Enhanced Heat Capacity of Molten Salt Nano-Materials for Concentrated Solar Power Application

2012 ◽  
Author(s):  
Ramaprasath Devaradjane ◽  
Donghyun Shin
Keyword(s):  
Heat Capacity ◽  
Energy Storage ◽  
Molten Salt ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Molten Salts ◽  
Solar Power ◽  
Storage Temperature ◽  
Nano Materials ◽  
Concentrated Solar Power

Storage of thermal energy using molten salt materials has been widely explored for concentrating solar power. Since these power plants use thermodynamic cycle, the overall system cycle efficiency significantly relies on the thermal energy storage temperature. Therefore, increasing the thermal energy storage temperature and decreasing the amount of material needed can result in reducing the cost of solar energy. Molten salts are stable up to 700°C, relatively cheap, and safe to the environment. However, the heat capacity of the molten salts is typically low (∼1.5 J/gK) compared to other thermal storage materials. The low heat capacity of molten salts can be improved by dispersing nanoparticles. In this study, we synthesized molten salt nanomaterial by dispersing oxide nanoparticles into selected molten salts. Heat capacity measurements were performed using a modulated differential scanning calorimeter. Materials characterization studies were performed using a scanning electron microscopy. Hence, we evaluated the use of the molten salt nanomaterials as thermal energy storage media in concentrated solar power applications. Increase in the specific heat capacity of the molten salt is also demonstrated on addition with Nano materials of specific size and quantity.

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

Nanomaterials ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 2266
Author(s):  
Binjian Ma ◽  
Donghyun Shin ◽  
Debjyoti Banerjee
Keyword(s):  
Heat Capacity ◽  
Energy Storage ◽  
Specific Heat ◽  
Molten Salt ◽  
Specific Heat Capacity ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Solar Power ◽  
Alumina Nanoparticles ◽  
Concentrated Solar Power

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.

Waste From Metallurgic Industry: A Sustainable High-Temperature Thermal Energy Storage Material for Concentrated Solar Power

2013 ◽  
Author(s):  
Nicolas Calvet ◽  
Guilhem Dejean ◽  
Lucía Unamunzaga ◽  
Xavier Py
Keyword(s):  
Heat Capacity ◽  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Solar Power ◽  
Low Cost ◽  
Concentrated Solar Power ◽  
Storage Material ◽  
Energy Storage Material ◽  
Thermal Energy Storage Material

The ambitious DOE SunShot cost target ($0.06/kWh) for concentrated solar power (CSP) requires innovative concepts in the collector, receiver, and power cycle subsystems, as well as in thermal energy storage (TES). For the TES, one innovative approach is to recycle waste from metallurgic industry, called slags, as low-cost high-temperature thermal energy storage material. The slags are all the non-metallic parts of cast iron which naturally rises up by lower density at the surface of the fusion in the furnace. Once cooled down some ceramic can be obtained mainly composed of oxides of calcium, silicon, iron, and aluminum. These ceramics are widely available in USA, about 120 sites in 32 States and are sold at a very low average price of $5.37/ton. The US production of iron and steel slag was estimated at 19.7 million tons in 2003 which guarantees a huge availability of material. In this paper, electric arc furnace (EAF) slags from steelmaking industry, also called “black slags”, were characterized in the range of temperatures of concentrated solar power. The raw material is thermo-chemically stable up to 1100 °C and presents a low cost per unit thermal energy stored ($0.21/kWht for ΔT = 100 °C) and a suitable heat capacity per unit volume of material (63 kWht/m3for ΔT = 100°C). These properties should enable the development of new TES systems that could achieve the TES targets of the SunShot (temperature above 600 °C, installed cost below $15/kWht, and heat capacity ≥25 kWht/m3). The detailed experimental results are presented in the paper. After its characterization, the material has been shaped in form of plates and thermally cycled in a TES system using hot-air as heat transfer fluid. Several cycles of charge and discharged were performed successfully and the concept was validated at laboratory scale. Apart from availability, low-cost, and promising thermal properties, the use of slag promotes the conservation of natural resources and is a noble solution to decrease the cost and to develop sustainable TES systems.

Viability Assessment of a Concentrated Solar Power Tower With a Supercritical CO2 Brayton Cycle Power Plant

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
Ali Sulaiman Alsagri ◽  
Andrew Chiasson ◽  
Mohamed Gadalla
Keyword(s):  
Energy Storage ◽  
Molten Salt ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Supercritical Co2 ◽  
Solar Power ◽  
Capacity Factor ◽  
Brayton Cycle ◽  
Concentrated Solar Power ◽  
Solar Power Tower

The aim of this study was to conduct thermodynamic and economic analyses of a concentrated solar power (CSP) plant to drive a supercritical CO2 recompression Brayton cycle. The objectives were to assess the system viability in a location of moderate-to-high-temperature solar availability to sCO2 power block during the day and to investigate the role of thermal energy storage with 4, 8, 12, and 16 h of storage to increase the solar share and the yearly energy generating capacity. A case study of system optimization and evaluation is presented in a city in Saudi Arabia (Riyadh). To achieve the highest energy production per unit cost, the heliostat geometry field design integrated with a sCO2 Brayton cycle with a molten-salt thermal energy storage (TES) dispatch system and the corresponding operating parameters are optimized. A solar power tower (SPT) is a type of CSP system that is of particular interest in this research because it can operate at relatively high temperatures. The present SPT-TES field comprises of heliostat field mirrors, a solar tower, a receiver, heat exchangers, and two molten-salt TES tanks. The main thermoeconomic indicators are the capacity factor and the levelized cost of electricity (LCOE). The research findings indicate that SPT-TES with a supercritical CO2 power cycle is economically viable with 12 h thermal storage using molten salt. The results also show that integrating 12 h-TES with an SPT has a high positive impact on the capacity factor of 60% at the optimum LCOE of $0.1078/kW h.

Experimental Study of Nanoengineered Molten Salts as Thermal Energy Storage in Solar Power Plants

2012 ◽  
Author(s):  
Hani Tiznobaik ◽  
Donghyun Shin
Keyword(s):  
Energy Storage ◽  
Physical Properties ◽  
High Temperatures ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Molten Salts ◽  
Solar Power ◽  
Operating Temperature ◽  
Concentrated Solar Power ◽  
Thermo Physical Properties

In a concentrated solar power (CSP), high operating temperature (over 500 °C) is the key for enhancing the efficiency of the system. The operating temperature of the system mainly relies on thermal energy storage (TES) material. Existing TES materials such as mineral oil or paraffin wax cannot be applicable at high temperatures, since these materials are not thermally stable over 400 °C. However, very few materials are suitable and reliable for the high temperatures. Using molten salts (e.g., alkali nitrate, alkali carbonate, alkali chloride, etc.) as thermal energy storage material is an alternative way due to several benefits. They are cheap and environmentally safe compared with the conventional TES materials. They are thermally stable at higher temperatures (over 500 °C). However, their usage is limited due to low thermo-physical properties (e.g. Cp is less than 1.6 J/g°C). The low thermo-physical properties can be improved by dispersing nanoparticles into the salts. In this study, nanomaterials were synthesized by dispersing inorganic nanoparticles into ionic salts. Modulated differential scanning calorimeter (MDSC) was used to measure the heat capacity of the nanomaterials. Scanning electron microscopy (SEM) was used for material characteristic analysis. Hence, the application of the nanomaterials as thermal energy storage in a concentrated solar power was explored.

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.

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