Experimental study of visual corona under aeronautic pressure conditions using low-cost imaging sensors

Visual corona tests have been broadly applied for identifying the critical corona points of diverse high-voltage devices, although other approaches based on partial discharge or radio interference voltage measurements are also widely applied to detect corona activity. Nevertheless, these two techniques must be applied in screened laboratories, which are scarce and expensive, require sophisticated instrumentation, and typically do not allow location of the discharge points. This paper describes the detection of the visual corona and location of the critical corona points of a sphere-plane gap configurations under different pressure conditions ranging from 100 to 20 kPa, covering the pressures typically found in aeronautic environments. The corona detection is made with a low-cost CMOS imaging sensor from both the visible and ultraviolet (UV) spectrum, which allows detection of the discharge points and their locations, thus significantly reducing the complexity and costs of the instrumentation required while preserving the sensitivity and accuracy of the measurements. The approach proposed in this paper can be applied in aerospace applications to prevent the arc tracking phenomenon, which can lead to catastrophic consequences since there is not a clear protection solution, due to the low levels of leakage current involved in the pre-arc phenomenon.Peer ReviewedPostprint (published version

A community electrification project: combination of microgrids and household systems fed by wind, PV or micro-hydro energies according to micro-scale resource evaluation and social constraints

When electrifying isolated rural communities, usually standardized solutions have been implemented using the same technology at all the points. However these solutions are not always appropriate to the community and its population. This article aims to describe the technical design of the electrification system of the community of Alto Peru (in the region of Cajamarca, Peru), where the adequate technology was used at each area according to micro-scale resource evaluation and the socioeconomic requirements of the population. Specifically four technologies were implemented: wind microgrids in highlands, a micro-hydro power plant in the presence of a waterfall, a PV microgrid in a group of points sheltered from the wind and individual PV systems in scattered points with low wind potential. This project brought electricity to 58 households, a health center, a school, a church, two restaurants and two shops.Peer ReviewedPostprint (author’s final draft

An on-board method to estimate the light-off temperature of diesel oxidation catalysts

