Predictive Second Order Sliding Control of Constrained Linear Systems with Application to Automotive Control Systems

This paper presents a new predictive second order sliding controller (PSSC) formulation for setpoint tracking of constrained linear systems. The PSSC scheme is developed by combining the concepts of model predictive control (MPC) and second order discrete sliding mode control. In order to guarantee the feasibility of the PSSC during setpoint changes, a virtual reference variable is added to the PSSC cost function to calculate the closest admissible set point. The states of the system are then driven asymptotically to this admissible setpoint by the control action of the PSSC. The performance of the proposed PSSC is evaluated for an advanced automotive engine case study, where a high fidelity physics-based model of a reactivity controlled compression ignition (RCCI) engine is utilized to serve as the virtual test-bed for the simulations. Considering the hard physical constraints on the RCCI engine states and control inputs, simultaneous tracking of engine load and optimal combustion phasing is a challenging objective to achieve. The simulation results of testing the proposed PSSC on the high fidelity RCCI model show that the developed predictive controller is able to track desired engine load and combustion phasing setpoints, with minimum steady state error, and no overshoot. Moreover, the simulation results confirm the robust tracking performance of the PSSC during transient operations, in the presence of engine cyclic variability.Comment: 6 pages, 5 figures, 2018 American Control Conferance (ACC), June 27-29, 2018, Milwaukee, WI, USA. [Accepted in Jan. 2018

