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.

Study of Specific Heat Capacity Enhancement of Molten Salt Nanomaterials for Solar Thermal Energy Storage (TES)

2012 ◽  
Author(s):  
Hongjoo Yang ◽  
Debjyoti Banerjee
Keyword(s):  
Heat Capacity ◽  
Energy Storage ◽  
Specific Heat ◽  
Molten Salt ◽  
Specific Heat Capacity ◽  
Power Plants ◽  
Eutectic Mixture ◽  
Solar Power Plants ◽  
Solvent Molecules ◽  
Compressed Layer

The overall thermal efficiency of solar power plants is highly sensitive to the operating characteristics of the Thermal Energy Storage (TES) devices. Enhancing the operating temperature of TES is imperative for enhancing the thermal efficacy of solar power plants. However, material property limitations for high temperature operation severely limit the choice of materials for TES. Molten salts and their eutectics are promising candidates for high temperature operation of TES. To enhance the thermal and operational efficiency of TES, the thermo-physical properties such as the specific heat capacity and thermal conductivity of the materials need to be maximized. The specific heat capacity (Cp) of molten salt is relatively smaller than other conventional TES materials. Recent studies have shown that addition of nanoparticles to molten salts can significantly enhance their specific heat capacity. Several transport and energy storage mechanisms have been proposed to account for these enhancements. Primarily, the layering of solvent molecules due to inter-molecular forces (due to competition between adhesive and cohesive forces) is observed at solid-liquid interface, leading to the formation of a more dense or “compressed layer” of solvent molecules on the dispersed nanoparticles. The formation and existence of the compressed layer has been demonstrated experimentally and from numerical predictions (e.g., Molecular Dynamics/ MD models). To verify the enhancement of specific heat capacity of molten salt nanofluids, the influence of compressed layer has been explored in this study. This implies that for the same amount (or concentration) of nanoparticle, the ratio of surface/volume of the individual nanoparticles can change significantly depending on the nanoparticles size and shape — which in turn can affect the mass fraction of the compressed layer formed on the surface of the nanoparticles. In this study, the specific heat capacity of the molten salt nanomaterials was investigated for: (a) silica nanoparticles in eutectic mixture of alkali chloride salt eutectics, and (b) silica nanoparticles in an eutectic mixture of alkali carbonate salts eutectics. The effect of the particle size distribution was considered in this study and it was observed that smaller nanoparticles contribute a larger proportion to the observed specific heat capacity enhancements. The size of distribution of the nanoparticles in the molten salt mixture/ nanomaterial (nanocomposites and nanofluids) was measured by using Scanning Electron Microscopy (SEM), and subsequently the actual number of nanoparticles (as a function of size) that were dispersed in molten salt fluid was calculated. The specific heat capacity of molten salt nanomaterial was calculated using a classical mixing model and by accounting for the contribution from the compressed layer in the mixture.

Experimental Study of the Effect of Nanoparticle Concentration on Thermo-Physical Properties of Molten Salt Nanofluids

2019 ◽  
Author(s):  
Hani Tiznobaik ◽  
Donghyun Shin
Keyword(s):  
Heat Capacity ◽  
Physical Properties ◽  
Specific Heat ◽  
Molten Salt ◽  
Specific Heat Capacity ◽  
Molten Salts ◽  
Power Plants ◽  
Nanoparticles Concentration ◽  
Thermo Physical Properties

Abstract Increased in thermo-physical properties of molten salt nanofluids have been reported. These findings makes molten salts nanofluids one of the most promising thermal energy storage media. One of the main application of these types of materials are in concentrated solar power plants. In this study, an investigation is performed on nanofluids specific heat capacity mechanisms in order to provide a reasonable description of the specific heat capacity enhancement of nanofluids. Then, a comprehensive experiments are performed on the effects of nanoparticles concentration on the specific heat capacity and materials characterization of molten salt nanofluids. This study is performed to analyze the optimum amount of nanoparticle and find the way to maximize the effects of nanoparticle on thermophysical properties of molten slat. Different molten salts nanofluids with varying nanoparticles concentration were synthesized. The specific heat capacities of mixtures were measured by a modulated scanning calorimeter. Moreover, the material characterization analyses were performed using scanning electron microscopy to investigate the micro-structural characterization of different nanofluids.

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.

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.

Experimental Study of Thermal Performance Enhancement of Molten Salt Nanomaterials

2018 ◽  
Author(s):  
Amirhossein Mostafavi ◽  
Vamsi Kiran Eruvaram ◽  
Donghyun Shin
Keyword(s):  
Heat Capacity ◽  
Specific Heat ◽  
Molten Salt ◽  
Specific Heat Capacity ◽  
Thermal Performance ◽  
Thermal Energy ◽  
Molten Salts ◽  
Elevated Temperatures ◽  
Performance Enhancement ◽  
Heat Transfer Fluid

