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Efficiency Optimization by In-Cycle Closed-Loop Combustion Control

Jorques Moreno, Carlos LU ; Stenlåås, Ola LU and Tunestål, Per LU (2021) In Control Engineering Practice
Abstract
This paper is a comprehensive review of in-cycle closed-loop combustion controllers to achieve higher indicated efficiencies. Closed-loop combustion control reduces the effect of external disturbances and system uncertainties, which permit tighter safety margins and robust operation with a reduced calibration effort. The paper combines different components of previous investigations by the authors, where the validation of on-line estimation methods, the in-cycle controllability and the effectiveness of different combustion controllers were addressed. The work is developed by the combination of simulations and experimental results on a Scania D13 engine. This paper focuses on the design of direct and indirect in-cycle closed-loop combustion... (More)
This paper is a comprehensive review of in-cycle closed-loop combustion controllers to achieve higher indicated efficiencies. Closed-loop combustion control reduces the effect of external disturbances and system uncertainties, which permit tighter safety margins and robust operation with a reduced calibration effort. The paper combines different components of previous investigations by the authors, where the validation of on-line estimation methods, the in-cycle controllability and the effectiveness of different combustion controllers were addressed. The work is developed by the combination of simulations and experimental results on a Scania D13 engine. This paper focuses on the design of direct and indirect in-cycle closed-loop combustion controllers with a pilot and main injection to maximize the indicated efficiency under hardware and emission constraints.
An in-cycle combustion controller is reviewed for the direct efficiency optimization based on an equivalent premixed cycle. By feedback from a virtual pilot mass sensor with a real-time accuracy of ±0.5mg/st, the controller is able to increase the indicated efficiency by +0.42%unit compared to open-loop operation. The effectiveness of the controller is limited due to the implementation restrictions and system non-linearities. These are overcome by the indirect controller design. A predictive controller can reduce the cyclic variance of pilot SOC to ±0.4CAD, pilot burnt mass to ±0.6mg, main SOC to ±0.3CAD and IMEP to ±0.2bar. Accurate predictions are possible by the on-line model adaptation. Furthermore, the controller can compensate for pilot misfire to reduce its effect on the CA50 shift from +2.6CAD to +0.5CAD. The reduced dispersion is included in a stochastic combustion model, where Monte Carlo simulations are used to optimize the set-point reference. The results indicate that the efficiency can be increased by +0.6%unit under maximum pressure, maximum pressure rise rate, maximum and minimum exhaust temperature.
Despite the controller effectiveness was quantified experimentally, the simulation results must be validated experimentally as well. Further investigations can focus on including constraints on emissions, how to handle the constraints on-line, the inclusion of additional injection pulses in the optimization, as well as variable valve timing actuation or injection of emissions reductants. (Less)
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Control Engineering Practice
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17 pages
publisher
Elsevier
ISSN
0967-0661
language
English
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yes
id
2574cdf9-4db4-4d26-9e76-ac163dd3f51c
date added to LUP
2021-04-20 09:57:34
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2021-04-20 12:32:23
@article{2574cdf9-4db4-4d26-9e76-ac163dd3f51c,
  abstract     = {This paper is a comprehensive review of in-cycle closed-loop combustion controllers to achieve higher indicated efficiencies. Closed-loop combustion control reduces the effect of external disturbances and system uncertainties, which permit tighter safety margins and robust operation with a reduced calibration effort. The paper combines different components of previous investigations by the authors, where the validation of on-line estimation methods, the in-cycle controllability and the effectiveness of different combustion controllers were addressed. The work is developed by the combination of simulations and experimental results on a Scania D13 engine. This paper focuses on the design of direct and indirect in-cycle closed-loop combustion controllers with a pilot and main injection to maximize the indicated efficiency under hardware and emission constraints.<br/>An in-cycle combustion controller is reviewed for the direct efficiency optimization based on an equivalent premixed cycle. By feedback from a virtual pilot mass sensor with a real-time accuracy of ±0.5mg/st, the controller is able to increase the indicated efficiency by +0.42%unit compared to open-loop operation. The effectiveness of the controller is limited due to the implementation restrictions and system non-linearities. These are overcome by the indirect controller design. A predictive controller can reduce the cyclic variance of pilot SOC to ±0.4CAD, pilot burnt mass to ±0.6mg, main SOC to ±0.3CAD and IMEP to ±0.2bar. Accurate predictions are possible by the on-line model adaptation. Furthermore, the controller can compensate for pilot misfire to reduce its effect on the CA50 shift from +2.6CAD to +0.5CAD. The reduced dispersion is included in a stochastic combustion model, where Monte Carlo simulations are used to optimize the set-point reference. The results indicate that the efficiency can be increased by +0.6%unit under maximum pressure, maximum pressure rise rate, maximum and minimum exhaust temperature.<br/>Despite the controller effectiveness was quantified experimentally, the simulation results must be validated experimentally as well. Further investigations can focus on including constraints on emissions, how to handle the constraints on-line, the inclusion of additional injection pulses in the optimization, as well as variable valve timing actuation or injection of emissions reductants.},
  author       = {Jorques Moreno, Carlos and Stenlåås, Ola and Tunestål, Per},
  issn         = {0967-0661},
  language     = {eng},
  publisher    = {Elsevier},
  series       = {Control Engineering Practice},
  title        = {Efficiency Optimization by In-Cycle Closed-Loop Combustion Control},
  year         = {2021},
}