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The Radiative Heat Transfer Properties of Molten Salts and Their Relevance to the Design of Advanced Reactors

Chaleff, Ethan S
http://orcid.org/0000-0001-7313-4884
http://rave.ohiolink.edu/etdc/view?acc_num=osu1480539289737113

Abstract Details

2016, Doctor of Philosophy, Ohio State University, Nuclear Engineering.
Molten salts, such as the fluoride salt eutectic LiF-NaF-KF (FLiNaK) or the transition metal fluoride salt KF-ZrF4, have been proposed as coolants for numerous advanced reactor concepts. These reactors are designed to operate at high temperatures where radiative heat transfer may play a significant role. If this is the case, the radiative heat transfer properties of the salt coolants are required to be known for heat transfer calculations to be performed accurately. Chapter 1 describes the existing literature and experimental efforts pertaining to radiative heat transfer in molten salts. The physics governing photon absorption by halide salts is discussed first, followed by a more specific description of experimental results pertaining to salts of interest. The phonon absorption edge in LiF-based salts such as FLiNaK is estimated and the technique described for potential use in other salts. A description is given of various spectral measurement techniques which might plausibly be employed in the present effort, as well as an argument for the use of integral techniques. Chapter 2 discusses the mathematical treatments required to approximate and solve for the radiative flux in participating materials. The differential approximation and the exact solutions to the radiative flux are examined, and methods are given to solve radiative and energy equations simultaneously. A coupled solution is used to examine radiative heat transfer to molten salt coolants. A map is generated of pipe diameters, wall temperatures, and average absorption coefficients where radiative heat transfer will increase expected heat transfer by more than 10% compared to convective methods alone. Chapter 3 presents the design and analysis of the Integral Radiative Absorption Chamber (IRAC). The IRAC employs an integral technique for the measurement of the entire electromagnetic spectrum, negating some of the challenges associated with the methods discussed in Chapter 1 at the loss of spectral information. The IRAC design is validated by modeling the experiment in Fluent which shows that the IRAC should be capable of measuring absorption coefficients within 10%. Chapter 4 contains a parallel effort to experimental techniques, whereby information on absorption in salts is pursued using the Density Functional Theory code VASP. Photon-electron interactions are studied in pure salts such as LiF and are shown to be broadly transparent. Transition metal Fluoride salts such as KF-ZrF4 are shown to be broadly opaque. The addition of small amounts of transition metal impurities is studied by insertion of Chromium into the salt mixtures, which causes otherwise transparent salts to exhibit absorption coefficients significant to heat transfer. The spectral absorption coefficient for FLiNaK with Chromium is presented as is the average absorption coefficient as a function of impurity concentration. Chapter 5 discusses experimental efforts undertaken at The Ohio State University. Challenges with the constructed experimental apparatus are discussed and suggestions for future improvement on the technique are included. Finally, Chapter 6 contains broad conclusions pertaining to radiative transfer in advanced reactors.
Thomas Blue, PhD (Advisor)
Wolfgang Windl, PhD (Committee Member)
Xiaodong Sun, PhD (Committee Member)
Merat Khafizov, PhD (Committee Member)
236 p.
Nuclear Engineering
molten salt; radiative heat transfer; nuclear reactor; advanced reactors; salt-cooled reactor; density functional theory; DFT;

Recommended Citations

Citations

  • Chaleff, E. S. (2016). The Radiative Heat Transfer Properties of Molten Salts and Their Relevance to the Design of Advanced Reactors [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1480539289737113

    APA Style (7th edition)

  • Chaleff, Ethan. The Radiative Heat Transfer Properties of Molten Salts and Their Relevance to the Design of Advanced Reactors. 2016. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1480539289737113.

    MLA Style (8th edition)

  • Chaleff, Ethan. "The Radiative Heat Transfer Properties of Molten Salts and Their Relevance to the Design of Advanced Reactors." Doctoral dissertation, Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1480539289737113

    Chicago Manual of Style (17th edition)

osu1480539289737113
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This open access ETD is published by The Ohio State University and OhioLINK.