Phase change materials(PCMs)offer a promising solution to address the challenges posed by intermittency and fluctuations in solar thermal utilization.However,for organic solid-liquid PCMs,issues such as leakage,low th...Phase change materials(PCMs)offer a promising solution to address the challenges posed by intermittency and fluctuations in solar thermal utilization.However,for organic solid-liquid PCMs,issues such as leakage,low thermal conductivity,lack of efficient solar-thermal media,and flamma-bility have constrained their broad applications.Herein,we present an innova-tive class of versatile composite phase change materials(CPCMs)developed through a facile and environmentally friendly synthesis approach,leveraging the inherent anisotropy and unidirectional porosity of wood aerogel(nanowood)to support polyethylene glycol(PEG).The wood modification process involves the incorporation of phytic acid(PA)and MXene hybrid structure through an evaporation-induced assembly method,which could impart non-leaking PEG filling while concurrently facilitating thermal conduction,light absorption,and flame-retardant.Consequently,the as-prepared wood-based CPCMs showcase enhanced thermal conductivity(0.82 W m^(-1)K^(-1),about 4.6 times than PEG)as well as high latent heat of 135.5 kJ kg^(-1)(91.5%encapsula-tion)with thermal durability and stability throughout at least 200 heating and cooling cycles,featuring dramatic solar-thermal conversion efficiency up to 98.58%.In addition,with the synergistic effect of phytic acid and MXene,the flame-retardant performance of the CPCMs has been significantly enhanced,showing a self-extinguishing behavior.Moreover,the excellent electromagnetic shielding of 44.45 dB was endowed to the CPCMs,relieving contemporary health hazards associated with electromagnetic waves.Overall,we capitalize on the exquisite wood cell structure with unidirectional transport inherent in the development of multifunctional CPCMs,showcasing the operational principle through a proof-of-concept prototype system.展开更多
The conversion and storage of photothermal energy using phase change materials(PCMs)represent an optimal approach for harnessing clean and sustainable solar energy.Herein,we encapsulated polyethylene glycol(PEG)in mon...The conversion and storage of photothermal energy using phase change materials(PCMs)represent an optimal approach for harnessing clean and sustainable solar energy.Herein,we encapsulated polyethylene glycol(PEG)in montmorillonite aerogels(3D-Mt)through vacuum impregnation to prepare 3D-Mt/PEG composite PCMs.When used as a support matrix,3D-Mt can effectively prevent PEG leakage and act as a flame-retardant barrier to reduce the flammability of PEG.Simultaneously,3D-Mt/PEG demonstrates outstanding shape retention,increased thermal energy storage density,and commendable thermal and chemical stability.The phase transition enthalpy of 3D-Mt/PEG can reach 167.53 J/g and remains stable even after 50 heating-cooling cycles.Furthermore,the vertical sheet-like structure of 3D-Mt establishes directional heat transport channels,facilitating efficient phonon transfer.This configuration results in highly anisotropic thermal conductivities that ensure swift thermal responses and efficient heat conduction.This study addresses the shortcomings of PCMs,including the issues of leakage and inadequate flame retardancy.It achieves the development and design of 3D-Mt/PEG with ultrahigh strength,superior flame retardancy,and directional heat transfer.Therefore,this work offers a design strategy for the preparation of high-performance composite PCMs.The 3D-Mt/PEG with vertically aligned and well-ordered array structure developed in this research shows great potential for thermal management and photothermal conversion applications.展开更多
This study is focused on the simulation and optimization of packed-bed solar thermal energy storage by using sand as a storage material and hot-water is used as a heat transfer fluid and storage as well.The analysis h...This study is focused on the simulation and optimization of packed-bed solar thermal energy storage by using sand as a storage material and hot-water is used as a heat transfer fluid and storage as well.The analysis has been done by using the COMSOL multi-physics software and used to compute an optimization charging time of the storage.Parameters that control this optimization are storage height,storage diameter,heat transfer fluid flow rate,and sand bed particle size.The result of COMSOL multi-physics optimized thermal storage has been validated with Taguchi method.Accordingly,the optimized parameters of storage are:storage height of 1.4m,storage diameter of 0.4 m,flow rate of 0.02 kg/s,and sand particle size 12 mm.Among these parameters,the storage diameter result is the highest influenced optimized parameter of the thermal storage fromthe ANOVA analysis.For nominal packed bed thermal storage,the charging time needed to attain about 520 K temperature is more than 3500 s,while it needs only about 2000 s for the optimized storage which is very significant difference.Average charging energy efficiency of the optimized is greater than the nominal and previous concrete-based storage by 13.7%,and 13.1%,respectively in the charging time of 2700 s.展开更多
