The Experts below are selected from a list of 216 Experts worldwide ranked by ideXlab platform
J. D. Powell - One of the best experts on this subject based on the ideXlab platform.
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A bit of information on identification with a zirconia sensor
Proceedings of 1995 American Control Conference - ACC'95, 1995Co-Authors: V.k. Jones, G.f. Franklin, J. D. PowellAbstract:Even though the zirconia-oxygen sensor serves as the primary feedback sensor in current production Fuel-Air Ratio control architectures, there has been no work investigating the use of the one-bit output of this sensor to identify spark-ignition engine system parameters. In this research, we present experimental and simulation data that show portions of the important engine dynamics can be determined with this nonlinear sensor using a new identification algorithm proposed in the paper. Comparisons will be made between using the zirconia-oxygen and a linear sensor for this purpose.
Ping Wang - One of the best experts on this subject based on the ideXlab platform.
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Feedforward Model Predictive Control of Fuel-Air Ratio for Lean-Burn Spark-Ignition Gasoline Engines of Passenger Cars
IEEE Access, 2019Co-Authors: Ping WangAbstract:Precise Fuel-Air Ratio (FAR) control on transient conditions is one of the key technologies for lean-burn spark-ignition (SI) engines. To improve fuel economy and reduce emissions, lean-burn engines must regulate their FAR immediately under different operating conditions. The precision of FAR control is limited by the large time-varying feedback delay which is caused by mixture combustion, exhaust gas transport, and lean NOx trap (LNT) module. Hence, a FAR predictive controller is proposed to track the desired FAR value precisely in the control framework of feedforward and feedback control. First of all, a feedforward predictive model for the FAR in the cylinder and a feedback predictive model for the FAR in the exhaust pipe with a time-delay characteristic are built respectively. Next, the FAR tracking requirement and the physical actuator constraints are transformed into the optimization objective function. Finally, a feedback/embedded feedforward predictive controller is designed, and the optimization problems are solved online to obtain the fuel injection quality. The simulation results based on GT-POWER illustrate that the proposed predictive control algorithm with feedforward predictive control can track the dynamic FAR precisely in a wide range. Meanwhile, the feedback controller decreases the effects of time delay and parameters uncertainty on the system dynamics.
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Model Prediction Control of Fuel-Air Ratio for Lean-Burn Spark Ignition Gasoline Engine
IFAC-PapersOnLine, 2018Co-Authors: Ping WangAbstract:Abstract Higher fuel economy and lower exhaust emissions for lean-burn spark-ignition (SI) engines depend significantly on precise Fuel-Air Ratio (FAR) control. In addition, in order to improve fuel economy and reduce emissions, it is crucial for lean-burn engine to change the FAR according to different operating conditions. However, the presence of large time-varying delay due to the engine combustion, exhaust emissions transmission and lean NOx trap (LNT) module in the engine is the primary limiting factor in the control of FAR. Hence, the FAR prediction control algorithm based on disturbance observer is proposed in this paper. First, a predictive model with time-delay characteristic is established. Second, state observer is designed to predict the future dynamic changes of the engine system, and disturbance observer is designed to estimate and predict disturbances. Finally, the physical constraints of the engine and the FAR control requirements are transformed into the optimization objective function, and the optimization problem is solved online to get the amount of fuel injection. The results of Matlab and GT-Power co-simulation show that FAR predictive control algorithm based on the disturbance observer not only can quickly track the desired FAR, but also can achieve a large range of precise control of FAR and reduce the delay and parameter uncertainty impact on system dynamics.
Christof Schulz - One of the best experts on this subject based on the ideXlab platform.
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Toluene LIF at elevated temperatures: implications for Fuel-Air Ratio measurements
Applied Physics B, 2005Co-Authors: W. Koban, J.d. Koch, R.k. Hanson, Christof SchulzAbstract:Toluene laser-induced fluorescence (LIF) was investigated for 266- and 248-nm excitation in the temperature range of 300–650 K in a nitrogen/oxygen bath gas of 1 bar total pressure with oxygen partial pressure in the range 0–400 mbar. Contrary to a popular assumption, the toluene LIF signal is not directly proportional to the fuel–air Ratio (termed the FAR-LIF assumption) for many conditions relevant to reciprocating IC engines. With increasing temperature, a higher oxygen partial pressure is required to justify the FAR-LIF assumption. The required oxygen pressure becomes unrealistic (>5 bar) for T>670 K at 266-nm excitation and for T>625 K at 248-nm excitation.
