Maintenance management balanced scorecard approach for urban transport fleets

[EN] Attending the important role of maintenance function in any production or service provider company, the measurement and assessment of maintenance performance is crucial for competitiveness and future survival. That situation is even more critical in urban transport fleets where some specific boundary conditions and special characteristics will affect maintenance policy and implementation. This paper presents a deep review of different studies worldwide to define the most proper and effective maintenance performance indicators, selecting and refining the most important ones to obtain a reduced maintenance management balanced scorecard. That balanced scorecard is proposed as a main tool for urban transport fleet maintenance managers to assess efficiency and effectiveness of maintenance processes and will be used as a basis for a future benchmarking process for this type of companies.Authors want to acknowledgement to EMT de Valencia and other ATUC company members their collaboration and involvement on works performed during the project for KPIs definition and selection. Special thanks to Engineer Santiago Ballester for sharing efforts and knowledge to develop that work.Macian Martinez, V.; Tormos, B.; Herrero, J. (2019). Maintenance management balanced scorecard approach for urban transport fleets. Eksploatacja i Niezawodnosc - Maintenance and Reliability. 21(2):226-236. https://doi.org/10.17531/ein.2019.2.6S22623621

Impact of injection settings on gaseous emissions and particle size distribution in the dual-mode dual-fuel concept

