Miedo o engaño: el encuadramiento de los atentados terroristas del 11-M en Madrid y la rendición de cuentas electoral

Este Documento de Trabajo explora los aspectos siguientes: -Los fallos de organización, de anticipación y de aprendizaje en el sistema de gestión de crisis de seguridad (alerta temprana y sorpresa estratégica, política informativa, filtraciones a la prensa y a la oposición de la policía y la inteligencia, politización partidista de los atentados terroristas) en comparación con el funcionamiento eficaz de la respuesta de emergencia. -Si el gobierno del Partido Popular gestionó mal sus relaciones con otras elites y periodistas, en especial porque no pudo encontrar unos esquemas convincentes que sustentasen su línea principal (el encuadre (frame) “la autoría de ETA”) durante los días previos a las elecciones y si el presidente Aznar perdió el control del encuadre debido a su falta de credibilidad. -Bajo estas circunstancias las elites oponentes, incluyendo a los periodistas opositores pudieron obtener tanta influencia sobre el encuadramiento (framing) como el gobierno, y desarrollaron su propia línea culpabilizando al gobierno (el encuadre “el gobierno miente”), ganando el conflicto de encuadramientos y las elecciones

Numerical Estimation of Wiebe Function Parameters Using Artificial Neural Networks in SI Engine

[EN] In modeling an Internal Combustion Engine, the combustion sub-model plays a critical role in the overall simulation of the engine as it provides the Mass Fraction Burned (MFB). Analytically, the Heat Release Rate (HRR) can be obtained using the Wiebe function, which is nothing more than a mathematical formulation of the MFB. The mentioned function depends on the following four parameters: efficiency parameter, shape factor, crankshaft angle, and duration of the combustion. In this way, the Wiebe function can be adjusted to experimentally measured values of the mass fraction burned at various operating points using a least-squares regression, and thus obtaining specific values for the unknown parameters. Nevertheless, the main drawback of this approach is the requirement of testing the engine at a given engine load/speed condition. Furthermore, the main objective of this study is to propose a predictive model of the Wiebe parameters for any operating point of the tested SI engine. For this purpose, an Artificial Neural Network (ANN) is developed from the experimental data. A criterion was defined to choose the best-trained network. Finally, the Wiebe parameters are estimated with the neural networks for different operating conditions. Moreover, the mass fractions burned generated from the Wiebe functions are compared with the respective experimental values from several operating points measured in the engine test bench. Small differences were found between the estimated and experimental mass fractions burned. Therefore, the effectiveness of the developed ANN model as a prediction tool for the engine MFB is verified.Torregrosa, AJ.; Broatch, A.; Olmeda, P.; Aceros, S. (2021). Numerical Estimation of Wiebe Function Parameters Using Artificial Neural Networks in SI Engine. SAE International. 1-10. https://doi.org/10.4271/2021-01-037911

Assessment of the improvement of internal combustion engines cooling system using nanofluids and nanoencapsulated phase change materials

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/10.1177/1468087420917494[EN] In recent years, due to the increasing need to reduce consumption of reciprocating internal combustion engines, new researches on different subsystems have raised. Among them, the use of nanofluids as a coolant medium seems to be an interesting alternative. In this work, the potential benefits of using nanofluids in the cooling system using an engine lumped model are studied. The methodology of the study starts with a whole description and validation of the model in both steady and transient conditions by means of a comparison with experimental results. Then, the potential benefits that could be obtained with the use of nanofluids are studied in a theoretical way. After that, the model is used to estimate the behavior of the system using different nanofluids in both stationary and transient conditions. The main results show that the advantages of using these new refrigerants are limited.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The equipment used in this work has been partially supported by FEDER project funds "Dotacion de infraestructuras cientifico tecnicas para el Centro Integral de Mejora Energetica y Medioambiental de Sistemas de Transporte (CiMeT)'' (grant number FEDER-ICTS-2012-06), framed in the operational program of unique scientific and technical infrastructure of the Spanish Government.Torregrosa, AJ.; Broatch, A.; Olmeda, P.; Dreif-Bennany, A. (2021). Assessment of the improvement of internal combustion engines cooling system using nanofluids and nanoencapsulated phase change materials. International Journal of Engine Research. 22(6):1939-1957. https://doi.org/10.1177/1468087420917494S1939195722

