Assessing the Long-Term Stability of Fatty Acids for Latent Heat Storage by Studying their Thermal Degradation Kinetics
Assessing the Long-Term Stability of Fatty Acids for Latent Heat Storage by Studying their Thermal Degradation Kinetics, R. Bayón, A. Bonanos, E. Rojas, Eurosun 2020, Online, 01-03/09/2020, ISES, Oral
Modelling a conveyor-belt solar receiver to dry and heat aggregates in hot mix asphalt industry
Modelling a conveyor-belt solar receiver to dry and heat aggregates in hot mix asphalt industry, D. Pardillos-Pobo, J. Gómez-Hernández, T. Otanicar, 2nd Solar Energy Systems Conference, Online, 12-14/08/2020, AIChE, Oral
Síntesis de óxidos no estequiométricos para la producción de gas de síntesis mediante ciclos termoquímicos
Síntesis de óxidos no estequiométricos para la producción de gas de síntesis mediante ciclos termoquímicos, A. Pérez, M. Orfila, M. Linares, R. Sanz, J. Marugán, R. Molina, J. A. Botas, IV Encuentro de Jóvenes Investigadores de la SECAT (IV JJII SECAT-2020), Bilbao, 13-15/07/2020, Universidad del País Vasco y Sociedad Española de Catálisis, Poster
Synthesis, Structural Features, and Hydrogen Adsorption Properties of Three New Flexible Sulfur-Containing Metal-Organic Frameworks
Synthesis, Structural Features, and Hydrogen Adsorption Properties of Three New Flexible Sulfur-Containing Metal-Organic Frameworks, H. Montes-Andrés, P. Leo, G. Orcajo, A. Rodríguez-Diéguez, D. Choquesillo-Lazarte, C. Martos, J. A. Botas, G. Calleja, Crystal Growth & Design, 20, 6707-6714, 2020, Online version, https://pubs.acs.org/doi/abs/10.1021/acs.cgd.0c00857
Abstract
Three novel flexible sulfur-containing MOF materials named Co-URJC-5, Cu-URJC-6 and Zn-URJC-7, based on the 5,5′-thiodiisophthalic acid linker have been synthesized through solvothermal methods and characterized by different physicochemical techniques. Hydrogen adsorption analysis at room temperature reveals that these compounds display a gate-opening type adsorption mechanism at low pressures, attributed to the flexible nature of the H4TBTC ligand. This behavior is even more noticeable for Cu-URJC-6, since the layer arrangement by π–π stacking interactions between the aromatic layers could contribute to the flexibility of the structure. These results can be considered as a representative example to elucidate how MOF structures are built using flexible ligands and more significantly as a promising route for designing materials with selective gas sorption properties.
Two Isostructural URJC-4 Materials: From Hydrogen Physisorption to Heterogeneous Reductive Amination through Hydrogen Molecule Activation at Low Pressure
Two Isostructural URJC-4 Materials: From Hydrogen Physisorption to Heterogeneous Reductive Amination through Hydrogen Molecule Activation at Low Pressure, H. Montes-Andrés, P. Leo, A. Muñoz, A. Rodríguez-Diéguez, G. Orcajo, D. Choquesillo-Lazarte, C. Martos, F. Martínez, J. A. Botas, G. Calleja, Inorg. Chem., 59, 21, 15733–15740, 2020, Online version, https://pubs.acs.org/doi/abs/10.1021/acs.inorgchem.0c02127
Abstract
Herein, two novel isostructural metal–organic frameworks (MOFs) M-URJC-4 (M = Co, Ni; URJC = “Universidad Rey Juan Carlos”) with open metal sites, permanent microposity, and large surface areas and pore volumes have been developed. These novel MOFs, with polyhedral morphology, crystallize in the monoclinic P21/c space group, exhibiting a three-dimensional structure with microporous channels along the c axis. Initially, they were fully characterized and tested in hydrogen (H2) adsorption at different conditions of temperature and pressure. The physisorption capacities of both materials surpassed the gravimetric H2 uptake shown by most MOF materials under the same conditions. On the basis of the outstanding adsorption properties, the Ni-URJC-4 material was used as a catalyst in a one-pot reductive amination reaction using various carbonyl compounds and primary amines. A possible chemical pathway to obtain secondary amines was proposed via imine formation, and remarkable performances were accomplished. This work evidences the dual ability of M-URJC-4 materials to be used as a H2 adsorbent and a catalyst in reductive amination reactions, activating molecular H2 at low pressures for the reduction of C═N double bonds and providing reference structural features for the design of new versatile heterogeneous materials for industrial application.
Exploring the alternative MnO-Na2CO3 thermochemical cycle for water splitting
Exploring the alternative MnO-Na2CO3 thermochemical cycle for water splitting, A. Bayón, V. A. de la Peña O’Shea, D. P. Serrano, J. M. Coronado, Journal of CO₂ Utilization, 42, 101264, 2020, Online version, https://www.sciencedirect.com/science/article/abs/pii/S2212982020305035
Abstract
Thermochemical cycles for H2O and CO2 splitting using CeO2 have demonstrated high efficiency (> 5%) and fast kinetics. Alternative multistage cycles based on stoichiometric oxides, such as Mn-Na, can potentially provide much larger efficiencies under less stringent operation conditions. However, these cycles consist of three stages operating at very different temperatures (from 50 °C to 1500 °C) and, accordingly, the overall energy yield of the cycle critically depends on efficient heat recovery. Despite of this, recently the Mn3O4–Na2CO3 cycle has shown a remarkable H2 production and high stability. To further enhance hydrogen generation rate, in this work we explore the feasibility of the novel cycle based on MnO, which can potentially increase the yield per cycle. Several samples of MnO with different physicochemical characteristics were investigated to establish the influence on the oxide physicochemical properties on hydrogen generation. A maximum conversion of 47 %, with a productivity of 20.1 μmol H2 min−1 g−1 were obtained using the MnO sample with relatively large surface area. As expected, this productivity is notably better than that obtained with Mn3O4 under identical conditions. Furthermore, the results obtained here reveals that low temperature hydrolysis under CO2 atmosphere can improve the Na extraction by more than 10 %. This enhances the cyclability of the process and it may allow coupling hydrogen production with CO2 capture. Furthermore, the thermal reduction of the solid product recovered after the carbonation stage yields nearly pure MnO, confirming experimental the feasibility of completing this alternative cycle.