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/10.1177/1468087419844413.[EN] Reactivity controlled compression ignition concept has been highlighted among the low temperature combustion strategies. However, this combustion strategy presents some problems related to high levels of hydrocarbon and carbon monoxide emissions at low load and high-pressure rise rate at high load. Therefore, to diminish these limitations, the dual-mode dual-fuel concept has been presented as an excellent alternative. This concept uses two fuels of different reactivity and switches from a dual-fuel fully premixed strategy (based on the reactivity controlled compression ignition concept) during low load to a diffusive nature during high load operation. However, the success of dual-mode dual-fuel concept depends to a large extent on the low reactivity/high reactivity fuel ratio and the injection settings. In this study, parametric variations of injection pressure and injection timing were experimentally performed to analyze the effect over each combustion process that encompasses the dual-mode dual-fuel concept and its consequent impact on gaseous and particles emissions, including an analysis of particle size distribution. The experimental results confirm how the use of an adequate injection strategy is indispensable to obtain low exhaust emission and a balance between the different pollutants. In the fully premixed reactivity controlled compression ignition strategy, the particles concentrations were dominated by nucleation mode; however, the increase in injection pressure and the advance of the diesel main injection timing provided a simultaneous reduction of nitrogen oxide and solid particles (accumulation mode). During the highly premixed reactivity controlled compression ignition strategy, the accumulation-mode particles increased, and their concentrations were higher when the diesel main injection timing advanced and injection pressure decreased, as well as there was a slight increase in nitrogen oxide emissions. Finally, in the dual-fuel diffusion strategy, the concentrations of accumulation-mode particles were higher and there was a considerable increase of these particles with the advance of the diesel main injection timing and the reduction of the injection pressure, while the nitrogen oxide emissions decreased.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This investigation has been funded by VOLVO Group Trucks Technology. The authors also acknowledge the Spanish economy and competitiveness ministry for partially supporting this research (HiReCo TRA2014-58870-R).Bermúdez, V.; Macian Martinez, V.; Villalta-Lara, D.; Soto, L. (2020). Impact of injection settings on gaseous emissions and particle size distribution in the dual-mode dual-fuel concept. International Journal of Engine Research. 21(4):561-577. https://doi.org/10.1177/1468087419844413S561577214Oppenauer, K. S., & Alberer, D. (2013). Soot formation and oxidation mechanisms during diesel combustion: Analysis and modeling impacts. International Journal of Engine Research, 15(8), 954-964. doi:10.1177/1468087413502661Rezaei, R., Dinkelacker, F., Tilch, B., Delebinski, T., & Brauer, M. (2016). Phenomenological modeling of combustion and NOx emissions using detailed tabulated chemistry methods in diesel engines. International Journal of Engine Research, 17(8), 846-856. doi:10.1177/1468087415619302Sarangi, A. K., Garner, C. P., McTaggart-Cowan, G. P., Davy, M. H., Wahab, E., & Peckham, M. (2012). The effects of split injections on high exhaust gas recirculation low-temperature diesel engine combustion. International Journal of Engine Research, 14(1), 68-79. doi:10.1177/1468087412450987Shi, L., Xiao, W., Li, M., Lou, L., & Deng, K. (2017). Research on the effects of injection strategy on LTC combustion based on two-stage fuel injection. Energy, 121, 21-31. doi:10.1016/j.energy.2016.12.128Singh, A. P., & Agarwal, A. K. (2012). Combustion characteristics of diesel HCCI engine: An experimental investigation using external mixture formation technique. Applied Energy, 99, 116-125. doi:10.1016/j.apenergy.2012.03.060Lu, X., Han, D., & Huang, Z. (2011). Fuel design and management for the control of advanced compression-ignition combustion modes. Progress in Energy and Combustion Science, 37(6), 741-783. doi:10.1016/j.pecs.2011.03.003Benajes, J., Novella, R., De Lima, D., & Thein, K. (2017). Impact of injection settings operating with the gasoline Partially Premixed Combustion concept in a 2-stroke HSDI compression ignition engine. Applied Energy, 193, 515-530. doi:10.1016/j.apenergy.2017.02.044Benajes, J., García, A., Domenech, V., & Durrett, R. (2013). An investigation of partially premixed compression ignition combustion using gasoline and spark assistance. Applied Thermal Engineering, 52(2), 468-477. doi:10.1016/j.applthermaleng.2012.12.025Benajes, J., García, A., Monsalve-Serrano, J., Balloul, I., & Pradel, G. (2017). Evaluating the reactivity controlled compression ignition operating range limits in a high-compression ratio medium-duty diesel engine fueled with biodiesel and ethanol. International Journal of Engine Research, 18(1-2), 66-80. doi:10.1177/1468087416678500Benajes, 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.2015.04.046Kavuri, C., Kokjohn, S. L., Klos, D. T., & Hou, D. (2016). Blending the benefits of reactivity controlled compression ignition and gasoline compression ignition combustion using an adaptive fuel injection system. International Journal of Engine Research, 17(8), 811-824. doi:10.1177/1468087415615255Benajes, 