Investigation of time–temperature dependency of heat capacity enhancement in molten salt nanofluids

Rizvi, Syed Muhammad Mujtaba; Far, Baha El; Nayfeh, Yousof; Shin, Donghyun

doi:10.1039/d0ra03666h

Cited by 11 publications

(10 citation statements)

References 86 publications

(165 reference statements)

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“…For alumina nanoparticles (∼10 nm), Shin and Banerjee 9 reported a 32% C P enhancement at a heating rate of 20 °C min −1 in the DSC test. In contrast, Rizvi et al 10 found a 2.53% C P enhancement at a heating rate of 10 °C min −1 for alumina nanoparticles having an average size of 10.8 nm. In addition, they reported that the specific heat capacity enhancement increases with decreasing heating rate with a maximum of 23.4% for a heating rate of 2 °C min −1 .…”

Section: Introductionmentioning

confidence: 83%

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

Parida

Basu

2023

RSC Adv.

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Section: Introductionmentioning

confidence: 83%

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

Parida

Basu

2023

RSC Adv.

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“…However, before any type of grain growth could occur, these nuclei must reach a critical radius. A critical radius is defined as the radius of nuclei that must be reached before it could grow independently into a grain 31 mathematically 9,32,33 :

r^{*} = - \frac{2 γ_{SL}}{Δ G_{v}} where Δ G_{v} = \frac{Δ H_{f} ((), T_{m} - T)}{T_{m}}

where, r * is the critical radius required to reach the stability of nuclei, Y SL is energy present at liquid‐solid interface, ΔG v is the difference of Gibbs free energy of two phases, ΔH f is the latent heat of formation, T m is a melting point. As Y SL , Δ H f , T m are constants, they can combine as:

r^{*} = ((), - \frac{2 γ_{SL} T_{m}}{normalΔ H_{f}}) ((), \frac{1}{T_{m} - T})

…”

Section: Discussionmentioning

confidence: 99%

Section: Heat Capacity Enhancementmentioning

confidence: 99%

“…[1][2][3][4][5] Reported molten salt nanofluids with enhanced heat capacity include carbonate salts, nitrate salts, and chloride salts. 1,2,[6][7][8] These salt eutectic mixtures have been studied for various thermophysical properties such as heat capacity, 9 viscosity, 10,11 and stability. 12 However, how the heat capacity enhancement is enhanced is still undiscovered.…”

Section: Introductionmentioning

confidence: 99%

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Heat capacity and viscosity of ternary carbonate nanofluids

Rizvi

Far

Shin

2020

Intl J of Energy Research

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Recent studies have shown that eutectic salt mixtures show remarkable enhancement in heat capacity after nanoparticles are dispersed at small concentrations. The exact mechanism behind these heat capacity enhancements is still inconclusive. However, recent studies proposed that the enhancement could be associated with nucleation and grain growth of salt dendritic structures. To investigate the hypothesis, we synthesized several samples of ternary carbonate salt mixture doped with 1% alumina nanoparticles and thermally cycled them at various heating rates and cooled them back to the solid-state during the synthesis procedure. It can affect the nucleation/grain growth of salt dendritic nanostructures and, as a result, there can be different heat capacity enhancements. A differential scanning calorimetry was employed to characterize the heat capacity values of the systems. It was observed that the heat capacity enhancements decreased with increases in the heating rates. The highest heat capacity enhancement was observed at the lowest heating rate (ie, 2 C/min). A transmission electron microscope was employed to confirm the effect of heating cycling rates on the formation of dendritic structures. Moreover, pH variation method was used to study the effect of the dendritic structures on the heat capacity of the mixture. Furthermore, a rheometer was employed to characterize the rheological behavior. It was observed that nanofluid samples showed shear-thinning behavior, whereas shear thinning was not observed in pure and nanofluid prepared with the pH variation method.

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“…A sample of 9-13 mg of the salt was extracted from the crucible and transferred into a Tzero hermetic pan (TA Instruments, New Castle, DE, USA), the pan was then heated on a hot plate (Isotemp Hotplate, Fisher Scientific, Waltham, MA, USA) at 500 • C for 5 min to remove any remaining moisture and then hermetically sealed with a lid (TA Instruments, New Castle, DE, USA). Each sample was heated inside the DSC at a slow heating rate of 2 • C/min starting from 200 • C up to 560 • C and cooled back to 200 • C, this step is known to promote higher heat capacity enhancements in molten salt nanofluids by inducing nano-structural changes in salt mixtures [32]. Then, the specific heat measurement took place in the DSC at a heating rate of 20 • C according to the standard heat capacity testing protocol (ASTM E-1269 [33]).…”

Section: Methodsmentioning

confidence: 99%

In Situ Synthesis of Alumina Nanoparticles in a Binary Carbonate Salt Eutectic for Enhancing Heat Capacity

et al. 2020

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A binary carbonate salt eutectic (Li2CO3-K2CO3)-based nanofluid was in situ synthesized by mixing with a precursor material, aluminum nitrate nonahydrate (Al(NO3)3·9H2O). Thermal decomposition of the precursor was successfully carried out to synthesize alumina (Al2O3) nanoparticles at 1 wt.% concentration. A thermogravimetric analysis (TGA) confirmed a complete thermal decomposition of aluminum nitrate nonahydrate to alumina nanoparticles. A transmission electron microscope (TEM) was employed to confirm the size and shape of the in situ formed nanoparticles; the result showed that they are spherical in shape and the average size was 28.7 nm with a standard deviation of 11.7 nm. Electron dispersive X-ray spectroscopy (EDS) confirmed the observed nanoparticles are alumina nanoparticles. A scanning electron microscope (SEM) was employed to study microstructural changes in the salt. A differential scanning calorimeter (DSC) was employed to study the heat capacity of the in situ synthesized nanofluid. The result showed that the heat capacity was enhanced by 21% at 550 °C in comparison with pure carbonate salt eutectic. About 10–11 °C decrease of the onset melting point of the binary carbonate salt eutectic was observed for the in situ synthesized nanofluids.

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Investigation of time–temperature dependency of heat capacity enhancement in molten salt nanofluids

Abstract: In this study, the time–temperature dependency of heat capacity enhancement in molten salt nanofluids was studied experimentally.

Cited by 11 publications

References 86 publications

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

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

Heat capacity and viscosity of ternary carbonate nanofluids

In Situ Synthesis of Alumina Nanoparticles in a Binary Carbonate Salt Eutectic for Enhancing Heat Capacity

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