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Llamas, X. & Eriksson, L. (2019). Control-oriented modeling of two-stroke diesel engines with exhaust gas recirculation for marine applications. Paper presented at Proceedings of the Institution of Mechanical Engineers. Journal of Engineering for the Maritime Environment (Part M), 233(2), 551-574
Open this publication in new window or tab >>Control-oriented modeling of two-stroke diesel engines with exhaust gas recirculation for marine applications
2019 (English)In: Journal of Engineering for the Maritime Environment (Part M), ISSN 1475-0902, E-ISSN 2041-3084, Vol. 233, no 2, p. 551-574Article in journal (Refereed) Published
Abstract [en]

Large marine two-stroke diesel engines are widely used as propulsion systems for shipping worldwide and are facing stricter NOx emission limits. Exhaust gas recirculation is introduced to these engines to reduce the produced combustion NOx to the allowed levels. Since the current number of engines built with exhaust gas recirculation is low and engine testing is very expensive, a powerful alternative for developing exhaust gas recirculation controllers for such engines is to use control-oriented simulation models. Unfortunately, the same reasons that motivate the use of simulation models also hinder the capacity to obtain sufficient measurement data at different operating points for developing the models. A mean value engine model of a large two-stroke diesel with exhaust gas recirculation that can be simulated faster than real time is presented and validated. An analytic model for the cylinder pressure that captures the effects of changes in the fuel control inputs is also developed and validated with cylinder pressure measurements. A parameterization procedure that deals with the low number of measurement data available is proposed. After the parameterization, the model is shown to capture the stationary operation of the real engine well. The transient prediction capability of the model is also considered satisfactory which is important if the model is to be used for exhaust gas recirculation controller development during transients. Furthermore, the experience gathered while developing the model about essential signals to be measured is summarized, which can be very helpful for future applications of the model. Finally, models for the ship propeller and resistance are also investigated, showing good agreement with the measured ship sailing signals during maneuvers. These models give a complete vessel model and make it possible to simulate various maneuvering scenarios, giving different loading profiles that can be used to investigate the performance of exhaust gas recirculation and other controllers during transients.

Place, publisher, year, edition, pages
Sage Publications, 2019
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:liu:diva-147828 (URN)10.1177/1475090218768992 (DOI)000470866500011 ()
Conference
Proceedings of the Institution of Mechanical Engineers
Note

Funding agencies: European Union [634135]

Available from: 2018-05-15 Created: 2018-05-15 Last updated: 2019-07-15
Llamas, X. & Eriksson, L. (2018). LiU CPgui: A Toolbox for Parameterizing Compressor Models. Linköping: Linköping University Electronic Press
Open this publication in new window or tab >>LiU CPgui: A Toolbox for Parameterizing Compressor Models
2018 (English)Report (Other academic)
Abstract [en]