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.2017.01.010Benajes, J., García, A., Monsalve-Serrano, J., & Boronat, V. (2017). Gaseous emissions and particle size distribution of dual-mode dual-fuel diesel-gasoline concept from low to full load. Applied Thermal Engineering, 120, 138-149. doi:10.1016/j.applthermaleng.2017.04.005Desantes, J. M., Bermúdez, V., Pastor, J. V., & Fuentes, E. (2004). Methodology for measuring exhaust aerosol size distributions from heavy duty diesel engines by means of a scanning mobility particle sizer. Measurement Science and Technology, 15(10), 2083-2098. doi:10.1088/0957-0233/15/10/019Payri, 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.2011.06.005Lapuerta, M., Armas, O., & Gómez, A. (2003). Diesel Particle Size Distribution Estimation from Digital Image Analysis. Aerosol Science and Technology, 37(4), 369-381. doi:10.1080/02786820300970Yinhui, W., Rong, Z., Yanhong, Q., Jianfei, P., Mengren, L., Jianrong, L., … Shijin, S. (2016). The impact of fuel compositions on the particulate emissions of direct injection gasoline engine. Fuel, 166, 543-552. doi:10.1016/j.fuel.2015.11.019Saxena, M. R., & Maurya, R. K. (2017). Effect of premixing ratio, injection timing and compression ratio on nano particle emissions from dual fuel non-road compression ignition engine fueled with gasoline/methanol (port injection) and diesel (direct injection). Fuel, 203, 894-914. doi:10.1016/j.fuel.2017.05.015Agarwal, A. K., Gupta, T., & Kothari, A. (2011). Particulate emissions from biodiesel vs diesel fuelled compression ignition engine. Renewable and Sustainable Energy Reviews, 15(6), 3278-3300. doi:10.1016/j.rser.2011.04.002Bonatesta, F., Chiappetta, E., & La Rocca, A. (2014). Part-load particulate matter from a GDI engine and the connection with combustion characteristics. Applied Energy, 124, 366-376. doi:10.1016/j.apenergy.2014.03.030Reijnders, J., Boot, M., & de Goey, P. (2018). Particle nucleation-accumulation mode trade-off: A second diesel dilemma? Journal of Aerosol Science, 124, 95-111. doi:10.1016/j.jaerosci.2018.06.013Überall, A., Otte, R., Eilts, P., & Krahl, J. (2015). A literature research about particle emissions from engines with direct gasoline injection and the potential to reduce these emissions. Fuel, 147, 203-207. doi:10.1016/j.fuel.2015.01.012Benajes, J. V., López, J. J., Novella, R., & García, A. (2008). ADVANCED METHODOLOGY FOR IMPROVING TESTING EFFICIENCY IN A SINGLE-CYLINDER RESEARCH DIESEL ENGINE. Experimental Techniques, 32(6), 41-47. doi:10.1111/j.1747-1567.2007.00296.xNazemi, M., & Shahbakhti, M. (2016). Modeling and analysis of fuel injection parameters for combustion and performance of an RCCI engine. Applied Energy, 165, 135-150. doi:10.1016/j.apenergy.2015.11.093Jain, A., Singh, A. P., & Agarwal, A. K. (2017). Effect of fuel injection parameters on combustion stability and emissions of a mineral diesel fueled partially premixed charge compression ignition (PCCI) engine. Applied Energy, 190, 658-669. doi:10.1016/j.apenergy.2016.12.164Brückner, C., Pandurangi, S. S., Kyrtatos, P., Bolla, M., Wright, Y. M., & Boulouchos, K. (2017). NOx emissions in direct injection diesel engines – part 1: Development of a phenomenological NOx model using experiments and three-dimensional computational fluid dynamics. International Journal of Engine Research, 19(3), 308-328. doi:10.1177/1468087417704312Desantes, 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.2014.10.080Schneider, J., Hock, N., Weimer, S., Borrmann, S., Kirchner, U., Vogt, R., & Scheer, V. (2005). Nucleation Particles in Diesel Exhaust:  Composition Inferred from In Situ Mass Spectrometric Analysis. Environmental Science & Technology, 39(16), 6153-6161. doi:10.1021/es049427mZhang, Y., Ghandhi, J., & Rothamer, D. (2017). Comparisons of particle size distribution from conventional and advanced compression ignition combustion strategies. International Journal of Engine Research, 19(7), 699-717. doi:10.1177/1468087417721089Kosaka, H., Aizawa, T., & Kamimoto, T. (2005). Two-dimensional imaging of ignition and soot formation processes in a diesel flame. International Journal of Engine Research, 6(1), 21-42. doi:10.1243/146808705x7347Corcione, F. E., Merola, S. S., & Vaglieco, B. M. (2002). Evaluation of temporal and spatial distribution of nanometric particles in a diesel engine by broadband optical techniques. International Journal of Engine Research, 3(2), 93-101. doi:10.1243/14680870260127882Li, X., Guan, C., Luo, Y., & Huang, Z. (2015). Effect of multiple-injection strategies on diesel engine exhaust particle size and nanostructure. Journal of Aerosol Science, 89, 69-76. doi:10.1016/j.jaerosci.2015.07.008Seong, H. J., & Boehman, A. L. (2012). Studies of soot oxidative reactivity using a diffusion flame burner. Combustion and Flame, 159(5), 1864-1875. doi:10.1016/j.combustflame.2012.01.009Desantes, J. M., Bermúdez, V., García, A., & Linares, W. G. (2011). A Comprehensive Study of Particle Size Distributions with the Use of PostInjection Strategies in DI Diesel Engines. Aerosol Science and Technology, 45(10), 1161-1175. doi:10.1080/02786826.2011.582898Pickett, L. M., & Siebers, D. L. (2004). Soot in diesel fuel jets: effects of ambient temperature, ambient density, and injection pressure. Combustion and Flame, 138(1-2), 114-135. doi:10.1016/j.combustflame.2004.04.006Matthias, N., Farron, C., Foster, D. E., Andrie, M., Krieger, R., Najt, P., … Zelenyuk, A. (2011). Particulate Matter Sampling and Volatile Organic Compound Removal for Characterization of Spark Ignited Direct Injection Engine Emissions. SAE International Journal of Fuels and Lubricants, 5(1), 399-409. doi:10.4271/2011-01-210