Development and Validation of a Submodel for Thermal Exchanges in the Hydraulic Circuits of a Global Engine Model

[EN] To face the current challenges of the automotive industry, there is a need for computational models capable to simulate the engine behavior under low-temperature and low-pressure conditions. Internal combustion engines are complex and have interconnected systems where many processes take place and influence each other. Thus, a global approach to engine simulation is suitable to study the entire engine performance. The circuits that distribute the hydraulic fluids -liquid fuels, coolants and lubricants- are critical subsystems of the engine. This work presents a 0D model which was developed and set up to make possible the simulation of hydraulic circuits in a global engine model. The model is capable of simulating flow and pressure distributions as well as heat transfer processes in a circuit. After its development, the thermo-hydraulic model was implemented in a physical based engine model called Virtual Engine Model (VEMOD), which takes into account all the relevant relations among subsystems. In the present paper, the thermo-hydraulic model is described and then it is used to simulate oil and coolant circuits of a diesel engine. The objective of the work is to validate the model under steady-state and transient operation, with focus on the thermal evolution of oil and coolant. For validation under steady-state conditions, 22 operating points were measured and simulated, some of them in cold environment. In general, good agreement was obtained between simulation and experiments. Next, the WLTP driving cycle was simulated starting from warmed-up conditions and from ambient temperature. Results were compared with the experiment, showing that modeled trends were close to those experimentally measured. Thermal evolutions of oil and coolant were predicted with mean errors between 0.7 °C and 2.1 °C. In particular, the warm-up phase was satisfactorily modeled.This research has been partially funded by the European Union’s Horizon 2020 Framework Programme for research, technological development and demonstration under grant agreement 723976 (“DiePeR”) and by the Spanish government under the grant agreement TRA2017-89894-R. Josep SalvadorIborra was supported by Universitat Politècnica de València through the contract FPI-S2-2016-1357 of the program PAID01-16. The authors wish to thank Renault SAS, especially P. Mallet and E. Gaïffas, for supporting this research. Jaime Monfort San Segundo is acknowledged for his helpful collaboration in the code implementationBroatch, A.; Olmeda, P.; Martín, J.; Salvador-Iborra, J. (2018). Development and Validation of a Submodel for Thermal Exchanges in the Hydraulic Circuits of a Global Engine Model. SAE Technical Papers. https://doi.org/10.4271/2018-01-0160

Experimental study of the influence of exhaust gas recirculation on heat transfer in the firedeck of a direct injection diesel engine

[EN] Emissions control is a key topic for internal combustion engine development. One of the most widespread technologies to reduce the formation of nitrogen oxides is the recirculation of exhaust gas to the engine intake. Besides, carbon dioxide emissions from internal combustion engines can be reduced by increasing engine efficiency. A relevant factor for engine efficiency is heat rejection. The interaction between heat transfer and exhaust gas recirculation is not fully understood. In this paper, an experimental study is presented which aims to shed light on the influence of high pressure exhaust gas recirculation on heat transfer. Three operating points were analyzed. Heat flux was calculated at several locations of the firedeck from temperature measurements. The results showed that the influence of exhaust gas recirculation on heat transfer was significant. Reductions of heat flux up to 18% were observed. The largest reduction was found in the area near the center of the firedeck. To contextualize the findings in the framework of emissions reduction, the trade-off between nitrogen oxides and carbon dioxide was assessed for all test points.The authors acknowledge General Motors Global R&D for supporting this research. The equipment used in this work was partially supported by FEDER project funds Dotación de infraestructuras científico técnicas para el Centro Integral de Mejora Energética y Medioambiental de Sistemas de Transporte (CiMeT), (FEDER-ICTS-2012-06) , framed in the operational program of unique scientific and technical infrastructure of the Ministry of Science and Innovation of Spain. Josep Salvador-Iborra was partially supported through contract FPI-S2-2016-1357 of Programa de Apoyo para la Investigación y Desarrollo (PAID-01-16) of Universitat Politècnica de València.Torregrosa, AJ.; Broatch, A.; Olmeda, P.; Salvador-Iborra, J.; Warey, A. (2017). Experimental study of the influence of exhaust gas recirculation on heat transfer in the firedeck of a direct injection diesel engine. Energy Conversion and Management. 153:304-312. https://doi.org/10.1016/j.enconman.2017.10.003S30431215

