Suchergebnisse

Salt hydrates are an appealing option to be used as sorption materials in thermal energy storage (TES). In this work, strontium bromide and magnesium sulphate have been selected as one of the most promising salt hydrates since they present high energy storage density (>130 kWh/m3) and efficiency (>20%). One of the main drawbacks of sorption materials rely on control the hydratation-dehydratation process but there are other parameters that can modify this behaviour as the corrosive potential of these salts in contact with the container material selected for the application. Hence, four different metal container materials, specifically stainless steel, copper, aluminium, and carbon steel have been tested in SrBr2$6H2O and MgSO4$7H2O hydrate salts, during 100 h at dehydratation conditions. After the gravimetric and micrograph analysis carried out via scanning electron microscopy (SEM) study, only carbon steel is not recommended for this application in contact with SrBr2$6H2O, obtaining a corrosion rate of 0.038 mm/year, with a metallographic corrosion layer thickness of 25.2 mm. Aluminium, copper and stainless steel showed a better corrosion resistance also in SrBr2$6H2O and MgSO4$7H2O with corrosion rates below 0.008 mm/year. ; This work was partially funded by the Ministerio de Ciencia, Innovación y Universidades de España (RTI2018-093849-B-C31 - MCIU/AEI/FEDER, UE). The authors would like to thank the Catalan Government for the quality accreditation given to their research group GREiA (2017 SGR 1537). GREiA is a certified agent TECNIO in the category of technology developers from the Government of Catalonia. This work is partially supported by ICREA under the ICREA Academia programme.

For seasonal energy storage using solar energy in buildings heating and DHW, thermochemical technology represents the most promising alternative due to the virtually absence of heat losses during storage period. This work focuses on silicone foams, filled by MgSO4·7H2O, as innovative composite sorbents for sorption thermal energy storage applications. The necessity to enclose the salt hydrate in the polymeric foam arises for overcoming the issue of swelling, agglomeration, and/or deliquescence of the salt during its de/hydration process. Indeed, the foam with its flexible structure allows the safe volume expansion during the hydration phase of the salt. The foam samples presented in this paper were obtained by mixing the salt hydrate at various percentages (from 40 wt% up to 70 wt%) with a mixture of two water vapour permeable silicones. The foams were characterized by a complete physicochemical and morphological examination in order to evaluate their actual application in sorption energy storage systems. It was demonstrated that a good link seems to be established between the foam and the salt, and that the de/hydration capacity of the salt is not hindered by the foaming process, storage ability and storage density of the composites are expected to be in line with those of the pure material. ; The present work has been partially funded by PON "Ricerca e Competitività 2007-13" PON03PE_00206_2 S5 – Smart Small Scale Solar Systems and by the Spanish government (ENE2015-64117-C5-1-R (MINECO/FEDER)). The authors from the University of Lleida would like to thank the Catalan Government for the quality accreditation given to their research group (2014 SGR 123). Aran Solé would like to thank Ministerio de Economía y Competitividad de España for Grant Juan de la Cierva, FJCI-2015-25741.

The improvement of thermal energy storage systems implemented in solar technologies increases not only their performance but also their dispatchability and competitiveness in the energy market. Latent heat thermal energy storage systems are one of those storing methods. Therefore, the need of finding the best materials for each application becomes an appealing research subject. The main goal of this paper is to find suitable and economically viable materials able to work as phase change material (PCM) within the temperature range of 210-270 ºC and endure daily loading and unloading processes in a system with Fresnel collector and an organic Rankine cycle (ORC). Twenty-six materials have been tested and characterized in terms of their thermophysical conditions, thermal and cycling stability, and health hazard. Two materials out of the 26 candidates achieved the last stage of the selection process. However, one of the two finalists would require an inert working atmosphere, which would highly increase the cost for the real scale application. This leads to a unique suitable material, solar salt (40 wt % KNO3/60 wt % NaNO3). ; This work was partially funded by the European Union's Horizon 2020 Research & Innovation Programme under Grant Agreement 723596 with reference name Innova MicroSolar. This work was partially funded by the Ministerio de Economía y Competitividad de España (ENE2015-64117-C5-1-R (MINECO/FEDER) and ENE2015-64117-C5-3-R (MINECO/FEDER)). The authors would like to thank the Catalan Government for the quality accreditation given to their research group (2017 SGR 1537). GREA is certified agent TECNIO in the category of technology developers from the Government of Catalonia. José Miguel Maldonado would like to thank the Spanish Government for his research fellowship (BES-2016-076554). Aran Solé would like to thank Ministerio de Economía y Competitividad de España for Grant Juan de la Cierva, FJCI-2015-25741. Alvaro de Gracia has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 712949. Angel G. Fernández would like to acknowledge the financial support provided by GIZ "Programa de pasantía en el extranjero en tecnologías de concentración solar para investigadores" and CONICYT/FONDAP 15110019 "Solar Energy Research Center" SERC-Chile.