In-Cylinder Pressure-Based Control of Premixed Dual-Fuel Combustion

[ES] La actual crisis climática ha instado a la comunidad investigadora y a los fabricantes a brindar soluciones para hacer que el sector del transporte sea más sostenible. De entre las diversas tecnologías propuestas, la combustión a baja temperatura ha sido objeto de una extensa investigación. La combustión premezclada dual-fuel es uno de los conceptos que abordan el compromiso de NOx-hollín en motores de encendido por compresión manteniendo alta eficiencia térmica. Esta combustión hace uso de dos combustibles con diferentes reactividades para mejorar la controlabilidad de este modo de combustión en un amplio rango de funcionamiento. De manera similar a todos los modos de combustión premezclados, esta combustión es sensible a las condiciones de operación y suele estar sujeta a variabilidad cíclica con gradientes de presión significativos. En consecuencia, se requieren estrategias de control avanzadas para garantizar un funcionamiento seguro y preciso del motor. El control en bucle cerrado es una herramienta eficaz para abordar los desafíos que plantea la combustión premezclada dual-fuel. En este tipo de control, para mantener el funcionamiento deseado, las acciones de control se adaptan y corrigen a partir de una retroalimentación con las señales de salida del motor. Esta tesis presenta estrategias de control basadas en la medición de la señal de presión en el cilindro, aplicadas a motores de combustión premezclada dual-fuel. En ella se resuelven diversos aspectos del funcionamiento del motor mediante el diseño de controladores dedicados, haciéndose especial énfasis en analizar e implementar estas soluciones a los diferentes niveles de estratificación de mezcla considerados en estos motores (es decir, totalmente, altamente y parcialmente premezclada). Inicialmente, se diseñan estrategias de control basadas en el procesamiento de la señal de presión en el cilindro y se seleccionan acciones proporcionales-integrales para asegurar el rendimiento deseado del motor sin exceder las limitaciones mecánicas del motor. También se evalúa la técnica extremum seeking para realizar una supervisión de una combustión eficiente y la reducción de emisiones de NOx. Luego se analiza la resonancia de la presión en el cilindro y se implementa un controlador similar a aquel usado para el control de knock para garantizar el funcionamiento seguro del motor. Finalmente, se utilizan modelos matemáticos para diseñar un modelo orientado a control y un observador que tiene como objetivo combinar las señales medidas en el motor para mejorar las capacidades de predicción y diagnóstico en dicha configuración de motor. Los resultados de este trabajo destacan la importancia de considerar el control en bucle cerrado para abordar las limitaciones encontradas en los modos de combustión premezclada. En particular, el uso de la medición de presión en el cilindro muestra la relevancia y el potencial de esta señal para desarrollar estrategias de control complejas y precisas.[CA] L'actual crisi climàtica ha instat a la comunitat investigadora i als fabricants a brindar solucions per a fer que el sector del transport siga més sostenible. D'entre les diverses tecnologies proposades, la combustió a baixa temperatura ha sigut objecte d'una extensa investigació. La combustió premesclada dual-fuel és un dels conceptes que aborden el compromís de NOx-sutge en motors d'encesa per compressió mantenint alta eficiència tèrmica. Aquesta combustió fa ús de dos combustibles amb diferents reactivitats per a millorar la controlabilitat d'aquest tipus de combustió en un ampli rang de funcionament. De manera similar a tots els tipus de combustió premesclada, aquesta combustió és sensible a les condicions d'operació i sol estar subjecta a variabilitat cíclica amb gradients de pressió significatius. En conseqüència, es requereixen estratègies de control avançades per a garantir un funcionament segur i precís del motor. El control en bucle tancat és una eina eficaç per a abordar els desafiaments que planteja la combustió premesclada dual-fuel. En aquesta mena de control, per a mantindre el funcionament desitjat, les accions de control s'adapten i corregeixen a partir d'una retroalimentació amb els senyals d'eixida del motor. Aquesta tesi presenta estratègies de control basades en el mesurament del senyal de pressió en el cilindre, aplicades a motors de combustió premesclada dual-fuel. En ella es resolen diversos aspectes del funcionament del motor mitjançant el disseny de controladors dedicats, fent-se especial èmfasi a analitzar i implementar aquestes solucions als diferents nivells d'estratificació de mescla considerats en aquests motors (és a dir, totalment, altament i parcialment premesclada). Inicialment, es dissenyen estratègies de control basades en el processament del senyal de pressió en el cilindre i se seleccionen accions proporcionals-integrals per a assegurar el rendiment desitjat del motor sense excedir les limitacions mecàniques del motor. També s'avalua la tècnica extremum seeking per a realitzar una supervisió d'una combustió eficient i la reducció d'emissions de NOx. Després s'analitza la ressonància de la pressió en el cilindre i s'implementa un controlador similar a aquell usat per al control de knock per a garantir el funcionament segur del motor. Finalment, s'utilitzen models matemàtics per a dissenyar un model orientat a control i un observador que té com a objectiu combinar els senyals mesurats en el motor per a millorar les capacitats de predicció i diagnòstic en aquesta configuració de motor. Els resultats d'aquest treball destaquen la importància de considerar el control en bucle tancat per a abordar les limitacions trobades en la combustió premesclada. En particular, l'ús del mesurament de pressió en el cilindre mostra la rellevància i el potencial d'aquest senyal per a desenvolupar estratègies de control complexes i precises.[EN] The current climate crisis has urged the research community and manufacturers to provide solutions to make the transportation sector cleaner. Among the various technologies proposed, low temperature combustion has undergone extensive investigation. Premixed dual-fuel combustion is one of the concepts addressing the NOx-soot trade-off in compression ignited engines, while maintaining high thermal efficiency. This combustion makes use of two fuels with different reactivities in order to improve the controllability of this combustion mode over a wide range of operation. Similarly to all premixed combustion modes, this combustion is nevertheless sensitive to the operating conditions and traditionally exhibits cycle-to-cycle variability with significant pressure gradients. Consequently, advanced control strategies to ensure a safe and accurate operation of the engine are required. Feedback control is a powerful approach to address the challenges raised by the premixed dual-fuel combustion. By measuring the output signals from the engine, strategies can be developed to adapt and correct the control actions to maintain the desired operation. This thesis presents control strategies, based on the in-cylinder pressure signal measurement, applied to premixed dual-fuel combustion engines. Various objectives were addressed by designing dedicated controllers, where a special emphasis was made towards analyzing and implementing these solutions to the different levels of mixture stratification considered in these engines (i.e., fully, highly and partially premixed). At first, feedback control strategies based on the in-cylinder pressure signal processing were designed. Proportional-integral actions were selected to ensure the desired engine performance without exceeding the mechanical constraints of the engine. Extremum seeking was evaluated to track efficient combustion phasing and NOx emissions reduction. The in-cylinder pressure resonance was then analyzed and a knock-like controller was implemented to ensure safe operation of the engine. Finally, mathematical models were used to design a control-oriented model and a state observer that aimed to leverage the signals measured in the engine to improve the prediction and diagnostic capabilities in such engine configuration. The results from this work highlighted the importance of considering feedback control to address the limitations encountered in premixed combustion modes. Particularly, the use of the in-cylinder pressure measurement showed the relevance and potential of this signal to develop complex and accurate control strategies.This thesis was financially supported by the Programa Operativo del Fondo Social Europeo (FSE) de la Comunitat Valenciana 2014-2020 through grant ACIF/2018/141.Barbier, ARS. (2022). In-Cylinder Pressure-Based Control of Premixed Dual-Fuel Combustion [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/18327

