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Mechanism of heat capacity enhancement in molten salt nanofluids.

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Title: Mechanism of heat capacity enhancement in molten salt nanofluids.
Authors: Rizvi, Syed Muhammad Mujtaba1 (AUTHOR), Shin, Donghyun1 (AUTHOR) shin1d@cmich.edu
Source: International Journal of Heat & Mass Transfer. Nov2020, Vol. 161, pN.PAG-N.PAG. 1p.
Subjects: Heat capacity, Nanofluids, Fused salts, Dendritic crystals, Heterogenous nucleation, Discontinuous precipitation
Abstract: • Large variations in heat capacity enhancements were observed for various molten salt nanofluids. • 25% enhanced heat capacity observed in a molten salt nanofluid with dendritic nanostructure formation. • No significant heat capacity change observed in a molten slat nanofluid without dendritic nanostructure formation. • Material characterization discovered diluting the nanofluid sample with water hindered already formed dendritic nanostructures. • Inadequate control of moisture could be one reason behind the large variations in heat capacity enhancements between research groups. Recent studies (Shin et al., 2014; Tiznobaik and Shin, 2013) in molten salt nanofluids have discussed the possibility of the development of nano dendritic structures as a mechanism behind heat capacity enhancements. It is established that these nanostructures enhance heat capacity due to their increased surface area. Shin et al. explained that these structures might be resulting from micro-segregation in salt eutectic due to differences in the level of attraction between different types of salts and nanoparticles. However, it does not explain how this segregated salt develops into dendrites. In this study, Tiznobaik's work is further exploited and explained based on nucleation and grain growth of nucleated salt. It is proposed that segregated nucleate on the surface of nanoparticles via heterogeneous nucleation and grow into dendritic through single-dimensional grain growth. Experimental verification for heat capacity enhancement performed on differential scanning calorimeter (DSC). Transmission electron miscroscope (TEM) was employed imaging dendritic strcutures. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
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Abstract:• Large variations in heat capacity enhancements were observed for various molten salt nanofluids. • 25% enhanced heat capacity observed in a molten salt nanofluid with dendritic nanostructure formation. • No significant heat capacity change observed in a molten slat nanofluid without dendritic nanostructure formation. • Material characterization discovered diluting the nanofluid sample with water hindered already formed dendritic nanostructures. • Inadequate control of moisture could be one reason behind the large variations in heat capacity enhancements between research groups. Recent studies (Shin et al., 2014; Tiznobaik and Shin, 2013) in molten salt nanofluids have discussed the possibility of the development of nano dendritic structures as a mechanism behind heat capacity enhancements. It is established that these nanostructures enhance heat capacity due to their increased surface area. Shin et al. explained that these structures might be resulting from micro-segregation in salt eutectic due to differences in the level of attraction between different types of salts and nanoparticles. However, it does not explain how this segregated salt develops into dendrites. In this study, Tiznobaik's work is further exploited and explained based on nucleation and grain growth of nucleated salt. It is proposed that segregated nucleate on the surface of nanoparticles via heterogeneous nucleation and grow into dendritic through single-dimensional grain growth. Experimental verification for heat capacity enhancement performed on differential scanning calorimeter (DSC). Transmission electron miscroscope (TEM) was employed imaging dendritic strcutures. [ABSTRACT FROM AUTHOR]
ISSN:00179310
DOI:10.1016/j.ijheatmasstransfer.2020.120260