Concentrating solar power (CSP) plants are one of the main technologies harvesting solar energy indirectly. In CSP systems, solar radiant light is concentrated into a focal receiver, where heat transfer fluid (HTF) as the energy carrier absorbs solar radiation. Thermal energy storage (TES) is the key method to expand operational time of CSP plants. Consequently, thermo-physical properties of the HTF is an important factor in transferring thermal energy. One of the promising chemicals for this purpose is a mixture of molten salts with stable properties at elevated temperatures. However, low thermal properties of molten salts, such as specific heat capacity (cp) around 1.5 kJ/kg°C, constrain thermal performance of CSP systems. Recently, many studies have been conducted to overcome this shortcoming, by adding minute concentration of nanoparticles. In this work, the selected molten salt eutectic is a mixture of LiNO3–NaNO3 by composition of 54:46 mol. % plus dispersing Silicon Dioxide (SiO2) nanoparticles with 10nm particle size. The results from the measured specific heat capacity by modulated differential scanning calorimeter (MDSC) shows a 9% cp enhancement. Moreover, the viscosity of the mixture is measured by a rheometer and the results show that the viscosity of molten salt samples increases by 27% and this may result in increasing the pumping energy of the HTF. Consequently, overall thermal performance of the selected mixture is investigated by figure of merit (FOM) analysis. The interesting results show an enhancement of the thermal storage of this mixture disregard with the viscosity increase effect.

Investigation of Molten Salt Nanomaterial as Thermal Energy Storage in Concentrated Solar Power

2012 ◽  
Author(s):  
Bharath Dudda ◽  
Donghyun Shin
Keyword(s):  
Heat Capacity ◽  
Energy Storage ◽  
Specific Heat ◽  
Molten Salt ◽  
Specific Heat Capacity ◽  
Thermal Energy ◽  
Molten Salts ◽  
Oxide Nanoparticles ◽  
Concentrated Solar Power ◽  
Mineral Oils

It is a known fact that the solar energy is the most abundant form of renewable source of energy available abundantly in most of the areas. It is relatively the most promising form of renewable energy through which many developed countries like US, Spain are generating electricity using CSP, PV, and other forms of solar cells. This paper mainly focuses on the Concentrated Solar Power (CSP) and about the method of enhancing the Thermal Energy Storage (TES) capacity. Here, we use molten salt as the Heat Transfer Fluid (HTF) as an alternative to mineral oils and other commonly used HTF. The reasons behind using molten salts have also been listed in the paper. The major disadvantage in molten salts as a HTF is their low specific heat capacity compared to mineral oils. The low specific heat capacity of molten salt can be enhanced by dispersing oxide nanoparticles. In this paper, we synthesized molten salt nanomaterials by dispersing oxide nanoparticles in to selcte4d molten salts. Specific heat capacity measurement was performed using a modulated differential scanning calorimeter (MDSC). Hence, we evaluated the use of molten salt nanomaterials as HTF in CSP.

scholarly journals Concentrated Solar Power Plants with Molten Salt Storage: Economic Aspects and Perspectives in the European Union

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Andrzej Bielecki ◽  
Sebastian Ernst ◽  
Wioletta Skrodzka ◽  
Igor Wojnicki
Keyword(s):  
Molten Salt ◽  
Molten Salts ◽  
Power Plants ◽  
Solar Power ◽  
Economic Aspects ◽  
The European Union ◽  
Concentrated Solar Power ◽  
Eu Legislation ◽  
Solar Power Plants ◽  
Concentrated Solar Power Plants

Concentrated solar power plants belong to the category of clean sources of renewable energy. The paper discusses the possibilities for the use of molten salts as storage in modern CSP plants. Besides increasing efficiency, it may also shift their area of application: thanks to increased controllability, they may now be used not only to cover baseload but also as more agile, dispatchable generators. Both technological and economic aspects are presented, with focus on the European energy sector and EU legislation. General characteristics for CSP plants, especially with molten salt storage, are discussed. Perspectives for their development, first of all in economic aspects, are considered.

Determination of the Thermal Properties of a PCB by Coupled Numerical and Experimental Approach

2020 ◽  
Author(s):  
Yener Usul ◽  
Mustafa Özçatalbaş
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Thermal Properties ◽  
Numerical Analysis ◽  
Specific Heat ◽  
Specific Heat Capacity ◽  
Thermal Analyses ◽  
Analysis Model ◽  
Linear Temperature ◽  
Coefficient Of Thermal Conductivity

Abstract Increasing demand for usage of electronics intensely in narrow enclosures necessitates accurate thermal analyses to be performed. Conduction based FEM (Finite Element Method) is a common and practical way to examine the thermal behavior of an electronic system. First step to perform a numerical analysis for any system is to set up the correct analysis model. In this paper, a method for obtaining the coefficient of thermal conductivity and specific heat capacity of a PCB which has generally a complex composite layup structure composed of conductive layers, and dielectric layers. In the study, above mentioned properties are obtained performing a simple nondestructive experiment and a numerical analysis. In the method, a small portion of PCB is sandwiched from one side at certain pressure by jaws. A couple of linear temperature profiles are applied to the jaws successively. Unknown values are tuned in the analysis model until the results of FEM analysis and experiment match. The values for the coefficient of thermal conductivity and specific heat capacity which the experiment and numerical analysis results match can be said to be the actual values. From this point on, the PCB whose thermal properties are determined can be analyzed numerically for any desired geometry and boundary condition.

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