[EN] Current diesel engine regulations include on-board diagnostic requirements so that after-treatment systems need on-board methods to detect their aging state through the available measurements. In a state-of-the-art diesel exhaust line, two temperature and lambda measurements can be found upstream and downstream of the diesel oxidation catalyst. Thus, the strategy presented in this article makes use of these measurements to estimate the light-off temperature, which has been widely studied as a characteristic of diesel oxidation catalyst aging. The light-off temperature estimation potential is evaluated first under dynamic engine operating conditions, in which lambda measurements are proved to be precise enough to detect oxidation. However, dynamic conditions make the association of a representative temperature with an oxidation event difficult. Therefore, the method makes use of more controlled conditions at idle, during which the exhaust temperature decreases avoiding dynamics of normal driving conditions. During the idle, post-injection pulses are applied to determine whether oxidation occurs at a representative temperature measured by the upstream temperature sensor. The result of each pulse is used to generate a database. Then, after a long enough time window, the database generated will allow characterizing non-oxidation and oxidation temperatures, with an intermediate interval of indefinition. This article shows how the temperatures of these ranges increase as the light-off temperature increases, thereby validating the proposed method for light-off temperature estimation.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 Econom¿¿a, Industria y Competitividad through project TRA2016-78717-R.Guardiola, C.; Pla Moreno, B.; Bares-Moreno, P.; Mora, J. (2020). An on-board method to estimate the light-off temperature of diesel oxidation catalysts. International Journal of Engine Research. 21(8):1480-1492. https://doi.org/10.1177/146808741881796514801492218Guardiola, C., Pla, B., Piqueras, P., Mora, J., & Lefebvre, D. (2017). Model-based passive and active diagnostics strategies for diesel oxidation catalysts. Applied Thermal Engineering, 110, 962-971. doi:10.1016/j.applthermaleng.2016.08.207Blanco-Rodriguez, D., Vagnoni, G., & Holderbaum, B. (2016). EU6 C-Segment Diesel vehicles, a challenging segment to meet RDE and WLTP requirements. IFAC-PapersOnLine, 49(11), 649-656. doi:10.1016/j.ifacol.2016.08.094Ye, S., Yap, Y. H., Kolaczkowski, S. T., Robinson, K., & Lukyanov, D. (2012). Catalyst ‘light-off’ experiments on a diesel oxidation catalyst connected to a diesel engine—Methodology and techniques. Chemical Engineering Research and Design, 90(6), 834-845. doi:10.1016/j.cherd.2011.10.003Li, J., Szailer, T., Watts, A., Currier, N., & Yezerets, A. (2012). Investigation of the Impact of Real-World Aging on Diesel Oxidation Catalysts. SAE International Journal of Engines, 5(3), 985-994. doi:10.4271/2012-01-1094Wiebenga, M. H., Kim, C. H., Schmieg, S. J., Oh, S. H., Brown, D. B., Kim, D. H., … Peden, C. H. F. (2012). Deactivation mechanisms of Pt/Pd-based diesel oxidation catalysts. Catalysis Today, 184(1), 197-204. doi:10.1016/j.cattod.2011.11.014Mallamo, F., Longhi, S., Millo, F., & Rolando, L. (2013). Modeling of diesel oxidation catalysts for calibration and control purpose. International Journal of Engine Research, 15(8), 965-979. doi:10.1177/1468087413492526Mohammadpour, J., Franchek, M., & Grigoriadis, K. (2011). A survey on diagnostic methods for automotive engines. International Journal of Engine Research, 13(1), 41-64. doi:10.1177/1468087411422851Tourlonias, P., & Koltsakis, G. (2011). Model-based comparative study of Euro 6 diesel aftertreatment concepts, focusing on fuel consumption. International Journal of Engine Research, 12(3), 238-251. doi:10.1177/1468087411405104Guardiola, C., Pla, B., Blanco-Rodriguez, D., Mazer, A., & Hayat, O. (2013). A bias correction method for fast fuel-to-air ratio estimation in diesel engines. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, 227(8), 1099-1111. doi:10.1177/0954407012473415Guardiola, C., Dolz, V., Pla, B., & Mora, J. (2016). Fast estimation of diesel oxidation catalysts inlet gas temperature. Control Engineering Practice, 56, 148-156. doi:10.1016/j.conengprac.2016.08.02

Adaptive calibration for reduced fuel consumption and emissions

This paper presents a model-based approach for continuously adapting an engine calibration to the traffic and changing pollutant emission limits. The proposed strategy does not need additional experimental tests beyond those required by the traditional calibration approach. The method utilises information currently available in the engine control unit to adapt the engine control to the particular driving patterns of a given driver. Additional information about the emissions limits should be provided by an external structure if an adaptation to the pollutant immission is required. The proposed strategy has been implemented in a light-duty diesel engine, and showed a good potential to keep NOx emissions around a defined limit.Guardiola, C.; Pla Moreno, B.; Bares-Moreno, P.; Waschl, H. (2016). Adaptive calibration for reduced fuel consumption and emissions. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. 230(14):2002-2014. doi:10.1177/0954407016636977S200220142301

Energy Management of Hybrid Electric Urban Bus by Off-Line Dynamic Programming Optimization and One-Step Look-Ahead Rollout