A one-dimensional modeling study on the effect of advanced insulation coatings on internal combustión engine efficiency

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/10.1177/1468087420921584.[EN] This article presents a study of the impact on engine efficiency of the heat loss reduction due to in-cylinder coating insulation. A numerical methodology based on one-dimensional heat transfer model is developed. Since there is no analytic solution for engines, the one-dimensional model was validated with the results of a simple "equivalent" problem, and then applied to different engine boundary conditions. Later on, the analysis of the effect of different coating properties on the heat transfer using the simplified one-dimensional heat transfer model is performed. After that, the model is coupled with a complete virtual engine that includes both thermodynamic and thermal modeling. Next, the thermal flows across the cylinder parts coated with the insulation material (piston and cylinder head) are predicted and the effect of the coating on engine indicated efficiency is analyzed in detail. The results show the gain limits, in terms of engine efficiency, that may be obtained with advanced coating solutions.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The equipment used in this work has been partially supported by FEDER project funds "otacion de infraestructuras cientifico tecnicas para el Centro Integral de Mejora Energetica y Medioambiental de Sistemas de Transporte (CiMeT)'' (Grant No. FEDER-ICTS-2012-06), framed in the operational program of unique scientific and technical infrastructure of the Spanish Government. This project has received funding from the European Union's Horizon 2020 research and innovation program under Grant Agreement No. 724084.Broatch, A.; Olmeda, P.; Margot, XM.; Gómez-Soriano, J. (2021). A one-dimensional modeling study on the effect of advanced insulation coatings on internal combustión engine efficiency. International Journal of Engine Research. 22(7):2390-2404. https://doi.org/10.1177/1468087420921584S23902404227Benajes, J., Novella, R., De Lima, D., & Tribotte, P. (2015). Investigation on Multiple Injection Strategies for Gasoline PPC Operation in a Newly Designed 2-Stroke HSDI Compression Ignition Engine. SAE International Journal of Engines, 8(2), 758-774. doi:10.4271/2015-01-0830Torregrosa, A. J., Broatch, A., Novella, R., Gomez-Soriano, J., & Mónico, L. F. (2017). Impact of gasoline and Diesel blends on combustion noise and pollutant emissions in Premixed Charge Compression Ignition engines. Energy, 137, 58-68. doi:10.1016/j.energy.2017.07.010Al-Muhsen, N. F. O., Huang, Y., & Hong, G. (2019). Effects of direct injection timing associated with spark timing on a small spark ignition engine equipped with ethanol dual-injection. Fuel, 239, 852-861. doi:10.1016/j.fuel.2018.10.118Broatch, A., Olmeda, P., Margot, X., & Gomez-Soriano, J. (2019). Numerical simulations for evaluating the impact of advanced insulation coatings on H2 additivated gasoline lean combustion in a turbocharged spark-ignited engine. Applied Thermal Engineering, 148, 674-683. doi:10.1016/j.applthermaleng.2018.11.106Berni, F., Cicalese, G., & Fontanesi, S. (2017). A modified thermal wall function for the estimation of gas-to-wall heat fluxes in CFD in-cylinder simulations of high performance spark-ignition engines. Applied Thermal Engineering, 115, 1045-1062. doi:10.1016/j.applthermaleng.2017.01.055Zhang, L. (2018). Parallel simulation of engine in-cylinder processes with conjugate heat transfer modeling. Applied Thermal Engineering, 142, 232-240. doi:10.1016/j.applthermaleng.2018.06.084Poubeau, A., Vauvy, A., Duffour, F., Zaccardi, J.