Thermo-Economic Optimization of Solar Thermal Devices by Coherent Integration of Technologies
Thermo-Economic Optimization of Solar Thermal Devices by Coherent Integration of Technologies, J. Cano Nogueras, Energy and Power Engineering, 12, 671-707, 2020, Online version, https://www.scirp.org/journal/paperinformation.aspx?paperid=104404
Abstract
Radiation is a form of energy where the angular variable of the direction of its photons has a primary importance, particularly for radiation concentration processes, which are essential tools to reach high temperatures from radiation beams (as the solar ones) with moderate intensities. Solar radiation cannot be used directly to feed thermodynamic cycles, and optical concentration must be applied to that goal. In general, reflection from mirrors is preferred to refraction by lenses in this case, because they have less optical aberrations. Concentration conveys very high temperatures in the receiver. However, the higher the temperature, the lower the efficiency of the solar thermal apparatus. Besides that, economy also suffers quite a lot when going to very high concentration factors, which is one of the main burdens in the development of Solar Thermal Energy. A new configuration of solar radiation concentrator is presented. It includes a salient innovation in the way the mirrors are given the right curvature by mechanical forces. Those mirrors are originally flat and do not need any special thermal treatment for this purpose. The whole device concept has been guided by the principle of thermoeconomic coherence, which requires similar efforts in all degrees of freedom that have strong influence in the performance and cost of the system. The paper shows the decision tree that has oriented the project, following the principle of equilibrium in efforts, which leads to a design window of moderate values in the main variables. The prototype of this new configuration has already been built, and the first stage of research is considered to be finished, because the prototype has shown excellent conditions to include selected (fitting) technologies at a very low cost.
Proposal of a new design of source heat exchanger for the technical feasibility of solar thermal plants coupled to supercritical power cycles
Proposal of a new design of source heat exchanger for the technical feasibility of solar thermal plants coupled to supercritical power cycles, M. J. Montes, J. I. Linares, R. Barbero, A. Rovira, Solar Energy, 211, 1027-1041, 2020, Online version, https://www.sciencedirect.com/science/article/pii/S0038092X20310999
Abstract
Solar thermal power plants coupled to supercritical CO2 cycles seems to be a way to increase the global solar-to-electric efficiency. For that, the concentrating solar technology that is best integrated is the molten salt central receiver with a thermal energy storage associated. This work is focused on one of the main challenges of this scheme: the source heat exchanger transferring the thermal energy from the molten salt in the solar field to the CO2 in the power cycle. A new design, based on the printed circuit heat exchanger technology is proposed, that withstands the pressure difference and avoids the molten salt plugging when circulating through microchannels. The thermo-mechanic model of this heat exchanger is also calculated. This work also addresses a thermo-economic optimization of the printed circuit heat exchanger proposed. For that, it is considered the global performance of the solar thermal plant for three layouts: recompression, intercooling and partial-cooling cycles. This optimization yields to a great reduction in the investment cost of these source heat exchangers, achieving the lowest cost in the partial-cooling configuration, followed by the intercooling and finally, the recompression. This trend is also observed in the global performance of the solar plant, so the partial-cooling layout is the one with the lowest levelized cost of electricity; this value is similar to that of the intercooling layout, and both are well below from the cost in the recompression layout, which results the most expensive configuration.
Experimental Devices to Investigate the Long-Term Stability of Phase Change Materials under Application Conditions
Experimental Devices to Investigate the Long-Term Stability of Phase Change Materials under Application Conditions, C. Rathgeber, S. Hiebler, R. Bayón, L. F. Cabeza, G. Zsembinszki, G. Englmair, M. Dannemand, G. Diarce, O. Fellmann, R. Ravotti, D. Groulx, A. C. Kheirabadi, S. Gschwander, S. Höhlein, A. König-Haagen, N. Beaupere, L. Zalewski, Applied Sciences, 10, 7968, 2020, Online version, https://www.mdpi.com/2076-3417/10/22/7968
Abstract
An important prerequisite to select a reliable phase change material (PCM) for thermal energy storage applications is to test it under application conditions. In the case of solid–liquid PCM, a large amount of thermal energy can be stored and released in a small temperature range around the solid–liquid phase transition. Therefore, to test the long-term stability of solid–liquid PCM, they are subjected to melting and solidification processes taking into account the conditions of the intended application. In this work, 18 experimental devices to investigate the long-term stability of PCM are presented. The experiments can be divided into thermal cycling stability tests, tests on PCM with stable supercooling, and tests on the stability of phase change slurries (PCS). In addition to these experiments, appropriate methods to investigate a possible degradation of the PCM are introduced. Considering the diversity of the investigated devices and the wide range of experimental parameters, further work toward a standardization of PCM stability testing is recommended.
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