Assessment of low-viscosity oil performance and degradation in a heavy duty engine real-world fleet test

Low viscosity engine oils (LVO) are considered one of the most interesting solutions for improving fuel economy in internal combustion engines (ICE). There are different studies involving LVO and ICE, but currently limited data are available regarding real-world performance of LVO in a real service fleet. Included in a broadest study related with fuel consumption saving effects and performance of LVO in a real service fleet, the aim of this work is to present the results obtained in terms of comparative oil performance. So, on this test, a comparative analysis using 39 buses was performed, based on a deep and extensive oil analysis program to assess those aspects above mentioned. Two engine technologies (Diesel and CNG) were considered and four different lubricants, two of them LVO and other two used as a reference baseline. The test duration comprised two oil drain intervals of 30000 km each one, totalizing more than 2 million of kilometers accumulated. Results have shown that LVO presented an excellent performance along the oil drain interval (ODI), even improving some characteristics of the baseline oils with higher viscosity values. Results have shown that oil degradation is more dependent on engine technology, but in any case presented a penalization in terms of ODI reduction, a key indicator for end-users related with maintenance costs. In the case of CNG engines, higher oil degradation in terms of oil oxidation and nitration was observed.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This study was funded by the Spanish Ministerio de Ciencia e Innovacion (Project no. TRA2012-30907).Macian Martinez, V.; Tormos Martínez, BV.; Miró Mezquita, G.; Pérez, T. (2016). Assessment of low-viscosity oil performance and degradation in a heavy duty engine real-world fleet test. Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology. 230(6):729-743. doi:10.1177/1350650115619612S729743230

Experimental assessment and validation of an oil ferrous wear debris sensors family for wind turbine gearboxes