-M., Paola, G. de, & Abramczuk, M. (2018). Modeling investigation of thermal insulation approaches for low heat rejection Diesel engines using a conjugate heat transfer model. International Journal of Engine Research, 20(1), 92-104. doi:10.1177/1468087418818264Rakopoulos, C. D., Rakopoulos, D. C., Mavropoulos, G. C., & Giakoumis, E. G. (2004). Experimental and theoretical study of the short term response temperature transients in the cylinder walls of a diesel engine at various operating conditions. Applied Thermal Engineering, 24(5-6), 679-702. doi:10.1016/j.applthermaleng.2003.11.002Kawaguchi, A., Wakisaka, Y., Nishikawa, N., Kosaka, H., Yamashita, H., Yamashita, C., … Tomoda, T. (2019). Thermo-swing insulation to reduce heat loss from the combustion chamber wall of a diesel engine. International Journal of Engine Research, 20(7), 805-816. doi:10.1177/1468087419852013Powell, T., O’Donnell, R., Hoffman, M., Filipi, Z., Jordan, E. H., Kumar, R., & Killingsworth, N. J. (2019). Experimental investigation of the relationship between thermal barrier coating structured porosity and homogeneous charge compression ignition engine combustion. International Journal of Engine Research, 22(1), 88-108. doi:10.1177/1468087419843752Somhorst, J., Oevermann, M., Bovo, M., & Denbratt, I. (2019). Evaluation of thermal barrier coatings and surface roughness in a single-cylinder light-duty diesel engine. International Journal of Engine Research, 22(3), 890-910. doi:10.1177/1468087419875837Kosaka, H., Wakisaka, Y., Nomura, Y., Hotta, Y., Koike, M., Nakakita, K., & Kawaguchi, A. (2013). Concept of «Temperature Swing Heat Insulation» in Combustion Chamber Walls, and Appropriate Thermo-Physical Properties for Heat Insulation Coat. SAE International Journal of Engines, 6(1), 142-149. doi:10.4271/2013-01-0274Wakisaka, Y., Inayoshi, M., Fukui, K., Kosaka, H., Hotta, Y., Kawaguchi, A., & Takada, N. (2016). Reduction of Heat Loss and Improvement of Thermal Efficiency by Application of «Temperature Swing» Insulation to Direct-Injection Diesel Engines. SAE International Journal of Engines, 9(3), 1449-1459. doi:10.4271/2016-01-0661Rakopoulos, C. D., Mavropoulos, G. C., & Hountalas, D. T. (2000). Measurements and analysis of load and speed effects on the instantaneous wall heat fluxes in a direct injection air-cooled diesel engine. International Journal of Energy Research, 24(7), 587-604. doi:10.1002/1099-114x(20000610)24:73.0.co;2-fKikusato, A., Terahata, K., Jin, K., & Daisho, Y. (2014). A Numerical Simulation Study on Improving the Thermal Efficiency of a Spark Ignited Engine --- Part 2: Predicting Instantaneous Combustion Chamber Wall Temperatures, Heat Losses and Knock ---. SAE International Journal of Engines, 7(1), 87-95. doi:10.4271/2014-01-1066Broatch, A., Olmeda, P., Margot, X., & Escalona, J. (2019). New approach to study the heat transfer in internal combustion engines by 3D modelling. International Journal of Thermal Sciences, 138, 405-415. doi:10.1016/j.ijthermalsci.2019.01.006Torregrosa, A. J., Olmeda, P., Martín, J., & Romero, C. (2011). A Tool for Predicting the Thermal Performance of a Diesel Engine. Heat Transfer Engineering, 32(10), 891-904. doi:10.1080/01457632.2011.548639Andruskiewicz, P., Najt, P., Durrett, R., & Payri, R. (2017). Assessing the capability of conventional in-cylinder insulation materials in achieving temperature swing engine performance benefits. International Journal of Engine Research, 19(6), 599-612. doi:10.1177/1468087417729254Payri, F., Molina, S., Martín, J., & Armas, O. (2006). Influence of measurement errors and estimated parameters on combustion diagnosis. Applied Thermal Engineering, 26(2-3), 226-236. doi:10.1016/j.applthermaleng.2005.05.006Payri, F., Olmeda, P., Guardiola, C., & Martín, J. (2011). Adaptive determination of cut-off frequencies for filtering the in-cylinder pressure in diesel engines combustion analysis. Applied Thermal Engineering, 31(14-15), 2869-2876. doi:10.1016/j.applthermaleng.2011.05.012Payri, F., Olmeda, P., Martín, J., & García, A. (2011). A complete 0D thermodynamic predictive model for direct injection diesel engines. Applied Energy, 88(12), 4632-4641. doi:10.1016/j.apenergy.2011.06.005Olmeda, P., Martín, J., Arnau, F. J., & Artham, S. (2019). Analysis of the energy balance during World harmonized Light vehicles Test Cycle in warmed and cold conditions using a Virtual Engine. International Journal of Engine Research, 21(6), 1037-1054. doi:10.1177/146808741987859