Reactivity controlled compression ignition engine: Pathways towards commercial viability

© 2020 Elsevier Ltd. All rights reserved. This manuscript is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International Licence (http://creativecommons.org/licenses/by-nc-nd/4.0/).Reactivity-controlled compression ignition (RCCI) is a promising energy conversion strategy to increase fuel efficiency and reduce nitrogen oxide (NOx) and soot emissions through improved in-cylinder combustion process. Considering the significant amount of conducted research and development on RCCI concept, the majority of the work has been performed under steady-state conditions. However, most thermal propulsion systems in transportation applications require operation under transient conditions. In the RCCI concept, it is crucial to investigate transient behavior over entire load conditions in order to minimize the engine-out emissions and meet new real driving emissions (RDE) legislation. This would help further close the gap between steady-state and transient operation in order to implement the RCCI concept into mass production. This work provides a comprehensive review of the performance and emissions analyses of the RCCI engines with the consideration of transient effects and vehicular applications. For this purpose, various simulation and experimental studies have been reviewed implementing different control strategies like control-oriented models particularly in dual-mode operating conditions. In addition, the application of the RCCI strategy in hybrid electric vehicle platforms using renewable fuels is also discussed. The discussion of the present review paper provides important insights for future research on the RCCI concept as a commercially viable energy conversion strategy for automotive applications.Peer reviewe

Closed-loop control of a dual-fuel engine working with different combustion modes using in-cylinder pressure feedback