[EN] Purpose - The purpose of this study was to perform a complete experimental assessment of a family of oil ferrous wear debris sensor is performed. The family comprised the original sensor and its re-engineered evolution, which is capable of detecting both amount and size of wear debris particles trapped by the sensor and some predefined oil condition properties. Design/methodology/approach ¿ In this work, the first step was to perform a design of experiments for the sensor validation. A specially defined test rig was implemented, and different ferrous wear debris was collected. For each sensor, two different tests were performed. The first test was called a ¿void test¿, where quantified amounts of debris were collided with the sensor without oil. The second one was a dynamic test, where the sensor was installed in the test rig and different amounts of wear debris were added at a constant rate. In addition, specific tests related with oil properties detection were studied. Findings ¿ The results show excellent correlation of the sensor output signal with the amount of wear debris and a satisfactory detection of debris size in all ranges. Also, the dynamic test presented adequate representativeness, and sensors performed well in this scenario. Practical implications ¿ This paper shows the practical implementation of this type of sensor and the usual detection range and rate of detection for different debris size and quantities. Originality/value ¿ This work has a great utility for maintenance managers and equipment designers to fully understand the potential of this type of sensor and its suitability for the application required.Authors would like to thank Iberdrola Generacion S.A. for their support in this project and Universitat Politecnica de Valencia for its support through contract FPI-S2-2015-1065 of Programa de Apoyo para la Investigacion y Desarrollo (PAID). Additionally, the authors would like to especially thank Daniel Veintimilla for their help in this work.Macian Martinez, V.; Tormos, B.; Miró Mezquita, G.; Rodes, I. (2018). Experimental assessment and validation of an oil ferrous wear debris sensors family for wind turbine gearboxes. Sensor Review. 38(1):84-91. https://doi.org/10.1108/SR-04-2017-0065S8491381Chiou, Y.-C., Lee, R.-T., & Tsai, C.-Y. (1998). An on-line Hall-effect device for monitoring wear particle in oils. Wear, 223(1-2), 44-49. doi:10.1016/s0043-1648(98)00289-0Du, L., & Zhe, J. (2011). A high throughput inductive pulse sensor for online oil debris monitoring. Tribology International, 44(2), 175-179. doi:10.1016/j.triboint.2010.10.022Holmberg, K., Adgar, A., Arnaiz, A., Jantunen, E., Mascolo, J., & Mekid, S. (Eds.). (2010). E-maintenance. doi:10.1007/978-1-84996-205-6Sheng, S. (2013), Report on Wind Turbine Subsystem Reliability - A Survey of Various Databases, NREL/PR-5000-59111

Low viscosity engine oils: Study of wear effects and oil key parameters in a heavy duty engine fleet test

Low viscosity engine oils (LVO) are considered key contributor for improving fuel economy in internal combustion engines (ICE). Attending that the use of LVO could imply a variation in tribological states found in ICE, this work's aim is to test LVO in real fleet, with emphasis on engine wear and oil key performance indicators. This test comprised 39 buses, two engine technologies and four different lubricants. For each sample, the elemental composition of the wear debris by ICP-AES and HTHS viscosity of the oil were measured among other properties. The results showed that, with a correct oil formulation, there is no significant difference when using LVO in terms of engine wear, HTHS viscosity variation and oil consumption. (C) 2015 Elsevier Ltd. All rights reserved.The authors would like to thank the Spanish Ministerio de Ciencia e Innovacion for its funding in this project (Project no. TRA2012-30907), and thank Repsol and EMT de Valencia for their collaboration. Additionally, the authors would like to thank Ruth Calatayud, Lorena Garzon, Leonardo Ramirez and Santiago Ballester for their help in this work.Macian Martinez, V.; Tormos Martínez, BV.; Ruiz Rosales, S.; Miró Mezquita, G. (2016). Low viscosity engine oils: Study of wear effects and oil key parameters in a heavy duty engine fleet test. Tribology International. 94:240-248. doi:10.1016/j.triboint.2015.08.028S2402489

Application and benchmarking of a direct method to optimize the fuel consumption of a diesel electric locomotive

[EN] This paper addresses the optimal control of a long-haul passenger train to deliver minimum-fuel operations. Contrary to the common Pontryagin minimum principle approach in railroad-related literature, this work addresses this optimal control problem with a direct method of optimization, the use of which is still marginal in this field. The implementation of a particular direct method based on the Euler collocation scheme and its transcription into a nonlinear problem are described in detail. In this paper, this optimization technique is benchmarked with well-known optimization methods in the literature, namely dynamic programming and the Pontryagin minimum principle, by simulating a real route. The results showed that the direct methods are on the same level of optimality compared with other algorithms while requiring reduced computational time and memory and being able to handle very complex dynamic systems. The performance of the direct method is also compared to the real trajectory followed by the train operator and exhibits up to 20% of fuel saving in the example route.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The authors acknowledge the support of Spanish Ministerio de Economı´a, Industria y Competitividad through project TRA2016-78717-R.Macian Martinez, V.; Guardiola, C.; Pla Moreno, B.; Reig, A. (2018). Application and benchmarking of a direct method to optimize the fuel consumption of a diesel electric locomotive. Proceedings of the Institution of Mechanical Engineers Part F Journal of Rail and Rapid Transit. 232(9):2272-2289. https://doi.org/10.1177/0954409718772133S22722289232