A toolbox for parameterizing the ellipse model, that is a control-oriented compressor model, to any given measured compressor map is described in detail in this document. The compressor model has been developed in previous publications and shown to be capable of accurately reproducing the measured data obtained from gas stand measurements, for a wide range of compressors, starting from small automotive applications to large compressors used in marine propulsion. In addition, it has been shown that it is possible to extrapolate both mass flow and efficiency to the unmeasured low speed region of the compressor in a physical way. The parameterization algorithm is based on Total Least Squares (TLS), which is shown here and in previous publications to be a fast and reliable approach to fit the compressor model to the map. The toolbox is implemented in a Matlab Graphical User Interface (GUI) in order to make it easy for the user to parameterize the compressor model. To demonstrate the workflow and ease of use, a complete step-by-step example of how to work with the toolbox is provided. To further facilitate the user in applying the model, the package also provides implementations of the ellipse compressor model both as a Matlab function and as a Simulink block. This way, the user can quickly and reliably use the results of the parameterization process in a desired application, e.g. including the compressor model of a given compressor map in a combustion engine simulation model.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2018. p. 45
Series
LiTH-ISY-R, ISSN 1400-3902 ; 3102
Keywords
Compressor Model, Parameterization, Software
National Category
Control Engineering
Identifiers
urn:nbn:se:liu:diva-144398 (URN)LiTH-ISY-R-3102 (ISRN)
Funder
VINNOVA, LinkSIC
Available from: 2018-01-18 Created: 2018-01-18 Last updated: 2018-01-18Bibliographically approved
Llamas, X. (2018). Modeling and Control of EGR on Marine Two-Stroke Diesel Engines. (Doctoral dissertation). Linköping: Linköping University Electronic Press
Open this publication in new window or tab >>Modeling and Control of EGR on Marine Two-Stroke Diesel Engines
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The international marine shipping industry is responsible for the transport of around 90% of the total world trade. Low-speed two-stroke diesel engines usually propel the largest trading ships. This engine type choice is mainly motivated by its high fuel efficiency and the capacity to burn cheap low-quality fuels. To reduce the marine freight impact on the environment, the International Maritime Organization (IMO) has introduced stricter limits on the engine pollutant emissions. One of these new restrictions, named Tier III, sets the maximum NOx emissions permitted. New emission reduction technologies have to be developed to fulfill the Tier III limits on two-stroke engines since adjusting the engine combustion alone is not sufficient. There are several promising technologies to achieve the required NOx reductions, Exhaust Gas Recirculation (EGR) is one of them.  For automotive applications, EGR is a mature technology, and many of the research findings can be used directly in marine applications. However, there are some differences in marine two-stroke engines, which require further development to apply and control EGR.

The number of available engines for testing EGR controllers on ships and test beds is low due to the recent introduction of EGR. Hence, engine simulation models are a good alternative for developing controllers, and many different engine loading scenarios can be simulated without the high costs of running real engine tests. The primary focus of this thesis is the development and validation of models for two-stroke marine engines with EGR. The modeling follows a Mean Value Engine Model (MVEM) approach, which has a low computational complexity and permits faster than real-time simulations suitable for controller testing. A parameterization process that deals with the low measurement data availability, compared to the available data on automotive engines, is also investigated and described. As a result, the proposed model is parameterized to two different two-stroke engines showing a good agreement with the measurements in both stationary and dynamic conditions.

Several engine components have been developed. One of these is a new analytic in-cylinder pressure model that captures the influence of the injection and exhaust valve timings without increasing the simulation time. A new compressor model that can extrapolate to low speeds and pressure ratios in a physically sound way is also described. This compressor model is a requirement to be able to simulate low engine loads. Moreover, a novel parameterization algorithm is shown to handle well the model nonlinearities and to obtain a good model agreement with a large number of tested compressor maps. Furthermore, the engine model is complemented with dynamic models for ship and propeller to be able to simulate transient sailing scenarios, where good EGR controller performance is crucial. The model is used to identify the low load area as the most challenging for the controller performance, due to the slower engine air path dynamics. Further low load simulations indicate that sensor bias can be problematic and lead to an undesired black smoke formation, while errors in the parameters of the controller flow estimators are not as critical. This result is valuable because for a newly built engine a proper sensor setup is more straightforward to verify than to get the right parameters for the flow estimators.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2018. p. 200
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1904
Keywords
Modeling for control, Ship Propulsion, Dynamic Simulation, Exhaust Gas Recirculation, Mean Value Engine Model, Parameterization, Compressor, Model Extrapolation
National Category
Control Engineering Vehicle Engineering
Identifiers
urn:nbn:se:liu:diva-144596 (URN)10.3384/diss.diva-144596 (DOI)9789176853689 (ISBN)
Public defence
2018-03-23, Ada Lovelace, Ingång 27, B-huset, Campus Valla, Linköping, 10:15 (English)
Opponent
Supervisors
Funder
EU, Horizon 2020, 634135Vinnova, LINK-SIC
Available from: 2018-01-30 Created: 2018-01-30 Last updated: 2019-09-30Bibliographically approved
Llamas, X. & Eriksson, L. (2017). Control-Oriented Compressor Model with Adiabatic Efficiency Extrapolation. SAE International Journal of Engines, 10(4)
Open this publication in new window or tab >>Control-Oriented Compressor Model with Adiabatic Efficiency Extrapolation
2017 (English)In: SAE International Journal of Engines, ISSN 1946-3936, E-ISSN 1946-3944, Vol. 10, no 4Article in journal (Refereed) Published
Abstract [en]