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Tracer-LIF diagnostics: quantitative measurement of fuel concentRation, temperature and fuel/air Ratio in practical combustion systems
Progress in Energy and Combustion Science, 2005Co-Authors: Christof Schulz, Volker SickAbstract:Abstract The safe, clean, and reliable opeRation of combustion devices depends to a large degree on the exact control of the fuel/air mixing process prior to ignition. Therefore, quantitative measurement techniques that characterize the state of the fresh gas mixture are crucial in modern combustion science and engineering. This paper presents the fundamental concepts for how to devise and apply quantitative measurement techniques for studies of fuel concentRation, temperature, and fuel/air Ratio in practical combustion systems, with some emphasis on internal combustion engines. The paper does not attempt to provide a full literature review of quantitative imaging diagnostics for practical combustion devices; rather it focuses on explaining the concepts and illustrating these with selected examples. These examples focus on application to primarily gaseous situations. The photophysics of organic molecules is presented in an overview followed by discussions on specific details of the temperature-, pressure-, and mixture-dependence of the laser-induced fluorescence strength of aliphatic ketones, like acetone and 3-pentanone, and toluene. Models that describe the fluorescence are discussed and evaluated with respect to their functionality. Examples for quantitative applications are categorized in order of increased complexity. These examples include simple mixing experiments under isothermal and isobaric conditions, fuel/air mixing in engines, temperature measurements, and mixing studies where fuel and oxygen concentRations vary. A brief summary is given on measurements of fuel concentRations in multiphase systems, such as laser‐induced exciplex spectroscopy. Potentially adverse effects that added tracers might have on mixture formation, combustion, and the faithful representation of the base fuel distribution are discussed. Finally, a brief section describes alternative techniques to tracer-based measurements that allow studies of fuel/air mixing processes in practical devices. The paper concludes with a section that addresses key issues that remain as challenges for continued research towards the improvement of quantitative, tracer-based LIF measurements.
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tracer lif diagnostics quantitative measurement of fuel concentRation temperature and fuel air Ratio in practical combustion systems
Progress in Energy and Combustion Science, 2005Co-Authors: Christof Schulz, Volker SickAbstract:Abstract The safe, clean, and reliable opeRation of combustion devices depends to a large degree on the exact control of the fuel/air mixing process prior to ignition. Therefore, quantitative measurement techniques that characterize the state of the fresh gas mixture are crucial in modern combustion science and engineering. This paper presents the fundamental concepts for how to devise and apply quantitative measurement techniques for studies of fuel concentRation, temperature, and fuel/air Ratio in practical combustion systems, with some emphasis on internal combustion engines. The paper does not attempt to provide a full literature review of quantitative imaging diagnostics for practical combustion devices; rather it focuses on explaining the concepts and illustrating these with selected examples. These examples focus on application to primarily gaseous situations. The photophysics of organic molecules is presented in an overview followed by discussions on specific details of the temperature-, pressure-, and mixture-dependence of the laser-induced fluorescence strength of aliphatic ketones, like acetone and 3-pentanone, and toluene. Models that describe the fluorescence are discussed and evaluated with respect to their functionality. Examples for quantitative applications are categorized in order of increased complexity. These examples include simple mixing experiments under isothermal and isobaric conditions, fuel/air mixing in engines, temperature measurements, and mixing studies where fuel and oxygen concentRations vary. A brief summary is given on measurements of fuel concentRations in multiphase systems, such as laser‐induced exciplex spectroscopy. Potentially adverse effects that added tracers might have on mixture formation, combustion, and the faithful representation of the base fuel distribution are discussed. Finally, a brief section describes alternative techniques to tracer-based measurements that allow studies of fuel/air mixing processes in practical devices. The paper concludes with a section that addresses key issues that remain as challenges for continued research towards the improvement of quantitative, tracer-based LIF measurements.