This is the author¿s version of a work that was accepted for publication in International Journal of Engine Research. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published as https://doi.org/10.1177/1468087419835327.[EN] This work presents a closed-loop combustion control concept using in-cylinder pressure as a feedback in a dual-fuel combustion engine. At low load, reactivity controlled compression ignition combustion was used while a diffusive dual-fuel combustion was performed at higher loads. The aim of the presented controller is to maintain the indicated mean effective pressure and the combustion phasing at a target value, and to keep the maximum pressure derivative under a limit to avoid engine damage in all the combustion modes by cyclically adapting the injection settings. Various tests were performed at steady-state conditions showing good abilities to fulfil the expected operating conditions but also to reject disturbances such as intake pressure or exhaust gas recirculation variations. Finally, the proposed control strategy was tested during a load transient resulting in a combustion switching-mode and the results exhibited the closed-loop potential for controlling such combustion concept.The author(s) disclosed receipt of the following finan-cial support for the research, authorship, and/or publi-cation of this article: The authors acknowledge the support of Spanish Ministerio de Economia, Industria y Competitividad through project TRA2016-78717-R. Alvin Barbier received a funding through the grant ACIF/2018/141 from the Generalitat Valenciana and the European Social Fund.Guardiola, C.; Pla Moreno, B.; Bares-Moreno, P.; Barbier, ARS. (2020). Closed-loop control of a dual-fuel engine working with different combustion modes using in-cylinder pressure feedback. International Journal of Engine Research. 21(3):484-496. https://doi.org/10.1177/1468087419835327S484496213Kusaka, J., Sueoka, M., Takada, K., Ohga, Y., Nagasaki, T., & Daisho, Y. (2005). A basic study on a urea-selective catalytic reduction system for a medium-duty diesel engine. International Journal of Engine Research, 6(1), 11-19. doi:10.1243/146808705x7310Hull, A., Golubkov, I., Kronberg, B., & van Stam, J. (2006). Alternative Fuel for a Standard Diesel Engine. International Journal of Engine Research, 7(1), 51-63. doi:10.1243/146808705x30549Sung, K., Kim, J., & Reitz, R. D. (2009). Experimental study of pollutant emission reduction for near-stoichiometric diesel combustion in a three-way catalyst. International Journal of Engine Research, 10(5), 349-357. doi:10.1243/14680874jer04109Johnson, T. V. (2009). Review of diesel emissions and control. International Journal of Engine Research, 10(5), 275-285. doi:10.1243/14680874jer04009Yun, H., & Reitz, R. D. (2005). Combustion optimization in the low-temperature diesel combustion regime. International Journal of Engine Research, 6(5), 513-524. doi:10.1243/146808705x30576Kook, S., Bae, C., & Kim, J. (2007). Diesel-fuelled homogeneous charge compression ignition engine with optimized premixing strategies. International Journal of Engine Research, 8(1), 127-137. doi:10.1243/14680874jer02506Ogawa, H., Azuma, K., & Miyamoto, N. (2007). Combustion control and operating range expansion in an homogeneous charge compression ignition engine with suppression of low-temperature oxidation by methanol: Influence of compression ratio and octane number of main fuel. International Journal of Engine Research, 8(1), 139-145. doi:10.1243/14680874jer01606Yao, M., Zheng, Z., & Liu, H. (2009). Progress and recent trends in homogeneous charge compression ignition (HCCI) engines. Progress in Energy and Combustion Science, 35(5), 398-437. doi:10.1016/j.pecs.2009.05.001Reitz, R. D. (2013). Directions in internal combustion engine research. Combustion and Flame, 160(1), 1-8. doi:10.1016/j.combustflame.2012.11.002Imtenan, S., Varman, M., Masjuki, H. H., Kalam, M. A., Sajjad, H., Arbab, M. I., & Rizwanul Fattah, I. M. (2014). Impact of low temperature combustion attaining strategies on diesel engine emissions for diesel and biodiesels: A review. Energy Conversion and Management, 80, 329-356. doi:10.1016/j.enconman.2014.01.020Paykani, A., Kakaee, A.