Downsizing and turbocharging with single or multiple stages has been one of the main solutions to decrease fuel consumption and harmful exhaust emissions, while keeping a sufficient power output. An accurate and reliable control-oriented compressor model can be very helpful during the development phase, as well as for engine calibration, control design, diagnostic purposes or observer design. A complete compressor model consisting of mass flow and efficiency models is developed and motivated. The proposed model is not only able to represent accurately the normal region measured in a compressor map but also it is capable to extrapolate to low compressor speeds. Moreover, the efficiency extrapolation is studied by analyzing the known problem with heat transfer from the hot turbine side, which introduces errors in the measurements done in standard gas stands. Since the parameterization of the model is an important and necessary step in the modeling, a tailored parameterization approach is presented based on Total Least Squares. A standard compressor map is the only data required to parameterize the model. The parameterization is tested with a database of more than 230 compressor maps showing that it can deal well with different compressor sizes and characteristics. Also, general initialization values for the model parameters are provided using the complete database parameterization results. The results show that the model accuracy is good and in general achieves relative errors below one percent. A comparison of the model accuracy for compressor maps with and without heat transfer influence is carried out, showing a similar model accuracy for both cases but better when no heat transfer is present. Furthermore, it is shown that the model is capable to predict the efficiency characteristics at low speed of two compressor maps, measured with near adiabatic conditions.

Place, publisher, year, edition, pages
United States: S A E Inc., 2017
National Category
Control Engineering Vehicle Engineering
Identifiers
urn:nbn:se:liu:diva-136799 (URN)10.4271/2017-01-1032 (DOI)
Funder
EU, Horizon 2020, 634135
Available from: 2017-04-26 Created: 2017-04-26 Last updated: 2018-01-30Bibliographically approved
Llamas, X. & Eriksson, L. (2017). Parameterizing Compact and Extensible Compressor Models Using Orthogonal Distance Minimization. Journal of engineering for gas turbines and power, 139(1), 012601-1-012601-10, Article ID GTP-15-1569.
Open this publication in new window or tab >>Parameterizing Compact and Extensible Compressor Models Using Orthogonal Distance Minimization
2017 (English)In: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 139, no 1, p. 012601-1-012601-10, article id GTP-15-1569Article in journal (Refereed) Published
Abstract [en]

A complete and compact control-oriented compressor model consisting of a mass flow submodel and an efficiency submodel is described. The final application of the model is a complete two-stroke mean value engine model (MVEM) which requires simulating the compressor operating at the low-flow and low-pressure ratio area. The model is based on previous research done for automotive-size compressors, and it is shown to be general enough to adapt well to the characteristics of the marine-size compressors. A physics-based efficiency model allows, together with the mass flow model, extrapolating to low-pressure ratios. The complexity of the model makes its parameterization a difficult task; hence, a method to efficiently estimate the 19 model parameters is proposed. The method computes analytic model gradients and uses them to minimize the orthogonal distances between the modeled speed lines (SpLs) and the measured points. The results of the parameter estimation are tested against nine different standard marine-size maps showing good agreement with the measured data. Furthermore, the results also show the importance of estimating the parameters of the mass flow and efficiency submodels at the same time to obtain an accurate model. The extrapolation capabilities to low-load regions are also tested using low-load measurements from an automotive-size compressor. It is shown that the model follows the measured efficiency trend down to low loads.