[EN] Due to the growing air quality concern in urban areas and rising fuel prices, urban bus fleets are progressively turning to hybrid electric vehicles (HEVs) which show higher efficiency and lower emissions in comparison with conventional vehicles. HEVs can reduce fuel consumption and emissions by combining different energy sources (i.e., fuel and batteries). In this sense, the performance of HEVs is strongly dependent on the energy management strategy (EMS) which coordinates the energy sources available to exploit their potential. While most EMSs are calibrated for general driving conditions, this paper proposes to adapt the EMS to the specific driving conditions on a particular bus route. The proposed algorithm relies on the fact that partial information on the driving cycle can be assumed since, in the case of a urban bus, the considered route is periodically covered. According to this hypothesis, the strategy presented in this paper is based on estimating the driving cycle from a previous trip of the bus in the considered route. This initial driving cycle is used to compute the theoretical optimal solution by dynamic programming. The obtained control policy (particularly the cost-to-go matrix) is stored and used in the subsequent driving cycles by applying one-step look-ahead roll out, then, adapting the EMS to the actual driving conditions but exploiting the similarities with previous cycles in the same route. To justify the proposed strategy, the paper discusses the common patterns in different driving cycles of the same bus route, pointing out several metrics that show how a single cycle captures most of the key parameters for EMS optimization. Then, the proposed algorithm (off-line dynamic programming optimization and one-step look-ahead rollout) is described. Results obtained by simulation show that the proposed method is able to keep the battery charge within the required range and achieve near-optimal performance, with only a 1.9% increase in fuel consumption with regards to the theoretical optimum. As a reference for comparison, the equivalent consumption minimization strategy (ECMS), which is the most widespread algorithm for HEV energy management, produces an increase in fuel consumption with respect to the optimal solution of 11%.This research was funded by Ministerio de Ciencia e Innovacion, through the Proyectos I+D+i 2020 Program, grant number PID2020-119691RB-I00.Tormos, B.; Pla Moreno, B.; Bares-Moreno, P.; Pinto, D. (2022). Energy Management of Hybrid Electric Urban Bus by Off-Line Dynamic Programming Optimization and One-Step Look-Ahead Rollout. Applied Sciences. 12(9):1-19. https://doi.org/10.3390/app1209447411912

Cycle by Cycle Trapped Mass Estimation for Diagnosis and Control

The development of one cycle resolution control strategies and the research at HCCI engines demands an accurate estimation of the trapped mass. In contrast to current methods for determining the mass flow, which are only able to determine averaged values of the flow entering the cylinders, the present paper proposes a methodology based on the in-cylinder pressure resonance. The determination of such frequency allows inferring the cylinder mass with one cycle resolution. In addition, the method permits determining error metrics based on the mass conservation principle. Validation results for a reactivity controlled compression ignition (RCCI) engine equipped with electrohydraulic variable valve timing (VVT) are presented to illustrate the performance of the methodGuardiola, C.; Pla Moreno, B.; Blanco-Rodriguez, D.; Bares Moreno, P. (2014). Cycle by Cycle Trapped Mass Estimation for Diagnosis and Control. SAE International Journal of Engines. 7(3):1-9. doi:10.4271/2014-01-1702S197

Adaptive calibration of Diesel engine injection for minimising fuel consumption with constrained NOx emissions in actual driving missions

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/10.1177/1468087420918800[EN] This article proposes a method for fuel minimisation of a Diesel engine with constrained NOx emission in actual driving mission. Specifically, the methodology involves three developments: The first is a driving cycle prediction tool which is based on the space-variant transition probability matrix obtained from an actual vehicle speed dataset. Then, a vehicle and an engine model is developed to predict the engine performance depending on the calibration for the estimated driving cycle. Finally, a controller is proposed which adapts the start-of-injection calibration map to fulfil the NOx emission constraint while minimising the fuel consumption. The calibration is adapted during a predefined time window based on the predicted engine performance on the estimated cycle and the difference between the actual and the constraint on engine NOx emissions. The method assessment was done experimentally in the engine test set-up. The engine performace using the method is compared with the state-of-the-art static calibration method for different NOx emission limits on real driving cycles. The online implementation of the method shows that the fuel consumption can be reduced by 3%-4% while staying within the emission limits, indicating that the estimation method is able to capture the main driving cycle characterstics.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 Ministrrio de Economia, Industria y Competitivad through project TRA2016-78717-R.Luján, JM.; Pla Moreno, B.; Bares-Moreno, P.; Pandey, V. (2021). Adaptive calibration of Diesel engine injection for minimising fuel consumption with constrained NOx emissions in actual driving missions. International Journal of Engine Research. 22(6):1896-1905. https://doi.org/10.1177/1468087420918800S1896190522