-H., Rahnama, P., & Reitz, R. D. (2015). Progress and recent trends in reactivity-controlled compression ignition engines. International Journal of Engine Research, 17(5), 481-524. doi:10.1177/1468087415593013Hanson, R. M., Kokjohn, S. L., Splitter, D. A., & Reitz, R. D. (2010). An Experimental Investigation of Fuel Reactivity Controlled PCCI Combustion in a Heavy-Duty Engine. SAE International Journal of Engines, 3(1), 700-716. doi:10.4271/2010-01-0864Kokjohn, S. L., Hanson, R. M., Splitter, D. A., & Reitz, R. D. (2011). Fuel reactivity controlled compression ignition (RCCI): a pathway to controlled high-efficiency clean combustion. International Journal of Engine Research, 12(3), 209-226. doi:10.1177/1468087411401548Molina, S., García, A., Pastor, J. M., Belarte, E., & Balloul, I. (2015). Operating range extension of RCCI combustion concept from low to full load in a heavy-duty engine. Applied Energy, 143, 211-227. doi:10.1016/j.apenergy.2015.01.035Reitz, R. D., & Duraisamy, G. (2015). Review of high efficiency and clean reactivity controlled compression ignition (RCCI) combustion in internal combustion engines. Progress in Energy and Combustion Science, 46, 12-71. doi:10.1016/j.pecs.2014.05.003Benajes, J., Molina, S., García, A., & Monsalve-Serrano, J. (2015). Effects of direct injection timing and blending ratio on RCCI combustion with different low reactivity fuels. Energy Conversion and Management, 99, 193-209. doi:10.1016/j.enconman.2015.04.046Benajes, J., Pastor, J. V., García, A., & Boronat, V. (2016). A RCCI operational limits assessment in a medium duty compression ignition engine using an adapted compression ratio. Energy Conversion and Management, 126, 497-508. doi:10.1016/j.enconman.2016.08.023Benajes, J., García, A., Monsalve-Serrano, J., & Boronat, V. (2017). Achieving clean and efficient engine operation up to full load by combining optimized RCCI and dual-fuel diesel-gasoline combustion strategies. Energy Conversion and Management, 136, 142-151. doi:10.1016/j.enconman.2017.01.010Shaver, G. M., Roelle, M. J., Caton, P. A., Kaahaaina, N. B., Ravi, N., Hathout, J.-P., … Gerdes, J. C. (2005). A physics-based approach to the control of homogeneous charge compression ignition engines with variable valve actuation. International Journal of Engine Research, 6(4), 361-375. doi:10.1243/146808705x30512Caton, P. A., Song, H. H., Kaahaaina, N. B., & Edwards, C. F. (2005). Residual-effected homogeneous charge compression ignition with delayed intake-valve closing at elevated compression ratio. International Journal of Engine Research, 6(4), 399-419. doi:10.1243/146808705x30431Dempsey, A. B., Walker, N. R., Gingrich, E., & Reitz, R. D. (2014). Comparison of Low Temperature Combustion Strategies for Advanced Compression Ignition Engines with a Focus on Controllability. Combustion Science and Technology, 186(2), 210-241. doi:10.1080/00102202.2013.858137Ritter, D., Andert, J., Abel, D., & Albin, T. (2017). Model-based control of gasoline-controlled auto-ignition. International Journal of Engine Research, 19(2), 189-201. doi:10.1177/1468087417717399Carlucci, A. P., Laforgia, D., Motz, S., Saracino, R., & Wenzel, S. P. (2014). Advanced closed loop combustion control of a LTC diesel engine based on in-cylinder pressure signals. Energy Conversion and Management, 77, 193-207. doi:10.1016/j.enconman.2013.08.054Ott, T., Zurbriggen, F., Onder, C., & Guzzella, L. (2013). Cylinder Individual Feedback Control of Combustion in a Dual Fuel Engine. IFAC Proceedings Volumes, 46(21), 600-605. doi:10.3182/20130904-4-jp-2042.00080Hanson, R., & Reitz, R. D. (2013). Transient RCCI Operation in a Light-Duty Multi-Cylinder Engine. SAE International Journal of Engines, 6(3), 1694-1705. doi:10.4271/2013-24-0050Indrajuana, A., Bekdemir, C., Luo, X., & Willems, F. (2016). Robust Multivariable Feedback Control of Natural Gas-Diesel RCCI Combustion. IFAC-PapersOnLine, 49(11), 217-222. doi:10.1016/j.ifacol.2016.08.033Luján, J. M., Galindo, J., Serrano, J. R., & Pla, B. (2008). A methodology to identify the intake charge cylinder-to-cylinder distribution in turbocharged direct injection Diesel engines. Measurement Science and Technology, 19(6), 065401. doi:10.1088/0957-0233/19/6/065401Payri, F., Broatch, A., Salavert, J. M., & Martín, J. (2010). Investigation of Diesel combustion using multiple injection strategies for idling after cold start of passenger-car engines. Experimental Thermal and Fluid Science, 34(7), 857-865. doi:10.1016/j.expthermflusci.2010.01.014Kokjohn, S. L., Hanson, R. M., Splitter, D. A., & Reitz, R. D. (2009). Experiments and Modeling of Dual-Fuel HCCI and PCCI Combustion Using In-Cylinder Fuel Blending. SAE International Journal of Engines, 2(2), 24-39. doi:10.4271/2009-01-2647Desantes, J. M., Benajes, J., García, A., & Monsalve-Serrano, J. (2014). The role of the in-cylinder gas temperature and oxygen concentration over low load reactivity controlled compression ignition combustion efficiency. Energy, 78, 854-868. doi:10.1016/j.energy.2014.10.08