Place, publisher, year, edition, pages
ASME Press, 2017
National Category
Applied Mechanics
Identifiers
urn:nbn:se:liu:diva-136199 (URN)10.1115/1.4034152 (DOI)000395511600016 ()
Note

Funding Agencies|European Union [634135]

Available from: 2017-04-03 Created: 2017-04-03 Last updated: 2019-04-02Bibliographically approved
Llamas, X. & Eriksson, L. (2016). A Model of a Marine Two-Stroke Diesel Engine with EGR for Low Load Simulation. In: 9th EUROSIM Congress: . Paper presented at 9th EUROSIM Congress on Modelling and Simulation. 12 - 16 September 2016 in Oulu, Finland..
Open this publication in new window or tab >>A Model of a Marine Two-Stroke Diesel Engine with EGR for Low Load Simulation
2016 (English)In: 9th EUROSIM Congress, 2016Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

A mean value engine model of a two-stroke ma-rine diesel engine with EGR that is capable of simulatingduring low load operation is developed. In order to beable to perform low load simulations, a compressor modelcapable of low speed extrapolation is also investigated andparameterized for two different compressors. Moreover, aparameterization procedure to get good parameters for bothstationary and dynamic simulations is described and applied.The model is validated for two engine layouts of the same testengine but with different turbocharger units. The simulationresults show a good agreement with the different measuredsignals, including the oxygen content in the scavengingmanifold.

Keywords
Modeling, Parameterization, Simulations, Exhaust gas recirculation, Combustion engines
National Category
Vehicle Engineering Control Engineering
Identifiers
urn:nbn:se:liu:diva-136804 (URN)
Conference
9th EUROSIM Congress on Modelling and Simulation. 12 - 16 September 2016 in Oulu, Finland.
Funder
EU, Horizon 2020, 634135
Available from: 2017-04-26 Created: 2017-04-26 Last updated: 2018-02-22Bibliographically approved
Alegret, G., Llamas, X., Vejlgaard-Laursen, M. & Eriksson, L. (2015). Modeling of a Large Marine Two-Stroke Diesel Engine with Cylinder Bypass Valve and EGR System. In: Roberto Galeazzi and Mogens Blanke (Ed.), 10th IFAC Conference on Manoeuvring and Control of Marine Craft MCMC 2015: Copenhagen, 24–26 August 2015: . Paper presented at 10th IFAC Conference on Manoeuvring and Control of Marine Craft (pp. 273-278). IFAC Papers Online, 48
Open this publication in new window or tab >>Modeling of a Large Marine Two-Stroke Diesel Engine with Cylinder Bypass Valve and EGR System
2015 (English)In: 10th IFAC Conference on Manoeuvring and Control of Marine Craft MCMC 2015: Copenhagen, 24–26 August 2015 / [ed] Roberto Galeazzi and Mogens Blanke, IFAC Papers Online, 2015, Vol. 48, p. 273-278Conference paper, Published paper (Refereed)
Abstract [en]

A nonlinear mean value engine model (MVEM) of a two-stroke turbocharged marine diesel engine is developed, parameterized and validated against measurement data. The goal is to have a computationally fast and accurate engine model that captures the main dynamics and can be used in the development of control systems for the newly introduced EGR system. The tuning procedure used is explained, and the result is a six-state MVEM with seven control inputs that capture the main system dynamics.

