The Experts below are selected from a list of 93582 Experts worldwide ranked by ideXlab platform
C Y Zhao - One of the best experts on this subject based on the ideXlab platform.
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multi physics modeling of thermochemical Heat Storage with enhance Heat transfer
Applied Thermal Engineering, 2021Co-Authors: Tao Shi, Biao Lei, C Y ZhaoAbstract:Abstract Thermochemical Heat Storage technology is an important component in energy system, and plays a key role in the balance of energy supply and demand. A multi-physics model is constructed to study the hydration process in a tubular reactor, including fluid flow, Heat transfer and reaction. Variations of temperature and conversion of CaO are discussed in detailed to reveal exothermic reaction characteristics. Besides, effects of different reaction conditions during hydration are studied, such as porosity, temperature, pressure, flow rate and thermal conductivity. It is found that the low thermal conductivity of solid-phase is the most important factor which limits the reaction. The Heat transfer process can be greatly promoted by adding fins, due to the high Heat conductivity. However, the relationship between the reactor structure and the performance of the thermochemical Heat Storage is not quantitatively clear. The present study aims to investigate the impact of the arrangement of fins on the hydration process. Finally, different types of fins with high thermal conductivity are employed in the reactor. Attributing to the fact that the equilibrium temperature is affected by the vapor pressure, thermochemical reactors with different fin configurations have different flow characteristics and pressure drops, leading to different reaction characteristics. It is shown that the exothermic time was reduced to 84.32% (axial fins), 89.97% (radial fins), and 88.71% (spiral fins) of the original, respectively. This study can reveal the coupling relations of multi-physics fields in thermochemical Heat Storage, and provide theoretical basis for the design of thermochemical Heat Storage reactors.
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development of granular thermochemical Heat Storage composite based on calcium oxide
Renewable Energy, 2020Co-Authors: B Q Xia, C Y Zhao, J Yan, Azhar Abbas KhosaAbstract:Abstract Thermochemical Heat Storage is a promising technology for the efficient utilization of renewable energy. Among available thermochemical systems, the CaO/Ca(OH)2 system is the most popular because of availability and cost. However, poor powder properties and low Heat Storage rates hinder the successful implementation of this system. This study presented a novel synthetic method of granular composites based on carboxymethyl cellulose sodium (CMC) and vermiculite in order to mitigate the drawbacks of natural materials and stabilize the size of materials for use in moving bed reactors. TGA and DSC experiments and some essential characterizations were done in order to evaluate the improvements on the basis of three objectives: the Heat Storage rate, Heat Storage density, and mechanical properties, compared with natural materials. Results showed that the granular composite still had great structural integrity after several dehydration/hydration cycles, whereas compacted natural materials had fragmented. Additionally, composite had a higher Heat Storage rate than natural materials. The gravimetric Storage density of granular composite was slightly reduced while the volumetric Storage density was enhanced up to approximately 124% as compared to the powdery Ca(OH)2 material. It was concluded that present synthetic method is a promising route for the development of Ca-based composite materials.
