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Corrosion of Commercial Alloys in Thermal Energy Storage Material of Molten MgCl2/KCl/NaCl under Inert Atmosphere

Ding, Wenjin and Xiu, Yanlei and Bonk, Alexander and Bauer, Thomas and Shi, Hao and Jianu, Adrian and Weisenburger, Alfons (2018) Corrosion of Commercial Alloys in Thermal Energy Storage Material of Molten MgCl2/KCl/NaCl under Inert Atmosphere. IRES 2018, 13.-15. März, 2018, Düsseldorf, Germany.

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Abstract

Molten chloride salt mixtures are promising thermal energy storage (TES) materials to be applied in concentrating solar power (CSP) plants, due to their high thermal stability, good thermal conductivity, high heat capacity but low price. Their high thermal stability makes them appropriate candidates to replace the commercial TES materials in CSP - nitrate salt mixtures (stable up to 550 °C), when higher operating temperatures are required (up to 700 °C) for higher efficiency of thermal to electrical energy conversion. However, the application of molten chloride salts at higher temperatures causes additional challenges such as increased corrosiveness of containers and structural materials. It is well known that the corrosion rates significantly depend on the concentration of corrosive hydroxide impurities in the salts, which arise mainly from water and oxygen existing in the salts and/or the atmosphere above the salts, since they can produce very corrosive H+ ions. However, to our knowledge, few publications quantitatively show the effect of the corrosive hydroxide impurities on the corrosion rates. In our previous work, an electrochemical method based on cyclic voltammetry (CV) has been developed to fast in-situ measure the concentration of the hydroxide impurities in molten MgCl2/KCl/NaCl (60/20/20 mole%) salts at 500-700 °C. In this work, we use an electrochemical method based on open-circuit voltage (OCV) and potentiodynamic polarization (PP) to fast in-situ measure the corrosion rates of studied alloys in molten chlorides, when the concentration of the corrosive hydroxide impurities varies in a wide range. By analyzing the data from CV and PP, the effects of the hydroxide impurities and the temperature on the corrosion rates are investigated quantitatively. This helps to develop an advanced technology, which could effectively and affordably control the concentration of the impurities in operating molten chloride salts, and thus the corrosion of structural metallic components in contact with the molten salts.

Item URL in elib:https://elib.dlr.de/125822/
Document Type:Conference or Workshop Item (Poster)
Title:Corrosion of Commercial Alloys in Thermal Energy Storage Material of Molten MgCl2/KCl/NaCl under Inert Atmosphere
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Ding, WenjinWenjin.Ding (at) dlr.dehttps://orcid.org/0000-0001-5037-5810
Xiu, YanleiYanlei.Xiu (at) dlr.deUNSPECIFIED
Bonk, AlexanderAlexander.Bonk (at) dlr.dehttps://orcid.org/0000-0002-0676-7267
Bauer, Thomasthomas.bauer (at) dlr.dehttps://orcid.org/0000-0003-4080-7944
Shi, HaoInstitute for Pulsed Power and Microwave Technology, Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen, GermanyUNSPECIFIED
Jianu, AdrianInstitute for Pulsed Power and Microwave Technology, Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen, GermanyUNSPECIFIED
Weisenburger, AlfonsInstitute for Pulsed Power and Microwave Technology, Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen, GermanyUNSPECIFIED
Date:15 March 2018
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Status:Published
Keywords:Concentrating solar power (CSP), corrosion, cyclic voltammetry (CV), molten salt, hydroxide impurities, potentiodynamic polarization (PP).
Event Title:IRES 2018
Event Location:Düsseldorf, Germany
Event Type:international Conference
Event Dates:13.-15. März, 2018
Organizer:EUROSOLAR The European Association for Renewable Energy
HGF - Research field:Energy
HGF - Program:Storage and Cross-linked Infrastructures
HGF - Program Themes:Thermal Energy Storage
DLR - Research area:Energy
DLR - Program:E SP - Energy Storage
DLR - Research theme (Project):E - Thermochemical Processes (Storage)
Location: Stuttgart
Institutes and Institutions:Institute of Engineering Thermodynamics > Thermal Process Technology
Deposited By: Ding, Wenjin
Deposited On:10 Jan 2019 15:40
Last Modified:10 Jan 2019 15:40

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