18 results on '"Solar salt"'
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2. Life Cycle Assessment of the Fluids Used in a Concentrated Solar Power Plant.
- Author
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Javier Pérez, Francisco, Batuecas, Esperanza, Encinas-Sánchez, Víctor, Isabel Lasanta, María, Teresa de Miguel, María, García-Martín, Gustavo, Mayo, Carlos, and Díaz, Ricardo
- Subjects
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SOLAR power plants , *FUSED salts , *SYNTHETIC lubricants , *HEAT transfer fluids , *PRODUCT life cycle assessment - Abstract
In the present work, the environmental damage of two types of molten salts and synthetic oil has been evaluated with the aim of deciding whether the use of molten salts is more suitable than synthetic oil from an environmental point of view. To this end Life Cycle Assessment has been used, since it offers numerous advantages in the assessment of aspects associated with the development of a product and its potential impact throughout the life of a given product from raw material acquisition, processing, manufacturing, use and finally its disposal. According to the results, the replacement of the VP-1 like thermal oil by molten salts is absolutely recommended from an environmental perspective, since the environmental impact of molten salts appear to be reduced in comparison to Therminol®VP-1. Thus, direct systems, in which thermal storage and heat transfer fluid are unified using molten salts, emerge to improve the power cycle performance, these being a good option not only from the known technical point of view, but also from the environmental point of view. Life Cycle Assessment seems to be a suitable and necessary methodology to quantify the environmental impacts of fluids, materials, and O&M in CSP plants. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
3. Electrochemical impedance spectroscopy (EIS): An efficient technique for monitoring corrosion processes in molten salt environments in CSP applications.
- Author
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Encinas-Sánchez, V., de Miguel, M.T., Lasanta, M.I., García-Martín, G., and Pérez, F.J.
- Subjects
- *
IMPEDANCE spectroscopy , *CORROSION & anti-corrosives , *FUSED salts , *MARTENSITIC stainless steel , *GRAVIMETRIC analysis , *ANALYTICAL chemistry - Abstract
Abstract This study assessed the behaviour of a constructive material in CSP plants, namely ferritic-martensitic steel, with molten NaNO 3 /KNO 3 (60/40 wt%), also known as Solar Salt. To this end, EIS is presented as a suitable technique to evaluate and monitor the resistance of this material to Solar Salt at 580 °C. Tests were performed up to 1000 h and results were also supported by gravimetric and microstructural characterisation of the samples and chemical analysis of the salt. According to the EIS results, a diffusion-controlled reaction occurred during contact, which indicates that the corrosion process follows a porous layer mechanism. The results also indicated variations in corrosion layer thickness and instability of the salt during the whole test. The EIS results were also used for determining the corrosion rate, this being estimated at ~300 µm year−1. Results obtained by EIS were in line with the behaviour of P91 steel as measured by gravimetric, morphological and chemical analysis. Thus, the results confirm the suitability of EIS for monitoring corrosion processes in real-time of constructive materials in CSP plants. Highlights • EIS was used to monitor the corrosion resistance of a constructive material in CSP. • The behaviour of P91 in Solar Salt at 580 °C was evaluated and monitored for 1000 h. • EIS results indicated that the corrosion process follows a porous layer mechanism. • The EIS results estimated a corrosion rate of P91 at ~300 µm year−1. • Results obtained by EIS were in line with the ones obtained by other techniques. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
4. Dynamic Pilot Plant Facility for Applications in CSP: Evaluation of Corrosion Resistance of A516 in a Nitrate Molten Salt Mixture.
- Author
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Pérez, Francisco Javier, Encinas-Sánchez, Víctor, García-Martín, Gustavo, Lasanta, María Isabel, and de Miguel, María Teresa
- Subjects
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FUSED salts , *CORROSION resistance , *SOLAR energy , *DYNAMIC testing , *SOLAR power plants , *THERMAL efficiency , *THERMOCYCLING - Abstract
This paper evaluates the corrosion of A516 carbon steel in the binary Solar Salt (60 wt.% NaNO3/40 wt.% KNO3) by immersion tests with continuous salt flow at 500 °C. To this end, a novel patented experimental facility enabling dynamic degradation tests of materials in contact with molten mediums was developed and used. Experimental results showed greater corrosion rates and thicker oxide layers in samples subjected to tests with continuous salt flow than the static ones. The dynamic test facility simulates real conditions (flux, thermocycling, etc.) of a CSP plant. The patented experimental pilot plant is a great step forward in learning about the physicochemical properties and behavior of molten salts and also behavior of substrates in contact with them under realistic working conditions. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
5. Rheology of Solar-Salt based nanofluids for concentrated solar power. Influence of the salt purity, nanoparticle concentration, temperature and rheometer geometry.