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Medium- and high-temperature latent and thermochemical Heat Storage using metals and metallic compounds as Heat Storage media: A technical review
'Elsevier BV', 2020Co-Authors: Zhao Y, C Y Zhao, Cn Markides, Wang H, Li WAbstract:Latent and thermochemical Heat Storage technologies are receiving increased attention due to their important role in addressing the challenges of variable renewable energy generation and waste Heat availability, as well as the mismatch between energy supply and demand in time and space. However, as the operating Storage temperature increases, a series of challenging technical problems arise, such as complex Heat transfer mechanisms, increased corrosion, material failure, reduced strength, and high-temperature measurement difficulties, especially for metals and metallic compounds as Heat Storage media. This paper reviews the latest research progress in medium- and high-temperature latent and thermochemical Heat Storage using metals and metallic compounds as Storage media from a technical perspective and provides useful information for researchers and engineers in the field of energy Storage. In this paper, the status and challenges of medium- and high-temperature latent and thermochemical Heat Storage are first introduced, followed by an assessment of metals and metallic compounds as Heat Storage media in latent and thermochemical Heat Storage applications. This is followed by a comprehensive review of three key issues associated with medium/high-temperature latent Heat Storage applications: Heat transfer enhancement, stability and corrosion, as well as a discussion of four key issues associated with medium/high-temperature thermochemical Heat Storage: Heat transfer, cycling stability, mechanical property and reactor/system design. Finally, the prospects of medium/high-temperature latent and thermochemical Heat Storage are summarized
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mesoscopic exploration on mass transfer in porous thermochemical Heat Storage materials
International Journal of Heat and Mass Transfer, 2019Co-Authors: B Q Xia, Z H Pan, J Yan, C Y ZhaoAbstract:Abstract Mass transfer is the key characteristic that affects the charging and discharging performance of the porous materials used in thermochemical Heat Storage systems. Therefore, an algorithm is required to simulate the transport process within Heat Storage materials and to accurately evaluate the effective diffusion coefficient. This study is about porous calcium oxide, which is widely used in CaO-Ca(OH)2 or CaO-CaCO3 Heat Storage systems. In this paper, the fractal porous media that resemble real Heat Storage materials are reconstructed by a random walk method. Furthermore, the gas diffusion process through complicated porous microstructures within fractal porous media is simulated by an efficient lattice Boltzmann method. Results indicate that thermochemical Heat Storage materials have great fractal characteristic and materials with larger fractal dimension have more diffusion resistance. The effective gas diffusion coefficients of CaO and Ca(OH)2 are obtained from the ratios of effective gas diffusion coefficient and bulk gas diffusion coefficient that are 0.228 and 0.188 for CaO and Ca(OH)2, respectively. Additionally, it is found that calcium oxide samples prepared at higher temperatures have the poorer exothermic performance because of the poorer gas diffusion. Moreover, the correlation between the effective diffusion coefficients and the porosity of porous materials is numerically predicted and evaluated. The fractal model-LBM method developed in this paper may serve as a great tool for easy estimation of effective diffusion coefficients and mass transfer.
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gas solid thermochemical Heat Storage reactors for high temperature applications
Energy, 2017Co-Authors: Z H Pan, C Y ZhaoAbstract:Abstract Reversible reactions exhibit considerable potential for thermal energy Storage because of their high energy density and capability for long-term Storage at ambient temperature. This paper presents the research progress on gas–solid thermochemical Heat Storage reactors and their corresponding systems. The comprehensive state-of-the-art knowledge on gas–solid thermochemical reactors, namely, packed bed, continuous, and direct-type reactors, for high-temperature Heat Storage applications is reviewed. Up till now, the performance of packed bed reactors has been extensively investigated. However, the intrinsic drawbacks of packed bed reactors limit their applications. Continuous and direct-type reactors can efficiently store Heat, but studies on these reactors are still on the stage of material characterization and prototype designing. Various numerical studies have successfully predicted the reaction trends in the three reactors to elucidate their performances and features. In these studies, porous thermochemical materials are studied on the scale of representative element volume. So far, numerical or experimental approaches have been rarely used to investigate physical and chemical processes at the particle scale. Energy and exergy analyses on conceptual thermochemical Heat Storage systems came into existence recently. In the future, more efficiency analyses based on practical experimental results are required.
Laxmikant Sahoo - One of the best experts on this subject based on the ideXlab platform.