Model optymalizacji czasuwymiany floty. Analiza porównawcza flot miejskiego transportu publicznego z zastosowaniem symulacji Monte Carlo

[Otro] W niniejszej pracy przedstawiono analiz¿ kosztów pracy i utrzymania flot transportowych w dwóch krajach: Hiszpanii i Brazylii. Dla celów analizy, zaproponowano model optymalizacji stanowi¿cy po¿¿czenie tradycyjnej Analizy Kosztów Cyklu ¿ycia (LCC) oraz modelu symulacji Monte Carlo. wyniki potwierdzi¿y trafno¿¿ modelu oraz pokaza¿y, ¿e koszty ponoszone w przypadku floty brazylijskiej by¿y ni¿sze. Zaproponowany model mo¿e znale¿¿ zastosowanie zarówno w praktyce jak i w dalszych badaniach.[EN] This paper presents a comparative analysis of operation and maintenance costs of the transport fleets in two countries: Spain and Brazil. For this analysis, the research proposed an optimization model which is a combination of the traditional Life Cycle Cost Analysis methodology (LCC) and simulation model Monte Carlo. The results indicated the successful of model and show the lower cost in the Brazilian fleet. The evidences may be useful for other practices and researches.Macian Martinez, V.; Tormos, B.; De Sa-Riechi, JL. (2017). Time Replacement Optimization Model: Comparative Analysis of Urban Transport Fleets Using Monte Carlo Simulation. Eksploatacja i Niezawodnosc - Maintenance and Reliability. 19(2):151-157. doi:10.17531/ein.2017.2.1S15115719

Methodology to design a bottoming Rankine cycle, as a waste energy recovering system in vehicles. Study in a HDD engine

This article describes a methodology for the optimization of a bottoming cycle as a waste heat recovering system in vehicles. The methodology is applied to two particular cases in order to evaluate the preliminary energetic and technical feasibility of the implementation of a bottoming cycle in a heavy duty diesel (HDD) engine considering two different criteria. Initially, a study of the different waste heat sources of the engine is described. In this study, the power and exergy of each heat source is quantified, in order to evaluate which sources are suitable to be used in the bottoming cycle. The optimum working fluids to run the cycles are selected (water and R245fa). Then, the ideal Rankine cycle is optimized for the two different working fluids and different sets of heat sources (all the available heat sources and the sources with high exergy respectively) throughout the engine operating range, reaching a maximum improvement of 15% of the fuel consumption of the engine. Later, a study of the minimum temperature difference between the hot and cold flow of the heat exchangers is described. The improvements in fuel consumption and the size of the installed heat exchanger are related to this temperature difference. Finally, the non-ideal behavior of the machines (pump and expander) is analyzed, obtaining a maximum improvement of 10% in brake specific fuel consumption (bsfc).This work was partially funded by the "Programa de Formacion de Profesorado Universitario (FPU)", "Programa de Apoyo a la Investigacion y Desarrollo de la Universidad Politecnica de Valencia 2010", "Proyectos I + D para grupos de investigacion emergentes 2011" and "Programa de apoyo a la investigacion y desarrollo de la U.P.V (PAID-06-09)". The authors thank J. Dahlqvist for his help in improving the English grammar.Macian Martinez, V.; Serrano Cruz, JR.; Dolz Ruiz, V.; Sánchez Serrano, J. (2013). Methodology to design a bottoming Rankine cycle, as a waste energy recovering system in vehicles. Study in a HDD engine. Applied Energy. 104:758-771. https://doi.org/10.1016/j.apenergy.2012.11.075S75877110

Improved fleet operation and maintenance through the use of low viscosity engine oils: fuel economy and oil performance

