Specific heat mechanism of molten salt nanofluids

2014 ◽  
Vol 104 (12) ◽  
pp. 121914 ◽  
Author(s):  
D. Shin ◽  
H. Tiznobaik ◽  
D. Banerjee
Keyword(s):  
Specific Heat ◽  
Molten Salt ◽  
Heat Mechanism

scholarly journals Anomalous Increase in Specific Heat of Binary Molten Salt-Based Graphite Nanofluids for Thermal Energy Storage

2018 ◽  
Vol 8 (8) ◽  
pp. 1305 ◽  
Author(s):  
Hyun Kim ◽  
Byeongnam Jo
Keyword(s):  
Specific Heat ◽  
Molten Salt ◽  
Base Fluid ◽  
Solid Phase ◽  
Layer Structure ◽  
Synthesis Process ◽  
Nanoparticle Concentration ◽  
Anomalous Increase ◽  
Salt Mixtures ◽  
Graphite Nanoparticles

An anomalous increase of the specific heat was experimentally observed in molten salt nanofluids using a differential scanning calorimeter. Binary carbonate molten salt mixtures were used as a base fluid, and the base salts were doped with graphite nanoparticles. Specific heat measurements of the nanofluids were performed to examine the effects of the composition of two salts consisting of the base fluid. In addition, the effect of the nanoparticle concentration was investigated as the concentration of the graphite nanoparticles was varied from 0.025 to 1.0 wt %. Moreover, the dispersion homogeneity of the nanoparticles was explored by increasing amount of surfactant in the synthesis process of the molten salt nanofluids. The results showed that the specific heat of the nanofluid was enhanced by more than 30% in the liquid phase and by more than 36% in the solid phase at a nanoparticle concentration of 1 wt %. It was also observed that the concentration and the dispersion homogeneity of nanoparticles favorably affected the specific heat enhancement of the molten salt nanofluids. The dispersion status of graphite nanoparticles into the salt mixtures was visualized via scanning electron microscopy. The experimental results were explained according to the nanoparticle-induced compressed liquid layer structure of the molten salts.

scholarly journals The Effects of Nanoparticles on the Specific Heat Capacity of Molten Salts

2018 ◽  
Vol 5 ◽  
pp. 56-65
Author(s):  
Alexander Foldi ◽  
Duy Khang Simba Nguyen ◽  
Yeong Cherng Yap
Keyword(s):  
Heat Capacity ◽  
Thermal Properties ◽  
Specific Heat ◽  
Molten Salt ◽  
Specific Heat Capacity ◽  
Molten Salts ◽  
Power Plants ◽  
Renewable Energy Sources ◽  
Efficiency Increase ◽  
Solar Power Plants

The desire to increase the efficiency of existing renewable energy sources has been thoroughly researched over the past years. This meta study aimed to investigate existing methods used by previous researchers to increase the Specific Heat Capacity of Molten Salt used for Concentrated Solar Power Plants. Investigations into nanoparticles were explored because of the effect of particle size and concentration can potentially increase the specific heat capacity of the molten salt. Numerous nanoparticles have shown to improve the thermal properties such as Silica (SiO2), Alumina (Al2O3), Titania (TiO2). Our summation was that the addition of nanoparticles into Molten Salts shows an increase in desired thermal properties of the Molten Salts. An efficiency increase of up to 28% was noted in the SHC (Cp) of the Molten Salts when Nanoparticles of 60nm were introduced.

scholarly journals The Effect of In Situ Synthesis of MgO Nanoparticles on the Thermal Properties of Ternary Nitrate

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5737
Author(s):  
Zhiyu Tong ◽  
Linfeng Li ◽  
Yuanyuan Li ◽  
Qingmeng Wang ◽  
Xiaomin Cheng
Keyword(s):  
Heat Transfer ◽  
Heat Capacity ◽  
Thermal Properties ◽  
Specific Heat ◽  
Molten Salt ◽  
Specific Heat Capacity ◽  
Ternary Eutectic ◽  
Mgo Nanoparticles ◽  
Nitrate System

The multiple eutectic nitrates with a low melting point are widely used in the field of solar thermal utilization due to their good thermophysical properties. The addition of nanoparticles can improve the heat transfer and heat storage performance of nitrate. This article explored the effect of MgO nanoparticles on the thermal properties of ternary eutectic nitrates. As a result of the decomposition reaction of the Mg(OH)2 precursor at high temperature, MgO nanoparticles were synthesized in situ in the LiNO3–NaNO3–KNO3 ternary eutectic nitrate system. XRD and Raman results showed that MgO nanoparticles were successfully synthesized in situ in the ternary nitrate system. SEM and EDS results showed no obvious agglomeration. The specific heat capacity of the modified salt is significantly increased. When the content of MgO nanoparticles is 2 wt %, the specific heat of the modified salt in the solid phase and the specific heat in the liquid phase increased by 51.54% and 44.50%, respectively. The heat transfer performance of the modified salt is also significantly improved. When the content of MgO nanoparticles is 5 wt %, the thermal diffusion coefficient of the modified salt is increased by 39.3%. This study also discussed the enhancement mechanism of the specific heat capacity of the molten salt by the nanoparticles mainly due to the higher specific surface energy of MgO and the semi-solid layer that formed between the MgO nanoparticles and the molten salt.

