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Debjyoti Banerjee - One of the best experts on this subject based on the ideXlab platform.
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Review of Molten Salt Nanofluids
Volume 1: Heat Transfer in Energy Systems; Thermophysical Properties; Theory and Fundamentals in Heat Transfer; Nanoscale Thermal Transport; Heat Tran, 2016Co-Authors: Farzam Mortazavi, Debjyoti BanerjeeAbstract:Literature review of Molten Salt nanofluids is performed in this study with focus on the thermo-fluidic properties and performance in thermal management applications. The colloidal mixture of nanoparticles in a base liquid phase is called nanofluid. Molten Salts such as alkali nitrate eutectics, alkali carbonate eutectics and alkali chloride eutectics have high melting temperatures. These materials are suitable for various high temperature applications, including as Heat Transfer Fluid (HTF), Thermal Energy Storage (TES), Concentrated Solar Power (CSP) plants, nuclear power, etc. The major drawback of Molten Salt materials is their low thermal conductivity and specific heat capacity. Enhancing the thermo-physical properties of Molten Salt materials can lower the cost of power production involving these materials (e.g., as HTF and/ or TES in CSP or nuclear power plants. Mixing Molten alt eutectics with nanoparticles (e.g., Molten Salt nanofluids) can provide a cost-effective technique for enhancing the specific heat capacity and thermal conductivity which in turn can enable the reduction in the cost of power production. In this review - the following topics involving Molten Salt nanofluids were explored: thermo-physical property measurements, numerical modeling (e.g., Molecular Dynamics/ MD simulations), materials characterization (e.g., using electron microscopy techniques — such as SEM and TEM). For example, SEM studies in conjunction with MD simulation results confirm the formation of a dense layer of fluid molecules on the surface of nanoparticles that can enhance the specific heat capacity of these Molten Salt nanomaterials. Subsequently the concepts of nanofins was explored (which involves the study of interfacial thermal impedance, such as resistance, capacitance and diodicity). The contribution of these interfacial thermal impedances to the enhancement of specific heat capacity and thermal conductivity are also explored. Specific heat enhancement as high as 100% has been observed for various Molten Salt eutectics when doped with 1.5% (weight) silica nanoparticles. Various synthesis protocols such as one-step, two-step and three-step methods as well as conventional experimental methods used for specific heat capacity measurement are compared and examined. A review of the effects of concentration, nanoparticle size, temperature, base fluid, and nanofluid chemical properties is also performed. Other topics of interest are the anomalous enhancement of thermal conductivity in Molten Salt nanofluids which contradict typical predictions obtained from using the effective medium theory. The available data in literature shows enhancement in thermal conductivity by as much as 35–45% for carbonate eutectics doped with silica nanoparticles at 1% mass fraction. The possible mechanisms suggested for this improvement are briefly discussed and compared with experimental observations (e.g., using SEM). In addition, nanofluids often display non-Newtonian rheological behavior. This necessitates a rigorous study, since the applications of nanofluids will impact the required pumping power. Studies show that the rheological properties of Molten Salt nanofluids are a function of base Salt composition, shape of nanoparticles selected, chemical formula of nanoparticles, concentration of nanoparticles, size of nanoparticles, temperature, shear rate and synthesis protocol of the nanofluid. Several models are introduced to predict the viscosity variation along with their advantageous and disadvantages. SEM results show agglomeration of nanoparticles can be reduced by doping the nanofluids with very small values of mass fractions of additives such as Gum Arabic.
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Specific heat mechanism of Molten Salt nanofluids
Applied Physics Letters, 2014Co-Authors: Donghyun Shin, Hani Tiznobaik, Debjyoti BanerjeeAbstract:Controversial results have been reported for specific heat of conventional nanofluids and Molten Salt nanofluids. Some water-based and organic-based nanofluids showed decreases in specific heat, while Molten Salt-based nanofluids showed highly enhanced specific heat. In this study, we propose a distinct heat storage mechanism to explain enhanced specific heat of Molten Salt nanofluids and compare with the specific heat mechanism of conventional nanofluids.