- Author
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Muñoz-Sánchez, Belén, Nieto-Maestre, Javier, Veca, Elisabetta, Liberatore, Raffaele, Sau, Salvatore, Navarro, Helena, Ding, Yulong, Navarrete, Nuria, Juliá, J. Enrique, Fernández, Ángel G., and García-Romero, Ana
- Subjects
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SOLAR energy , *RHEOMETERS , *NANOFLUIDS , *RHEOLOGY , *VISCOSITY - Abstract
Solar Salt-based nanofluids have attracted significant scientific interest in recent years due to their improved thermal properties, making them strong candidates as thermal energy storage materials and/or heat transfer fluids in CSP plants. There have been reports on increased specific heat due to the addition of nanoparticles, however, there is a lack of comprehensive information on other essential properties affecting the heat transfer, such as the viscosity. This article concerns the rheological behaviour of nanofluids made of Solar Salt (mass percentage at 60% NaNO 3 – 40% KNO 3 ) as the base fluid and silica or alumina nanoparticles as additives. The evolution of these nanofluids viscosity as a function of the shear rate (1–1000 s −1 ) at a temperature range of 250–400 °C was measured and analysed. The impact of the salt purity (refined or industrial grade), the nanoparticle concentration (0.5–1.5 wt%) and the rheometer measuring configuration (coaxial cylinder or parallel plate) are examined. The results showed in general a Newtonian behaviour of the nanofluids with independency of the rheometer configuration. The relationship between the viscosity and the temperature follows an Arrhenius model. The influence of the nanoparticle concentration on the viscosity of the refined grade Solar Salt is analysed according to the Maron-Pierce and Kriegher-Dougherty models for the nanofluids containing alumina and silica nanoparticles respectively, due to their different shape. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
6. Experimental analysis of forced convective heat transfer of nitrate salt in a spirally grooved tube at high Reynolds numbers and temperatures.
- Author
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Frantz, Cathy, Buck, Reiner, Röger, Marc, and Hoffschmidt, Bernhard
- Subjects
- *
HEAT convection , *REYNOLDS number , *FUSED salts , *NITRATES , *NUSSELT number , *ENTHALPY , *FORCED convection , *PIPE flow - Abstract
• Review of the literature of the forced convective heat transfer of molten salts in enhanced tubes. • Measurement of the forced convective heat transfer of Solar Salt in a spirally grooved tube for 11000 < R e < 285000. • Comparison of the measured friction factor in a spirally grooved and a smooth tube to correlations from the literature. • Measurement of the Nusselt number at film temperatures above the chemical stability temperature limit of Solar Salt. The forced convective heat transfer and pressure difference of molten nitrate salt in a spirally grooved tube with a relative groove height e/2r i =0.017, a relative groove pitch p/2r i =0.913 and groove angle α=73.8° is experimentally investigated using a water-cooled induction heater setup. The data is provided for Reynolds numbers ranging between 11000 up to 285000 and Prandtl numbers from 3.7 to 10. The experiments are carried out for bulk salt temperatures ranging between 300 and 550 °C and for heating flux densities between 330 and 930 kW/m². Inner wall temperatures up to 633 °C are achieved with the setup, thus providing data on the behavior of the forced convective heat transfer as a function of inner wall temperature. The data is compared to the measurement results obtained with the same setup and a circular smooth tube as well as correlations and data from the literature in order to deduce relative Nusselt numbers and friction factors. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
7. A precise method to measure the specific heat of solar salt-based nanofluids.
- Author
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Muñoz-Sánchez, Belén, Nieto-Maestre, Javier, Imbuluzqueta, Gorka, Iparraguirre-Torres, Iñigo, Marañón, Izaskun, and García-Romero, Ana
- Subjects
- *
NANOFLUIDS , *HEAT storage devices , *SPECIFIC heat measurement , *SEA salt , *SOLAR power plant equipment , *DIFFERENTIAL scanning calorimetry - Abstract
A novel material has been developed for thermal energy storage at high temperatures (>300 °C) with enhanced thermal transport and storage properties. It is considered more efficient than the current molten salts used in the concentrated solar power plants. It is composed of an inorganic salt doped with a small percentage of nanoparticles (NPs), which are claimed to increase the specific heat compared with that of the raw salt. Thus, a precise determination of this thermal property is essential to perceive this enhancement. The specific heat of solar salt (SS) and a mixture of SS with 1 mass% of alumina NPs have been measured by the differential scanning calorimetry (DSC) technique. An isothermal procedure based on modulated DSC has been established to perform the measurements. The influence of the type of crucible, the amount of sample inside the crucible and the presence of moisture on the scattering of the data has been studied. Reliable results with a low uncertainty (<10%) were achieved by the use of T-zero aluminium hermetic crucibles, the mass increment of analysed sample (30 mg) and the absence of moisture inside the crucibles. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
8. Evaluation of corrosion resistance of A516 Steel in a molten nitrate salt mixture using a pilot plant facility for application in CSP plants.