[EN] For heavy-duty vehicles and road transportation, fuel consumption and associated CO2 emissions have been of great concern, which has led to the development and implementation of technologies to reduce their impact on the environment. Low viscosity engine oils have arisen as one proven cost-effective solution to increase the engine efficiency; however, for the heavy-duty vehide segment, engine protection against wear is a priority for end-users, and therefore there is some reluctance to the use of that new oil formulations. In this study, eight lubricant oils, representative of the HTHS viscosity reduction that heavy-duty oils have been undergoing and new API CK-4 and FA-4 categories, were evaluated for fuel economy, oil performance and engine wear, in a long-term test involving a fleet of 49 heavy-duty vehicles of four different engine technologies, some of them with diesel fuel and others with compressed natural gas. Results of fuel economy were positive for most of the buses' models. Regarding oil performance and wear, most of the formulations were found to be suitable for extended oil drain intervals (ODI); and although no alarming results were found, overall performance of the formulations of the fourth stage could lead to significant wear if the oil drain interval is extended. In this study, it should be noted that some of the information has been presented by the authors in other publications, here they are presented with the purpose of complementing the new results and summarize the entire test.Author Sophia Bastidas would like to thank the support of the program Ayudas de Investigacion y Desarrollo (PAID-01-17) of the Universitat Politecnica de Valencia.Macian Martinez, V.; Tormos, B.; Bastidas-Moncayo, KS.; Pérez, T. (2020). Improved fleet operation and maintenance through the use of low viscosity engine oils: fuel economy and oil performance. Eksploatacja i Niezawodnosc - Maintenance and Reliability. 22(2):201-211. https://doi.org/10.17531/ein.2020.2.3S20121122

Characterization of the turbulent flame front surface in spark ignition engines during spark ignition operation to identify controlled auto-ignition and abnormal combustion

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/10.1177/1468087420933780[EN] The combustion diagnostics and subsequent analysis are standardized tools based on the estimation of the heat release law (HRL). From this estimation, the different combustion parameters can be obtained: combustion phasing and duration, heat release rate, and so on. This analysis might be usually enough to study traditional spark ignition (SI) engines. However, with the new upcoming SI engines, this is probably not the case anymore, since different combustion modes can be operated in the same engine, as for instance a combination of SI and controlled auto-ignition (CAI) combustion modes. When different combustion modes are combined, it seems interesting to study in more depth the HRL, trying to get more data and to study the differences among the diverse combustion modes. Toward this end, a methodology to go deeper in the study of the HRL is proposed in this work, consisting of, mainly quantifying and taking into account the most relevant influencing parameters: the fuel properties (mainly its lower heating value), the in-cylinder oxygen content, the density of the burned and unburned zones, the laminar combustion speed, and the turbulence effect. With the proposed methodology, a standard SI combustion, developed by a flame front, can be characterized at any given operating point. This would allow to predict which the combustion developement would be, at this operating point, assuming it to be developed by a flame front. Subsequently, this SI combustion prediction can be compared to the one obtained experimentally, making it possible to identify and analyze abnormal combustion phenomena, as well as to study the differences between a combustion developed by a flame front (SI) and by auto-ignition (CAI). Derived from this work, an alternative equation to experimentally characterize the laminar combustion velocity has also been proposed, in order to improve its applicability in a wider range of fuel/air ratios and dilution degrees.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: the Spanish Ministry of Science, Innovation and Universities for funding the PhD. studies of Jorge Valero-Marco (contract BES-2016-077610). This work was partly funded by Renault, and by FEDER and the Spanish Government through project TRA2015-67136-R.Macian Martinez, V.; López, JJ.; Martín, J.; Valero-Marco, J. (2021). Characterization of the turbulent flame front surface in spark ignition engines during spark ignition operation to identify controlled auto-ignition and abnormal combustion. International Journal of Engine Research. 22(7):2149-2168. https://doi.org/10.1177/14680874209337802149216822