Energy analysis of a lithium-ion battery module for an e-bus application under different thermal boundaries

[EN] In this study, a methodology for the energy analysis of a lithium-ion battery module cooled by a serpentine cooling plate is proposed. A novel lumped electro-thermal model of a cooled module is calibrated and validated: thermal nodes are assigned to the Li-ion cells, the cooling plate, the thermal pad, and the coolant. The model is experimentally characterized and validated, and a maximum root mean square error equal to 1.44% for the electrical model is obtained; all the errors of the thermal models are kept below the 2%. The proposed approach allows to identify, with a low computational cost and reduced calculation time, the thermal evolution of the nodes depending on the environmental and operating conditions considered. This aspect is of fundamental importance to identify hot spots in the module and to prevent possible dangerous events such as thermal runaway. To highlight these advantages, an extended fast-charging parametric study of the module is carried out, considering 240 simulations, varying 4 parameters (ambient temperature, required electric power, temperature and coolant volumetric flow) and monitoring 3 variables (peak temperature in the module at the end of the charging process, thermal gradient, and time spent in the optimal temperature range), allowing to identify the combinations of operating parameters that permit the rapid charging of the module under optimal conditions. Furthermore, the energy analysis provides an estimation of the charging efficiency of the cells, which is around 90% for every considered thermal boundary. The heat generated by the cells, the heat dissipated into the coolant and the heat absorbed by the other module components are estimated: in a 4C charge, the 80% of total heat is dissipated into the coolant, while in a 1C charge, this aliquot is equal to 95%. The reduced computational time and cost make this model suitable both for cooling system design and for control strategies development.This work was supported by Generalitat Valenciana within the framework of the PROMETEO project "Contribution to the decarbon-ization of transport by optimizing the thermal management of vehicle batteries electrified" with reference number PROMETEO/2020/042. Luca Agizza is supported by grant ACIF/2021/005 funded by Conselleria de Innovacion, Universidades, Ciencia y Sociedad Digital of the Generalitat Valenciana.Broatch, A.; Olmeda, P.; Margot, X.; Agizza, L.; Fernández, M. (2023). Energy analysis of a lithium-ion battery module for an e-bus application under different thermal boundaries. Journal of Energy Storage. 73:1-22. https://doi.org/10.1016/j.est.2023.1091071227

On the Design of Heat Exchangers for Altitude Simulators

[EN] Altitude simulators for internal combustion engines are broadly used in order to simulate different atmospheric pressure and temperatures on a test bench. One of the main problems of these devices is their outlet temperature and in order to control it, at least one heat exchanger is needed. A methodology to define, select and analyses the best heat exchanger that fulfill the requirements is presented. The methodology combines CFD and 0D models with experimental test. The combination of these tools allows to adjust both the 0D and the CFD models. The adjusted 0D model will be used to perform parametric analysis that will help to select the best geometrical combinations considering heat transfer and pressure losses while the CFD model will help to find possible local deficiencies on the designed Heat Exchanger and, therefore, try to improve it. Finally, the adjusted 0D model have been used to perform parametric studies changing the most important geometric characteristics to analyze the effect on HEX performance.Broatch, A.; Olmeda, P.; Garcia Tiscar, J.; Roig-Villanueva, F. (2021). On the Design of Heat Exchangers for Altitude Simulators. SAE International. 1-12. https://doi.org/10.4271/2021-01-038811

