Advancing Radiative Heat Transfer Modeling in High-Temperature Liquid Salts

Carolyn Coyle, Emilio Baglietto, and Charles Forsberg*
Massachusetts Institute of Technology, Department of Nuclear Science and Engineering,
77 Massachusetts Avenue, Cambridge, Massachusetts 02139
Received December 9, 2019 | Accepted for Publication January 27, 2020

Abstract — Liquid salts have become more attractive as coolants for low-carbon power generation due to needs for high-temperature heat and affordable energy storage. Of particular interest are halide salts utilized in fluoride-salt-cooled high-temperature reactors, molten salt reactors, and high-magnetic-field fusion machines, as well as in concentrated solar power systems. Because of their high-temperature operation and semitransparent nature, the liquid salts in these designs may experience the effects of participating media radiative heat transfer (RHT). While some work has been conducted on measuring the thermophysical properties of these fluids, there is currently very little known about their radiative properties.

Here, we present the initial results of a two-part methodology to enhance RHT understanding and improve modeling in high-temperature liquid salts. First, an experimental apparatus designed to measure liquid chloride and fluoride salt absorption coefficients by Fourier transform infrared spectroscopy was
completed and validated with water measurements. Second, computational fluid dynamics (CFD) simulations were run to determine the contribution of thermal radiation to the overall heat transfer for flow between parallel plates. This geometry was used to verify code accuracy and investigate requirements for
absorption coefficient spectral banding. Future work will be to complete halide salt absorption measurements and couple them to the established CFD methods to identify geometries and temperatures where RHT is significant and enable prediction of heat transfer in such systems.

Keywords — Liquid salts, thermal radiation, infrared spectroscopy, computational fluid dynamics.
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