- Author
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García-Martín, G., Lasanta, M.I., Encinas-Sánchez, V., de Miguel, M.T., and Pérez, F.J.
- Subjects
- *
CORROSION resistance , *NITRATES , *PILOT plants , *CARBON steel , *DYNAMIC testing - Abstract
This paper evaluates the corrosion of A516 carbon steel in the binary Solar Salt (60 wt% NaNO 3 /40 wt% KNO 3 ) by dynamic immersion test at 500 °C. To this end, a novel patented experimental facility enabling dynamic degradation tests of materials in contact with molten mediums was developed and used. Experimental results showed greater corrosion rates and thicker oxide layers in samples subjected to dynamic tests than the static ones. The dynamic test facility allows the simulation of (such as flux, thermocycling, etc.) of a CSP plant. The patented experimental pilot plant is a great step forward in learning about the physicochemical properties and behaviour of molten salts and also behaviour of substrates in contact with them under realistic working conditions. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
9. Chemical equilibria and intrinsic kinetics of reactions in molten nitrate salt
- Author
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Sötz, Veronika Anna and Thess, André (Prof. Dr.)
- Subjects
CSP ,Equilibrium Reactions ,Thermische Prozesstechnik ,Reaction Kinetics ,Solar Salt ,Thermal Energy Storage ,Nitrate Salt - Abstract
Die Nitratsalzmischung „Solarsalz“ wird als Wärmespeichermedium in großtechnischen Speichersystemen eingesetzt, die wesentliche Bestandteile von konzentrierenden Solarkraftwerken sind, um die Stromproduktion der Nachfrage anzupassen. Die Speichertemperatur beträgt in bestehenden Systemen maximal 565 °C, soll aber zukünftig ansteigen, um den Wirkungsgrad bei der Verstromung und die Speicherkapazität zu erhöhen. Chemische Reaktionen in Flüssigsalz werden jedoch durch steigende Temperaturen beschleunigt und verstärkt, was zu thermischer Instabilität des Speichermaterials führt und wodurch vermehrt Zersetzungsprodukte einschließlich korrosiver Ionen und toxischer Gase entstehen. Ein grundlegendes Verständnis des Zersetzungsprozesses ist notwendig, um die Materialien bei erhöhten Temperaturen stabil zu halten. In dieser Dissertation sind Reaktionen, die relevanten Zersetzungsprodukte bilden, experimentell untersucht und mathematisch beschrieben. Die Reaktion von Nitrationen zu Nitritionen stellt den ersten Schritt des Zersetzungsprozesses dar und das zugehörige chemische Gleichgewicht ist in zwei Temperaturbereichen (450-550 und 560-630 °C) bestimmt. Die intrinsische Kinetik der Nitritbildung ist bis 550 °C durch thermogravimetrische Analyse untersucht. Das differentielle Zeitgesetz enthält die Kinetik der Hin- als auch der Rückreaktion. Die Zersetzung von Nitritionen weiter zu Oxidionen wird als zweiter Schritt betrachtet. Erstmalig zeigt diese Arbeit Experimente, die ein chemisches Gleichgewicht mit Beteiligung von Oxidionen in Solarsalz belegen. Der Zusatz nitroser Gase zum Spülgas (synthetische Luft) stabilisiert den Oxidgehalt, was bei 600 und 620 °C nachgewiesen ist. Diese Ergebnisse sind besonders wertvoll, da Oxidionen Stahlkorrosion in Solarsalz verstärken. Die intrinsische Kinetik der Oxidbildung ist in Luftatmosphäre bis 630 °C untersucht und mathematisch ausgedrückt. Die Kinetikparameter sind durch Fit der experimentellen Ergebnisse ermittelt. Insgesamt bilden die Zersetzungsreaktionen ein konsistentes Netzwerk, das durch chemische Gleichgewichte und die intrinsische Kinetik zweier Reaktionen beschrieben ist. Die Ergebnisse tragen zur Entwicklung der Flüssigsalz-Wärmespeichertechnologie durch Vorhersage der Solarsalzstabilität bei bestehenden und höheren Betriebstemperaturen bei.