Zhibin Zhu - One of the best experts on this subject based on the ideXlab platform.
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Molten Salt synthesis of ZnNb2O6 powder
Materials Research Bulletin, 2007Co-Authors: Liangzhai Guo, Jinhui Dai, Jintao Tian, Zhibin ZhuAbstract:Abstract Pure ZnNb2O6 powder was successfully prepared by the Molten Salt synthesis method using Nb2O5 and ZnO as raw materials and a mixture of NaCl and KCl as the solvent. The phase form and morphology of the prepared powder were characterized by X-ray diffraction and scanning electron microscopy. The effect of reacting temperature on phase formation was investigated. The results indicated that the single phase ZnNb2O6 powder can be obtained by the Molten Salt synthesis method at 600 °C, and the SEM photographs show that the grains of the powder are rod-like particles.
Jyung Choi - One of the best experts on this subject based on the ideXlab platform.
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Molten Salt method for the synthesis of zeolitic materials i zeolite formation in alkaline Molten Salt system
Microporous and Mesoporous Materials, 2000Co-Authors: Man Park, Choong Lyeal Choi, Jyung ChoiAbstract:Abstract The Molten-Salt method has been applied for the zeolitization of fly ash and other mineral wastes. Fly ash was converted into zeolitic materials by a simple thermal treatment at Molten states of some Salt mixtures without any addition of water. Various combinations of Salt mixtures were employed for the zeolitization of fly ash, using NaOH, KOH, or NH 4 F as mineralizer, and NaNO 3 , KNO 3 , or NH 4 NO 3 as stabilizer. The resultant zeolitic materials were composed of sodalite and cancrinite as major crystalline phases. This Molten-Salt method was also confirmed for the facile zeolitization of kaolinite, montmorillonite, and natural zeolite waste. The main zeolite species synthesized by the Molten-Salt method were dependent on the types of Salt mixture and raw material used. The Molten-Salt method developed in this study could open a new and alternative approach for the mass treatment of these mineral wastes at low cost, as well as for the improvement of the purity and alkalinity of zeolitic materials.
E. Merle-lucotte - One of the best experts on this subject based on the ideXlab platform.
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Numerical tools for Molten Salt reactors simulation
2009Co-Authors: X. Doligez, E. Merle-lucotte, D. Heuer, V. Ghetta, M. AllibertAbstract:Essentially, because the Salt is the moderator, the coolant and the fuel, the study of Molten Salt Reactor are specific. There are strong coupling between neutronics, and other part of physic field like the chemistry for instance. The system presented in this paper is called Molten Salt Fast Reactor which is a Molten Salt reactor with no moderator inside the core with a Salt composition which leads to a fast neutron spectrum. Previous studies showed that this concept (previously called Thorium Molten Salt Reactor – Non moderated) has very promising characteristics. We tried to explain computational problems due to the study of this concept, especially the coupling with the reprocessing and with the chemistry. Indeed, the reprocessing is done little by little in situ, so we have to consider it in our studies. We also show that the redox properties changes during operation because fissions change the Salt chemistry (it is a reductive process). Our program is a coupling between MCNP and a home made evolution code called REM. It was validated for thermal neutron and epithermal neutron spectrum but not for fast neutron spectrum, so a brief study with ERANOS of the MSFR is also presented here.
