Browsing by Author "Feijoo Conde, Jorge"

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    Appraisal of non-destructive in situ techniques to determine moisture- and salt crystallyzation-induced damage in dolostones
    (Journal of building engineering, 2022) Fort, R.; Feijoo Conde, Jorge; Varas-Muriel, M.J.; Navacerrada, M.A.; Barbero-Barrera, M.M.; Prida, D. de la
    The characterisation of both surface and subsurface pathologies (position, depth, width, …) that affects the porous materials used in building constructions, once in service, is important to establish the most suitable intervention strategy. In this sense, the use of non-destructive techniques allows the analysis of different properties without affecting the material. The present study shows the accuracy of different non-destructive in situ techniques, such as: electrical conductivity and capacitance, infrared thermography, ultrasonic pulse velocity, sound absorption, and electrical resistivity tomography, applied on dolostone ashlar stones outer façade of a sixteenthcentury belltower, affected by moisture and salt induced decay. The joint analysis of the results obtained with different techniques substantially improves the interpretation and characterisation of the detected pathologies, as they complement each other perfectly. Electrical resistivity tomography, which delivers resistivity cross-sections, yields very good results in detecting subsurface pathologies, and sound absorption is particularly useful for stone surfaces. In both cases, the frequency of the electric field and that of the acoustic emission to detect the extent of damage must be established in advance. The joint study of electrical conductivity and capacitance determines the degree of moisture/salts, both at the surface and subsurface, in the materials tested, one of the main causes of scaling and flaking in stony materials. However, the petrological characteristics of the materials used and the identification of the saline phases present must be known in advance to make a correct interpretation of the results.
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    Influence of alumina fixed-bed in steam reforming of glycerol for hydrogen production (7th International Conference on Renewable Energy and Conservation, ICREC 2022 November 18–20, 2022, Paris, France)
    (Energy Reports, 2023) Maceiras, Rocío; Feijoo Conde, Jorge; Alfonsín, Víctor; Pérez, Leticia; Álvarez-Feijoo, Miguel A.; Falcón, Pablo; Vallejo, Javier P.
    In this study, hydrogen production by steam reforming was carried out in a tubular fixed-bed reactor. The influence of some operating variables such as temperature, flow rate of the feeding glycerol solution and space velocity on hydrogen production under a non-catalyzed reaction was analyzed. The results showed that the hydrogen yield increased with temperature and decreased with the space velocity. As the feedstock flow rate increased, the hydrogen yield decreased rapidly. Compared with a reference experiment without fixed-bed, the use of non-porous alumina fixed-bed showed better results. Under the best reaction conditions (900 ◦C and a feedstock flow rate of 0.85 g/min), 17 L/h of syngas were obtained, with a purity of about 55% of hydrogen and a production of 2.7 moles of hydrogen by mol of glycerol.
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    Simultaneous desalination and consolidation treatment through the application of electrokinetic techniques
    (Construction and building materials, 2023) Feijoo Conde, Jorge; Gómez-Villalba, L.S.; Fort, R.; Rabanal, M.E.
    The vast majority of building materials that are heavily affected by salts require desalination and subsequent consolidation treatments. This double intervention entails a risk associated with the loss of material due to continuous contact with the affected surface. This study evaluates the effectiveness of an electrokinetic process of simultaneous desalination-consolidation of two types of stones (dolostone and limestone). The results show that it is possible to reduce the salts up to percentages of 100% and at the same time to fill the pores and fractures with insoluble compounds compatible with the materials to be treated, such as calcium-magnesium carbonates.