- Published
- 2021
- Full Text
- View/download PDF
10. Modeling of the Process Control of a High Performance Molten Salt Tower Receiver System Via State Machines
- Author
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Kunze, Tobias, Schwager, Christian, Frantz, Cathy, Ebert, Miriam, Teixeira, Carolina, and Christiano, José
- Subjects
Process Control ,CSP ,Solar Salt ,Solar Tower ,Simulation ,Nitrate Salt ,Receiver - Published
- 2021
11. Experimental Receiver Setup of a High Performance Molten Salt Test Receiver System
- Author
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Frantz, Cathy, Ebert, Miriam, Schlögl, Bärbel, Binder, Matthias, and Schuhbauer, Christian
- Subjects
Engineering ,CSP ,Solar Salt ,Solar Tower ,Nitrate Salt ,Receiver - Published
- 2021
12. Basic Engineering of a High Performance Molten Salt Tower Receiver System
- Author
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Cathy Frantz, Matthias Binder, Konrad Busch, Miriam Ebert, Andreas Heinrich, Nadine Kaczmarkiewicz, Bärbel Schlögl-Knothe, Tobias Kunze, Christian Schuhbauer, Markus Stetka, Christian Schwager, Michael Spiegel, Cristiano Teixeira Boura, Thomas Bauer, Alexander Bonk, Stefan Eisen, and Bernhard Funck
- Subjects
CSP ,Molten Salt ,Solar Salt ,Solar Tower ,Receiver - Published
- 2020
13. Thermo-optical simulation of a Star Receiver concept with molten nitrate salts
- Author
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Balusu, Shanmukha
- Subjects
CSP ,Solare Hochtemperatur-Technologien ,Molten Salt ,Solar Salt ,Solar Tower ,Receiver - Published
- 2020
14. Rheology of Solar-Salt based nanofluids for concentrated solar power. Influence of the salt purity, nanoparticle concentration, temperature and rheometer geometry
- Author
-
Elisabetta Veca, Ana García-Romero, J. Enrique Julia, Yulong Ding, Ángel G. Fernández, Salvatore Sau, Nuria Navarrete, Javier Nieto-Maestre, Helena Navarro, Belén Muñoz-Sánchez, and Raffaele Liberatore
- Subjects
Materials science ,Renewable Energy, Sustainability and the Environment ,020209 energy ,Rheometer ,Thermodynamics ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Thermal energy storage ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Shear rate ,Viscosity ,Nanofluid ,CSP ,Chemical engineering ,Rheology ,Heat transfer ,0202 electrical engineering, electronic engineering, information engineering ,Newtonian fluid ,rheology ,nanofluid ,nanoparticles ,solar salt ,0210 nano-technology ,TES - Abstract
Solar Salt-based nanofluids have attracted significant scientific interest in recent years due to their improved thermal properties, making them strong candidates as thermal energy storage materials and/or heat transfer fluids in CSP plants. There have been reports on increased specific heat due to the addition of nanoparticles, however, there is a lack of comprehensive information on other essential properties affecting the heat transfer, such as the viscosity. This article concerns the rheological behaviour of nanofluids made of Solar Salt (mass percentage at 60% NaNO3 – 40% KNO3) as the base fluid and silica or alumina nanoparticles as additives. The evolution of these nanofluids viscosity as a function of the shear rate (1–1000 s−1) at a temperature range of 250–400 °C was measured and analysed. The impact of the salt purity (refined or industrial grade), the nanoparticle concentration (0.5–1.5 wt%) and the rheometer measuring configuration (coaxial cylinder or parallel plate) are examined. The results showed in general a Newtonian behaviour of the nanofluids with independency of the rheometer configuration. The relationship between the viscosity and the temperature follows an Arrhenius model. The influence of the nanoparticle concentration on the viscosity of the refined grade Solar Salt is analysed according to the Maron-Pierce and Kriegher-Dougherty models for the nanofluids containing alumina and silica nanoparticles respectively, due to their different shape.