Effect of Synthesis Protocol in Enhancing Heat Capacity of Molten Salt Nanofluids

2020 ◽  
Author(s):  
Baha El Far ◽  
Syed Muhammad Mujtaba Rizvi ◽  
Yousof Nayfeh ◽  
Donghyun Shin
Keyword(s):  
Heat Capacity ◽  
Specific Heat ◽  
Molten Salt ◽  
Renewable Energy Sources ◽  
Temperature Stability ◽  
Underlying Mechanism ◽  
Energy Conversion Efficiency ◽  
Ternary Mixtures ◽  
High Temperature Stability ◽  
Synthesis Conditions

Abstract Concentrated solar power (CSP) incorporated with thermal energy storage (TES) is an appealing solar energy generation technology. TES stores heat during the daytime and releases it in the nighttime. As a result, CSP can produce continuously even at night. Storing heat by TES makes CSP a unique technology among various renewable energy sources which often suffer from the intermittency of energy supply (e.g., wind turbines without wind, photovoltaics at night, etc.). The energy conversion efficiency of CSP is directly related to the properties of the TES medium. Binary or ternary mixtures of molten salts (Solar Salt) are commonly used as the TES in CSP due to its high-temperature stability. Enhancing the thermophysical properties of the molten salt medium can significantly improve TES performance. Various studies have reported the anomalous specific heat enhancement of molten salt-based nanofluids. However, the underlying mechanism for this enhancement was yet discovered. In this study, the effect of different synthesis conditions on the resultant specific heat capacity of molten salt-based nanofluids was investigated. Several molten salt nanofluids (NaNO3–KNO3 with SiO nanoparticles at 1 wt. % concentration) were prepared at different thermal cycling conditions and their thermal performance was characterized by a differential scanning calorimeter (DSC).

A Literature Review on Novel Nitrate Molten Salt for Heat Storage

2021 ◽  
Vol 881 ◽  
pp. 87-94
Author(s):  
Jin Hua Chen
Keyword(s):  
Thermal Stability ◽  
Heat Capacity ◽  
Melting Point ◽  
Specific Heat ◽  
Molten Salt ◽  
Specific Heat Capacity ◽  
Molten Salts ◽  
Heat Storage ◽  
Stability Limit ◽  
Capacity Enhancement

Reducing the melting point, in creasing the thermal stability limit, and enhancing the specific heat capacity of molten salt are the research hotspots in the field of medium and high temperature energy storage in recent years. From the perspectives of the melting point, thermal stability limit, and specific heat capacity of nitrates, we summarize the melting point, thermal stability limit, and specific heat capacity enhancement of molten salts with different compositions and ratios. The melting points of molten salt with different compositions and ratios are compared. Furthermore, the enhancing effect of various nanomaterials on molten salt is elucidated. The application of nitrate molten salt is also summarized to provide a reference for the research and application of novel molten salts. Keywords: Nitrate Molten Salt; Melting Point; Thermal Stability Limit; Specific Heat Capacity; Application

Experimental Investigation of Molten Salt Nanofluid for Solar Thermal Energy Application

2011 ◽  
Author(s):  
Donghyun Shin ◽  
Debjyoti Banerjee
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Specific Heat ◽  
Molten Salt ◽  
Specific Heat Capacity ◽  
Thermal Energy ◽  
Molten Salts ◽  
Solar Power ◽  
Solar Thermal ◽  
Wide Range

The overall efficiency of a Concentrated Solar Power (CSP) system is critically dependent on the thermo-physical properties of the Thermal Energy Storage (TES) components and the Heat Transfer Fluid (HTF). Higher operating temperatures in CSP result in enhanced thermal efficiency of the thermodynamic cycles that are used in harnessing solar energy (e.g., using Rankine cycle or Stirling cycle). Particlularly, high specific heat capacity (Cp) and high thermal conductivity (k) of the HTF and TES materials enable reduction in the size and overall cost of solar power systems. However, only a limited number of materials are compatible for the high operating temperature requirements (exceeding 400°C) envisioned for the next generation of CSP systems. Molten salts have a wide range of melting point (200°C∼500°C) and are thermally stable up to 700°C. However, thermal property values of the molten salts are typically quite low (Cp is typically less than ∼2J/g-K and k is typically less than ∼1 W/m-K). To obviate these issues the molten salts can be doped with nanoparticles — resulting in the synthesis / formation of nanomaterials (nanocomposites and nanofluids). Nanofluids are colloidal suspensions formed by doping with minute concentration of nanoparticles. Nanofluids were reported for anomalous enhancement in their thermal conductivity values. In this study, molten salt-based nanofluids were synthesized by liquid solution method. A differential scanning calorimeter (DSC) was used to measure the specific heat capacity values of the proposed nanofluids. The observed enhancement in specific heat is then compared with predictions from conventional thermodynamic models (e.g. thermal equilibrium model or “simple mixing rule”). Transmission Electron Microscopy (TEM) is used to verify that minimal aggregation of nanoparticles occurred before and after the thermocycling experiments. Thermocycling experiments were conducted for repeated measurements of the specific heat capacity by using multiple freeze-thaw cycles of the nanofluids/ nano-composites, respectively. This study demonstrates the feasibility for using novel nanomaterials as high temperature nanofluids for applications in enhancing the operational efficiencies as well as reducing the cost of electricity produced in solar thermal systems utilizing CSP in combination with TES.

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