Browsing by Keyword "Molten salt"
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Item Lessons learned from corrosion of materials with molten salts during molten salt tank preheating(2022-10-15) Prieto, Cristina; Ruiz-Cabañas, Javier; Madina, Virginia; Fernández, A. Inés; Cabeza, Luisa F.; MATERIALES PARA CONDICIONES EXTREMASOne of the biggest challenges of concentrating solar power (CSP) is achieving cost-reduction in the thermal energy storage (TES) system. Operating conditions of molten salt CSP plants includes intermittent exposure of the TES tanks materials (i.e., carbon steel, stainless-steel) in contact with molten salt (NaNO3–KNO3). This manuscript evaluates the lessons learnt in the performance of such tank materials with molten salts under continuous and intermittent exposure in a demo plant for indirect thermal storage at 400 °C. This study shows that the hot tank upper section developed breakaway corrosion phenomena generating oxides layers, which easily delaminates from the base metal. This damage is produced by the tank preheating system, which introduced a non-controlled amount of CO2 inside the tanks. Then, the carbon steel upper section is exposed in the hot tank to a mixture composed by CO2, water vapour, and chlorides at high temperature, producing this type of attack. The materials tested are carbon and low alloyed steels types A516Gr70, A387Gr11 and A387Gr5, Cr–Mo steel A387Gr9, stainless steels types A304L, A316L and A347. The lessons learnt have been implemented in the commissioning of new commercial plants successfully.Item Molten salt-based nanofluids as efficient heat transfer and storage materials at high temperatures. An overview of the literature(2018-02) Muñoz-Sánchez, Belén; Nieto-Maestre, Javier; Iparraguirre-Torres, Iñigo; García-Romero, Ana; Sala-Lizarraga, Jose M.; Tecnalia Research & Innovation; VALORIZACIÓN DE RESIDUOSThe research in the field of nanofluids has experienced considerable advances from their discovery two decades ago. These liquid mixtures with tiny quantities (< 10% in volume) of nanometric size solid particles (< 100 nm) in suspension have a great potential for thermal management applications due to their excellent thermophysical properties. The so-called traditional nanofluids (based on water or industrial oils) have been extensively studied so far with a special focus on the enhancement observed in their thermal conductivity. Experimental results, mechanisms and models regarding these materials have been published and reviewed on a large number of articles. A new kind of nanofluids based on inorganic salts has been developed in the last few years with the aim of storing and transferring thermal energy at high temperatures. These Molten Salt-Based Nanofluids (MSBNFs) are characterized by a considerable increase of their specific heat due to the presence of particles at the nanometric scale. On the contrary, the specific heat of the traditional nanofluids is lower compared to that of the base fluid. This surprising behaviour has caused an opened debate in the scientific community, which is currently dealing with these controversial results and the lack of theories and models for these materials. This article reviews the published scientific contributions on MSBNFs. The influence of several facts on the specific heat is deeply analysed, as well as the synthesis methods. Other important aspects related to the behaviour and development of the MSBNFs such as the stability of the NanoParticles (NPs) in the molten salt, their latent heat, viscosity and thermal conductivity, have also been reviewed in this article. Finally, the difficulties and challenges concerning the further development of these materials have been summarized and the main conclusions have been listed.