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Thermal Analysis of a Solar Concentrating System Integrated with Sensible and Latent Heat Storage
Energy Procedia, 2015Co-Authors: Pramod Vasantrao Bhale, Manish K. Rathod, Laxmikant SahooAbstract:The scarcity and the up scaling cost of fossil fuels have forced everyone to look out for an alternative sources of energy. Most of the process Heat requirements of industries fall in the temperature range of 125-350 0C where solar concentrating collectors can meet most of the requirement. One of the most common problems that solar power generation systems face is the gap that exists between the availability of the solar resource and energy demand, causing the need for an effective method by which excess Heat collected during periods of high solar irradiation can be stored and retrieved later for use at night or during periods of darkness. The literature survey indicates that considerable amount of work in the area of thermal energy Storage is concerned with either sensible Heat Storage system or latent Heat Storage systems only and not much reported on the combined sensible and latent Heat Storage systems. Moreover, very limited attempts are made in the high temperature actual solar concentrating systems of considerable size. The purpose of this work is to investigate experimentally the thermal analysis of the concentrating solar system with sensible (without phase change material, PCM) and latent Heat energy Storage system. A 16 m2 solar concentrating collector was used for this purpose. A Heat exchanger was designed and fabricated to house the phase change material. A thermic fluid was pumped into the system via solar concentrator. The experimental results in the form of charging efficiency and overall efficiency with latent Heat and without latent Heat Storage (only sensible) were presented. During the discharging experiments it was observed that the combined system performs much better than the mere sensible Storage type system without phase change material for latent Heat Storage.
Klaus Schwarzer - One of the best experts on this subject based on the ideXlab platform.
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Heat TRANSFER ENHANCEMENT IN A LATENT Heat Storage SYSTEM
Solar Energy, 1999Co-Authors: Ramalingam Velraj, B. Hafner, C. Faber, R.v. Seeniraj, Klaus SchwarzerAbstract:Commercial acceptance and the economics of solar thermal technologies are tied to the design and development of efficient, cost-effective thermal Storage systems. Thermal Storage units that utilize latent Heat Storage materials have received greater attention in the recent years because of their large Heat Storage capacity and their isothermal behavior during the charging and discharging processes. One major issue that needs to be addressed is that most phase-change materials (PCM) with high energy Storage density have an unacceptably low thermal conductivity and hence Heat transfer enhancement techniques are required for any latent Heat thermal Storage (LHTS) applications. In the present paper the various Heat transfer enhancement methods for LHTS systems are discussed. Three different experiments to augment Heat transfer were conducted and the findings are reported.
R Z Wang - One of the best experts on this subject based on the ideXlab platform.
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experimental investigation on thermochemical Heat Storage using manganese chloride ammonia
Energy, 2018Co-Authors: T. Yan, R Z WangAbstract:Abstract Thermal energy Storage plays a key role in the application of renewable energy and low-grade thermal energy. A laboratory test unit of thermochemical Heat Storage with manganese chloride (MnCl2) as the reactive salt and ammonia (NH3) as the working gas was constructed, in which expanded graphite was used to improve the Heat and mass transfer performance of composite materials. The experimental campaigns show some promising conclusions on the Heat Storage performances of such a Storage unit. With 3.78 kg of composite materials, the highest thermochemical Heat Storage density is about 1391 kJ/kg when the charging and discharging temperature is 174 °C and 50 °C, respectively. The corresponding volume density of thermochemical Heat Storage is 179 kWh/m3. The maximum of thermochemical Heat Storage efficiency obtained is 48%. The maximum of instantaneous thermochemical Heat output power is more than 50 kW. The maximum for the average thermochemical Heat output power reaches to 9.9 kW under the experimental conditions. The application prospects of such a thermochemical Heat Storage system are presented. The promising results have been gained, but some problems must be envisaged. The improvement measures to overcome these problems are also brought forward in order to make the thermochemical Heat Storage technology realize a successful application in practical systems.
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A review of promising candidate reactions for chemical Heat Storage
Renewable and Sustainable Energy Reviews, 2015Co-Authors: T. Yan, T. X. Li, R Z Wang, Ruzhu Wang, L.w. Wang, Ishugah T. FredAbstract:Thermal energy Storage is a necessary technology for the application of renewable energy and low-grade thermal energy. Chemical Heat Storage has been proved to be a feasible and promising method to store thermal energy. As compared to other thermal energy Storage methods, chemical Heat Storage exhibits high energy Storage density as well as feasibility for long-duration energy Storage. In this paper, the basic principle of the chemical Heat Storage is firstly elaborated. Then the selection criteria of the chemical reaction are given. The aim of this review is to provide an insight into the promising candidate reactions for chemical Heat Storage application. The associated reversible chemical reactions available for thermal energy Storage systems are summarized. Ongoing research and development studies illustrate that chemical Heat Storage is a very favorable option for the different application when diverse promising candidate reactions are selected. As working temperature is one of the key parameters for thermal energy Storage systems, emphasis is given to the judgment of application temperature range for chemical Heat Storage. The determination of applicative temperature range of reversible chemical reactions is discussed. Besides, the challenge and prospect of the chemical Heat Storage technology are analyzed in the paper.