MODEL-BASED CONTROL OF AN RCCI ENGINE

Reactivity controlled compression ignition (RCCI) is a combustion strategy that offers high fuel conversion efficiency and near zero emissions of NOx and soot which can help in improving fuel economy in mobile and stationary internal combustion engine (ICE) applications and at the same time lower engine-out emissions. One of the main challenges associated with RCCI combustion is the difficulty in simultaneously controlling combustion phasing, engine load, and cyclic variability during transient engine operations. This thesis focuses on developing model based controllers for cycle-to-cycle combustion phasing and load control during transient operations. A control oriented model (COM) is developed by using mean value models to predict start of combustion (SOC) and crank angle of 50% mass fraction burn (CA50). The COM is validated using transient data from an experimental RCCI engine. The validation results show that the COM is able to capture the experimental trends in CA50 and indicated mean effective pressure (IMEP). The COM is then used to develop a linear quadratic integral (LQI) controller and model predictive controllers (MPC). Premixed ratio (PR) and start of injection (SOI) are the control variables used to control CA50, while the total fuel quantity (FQ) is the engine variable used to control load. The selection between PR and SOI is done using a sensitivity based algorithm. Experimental validation results for reference tracking using LQI and MPC show that the desired CA50 and IMEP can be attained in a single cycle during step-up and step-down transients and yield an average error of less than 1.6 crank angle degrees (CAD) in the CA50 and less than 35 kPa in the IMEP. This thesis presents the first study in the literature to design and implement LQI and MPC combustion controllers for RCCI engines

Powertrain Architectures and Technologies for New Emission and Fuel Consumption Standards

New powertrain design is highly influenced by CO2 and pollutant limits defined by legislations, the demand of fuel economy in for real conditions, high performances and acceptable cost. To reach the requirements coming from both end-users and legislations, several powertrain architectures and engine technologies are possible (e.g. SI or CI engines), with many new technologies, new fuels, and different degree of electrification. The benefits and costs given by the possible architectures and technology mix must be accurately evaluated by means of objective procedures and tools in order to choose among the best alternatives. This work presents a basic design methodology and a comparison at concept level of the main powertrain architectures and technologies that are currently being developed, considering technical benefits and their cost effectiveness. The analysis is carried out on the basis of studies from the technical literature, integrating missing data with evaluations performed by means of powertrain-vehicle simplified models, considering the most important powertrain architectures. Technology pathways for passenger cars up to 2025 and beyond have been defined. After that, with support of more detailed models and experimentations, the investigation has been focused on the more promising technologies to improve internal combustion engine, such as: water injection, low temperature combustions and heat recovery systems

Modeling combustion timing in an RCCI engine bymeans of a control oriented model

[EN] Reactivity controlled compression ignition (RCCI) engines as one of low temperature auto ignition combustion strategies have shown a good performance to reduce NO (x) and soot emission while increasing engine thermal efficiency. Combustion control of these types of engines is relatively complex because of their ignition type which makes it difficult to have a direct control on the start of the combustion. In this research, combustion phase of an RCCI engine was modeled with using a control-oriented method. The combustion properties such as start of the combustion, crank angle degree where 50 percent of the fuel is burnt(CA50) and the burn duration were modeled in this research. A modified knock integral model was used for start of combustion estimation. Using the effect of spontaneous front speed, burn duration was modeled where a mathematical model is developed; and Wiebe function is used to model CA50. Indicated mean effective pressure(IMEP) also estimated in this modeling. To validate the developed models, five experimental data sets from a heavy-duty RCCI engine were used. The results show the maximum mean errors of 1.7, 1.9 and 2.3 crank angle degree (CAD) for start of combustion, burn duration(BD) and the CA50, respectively and this quantity is 0.5 bar for IMEP in steady state condition. The transient condition of the engine operation was also investigated. The results and trends are promising in all characteristics of the combustion process especially in the modeling of the indicated mean effective pressure where the majority of the data have errors less than 1.5 bar.The authors acknowledge the support of Spanish Ministerio de Economia, Industria y Competitivad through project TRA2016-78717-R (AEI/FEDER, EU). Alvin Barbier participation was funded through grant ACIF/2018/141, Programa Operativo del Fondo Social Europeo (FSE) de la Comunitat Valenciana 2014-2020. Alireza Kakoee participation was funded through grants 43/3/298624 from Iran ministry of science, research and technology.Kakoee, A.; Bakhshan, Y.; Barbier, ARS.; Bares-Moreno, P.; Guardiola, C. (2020). Modeling combustion timing in an RCCI engine bymeans of a control oriented model. Control Engineering Practice. 97:1-15. https://doi.org/10.1016/j.conengprac.2020.1043211159