Place, publisher, year, edition, pages
IFAC Papers Online, 2015
Keywords
Engine modeling, diesel engines, parametrization, validation, nonlinear systems
National Category
Control Engineering Vehicle Engineering
Identifiers
urn:nbn:se:liu:diva-136802 (URN)10.1016/j.ifacol.2015.10.292 (DOI)2-s2.0-84992491352 (Scopus ID)
Conference
10th IFAC Conference on Manoeuvring and Control of Marine Craft
Available from: 2017-04-26 Created: 2017-04-26 Last updated: 2018-02-05Bibliographically approved
Llamas, X. & Eriksson, L. (2014). Optimal Transient Control of a Heavy DutyDiesel Engine with EGR and VGT. In: Boje, Edward, Xia, Xiaohua (Ed.), Proceedings of the 19th IFAC World Congress: . Paper presented at 19th IFAC World Congress (pp. 11854-11859). Cape Town, South Africa: IFAC Papers Online, 19
Open this publication in new window or tab >>Optimal Transient Control of a Heavy DutyDiesel Engine with EGR and VGT
2014 (English)In: Proceedings of the 19th IFAC World Congress / [ed] Boje, Edward, Xia, Xiaohua, Cape Town, South Africa: IFAC Papers Online, 2014, Vol. 19, p. 11854-11859Conference paper, Published paper (Refereed)
Abstract [en]

Optimal control of a heavy duty diesel engine with EGR and VGT during transients is investigated. Minimum time and fuel optimal control problems are defined for transients from low to high output torque. A validated diesel engine model is used with minor changes in order to be suitable for the selected solver. The problem is solved for several feasible minimum EGR fractions and smoke-limiter values in order to provide comparisons. The optimization results show that the smoke-limiter has great effect on the transient duration while the required EGR fraction influences the control signals' shape. The fuel optimal control keeps the control actuators more closed than the time optimal, however both time and fuel optimal results become very similar when high EGR fractions and smoke-limiter values are required.

Place, publisher, year, edition, pages
Cape Town, South Africa: IFAC Papers Online, 2014
Keywords
Nonlinear and optimal automotive control, Engine modelling and control
National Category
Control Engineering Vehicle Engineering Other Engineering and Technologies not elsewhere specified
Identifiers
urn:nbn:se:liu:diva-122630 (URN)10.3182/20140824-6-ZA-1003.01520 (DOI)
Conference
19th IFAC World Congress
Available from: 2015-11-13 Created: 2015-11-13 Last updated: 2018-02-01Bibliographically approved
Llamas, X., Eriksson, L. & Sundström, C. (2013). Fuel Efficient Speed Profiles for Finite Time Gear Shift with Multi-Phase Optimization. In: 54th SIMS Conference on Simulation and Modelling, SIMS 2013: . Paper presented at The 54th SIMS conference on Simulation and Modelling, Bergen, Norway, October 16-18, 2013.
Open this publication in new window or tab >>Fuel Efficient Speed Profiles for Finite Time Gear Shift with Multi-Phase Optimization
2013 (English)In: 54th SIMS Conference on Simulation and Modelling, SIMS 2013, 2013Conference paper, Published paper (Refereed)
Abstract [en]

A method that finds fuel optimal speed profiles for traveling a predefined distance is presented. The vehicle is modeled using a quasistatic formulation and an optimal control problem is defined. In addition, the solving method is based on a multi-phase optimization algorithm based on dynamic programming. This approach results in lower computational time than solving the problem directly with dynamic programming, it also makes the computational time independent of the travel distance. In addition, the simulation generated data can be used to get the solution to several optimal control problems in parallel that have additional constraints. Further a finite time gear shift model is presented to include the gear selection in the optimization problem. The problem also considers speed losses and fuel consumption during the maneuver. The results presented show the optimal speed and gear profiles to cover a distance, making special emphasis at the acceleration phase, where it is optimal to perform a fast acceleration to engage the highest gear as soon as possible. Finally a proposed application is to use the simulation data to provide eco-driving tips to the driver.

Keywords
Dynamic Programming, Simulation, Eco-driving
National Category
Vehicle Engineering Control Engineering
Identifiers
urn:nbn:se:liu:diva-136805 (URN)
Conference
The 54th SIMS conference on Simulation and Modelling, Bergen, Norway, October 16-18, 2013
Available from: 2017-04-26 Created: 2017-04-26 Last updated: 2017-06-02Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-1584-8165

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