Conjugate heat transfer study of the impact of "thermo-swing" coatings on internal combustion engines heat losses

[EN] To comply with the very strict emissions regulation the automotive industry is succeeding in developing ever more efficient engines, and there is scope for more improvements. In this regard, some investigations have suggested that insulating the combustion chamber walls of an internal combustion engine (ICE) yield low thermal losses. Most of the literature available on this topic presents simplified models that do not allow studying in detail the coating impact on engine efficiency. A more precise approach that consists in the combination of Computational Fluid Dynamics (CFD) and Conjugate Heat Transfer (CHT) simulations is used in this paper to predict the heat losses through the combustion chamber walls of a spark ignition (SI) engine. Two configurations are considered for the single cylinder engine: the metallic case and the same engine with coated piston and cylinder head. The insulation material has a low thermal conductivity (k 3.0.co;2-fDai, X. (Hunter), Singh, S., Krishnan, S. R., & Srinivasan, K. K. (2018). Numerical study of combustion characteristics and emissions of a diesel–methane dual-fuel engine for a wide range of injection timings. International Journal of Engine Research, 21(5), 781-793. doi:10.1177/1468087418783637Broatch, A., Olmeda, P., García, A., Salvador-Iborra, J., & Warey, A. (2017). Impact of swirl on in-cylinder heat transfer in a light-duty diesel engine. Energy, 119, 1010-1023. doi:10.1016/j.energy.2016.11.040Andruskiewicz, P., Najt, P., Durrett, R., Biesboer, S., Schaedler, T., & Payri, R. (2017). Analysis of the effects of wall temperature swing on reciprocating internal combustion engine processes. International Journal of Engine Research, 19(4), 461-473. doi:10.1177/1468087417717903Poubeau, A., Vauvy, A., Duffour, F., Zaccardi, J.-M., Paola, G. de, & Abramczuk, M. (2018). Modeling investigation of thermal insulation approaches for low heat rejection Diesel engines using a conjugate heat transfer model. International Journal of Engine Research, 20(1), 92-104. doi:10.1177/1468087418818264Broatch, A., Margot, X., Novella, R., & Gomez-Soriano, J. (2016). Combustion noise analysis of partially premixed combustion concept using gasoline fuel in a 2-stroke engine. Energy, 107, 612-624. doi:10.1016/j.energy.2016.04.045Broatch, A., Margot, X., Novella, R., & Gomez-Soriano, J. (2017). Impact of the injector design on the combustion noise of gasoline partially premixed combustion in a 2-stroke engine. Applied Thermal Engineering, 119, 530-540. doi:10.1016/j.applthermaleng.2017.03.081Yakhot, V., & Orszag, S. A. (1986). Renormalization group analysis of turbulence. I. Basic theory. Journal of Scientific Computing, 1(1), 3-51. doi:10.1007/bf01061452Redlich, O., & Kwong, J. N. S. (1949). On the Thermodynamics of Solutions. V. An Equation of State. Fugacities of Gaseous Solutions. Chemical Reviews, 44(1), 233-244. doi:10.1021/cr60137a013Issa, R. . (1986). Solution of the implicitly discretised fluid flow equations by operator-splitting. Journal of Computational Physics, 62(1), 40-65. doi:10.1016/0021-9991(86)90099-9Torregrosa, A., Olmeda, P., Degraeuwe, B., & Reyes, M. (2006). A concise wall temperature model for DI Diesel engines. Applied Thermal Engineering, 26(11-12), 1320-1327. doi:10.1016/j.applthermaleng.2005.10.021Torregrosa, A. J., Olmeda, P., Martín, J., & Romero, C. (2011). A Tool for Predicting the Thermal Performance of a Diesel Engine. Heat Transfer Engineering, 32(10), 891-904. doi:10.1080/01457632.2011.548639Lu, Y., Zhang, X., Xiang, P., & Dong, D. (2017). Analysis of thermal temperature fields and thermal stress under steady temperature field of diesel engine piston. Applied Thermal Engineering, 113, 796-812. doi:10.1016/j.applthermaleng.2016.11.07