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Fast Thorium Molten Salt Reactors started with Plutonium
2006Co-Authors: E. Merle-lucotte, D. Heuer, C. Le Brun, R. Brissot, E. Liatard, O. Méplan, A. Nuttin, L. MathieuAbstract:One of the pending questions concerning Molten Salt Reactors based on the {sup 232}Th/{sup 233}U fuel cycle is the supply of the fissile matter, and as a consequence the deployment possibilities of a fleet of Molten Salt Reactors, since {sup 233}U does not exist on earth and is not yet produced in the current operating reactors. A solution may consist in producing {sup 233}U in special devices containing Thorium, in Pressurized Water or Fast Neutrons Reactors. Two alternatives to produce {sup 233}U are examined here: directly in standard Molten Salt Reactors started with Plutonium as fissile matter and then operated in the Th/{sup 233}U cycle; or in dedicated Molten Salt Reactors started and fed with Plutonium as fissile matter and Thorium as fertile matter. The idea is to design a critical reactor able to burn the Plutonium and the minor actinides presently produced in PWRs, and consequently to convert this Plutonium into {sup 233}U. A particular reactor configuration is used, called 'unique channel' configuration in which there is no moderator in the core, leading to a quasi fast neutron spectrum, allowing Plutonium to be used as fissile matter. The conversion capacities of such Molten Salt Reactors are excellent. For Moltenmore » Salt Reactors only started with Plutonium, the assets of the Thorium fuel cycle turn out to be quickly recovered and the reactor's characteristics turn out to be equivalent to Molten Salt Reactors operated with {sup 233}U only. Using a combination of Molten Salt Reactors started or operated with Plutonium and of Molten Salt Reactors started with {sup 233}U, the deployment capabilities of these reactors fully satisfy the condition of sustainability. (authors)« less
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Fast Thorium Molten Salt Reactors started with Plutonium
2006Co-Authors: E. Merle-lucotte, D. Heuer, C. Le Brun, L. Mathieu, R. Brissot, E. Liatard, O. Méplan, A. NuttinAbstract:One of the pending questions concerning Molten Salt Reactors based on the 232Th/233U fuel cycle is the supply of the fissile matter, and as a consequence the deployment possibilities of a fleet of Molten Salt Reactors, since 233U does not exist on earth and is not yet produced in the current operating reactors. A solution may consist in producing 233U in special devices containing Thorium, in Pressurized Water or Fast Neutrons Reactors. Two alternatives to produce 233U are examined here: directly in standard Molten Salt Reactors started with Plutonium as fissile matter and then operated in the Th/233U cycle; or in dedicated Molten Salt Reactors started and fed with Plutonium as fissile matter and Thorium as fertile matter. The idea is to design a critical reactor able to burn the Plutonium and the minor actinides presently produced in PWRs, and consequently to convert this Plutonium into 233U. A particular reactor configuration is used, called unique channel configuration in which there is no moderator in the core, leading to a quasi fast neutron spectrum, allowing Plutonium to be used as fissile matter. The conversion capacities of such Molten Salt Reactors are excellent. For Molten Salt Reactors only started with Plutonium, the assets of the Thorium fuel cycle turn out to be quickly recovered and the reactors characteristics turn out to be equivalent to Molten Salt Reactors operated with 233U only. Using a combination of Molten Salt Reactors started or operated with Plutonium and of Molten Salt Reactors started with 233U, the deployment capabilities of these reactors fully satisfy the condition of sustainability.
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Molten Salt Reactors and Possible Scenarios for Future Nuclear Power Deployment
2004Co-Authors: E. Merle-lucotte, D. Heuer, C. Le Brun, L. Mathieu, R. Brissot, A. Billebaud, Sylvain David, C. Garzenne, O. Laulan, D. LecarpentierAbstract:An important fraction of the future energy demand may be satisfied by nuclear power. In this context, the possibilities of worldwide nuclear deployment are studied. We are convinced that the Molten Salt Reactors may play a central role in this deployment. The Molten Salt Reactor needs to be coupled to a reprocessing unit in order to extract the Fission Products which poison the core. The efficiency of this reprocessing has a crucial influence on reactor behavior especially for the breeding ratio. The Molten Salt Breeder Reactor project was based on an intensive reprocessing for high breeding purposes. A new concept of Thorium Molten Salt Reactor is presented here. Including this new concept in the worldwide nuclear deployment, to satisfy these power needs, we consider three typical scenarios, based on three reactor types: Pressurized Water Reactor, Fast Neutron Reactor and Thorium Molten Salt Reactor. The aim of this paper is to demonstrate, in a first hand that a Thorium Molten Salt Reactor can be realistic, with correct temperature coefficients and at least iso-breeder with slow reprocessing and new geometry; on the other hand that such Molten Salt Reactors enable a successful nuclear deployment, while minimizing fuel and waste management problems.
