Suchergebnisse

An experimental and numerical study has been performed to improve the understanding of the air/liquid interaction in an air-blasted breaking water sheet. This research is focused in the near field close to the exit slit, because it is in this region where instabilities develop and grow, leading to the sheet breakup. In the experiments, several relevant parameters were measured including the sheet oscillation frequency and wavelength, as well as the droplet size distribution and the amplification growth rate. The flow was also investigated using linear instability theory. In the context of existing papers on instability analysis, the numerical part of this work presents two unique features. First, the air boundary layer is taken into account, and the effects of air and liquid viscosity are revealed. Second, the equations are solved for the same parameter values as those in the experiments, enabling a direct comparison between calculations and measurements; although qualitatively the behaviour of the measured variables is properly described, quantitative agreement is not satisfactory. Limitations of the instability analysis in describing this problem are discussed. From all the collected data, it is confirmed that the oscillation frequency strongly depends on the air speed due to the near-nozzle air/water interaction. The wave propagates with accelerating interface velocity which in our study ranges between the velocity of the water and twice that value, depending on the air velocity. For a fixed water velocity, the oscillation frequency varies linearly with the air velocity. This behaviour can only be explained if the air boundary layer is considered. ; This project has been partially supported by the Comision Interministerial de Ciencia y Tecnolog a of the Spanish Government under contract AMB96-0427-C03- 01, and the Direccion General de Estudios Superiores under contracts PB96-0739- C03-03 and BFM2000-1328. The authors want to thank the referees for their insightful comments. ; Peer reviewed

Vanadium redox flow batteries are very promising technologies for large-scale, inter-seasonal energy storage. Tuning models from experimental data and estimating the state of charge is an important challenge for this type of devices. This work proposes a non-linear lumped parameter concentration model to describe the state of charge that differentiates the species concentrations in the different system components and allows to compute the effect of the most relevant over-potentials. Additionally, a scheme, based on the particle swarm global optimization methodology, to tune the model taking into account real experiments is proposed and validated. Finally, a novel state of charge estimation algorithm is proposed and validated. This algorithm uses a simplified version of previous models and a sliding mode control feedback law. All developments are analytically formulated and formally validated. Additionally, they have been experimentally validated in a home-made single vanadium redox flow battery cell. Proposed methods offer a constructive methodology to improve previous results in this field. ; This work was supported in part by the Spanish National Research Council Consejo Superior de Investigaciones Científicas (CSIC) under Project PIE-201980E101, in part by the Spanish Ministry of Science and Innovation through the Project DOVELAR (Ministerio de Ciencias yUniversidades (MCIU)/Agencia Estatal de Investigación (AEI)/Fondo Europeo de Desarrollo Regional (FEDER), Unión Europea (UE) under Grant RTI2018-096001-B-C31 and Grant RTI2018-096001-B-C32, in part by the Laboratorio de Investigación en Fluidodinámica y Tecnologías de la Combustión (LIFTEC) Research Team through the Aragon Government under Project LMP246_18, and to the group T01_20R, in part by the Universidad Politécnica de Cataluña (UPC) Research Team through the María de Maeztu Seal of Excellence to Instituto de Robótica e Informática (IRI) under Grant MDM-2016-0656, and in part by the Generalitat de Catalunya under Project 2017 SGR482.

The energy management strategy plays a major role in hybrid platforms powered by fuel cells (FCs) and batteries. This paper presents an assessment of energy management focused on fuel economy and battery degradation. Particularly, a proposed heuristic strategy and the widely known equivalent consumption minimization strategy are compared with the optimal solution obtained offline via dynamic programming. The case study is based on a real FC hybrid vehicle. Accordingly, the powertrain model of the vehicle used for the simulations is validated experimentally, and the profile of the power demand is measured from the real application. The results show that the proposed strategy offers the same performance as the equivalent consumption minimization strategy when the battery degradation is prioritized, and in comparison with the optimal off-line solution, it can be seen that there is still margin for improvement in terms of battery degradation. ; This work was supported in part by the Scholarship Program BECAR of Ministerio de Modernizacion of Argentina, under Project DPI2015-69286-C3-1-R and Project DPI2015-69286-C3-2-R (MINECO/FEDER) of the Spanish Government, in part by the European Commission H2020 through the Fuel Cell and Hydrogen Joint Undertaking Project under Project INN-BALANCE 735969 and Project REWIND LIFE13 ENV/ES/000280, in part by the Regional Government of Aragon to the Fluid Mechanics for a Clean Energy Research Group of LIFTEC under Grant T01_17R, in part by the Spanish State Research Agency through the Marí de Maeztu Seal of Excellence to IRI under Grant MDM-2016-0656, and in part by AGAUR of Generalitat de Catalunya through the Advanced Control Systems (SAC) Group under Grant 2017 SGR 482.

Trabajo presentado en el VII Symposium on Hydrogen, Fuel Cells and Advanced Batteries (HYCELTEC 2019), celebrado en Barcelona del 1 al 3 de julio de 2019. ; Authors acknowledge the financial support of the Secretariat of State for Research of the Spanish Ministry of Economy and Competitiveness under project DPI2015-69286-C3-1-R (MINECO/FEDER, UE). Support of the Regional Government of Aragon to the Fluid Mechanics for a Clean Energy Research Group (T01_17R) of the LIFTEC is also acknowledged.

Trabajo presentado en el VII Symposium on Hydrogen, Fuel Cells and Advanced Batteries (HYCELTEC 2019), celebrado en Barcelona del 1 al 3 de julio de 2019. ; Authors acknowledge the financial support of the Secretariat of State for Research of the Spanish Ministry of Economy and Competitiveness under project DPI2015-69286-C3-1-R (MINECO/FEDER, UE). Support of the Regional Government of Aragon to the Fluid Mechanics for a Clean Energy Research Group (T01_17R) of the LIFTEC is also acknowledged. C. Alegre acknowledges the support of MINECO for her Juan de la Cierva contract and L. Álvarez-Manuel acknowledges the funding provided by the European Social Fund and CSIC under the Youth Employment Initiative.

In the present research, the energy demanded by the wastewater treatment plant of a winery and the pumping station of the irrigation system of a vineyard is supplied by a stand-alone renewable energy system formed by three photovoltaic arrays connected to a microgrid. A relatively small battery maintains the stability and quality of the energy supply acting as a short-term energy storage. Hydrogen is generated in a production and refueling plant specifically designed for this project, and it is eventually used in a plug-in BEV properly modified as a hybrid vehicle by adding a PEM fuel cell. On the one hand, the technical and economic feasibility of the on-site electricity production for the winery and vineyard, compared to the commercial electricity from the grid and diesel gensets, is demonstrated. On the other hand, the diesel savings by the hydrogen generated on site are assessed. The electricity (72 MWh) and hydrogen (1214 m3) produced in the first year have saved the emission of around 27 tons of equivalent CO2. ; This work has been funded by the European Union LIFE+ under project LIFE13 ENV/ES/000280, and by the Secretariat of State for Research of the Spanish Ministry of Economy and Competitiveness under project DPI2015-69286-C3-1-R (MINECO/FEDER, UE). Support of the Regional Government of Aragon to the Experimental Fluid Dynamics Research Group (T03) of the LIFTEC is also acknowledged. ; Peer reviewed