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experimental investigation and performance analysis on a solar adsorption cooling system with without Heat Storage
Applied Energy, 2010Co-Authors: X Q Zhai, R Z WangAbstract:A solar adsorption cooling system which can be switched between a system with Heat Storage and a system without Heat Storage was designed. In the system with Heat Storage, a Heat Storage water tank was employed as the link between the solar collector circulation and the hot water circulation for the adsorption chillers. However, the Heat Storage water tank was isolated in the system without Heat Storage, and the hot water was directly circulated between the solar collector arrays and the adsorption chillers. It was found that the inlet and outlet temperatures for the solar collector arrays and the adsorption chillers in the system without Heat Storage were more fluctuant than those of the system with Heat Storage. Also found was that the system with Heat Storage operated stably because of the regulating effect by the Heat Storage water tank. However, under otherwise similar conditions, the cooling effect of the system without Heat Storage was similar to that of the system with Heat Storage. Compared with the system with Heat Storage, the system without Heat Storage has the advantages of higher solar collecting efficiency as well as higher electrical COP.
Ruud Cuypers - One of the best experts on this subject based on the ideXlab platform.
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thermochemical Heat Storage from reaction Storage density to system Storage density
Energy Procedia, 2016Co-Authors: A J De Jong, L D Van Vliet, Christophe Hoegaerts, C P M Roelands, Ruud CuypersAbstract:Long-term and compact Storage of solar energy is crucial for the eventual transition to a 100% renewable energy economy. For this, thermochemical materials provide a promising solution. The compactness of a long-term Storage system is determined by the thermochemical reaction, operating conditions, and system implementation with the necessary additional system components. Within the MERITS project a thermochemical Storage (TCS) system is being demonstrated using evacuated, closed TCS modules containing Na2S as active material. The present modules are expected to reach a Heat Storage density of 0.18GJ/m3. In this paper, we discuss the different factors leading to this Storage density, and argue that by further optimization of the selected reaction and architecture, the result may be improved to approximately 1GJ/m3, which would be a practical value for seasonal Heat Storage in buildings.
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thermochemical Heat Storage system design issues
Energy Procedia, 2014Co-Authors: Ardjan De Jong, C Christian J Finck, Fanny Trausel, Laurens Van Vliet, Ruud CuypersAbstract:Thermochemical materials (TCMs) are a promising solution for seasonal Heat Storage, providing the possibility to store excess solar energy from the warm season for later use during the cold season, and with that all year long sustainable energy. With our fixed bed, vacuum reactors using zeolite as TCM, we recently demonstrated long-term Heat Storage with satisfactory output power. For domestic application, however, it will be necessary to considerably increase Storage density and to reduce system costs. In this paper, we discuss issues on system, component and material levels for realizing a commercially attractive system. We first discuss a modular, fixed bed concept with a hot water Storage. We show that with proper dimensioning of TCM modules and hot water Storage, one can obtain a system where daily Storage and on-demand Heat delivery can be arranged by the hot water Storage, while demands on output power, power control and material stability during operation are relaxed as much as possible. We also discuss atmospheric and central reactor concepts, which may provide lower-cost TCS systems. An important issue on component level is the implementation of a low temperature source providing evaporation Heat in winter. We discuss several options, including the application of solar collectors in winter. Heat Storage density can be increased by an order of magnitude by applying hydration reactions of hygroscopic salts, but this introduces physical and chemical stability issues during repeated cycles of hydration and dehydration. We discuss several of these stability issues as well as possible stabilization in a composite TCM, which should also provide sufficient vapor and Heat transport.