Real-time predictive model for reactivity controlled compression ignition marine engines

Model-based design is proven to be essential for the development of control systems. This paper presents a real-time predictive control-orientated model (COM) for low-temperature combustion (LTC), dual-fuel, reactivity-controlled compression ignition (RCCI) engines. A comprehensive model-based design methodology must be capable of constructing an RCCI control-orientated model with high accuracy, high noise immunity, good response, predictivity in governing mechanisms, and low computation time. This work attains all of these for the first time for a cutting-edge RCCI marine engine. The real-time model (RTM) captures the key sensitivities of RCCI by controlling the total fuel energy and the blend ratio (BR) of two fuels, while also considering uncertainties arising from variations of inlet temperature and the gas exchange process. It provides not only the cycle-wise combustion indicators but also the crank-angle-based cylinder pressure trend. The RTM is derived by direct linearisation of a physics-based model and is successfully validated against experimental results from a large-bore, RCCI engine and the previously acknowledged UVATZ (University of Vaasa Advanced Thermo-kinetic Multi-zone) model. Validation covers both steady-state and transient modes. With high accuracy in several case studies representing typical load transients and air-path disturbance rejection tests, the model predicts maximum cylinder pressure (Pmax), crank-angle of 5 % burnt (CA5), crank-angle of 50 % burnt (CA50) and indicated mean effective pressure (IMEP) with root means square (RMS) errors of 8.6 %, 0.3 %, 0.6 %, and 0.6 % respectively. The average simulation time without any code optimisation is around 5 ms/cycle, offering sufficient real-time surplus to incorporate a semi-predictive emission submodel within the current approach.© 2023 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).fi=vertaisarvioitu|en=peerReviewed

Thermo-kinetic multi-zone modelling of low temperature combustion engines

Many researchers believe multi-zone (MZ), chemical kinetics–based models are proven, essential toolchains for development of low-temperature combustion (LTC) engines. However, such models are specific to the research groups that developed them and are not widely available on a commercial nor open-source basis. Consequently, their governing assumptions vary, resulting in differences in autonomy, accuracy and simulation speed, all of which affect their applicability. Knowledge of the models´ individual characteristics is scattered over the research groups´ publications, making it extremely difficult to see the bigger picture. This combination of disparities and dispersed information hinders the engine research community that wants to harness the capability of multi-zone modelling. This work aims to overcome these hurdles. It is a comprehensive review of over 120 works directly related to MZ modelling of LTC extended with an insight to primary sources covering individual submodels. It covers 16 distinctive modelling approaches, three different combustion concepts and over 60 different fuel/kinetic mechanism combination. Over 38 identified applications ranging from fundamental-level studies to control development. The work aims to provide sufficient detail of individual model design choices to facilitate creation of improved, more open multi-zone toolchains and inspire new applications. It also provides a high-level vision of how multi-zone models can evolve. The review identifies a state-of-the-art multi-zone model as an onion-skin model with 10–15 zones; phenomenological heat and mass transfer submodels with predictive in-cylinder turbulence; and semi-detailed reaction kinetics encapsulating 53-199 species. Together with submodels for heat loss, fuel injection and gas exchange, this modelling approach predicts in-cylinder pressure within cycle-to-cycle variation for a handful of combustion concepts, from homogeneous/premixed charge to reactivity-controlled compression ignition (HCCI, PCCI, RCCI). Single-core simulation time is around 30 minutes for implementations focused on accuracy: there are direct time-reduction strategies for control applications. Major tasks include a fast and predictive means to determine in-cylinder fuel stratification, and extending applicability and predictivity by coupling with commercial one-dimensional engine-modelling toolchains. There is also significant room for simulation speed-up by incorporating techniques such as tabulated chemistry and employing new solving algorithms that reduce cost of jacobian construction.© 2022 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).fi=vertaisarvioitu|en=peerReviewed