Jing Ding - One of the best experts on this subject based on the ideXlab platform.
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experimental and numerical studies on Molten Salt migration in porous system with phase change
International Journal of Heat and Mass Transfer, 2019Co-Authors: Yuanyuan Zhang, Weilong Wang, Jing DingAbstract:Abstract Molten Salt is promising high temperature heat transfer fluid, and its transport in porous media is an important problem for Molten Salt application. In this paper, Molten Salt migration and phase change in cold porous system packed with sand particles is experimentally and numerically studied. Experimental results show that high temperature Molten Salt continuously migrates and a transparent liquid Molten Salt layer appears during discharge stage with Molten Salt pouring into porous bed, and then it solidifies as white opaque solid block during post-discharge stage. A transient axial-symmetrical flow and heat transfer model is developed using volume of fluid model and linear approximation in mushy zone, and the simulated results very well fit with experiment. After Molten Salt discharges and contacts with the cold surface, a thin solid layer quickly forms for solidification, and then it gradually expands and finally becomes a solid block. Since the earlier solid layer hinders Molten Salt vertical flow, liquid Molten Salt will flow across the outer boundary of solid layer, and then Molten Salt layer below the surface becomes thicker. After Molten Salt totally solidifies, an inner region with little Molten Salt will probably exist inside Molten Salt solid block. The maximum migration region for Molten Salt in cold porous system is affected by structural and operating parameters. For larger porosity and particle diameter or higher Molten Salt temperature, Molten Salt flow in porous system has less flow resistance, and then the maximum migration height can be increased, while the migration diameter is reduced.
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Thermal performances of Molten Salt steam generator
Applied Thermal Engineering, 2016Co-Authors: Yibo Yuan, Jing DingAbstract:Abstract Molten Salt steam generator is the key technology for thermal energy conversion from high temperature Molten Salt to steam, and it is used in solar thermal power station and Molten Salt reactor. A shell and tube type Molten Salt steam generator was set up, and its thermal performance and heat transfer mechanism were studied. As a coupling heat transfer process, Molten Salt steam generation is mainly affected by Molten Salt convective heat transfer and boiling heat transfer, while its energy efficiency is also affected by the heat loss. As Molten Salt temperature increased, the energy efficiency first rose with the increase of heat flow absorbed by water/steam, and then slightly decreased for large heat loss as the absorbed heat flow still rising. At very high Molten Salt temperature, the absorbed heat flow decreased as boiling heat transfer coefficient dropping, and then the energy efficiency quickly dropped. As the inlet water temperature increased, the boiling region in the steam generator remarkably expanded, and then the steam generation rate and energy efficiency both rose with the overall heat transfer coefficient increasing. As the Molten Salt flow rate increased, the wall temperature rose and the boiling heat transfer coefficient first increased and then decreased according to the boiling curve, so the overall heat transfer coefficient first increased and then decreased, and then the steam generation rate and energy efficiency of steam generator both had maxima.
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Numerical Investigation of High-temperature Molten Salt Leakage
Energy Procedia, 2015Co-Authors: Jinhua Shan, Jing DingAbstract:Abstract As Molten Salt has been widely used in solar thermal power and nuclear power system, its leakage was an important problem. In this paper, the high-temperature Molten Salt leakage is simulated by considering the effects of phase change and flow dynamics. During the Molten Salt leakage process, the liquid Molten Salt is cooled by the ground and air, so it will solidify, and then a thin solidification layer of Molten Salt forms. The whole high-temperature Molten Salt leakage process consists of three subprocesses: spreading process, stable solid front formation process and solidification process after leakage. According to the simulation result, the radius of the leakage opening mainly affects the radius of nitrate solidification layer, while the leakage temperature and the leakage velocity will influence both the radius and thickness of Salt layer. Besides, different kinds of Molten Salt are also considered, and the radius of Molten Salt solidification layer with SYSU-N1 is smaller than that with Solar Salt.