- Published
- 2018
15. Electrochemical impedance spectroscopy (EIS): An efficient technique for monitoring corrosion processes in molten salt environments in CSP applications
- Author
-
V. Encinas-Sánchez, Francisco Perez, Gustavo García-Martín, M.I. Lasanta, and M.T. de Miguel
- Subjects
Materials science ,Corrosion monitoring ,Salt (chemistry) ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Corrosion ,CSP ,Porous layer ,Molten salt ,chemistry.chemical_classification ,EIS ,Renewable Energy, Sustainability and the Environment ,Metallurgy ,021001 nanoscience & nanotechnology ,Layer thickness ,Constructive material ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Dielectric spectroscopy ,chemistry ,Gravimetric analysis ,Solar Salt ,0210 nano-technology - Abstract
This study assessed the behaviour of a constructive material in CSP plants, namelyferritic-martensitic steel, withmoltenNaNO3/KNO3(60/40 wt%), also known asSolar Salt. To this end, EIS is presented as a suitable technique to evaluate and monitor the resistance of this material to Solar Salt at 580 °C. Tests were performed up to 1000 h and results were also supported by gravimetric and microstructuralcharacterisationof the samples andchemical analysisof the salt. According to the EIS results, adiffusion-controlled reactionoccurred during contact, which indicates that the corrosion process follows aporous layermechanism. The results also indicated variations in corrosionlayer thicknessand instability of the salt during the whole test. The EIS results were also used for determining thecorrosion rate, this being estimated at ~300 µm year−1. Results obtained by EIS were in line with the behaviour of P91 steel as measured by gravimetric, morphological and chemical analysis. Thus, the results confirm the suitability of EIS for monitoring corrosion processes in real-time of constructive materials in CSP plants.
- Published
- 2019
- Full Text
- View/download PDF
16. Material aspects of Solar Salt for sensible heat storage
- Author
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Nils Breidenbach, Nicole Pfleger, Stefanie Kaesche, Markus Eck, Doerte Laing, and Thomas Bauer
- Subjects
business.industry ,Mechanical Engineering ,Inorganic chemistry ,Thermal decomposition ,molten nitrate ,Potassium nitrate ,Molten salt Corrosion Nitrite formation Oxide formation Thermophysical properties ,Building and Construction ,Management, Monitoring, Policy and Law ,Thermal energy storage ,Thermal diffusivity ,Solar energy ,Solar salt ,chemistry.chemical_compound ,General Energy ,CSP ,chemistry ,Chemical engineering ,Sodium nitrate ,Molten salt ,Thermal analysis ,business - Abstract
For sensible thermal energy storage (TES) in liquids in the temperature range from 250 °C to 550 °C, a mixture of 60 wt% sodium nitrate (NaNO 3 ) and 40 wt% potassium nitrate (KNO 3 ), known as Solar Salt, is commonly utilized. At the time of writing, TES technology for concentrating solar power is the major application. Although commercial systems have been demonstrated, there are still several material aspects to be investigated. In this paper we address thermophysical properties and metallic corrosion, as well as thermal decomposition processes. The paper reviews temperature dependent thermophysical properties of Solar Salt. Deviations among the authors of these properties were small for the density (±1.5%), medium for the heat capacity (±7%) and large for thermal diffusivity and thermal conductivity values (±15%). The paper gives an overview of the various aspects of steel corrosion in molten alkali nitrate salts. From literature data, four steel type categories mainly depending on the temperature range are defined. The paper presents thermal stability examinations of Solar Salt and NaNO 3 by isothermal lab-scale tests and thermal analysis measurements. Salt analysis in the isothermal test showed a steadily increasing oxide level at a constant nitrite to nitrate ratio. The result shows that there are kinetic differences in the first decomposition process with nitrite formation and the second decomposition process with oxide formation. The impact of the partial oxygen pressure on the decomposition temperature was examined by thermogravimetric measurements. Measurements show an improved stability limit for higher partial oxygen pressures.
- Published
- 2013
17. Test setup for the experimental evaluation of the convective heat transfer for nitrate salt in tubular solar receivers
- Author
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Frantz, Cathy, Buck, Reiner, and Röger, Marc
- Subjects
Measurement ,Induction heating ,CSP ,Heat transfer ,Solar Salt ,Solar Tower ,Nusselt number ,Nitrate Salt ,Receiver
18. Preheat strategy of a molten salt test receiver
- Author
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Reisch, Isabell, Frantz, Cathy, Ebert, Miriam, Binder, Michael, and Schuhbauer, Christian
- Subjects
CSP ,Preheat strategy ,Thermal FEM ,Solar Salt ,Solar Tower ,operation strategy ,Nitrate Salt ,Receiver
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