DSpace Collection:
http://hdl.handle.net/10261/383
20190320T21:42:45Z

Optimal design and operational tests of a hightemperature PEM fuel cell for a combined heat and power unit
http://hdl.handle.net/10261/127398
Título: Optimal design and operational tests of a hightemperature PEM fuel cell for a combined heat and power unit
Autor: Barreras Toledo, Félix; Lozano Fantoba, Antonio; Roda, Vicente; Barroso Estébanez, Jorge; Martín, Jesús
Resumen: Development of new materials for polymer electrolyte membranes has allowed increasing the operational temperature of PEM fuel cell stacks above 120 °C. The present paper summarizes the main results obtained in a research devoted to the design, fabrication and operational tests performed on a hightemperature PEMFC prototype. A 5cell stack has been assembled with commercial Celtec P1000 hightemperature MEAs from BASF Fuel Cells, but the rest of elements and processes have been developed at LIFTEC research facilities. The stack includes different novelties, such as the way in which reactant gases are supplied to the flowfield, the design of the flowfield geometry for both anode and cathode plates, the concept of block that eases the assembling and maintenance processes, and the heating strategy for a very fast startup. The different procedures comprising the assembly, closing and conditioning stages are also widely described and discussed. Results obtained in the preliminary operational tests performed are very promising, and it is expected that the 30cells HTPEMFC stack will deliver an electric power 2.3 times larger than the one initially predicted.
20160111T10:21:47Z

Transient twodimensional simulation of real flood events in a mediterranean floodplain
http://hdl.handle.net/10261/100618
Título: Transient twodimensional simulation of real flood events in a mediterranean floodplain
Autor: GonzálezSanchis, María; Murillo, J.; Latorre Garcés, Borja; Comín, Francisco A.; GarcíaNavarro, P.
Resumen: The application of a twodimensional (2D) finite volume numerical model to real flood events in the Ebro River is presented. The hydraulic model used is based on the 2D transient shallowwater equations on the irregular bed that are able to compute flow advance over a dry bed. This study involves the reliable simulation of not only the flood wave advance but also the drying process in a series of events of different magnitude. The importance of the correct characterization of the roughness coefficient and the topography is emphasized in the study. The former is estimated from a previous classification of structurally homogeneous habitats, and the latter is defined by merging the digital terrain model data with a hydraulic river bed elevation reconstruction algorithm. The calibration of the full model resulting from the roughness, bed river, and flow simulation models is based on field measurements of the flooded area for two steady discharges. The validation is performed by comparing the numerical results with the water levels measured during five flood events at certain times, with the flooded area and time series of continuous point measurements of water depth during different situations throughout the year. Because the model provides correct predictions of the surface processes both for low and high flow discharges, the simulation results are used to analyze the present floodplain hydrodynamics. In the same way, different topographic scenarios, on the basis of changes in the hydraulic riverfloodplain connectivity, are generated to analyze their potentially beneficial effect in the floodplain geomorphic dynamics. © 2012 American Society of Civil Engineers.
20140731T11:37:40Z

Response to the comments on “Experimental study of the pressure drop in the cathode side of airforced opencathode proton exchange membrane fuel cells” by Dejan Brkić
http://hdl.handle.net/10261/56335
Título: Response to the comments on “Experimental study of the pressure drop in the cathode side of airforced opencathode proton exchange membrane fuel cells” by Dejan Brkić
Autor: Barreras Toledo, Félix; Lozano Fantoba, Antonio; López, A. M.
Resumen: Response to the comments on “Experimental study of the
pressure drop in the cathode side of airforced opencathode
proton exchange membrane fuel cells” by Dejan Brkic
Descripción: ver: https://digital.csic.es/handle/10261/50719
20120914T10:44:54Z

A framework about flow measurements by LDA–PDA as a spatiotemporal average: application to data postprocessing
http://hdl.handle.net/10261/56333
Título: A framework about flow measurements by LDA–PDA as a spatiotemporal average: application to data postprocessing
Autor: Calvo, E.; García, J. A.; Santolaya, José Luis; García, I.; Aísa, L.
Resumen: Phase Doppler anemometry (PDA) is a wellestablished technique to study twophase ﬂows
and its principles are also used in laser Doppler anemometry (LDA) for measurements of ﬂuid
velocity. Raw measurements of individual particle data require postprocessing to obtain
useful and consistent information (moments of velocity, particle concentration and ﬂux,
velocity autocorrelation, etc). This is called in this paper the reconstruction of statistical
information. In the 1970s, several basic algorithms to perform the statistical reconstruction
were developed for LDA measurements (such as the transit time method, the inverse velocity
method, etc). With the advent of PDA, the scientiﬁc community developed reconstruction
algorithms to obtain mean variables of the dispersed phase. All these basic algorithms were
expounded as unconnected methods, following independent threads not integrated into a
general framework. Assuming that the PDA works under ideal conditions (all particles that
cross the probe volume are validated), this paper provides a general formulation and fully
systematizes a large set of previous statistical reconstruction methods. In this paper, the
statistical reconstruction of both the dispersed and the continuous phase is uniﬁed: the
continuous phase postprocessing emerges as the same reconstruction method of the dispersed
phase. The general framework proposed offers many advantages. First, some previous
calculation methods of particle concentration turn out to be particular cases of this general
formulation. Second, it provides an easy way to deduce unbiased estimators of any statistical
parameter of the ﬂow. Third, a wide set of new postprocessing methods are proposed to be
tested by any member of the scientiﬁc community. In the fourth place, the generalized integral
method to compute the particle concentration also gives information about the probe volume
geometry and two new autocalibration algorithms are proposed: the integral calibration
method and the crosssection integral calibration method. Finally, a physical interpretation of
the statistical reconstruction process is provided: it is a spatiotemporal averaging of the
detected particle data, and some of the algorithms used are related to the Eulerian–Eulerian
mathematical description of multiphase ﬂows
20120914T10:33:00Z