Computational modelling of the local structure and thermophysical properties of ternary MgCl2-NaCl-KCl salt for thermal energy storage applications

Molten salts as heat transfer fluids (HTF) for concentrated solar power (CSP) plant application are considered as the best thermal storage medium, and more precisely molten chlorides, presenting a wide operating range and coupled with competitive cost. Furthermore, MgCl2-NaCl-KCl (MgNaK) mixture appeared as the most promising one but need further studies to better understand its thermophysical properties. Indeed, its hydrated form leads to the formation of corrosive compounds. In this research, two different methods are used to model the ternary mixture. The dehydration process is evaluated by thermodynamical calculations with Thermocalc software. Then, the local structure, thermal conductivity and viscosity are estimated by means of molecular dynamics simulation, with LAMMPS package. The results were close to past simulations studies and experimental references, but discrepancies need to be further minimized regarding some variable fluctuations

Corrosion study of Ni-based alloy in ternary chloride salt for thermal storage application

MgCl2/NaCl/KCl salt appeared as a high-potential heat transfer fluid for concentrated solar application, offering a wide operating range and low cost. Nevertheless, MgCl2 hydrates and atmosphere relative humidity are the limiting factors for a real scale CSP plant, leading to severe corrosion. Thus, Inconel 617 was tested at 700ºC up to 24 h in air atmosphere to simulate a punctual failure in the inertization system of a plant. XRD and SEM-EDX analysis showed unstable multilayers growing in cascade, highlighting chromium, aluminum, magnesium, and oxygen activities. Additionally, A radial growth of MgCr2O4 at the expense of MgO grains was visualized

Past research and future strategies for molten chlorides application in concentrated solar power technology

This review summarizes past research and future strategies for the improvement of the pair heat transfer fluids (HTF) - containing material, used in concentrated solar power (CSP) plants, focusing on the most interesting and promising HTF, chloride molten salts. Indeed, their low cost and operating range temperature make them very strong potential candidates for future CSP plants, furthermore improvable by wisely adding nanoparticles. Nevertheless, their well-known aggressive behaviour entails selecting a long-lasting resistant alloy, which requires a better understanding of its associated corrosion mechanisms and the influences of its alloying elements. Mitigation strategy mechanisms that come from salt impurities implying purification processes are also reviewed. Finally, thermogravimetric analysis (TGA) coupled with differential scanning calorimetry (DSC) for salt preparation, and numerical simulations on Thermocalc software modelling elements activities of selected alloys and their interaction with molten chlorides are discusse

Temperature effect and alloying elements impact on the corrosion behaviour of the alloys exposed to molten carbonate environments for CSP application

This investigation assesses the effect of the alloy composition and temperature in the corrosivity of the ternary carbonate eutectic, 32% Li2CO3, 33% Na2CO3, 35% K2CO3. To this end, an iron-based alloy, coded as 51Fe-24Cr-20Ni, and a nickel-based alloy, coded as 5Fe–23Cr-58Ni-8Mo, were exposed to the carbonate mixture for 500 h at 700 ºC, 750 ºC and 800 ºC under static atmospheric air. The results revealed that corrosion extension does not have a linear dependence on temperature. There are changes in the corrosion mechanism that depend on the temperature, but, in turn, they are directly influenced by the alloying elements of the material. The performance of the nickel-based substrate proved to be catastrophic at all the studied temperatures. The order from worst to best was 700 ºC > 750 ºC > 800 ºC. The presence of a high molybdenum concentration in the carbonate mixture in contact with this nickel-based alloy suggested that this element dissolution contributes to increasing the corrosivity of the mixture. By contrast, the iron-based alloy showed improved corrosion resistance, with an estimated corrosion rate in the order of hundreds of microns at the three temperatures. The best performance of the 51Fe-24Cr-20Ni alloy was achieved at 700 ºC, followed by that at 800 ºC, while the highest degradation was registered at 750 ºC. This investigation reinforced the idea of the complexity of the corrosion processes in molten carbonate. The equilibrium of corrosive species is very sensitive to an important number of parameters, meaning that modifications in the system conditions have a great impact on corrosivity. Hence, it is critical not to make assumptions when considering potential materials for carbonate containment in CSP technology

La ciencia y tecnología químicas al servicio de la sociedad: actividad formativa para los alumnos del Máster en Ciencia y Tecnología Químicas

Depto. de Química FísicaFac. de Ciencias QuímicasFALSEsubmitte

CHEM-E-CAR: From theory to practice. Construction of a prototype

El proyecto consiste en construir un prototipo de coche “Chem-E-Car” y constituir a la UCM como una de las primeras universidades españolas que participa en dicha competición internacional.The objective of the project consists of building a prototype car "Chem-E-Car" and constitute the UCM as one of the first Spanish universities participating in this international competition.FALSEsubmitte