V.k. Jones - One of the best experts on this subject based on the ideXlab platform.
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A bit of information on identification with a zirconia sensor
Proceedings of 1995 American Control Conference - ACC'95, 1995Co-Authors: V.k. Jones, G.f. Franklin, J. D. PowellAbstract:Even though the zirconia-oxygen sensor serves as the primary feedback sensor in current production Fuel-Air Ratio control architectures, there has been no work investigating the use of the one-bit output of this sensor to identify spark-ignition engine system parameters. In this research, we present experimental and simulation data that show portions of the important engine dynamics can be determined with this nonlinear sensor using a new identification algorithm proposed in the paper. Comparisons will be made between using the zirconia-oxygen and a linear sensor for this purpose.
W. M. Proscia - One of the best experts on this subject based on the ideXlab platform.
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Nonlinear heat-release/acoustic model for thermoacoustic instability in lean premixed combustors
Journal of Engineering for Gas Turbines and Power, 1999Co-Authors: A. A. Peracchio, W. M. ProsciaAbstract:Lean premixed combustors, such as those used in industrial gas turbines to achieve low emissions, are often susceptible to the thermoacoustic combustion instabilities, which manifest themselves as pressure and heat release oscillations in the combustor. These oscillations can result in increased noise and decreased durability due to vibRation and flame motion. A physically based nonlinear parametric model has been developed that captures this instability. It describes the coupling of combustor acoustics with the rate of heat release. The model represents this coupling by accounting for the effect of acoustic pressure fluctuations on the varying fuel/air Ratio being delivered to the flame, causing a fluctuating heat release due to both fuel air Ratio variations and flame front oscillations. If the phasing of the fluctuating heat release and pressure are proper, an instability results that grows into a limit cycle. The nonlinear nature of the model predicts the onset of the instability and additionally captures the resulting limit cycle. Tests of a lean premixed nozzle run at engine scale and engine operating conditions in the UTRC single nozzle rig, conducted under DARPA contract, exhibited instabilities. Parameters from the model were adjusted so that analytical results were consistent with relevant experimental data from this test. The parametric model captures the limit cycle behavior over a range of mean fuel air Ratios, showing the instability amplitude (pressure and heat release) to increase and limit cycle frequency to decrease as mean fuel air Ratio is reduced.
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Nonlinear Heat-Release/Acoustic Model for Thermoacoustic Instability in Lean Premixed Combustors
Volume 3: Coal Biomass and Alternative Fuels; Combustion and Fuels; Oil and Gas Applications; Cycle Innovations, 1998Co-Authors: A. A. Peracchio, W. M. ProsciaAbstract:Lean premixed combustors, such as those used in industrial gas turbines to achieve low emissions, are often susceptible to thermoacoustic combustion instabilities, which manifest themselves as pressure and heat release oscillations in the combustor. These oscillations can result in increased noise and decreased durability due to vibRation and flame motion. A physically based nonlinear parametric model has been developed that captures this instability. It describes the coupling of combustor acoustics with the rate of heat release. The model represents this coupling by accounting for the effect of acoustic pressure fluctuations on the varying fuel/air Ratio being delivered to the flame, causing a fluctuating heat release due to both fuel air Ratio variations and flame front oscillations. If the phasing of the fluctuating heat release and pressure are proper, an instability results that grows into a limit cycle. The nonlinear nature of the model predicts the onset of the instability and additionally captures the resulting limit cycle.Tests of a lean premixed nozzle run at engine scale and engine operating conditions in the UTRC Single Nozzle Rig, conducted under DARPA contract, exhibited instabilities. Parameters from the model were adjusted so that analytical results were consistent with relevant experimental data from this test. The parametric model captures the limit cycle behavior over a range of mean fuel air Ratios, showing the instability amplitude (pressure and heat release) to increase and limit cycle frequency to decrease as mean fuel air Ratio is reduced.Copyright © 1998 by ASME
