Compatibility of alumina forming alloys with LiNO3-containing molten salts for solar thermal plants

2022 ◽  
Vol 48 ◽  
pp. 103988
Author(s):  
Ángel G. Fernández ◽  
Fabiola Pineda ◽  
Edward Fuentealba ◽  
Domingo Jullian ◽  
Abdiel Mallco ◽  
...  
Keyword(s):  
Molten Salts ◽  
Solar Thermal

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.

scholarly journals Molten salt composition and composites for improved latent heat thermal energy storage

2017 ◽  
Vol 4 ◽  
pp. 46-58
Author(s):  
Jonathan Kotyla
Keyword(s):  
Thermal Conductivity ◽  
Renewable Energy ◽  
Molten Salt ◽  
Energy Demand ◽  
Molten Salts ◽  
Renewable Energy Sources ◽  
Expanded Graphite ◽  
Thermal Storage ◽  
High Heat ◽  
Solar Thermal

The growing concern over nonrenewable fuel sources, coupled with the continued increase of global energy demand has incentivised research into numerous new and pre-existing renewable energy sources. Concentrated solar thermal (CST) takes advantage of the high heat capacity of molten salts to provide an alternative solar solution to photovoltaic cells that allows reduced downtime through heat storage for use during suboptimal conditions. This meta-study examines the effectiveness of various eutectic Molten Salt compositions and materials as thermo-physical augmenters, with a focus on improved thermal conductivity when composited with molten salts as a method of enhancing the efficiency of concentrated solar thermal storage technology. The study is based on literature retrieved from scientific databases to investigate information available about enhancing LHTES technology. Research into carbon composites such as Expanded Graphite (EG) exhibits promising results revealing thermal conductivity increases as high as 40% in eutectic salt materials, however inconsistencies in measurements and materials used reveal a need for a greater analysis. Although molten salt thermal storage systems are not optimal in their current state, indication was found that composite storage mediums could potentially solidify their spot as a viable renewable energy source.

scholarly journals Thermal evaluation of molten salts for solar thermal energy storage

2014 ◽  
pp. 622-625 ◽  
Author(s):  
C. Villada ◽  
F. Bolívar ◽  
F. Jaramillo ◽  
J.G. Castaño ◽  
F. Echeverría
Keyword(s):  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Molten Salts ◽  
Solar Thermal ◽  
Solar Thermal Energy

Investigation of High Temperature Nanofluids for Solar Thermal Power Conversion and Storage Applications

2010 ◽  
Author(s):  
Donghyun Shin ◽  
Byeongnam Jo ◽  
Hyun-eun Kwak ◽  
Debjyoti Banerjee
Keyword(s):  
Heat Capacity ◽  
Thermal Properties ◽  
High Temperature ◽  
Energy Storage ◽  
Physical Properties ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Molten Salts ◽  
Solar Thermal ◽  
Thermo Physical Properties

The aim of this study is to investigate the enhancement of thermal properties of various high temperature nanofluids for solar thermal energy storage application. In concentrating solar power (CSP) systems, the thermo-physical properties of the heat transfer fluids (HTF) and the thermal energy storage (TES) materials are key to enhancing the overall system efficiency. Molten salts, such as alkali nitrates, alkali carbonates, or eutectics are considered as alternatives to conventional HTF to extend the capabilities of CSP. However, there is limited usage of molten salt eutectics as the HTF material, since the heat capacity of the molten salts are lower than that of conventional HTF. Nanofluid is a mixture of a solvent and nanoparticles. Well dispersed nanoparticles can be used to enhance thermo-physical properties of HTF. In this study, silica (SiO2) and alumina (Al2O3) nanoparticles as well as carbon nanotubes (CNT) were dispersed into a molten salt and a commercially available HTF. The specific heat capacity of the nanofluids were measured and applicability of such nanofluid materials for solar thermal storage applications were explored. Measurements performed using the carbonate eutectics and commercial HTF that are doped with inorganic and organic nano-particles show specific heat capacity enhancements exceeding 5–20% at concentrations of 0.05% to 2.0% by weight. Dimensional analyses and computer simulations were performed to predict the enhancement of thermal properties of the nanofluids. The computational studies were performed using Molecular Dynamics (MD) simulations.

scholarly journals High-efficiency solar thermoelectric conversion enabled by movable charging of molten salts

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Chao Chang ◽  
Zongyu Wang ◽  
Benwei Fu ◽  
Yulong Ji
Keyword(s):  
Solar Energy ◽  
Thermal Energy ◽  
Molten Salts ◽  
High Efficiency ◽  
Thermal Storage ◽  
Solar Thermal ◽  
Stable Operation ◽  
Solar Thermal Energy ◽  
Thermoelectric Converter ◽  
Thermoelectric Conversion

AbstractSolar energy as an abundant renewable resource has been investigated for many years. Solar thermoelectric conversion technology, which converts solar energy into thermal energy and then into electricity, has been developed and implemented in many important fields. The operation of solar–thermal–electric conversion systems, however, is strongly affected by the intermittency of solar radiation, which requires installation of thermal storage subsystems. In this work, we demonstrated a new solar–thermal–electric conversion system that consists of a thermoelectric converter and a rapidly charging thermal storage subsystem. A magnetic-responsive solar–thermal mesh was used as the movable charging source to convert incident concentrated sunlight into high-temperature heat, which can induce solid-to-liquid phase transition of molten salts. Driven by the external magnetic field, the solar–thermal mesh can move together with the receding solid–liquid interface thus rapidly storing the harvested solar–thermal energy within the molten salts. By connecting with a thermoelectric generator, the harvested solar–thermal energy can be further converted into electricity with a solar–thermal–electric energy conversion efficiency up to 2.56%, and the converted electrical energy can simultaneously light up more than 40 orange-colored LEDs. In addition to stable operation under sunlight, the charged thermal storage subsystem can release the stored heat and thus enables the solar–thermal–electric system to continuously generate electricity after removal of solar illumination.

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