| 1. |
- Ding, J., et al.
(författare)
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Theoretical prediction of the local structures and transport properties of binary alkali chloride salts for concentrating solar power
- 2017
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Ingår i: Nano Energy. - : Elsevier. - 2211-2855 .- 2211-3282. ; 39, s. 380-389
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Tidskriftsartikel (refereegranskat)abstract
- Comprehensive molecular simulations have been carried out to compute local structures and transport properties of different components of binary NaCl-KCl over a wide operating temperature range. The partial radial distribution functions, coordination number curves and angular distribution functions were calculated to analyze the influence of temperature and component on local structures of molten Alkali Chlorides. Transport properties were calculated by using reverse non-equilibrium molecular dynamics (RNEMD) simulations including densities, shear viscosity and thermal conductivity. The results show that ion clusters are considered to be formed and the distance of ion clusters become larger with increasing temperature which has great influence on macro-properties. The calculated properties have a good agreement with the experimental data, and similar method could be used to computationally calculate the properties of various molten salts and their mixtures.
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| 2. |
- Lu, Zhansheng, et al.
(författare)
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Several different charge transfer and Ce3+ localization scenarios for Rh-CeO2(111)
- 2014
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry (RSC). - 2050-7488 .- 2050-7496. ; 2:7, s. 2333-2345
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Tidskriftsartikel (refereegranskat)abstract
- We present DFT+U based electronic structure calculations in a p(3 x 3) slab supercell, for low coverages of atomically dispersed Rh interacting with the CeO2(111) surface, comparing Rh as an adatom, and as a dopant substituted into the surface layer. We find that, energetically, a Rh atom approaching a ceria(111) surface with both sparse O and Ce vacancies present strongly prefers to heal the Ce vacancies, but next it prefers to adsorb on a stoichiometric region rather than healing an O vacancy. In the adatom system, Rh is oxidized by electron transfer to a 4f orbital on one Ce ion in the surface layer, which is then nominally converted from Ce4+ -> Ce3+ (i.e. Rh adatoms are single donors). We show that there are a number of different local minima, with Ce3+ localization at 1st, 2nd or 3rd nearest neighbour Ce sites. The second neighbour is the most stable, but all are close in energy. In the Rh-doped system (Rh replaces Ce), Rh is oxidized by charge transfer to neighbouring O atoms, and Rh doping leads to deep acceptor and donor states. Rh is not stable in the O sublattice. Moreover, based on vacancy formation energies, we find that oxygen vacancy formation is strongly enhanced in the vicinity of Rh dopants, but slightly suppressed in the vicinity of Rh adatoms.
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| 3. |
- Pan, G., et al.
(författare)
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Thermal performance of a binary carbonate molten eutectic salt for high-temperature energy storage applications
- 2020
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Ingår i: Applied Energy. - : Elsevier Ltd. - 0306-2619 .- 1872-9118. ; 262
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Tidskriftsartikel (refereegranskat)abstract
- Molten carbonate eutectic salts are promising thermal storage and heat transfer fluid materials in solar thermal power plant with the feature of large specific heat capacity, wide operating temperature range and little corrosive. The high-temperature properties of molten carbonates should be determined accurately over the entire operating temperature for energy system design. In this paper, molecular dynamic simulation is used to study temperature and component dependence of microstructures and thermophysical properties of the binary carbonate molten salt. Negative linear temperature dependence of densities and thermal conductivities of binary mixtures of different components is confirmed with respect to the distances of ion clusters. Besides, positive linear temperature dependence of self-diffusion coefficient is also obtained. When temperature is constant, densities and thermal conductivities of binary mixtures are linearly related with components. Self-diffusion coefficients of CO32− firstly increase and then decrease with increasing mole fraction of Na2CO3. The temperature-thermophysical properties-composition correlation formulas are obtained, and the database of thermophysical properties of molten carbonate salts over the entire operating temperature is complemented, which will provide the essential data for heat transfer and storage system design, operation, and optimization in CSP.
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| 4. |
- Rong, Z., et al.
(författare)
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Experimental and theoretical investigation of an innovative composite nanofluid for solar energy photothermal conversion and storage
- 2022
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Ingår i: Journal of Energy Storage. - : Elsevier Ltd. - 2352-152X .- 2352-1538. ; 52
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Tidskriftsartikel (refereegranskat)abstract
- Molten salts play a key role in the heat transfer and thermal energy storage processes of concentrated solar power plants. A novel composite material was prepared in this work by adding micron-sized magnesium particles into Li2CO3-Na2CO3-K2CO3 molten salt, the heat transfer and thermal energy storage properties of the composites were studied experimentally. A stable composite nanofluid can be obtained, and a thermal conductivity of 0.728 W/(m·K) at 973 K with an enhancement of 31% is achieved for the Mg/molten carbonate nanofluid. And the strengthening mechanism of thermal conductivity was revealed by using ab-initio molecular dynamics method. It is found that the main bonding interactions exist between Mg and O atoms at the surface of Mg particles. A compressed ion layer with a more compact and ordered ionic structure is formed around Mg particles, and the Brownian motions of Mg particles lead to the micro-convections of carbonate ions around them. These factors are helpful to the enhancement of thermal conduction with the improved probability and frequency of ion collisions. This work can provide a guidance for further studies and applications on metal/molten salt composites with enhanced heat transfer and thermal energy storage capacity.
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| 5. |
- Ye, Y., et al.
(författare)
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Enhanced hydrogen storage of a LaNi5 based reactor by using phase change materials
- 2021
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Ingår i: Renewable energy. - : Elsevier Ltd. - 0960-1481 .- 1879-0682. ; 180, s. 734-743
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Tidskriftsartikel (refereegranskat)abstract
- Safe and efficient hydrogen storage technology is of great significance for large-scale hydrogen energy utilization. Using metal hydride (MH) materials such as LaNi5 for hydrogen storage is an effective way. In application, the heat and mass transfer characteristics in the reactor are one of the important factors and key problems affecting the hydrogen storage performance of MH. This paper proposes a novel hydrogen storage reactor installing a concentric finned tube heat exchanger and using phase change materials (PCM) by surrounding the reactor to improve heat transfer and hydrogen storage performance. A numerical model is built to describe transportation and reaction of two reactors with or without PCM. By comparison, the reactor surrounded by PCM has faster heat discharge and hydrogen absorption rate, and the absorption time is shortened by 50%. For the reactor with PCM, the optimal amount of PCM and the inlet velocity of heat transfer fluid (HTF) are investigated. The results show that the effective thermal conductivity of MH play a key role to improve heat transfer and reaction rate rather than that of PCM. Furthermore, increasing hydrogen supply pressure can effectively accelerate heat discharge and hydrogen absorption rate owning to larger temperature differences and improved reaction kinetics. © 2021
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