Synthesis and Characterization of Molten Salt Nanofluids for Thermal Energy Storage Application in Concentrated Solar Power Plants—Mechanistic Understanding of Specific Heat Capacity Enhancement

Abstract

Molten salts mixed with nanoparticles have been shown as a promising candidate as the thermal energy storage (TES) material in concentrated solar power (CSP) plants. However, the conventional method used to prepare molten salt nanofluid suffers from a high material cost, intensive energy use, and laborious process. In this study, solar salt-Al2O3 nanofluids at three different concentrations are prepared by a one-step method in which the oxide nanoparticles are generated in the salt melt directly from precursors. The morphologies of the obtained nanomaterials are examined under scanning electron microscopy and the specific heat capacities are measured using the temperature history (T-history) method. A non-linear enhancement in the specific heat capacity of molten salt nanofluid is observed from the thermal characterization at a nanoparticle mass concentration of 0.5%, 1.0%, and 1.5%. In particular, a maximum enhancement of 38.7% in specific heat is found for the nanofluid sample prepared with a target nanoparticle mass fraction of 1.0%. Such an enhancement trend is attributed to the formation of secondary nanostructure between the alumina nanoparticles in the molten salt matrix following a locally-dispersed-parcel pattern. These findings provide new insights to understanding the enhanced energy storage capacity of molten salt nanofluids.

On the specific heat capacity of HITEC-salt nanocomposites for concentrated solar power applications

“…For a detailed discussion on the T-history method and its calculations, see ref. 43–45. In the end, the surface morphology of the nanocomposites is investigated for possible representative microstructures using scanning electron microscopy (SEM; make: Carl Zeiss Ultra 55 field-emission scanning electron microscope) with an accelerating voltage of 5 kV at the Micro and Nano Characterization Facility (MNCF), Centre for Nano Science and Engineering, IISc Bangalore.…”

Molten salts: Potential candidates for thermal energy storage applications

“…One of the most recent initiatives to improve heat exchange and overall performance of CSPP and NPP is the addition of nano-particles, often known as nano-fluids, to the molten salts. 147,148 Nano-fluids are a new class of HTFs developed by diffusing nanoparticles (size <100 nm) in standard HTFs. 149 These nanoparticles might be organic, like fluorescent nanoparticles, or inorganic, like SiO 2 or silica, and Al 2 O 3 or alumina.…”

“…It was observed that efficiency of a TES using molten salts can be further enhanced by improving their thermo‐physical attributes. One of the most recent initiatives to improve heat exchange and overall performance of CSPP and NPP is the addition of nano‐particles, often known as nano‐fluids, to the molten salts 147,148 . Nano‐fluids are a new class of HTFs developed by diffusing nanoparticles (size <100 nm) in standard HTFs 149 .…”

Comparative Numerical Study of Thermal Features Analysis between Oldroyd-B Copper and Molybdenum Disulfide Nanoparticles in Engine-Oil-Based Nanofluids Flow

“…The preferred fluid properties are important for the selected process, to facilitate the optimal combination procedure for a specific nanofluid. Consequently, it is critical to develop a collection of mixture procedures for the nanofluids' choice group, when subjected to objective properties and processes [2][3][4][5][6].…”