In order to improve the thermal shock resistance of solar thermal heat transfer tube material, the mullite-cordierite composite ceramic as solar thermal heat transfer tube material were fabricated by pressureless sint...In order to improve the thermal shock resistance of solar thermal heat transfer tube material, the mullite-cordierite composite ceramic as solar thermal heat transfer tube material were fabricated by pressureless sintering using a-Al203, Suzhou kaolin, talc, and feldspar as starting materials. The important parameter for solar thermal transfer tube such as water absorption （W）, bulk density （Db）, and the mechanical properties were investigated. The phase composition and microstructure of the composite ceramics were analyzed by XRD and SEM. The experimental results show that the B3 sintered at 1 300 ℃ and holding for 3 h has an optimum thermal shock resistance. The bending strength loss rate of B3 is only 2% at 1 100℃ by air quenching-strength test and the sample can endure 30 times thermal shock cycling, and the water absorption, the bulk density and the bending strength are 0.32%, 2.58 g·cm-3, and 125.59 MPa respectively. The XRD analysis indicated that the phase compositions of the sample were mullite, cordierite, corundum, and spinel. The SEM images illustrate that the cordierite is prismatic grain and the mullite is nano rod, showing a good thermal shock resistance for composite ceramics as potential solar thermal power material.展开更多
Thermodynamic analysis of the reforming of methane with carbon dioxide alone （＂dry reforming＂） and with carbon dioxide and steam together （＂mixed reforming＂） is performed as part of a project which investigate...Thermodynamic analysis of the reforming of methane with carbon dioxide alone （＂dry reforming＂） and with carbon dioxide and steam together （＂mixed reforming＂） is performed as part of a project which investigates the suitability of these endothermic reactions for the storage of solar thermal energy. The Gibbs free energy minimization method was employed to identify thermodynamically optimal operating conditions for dry reforming as well as mixed reforming with a desired H2/CO molar ratio of 2. The non-stoichiometric equilibrium model was developed using FactSage software to conduct the thermodynamic calculations for carbon formation, H2/CO ratio, CH4 conversion and H2 yield as a function of reaction temperature, pressure and reactant molar ratios. Thermodynamic calculations demonstrate that in the mixed reforming process, optimal operating conditions in a carbon-free zone are under H2O/CH4 /CO2 =1.0/1.0/0.5, p = 1 to 10 bar and T = 800 to 850℃ for the production of syngas with a H2 /CO molar ratio of 2. Under the optimal conditions, the maximum H2 yield of 88.0% is achieved at 1 bar and 850℃ with a maximum CH4 conversion of 99.3%. In the dry reforming process, a carbon formation regime is always present at a CO2/CH4 molar ratio of 1 for T = 700 1000℃ and p = 1-30 bar, whereas a carbon-free regime can be obtained at a CO2/CH4 molar ratio greater than 1.5 and T≥800℃.展开更多
The Al2O3-ZrO2（3Y）-SiC composite ceramics used in solar thermal power were prepared by micrometric Al2O3,nano-ZrO2 and SiC powders under the condition of pressureless sintering.The bulk density and bending strength ...The Al2O3-ZrO2（3Y）-SiC composite ceramics used in solar thermal power were prepared by micrometric Al2O3,nano-ZrO2 and SiC powders under the condition of pressureless sintering.The bulk density and bending strength of samples with 10vol% nano-ZrO2 sintered at 1480℃ were 3.222 g/cm3 and 160.4MPa,respectively.The bending strength of samples after 7 times thermal shock tests （quenching from 1000℃ to 25℃ in air medium） is 132.0MPa,loss rate of bending strength is only 17%.The effect of nano-ZrO2 content on the microstructure and performance of Al2O3-ZrO2（3Y）-SiC composite ceramic was investigated.The experimental results show that the bending strength of samples with above 10vol% nano-ZrO2 content has decreased,because the volume expansion resulting from t-ZrO2 to m-ZrO2 phase transformation is excessive;Adding proper nano-ZrO2 would be contributed to improve the thermal shock resistance of the composite ceramics.The Al2O3-ZrO2（3Y）-SiC composite ceramic has promising potential application in solar thermal power.展开更多
Green conditions have been developed for the synthesis of substituted 2-aminothiophenes employing multicomponent reactions of a ketone with active methylene nitrile and elemental sulphur induced by free solar thermal ...Green conditions have been developed for the synthesis of substituted 2-aminothiophenes employing multicomponent reactions of a ketone with active methylene nitrile and elemental sulphur induced by free solar thermal energy.展开更多
High-temperature thermal storage material is one of the critical materials of solar thermal power generation system. Andalusite, kaolin, talc, γ-Al2O3 and partially stabilized zireonia were used as the raw materials,...High-temperature thermal storage material is one of the critical materials of solar thermal power generation system. Andalusite, kaolin, talc, γ-Al2O3 and partially stabilized zireonia were used as the raw materials, and in-situ synthesis of cordierite was adopted to fabricate thermal storage material for solar thermal power generation via pressureless sintering. The phase compositions, microstructures and thermal shock resistances of the sintered samples were analyzed by XRD, SEM and EDS, and the corresponding mechanical properties were measured. The results show that the major phases of the samples are mullite and zirconium silicate, and the pores distribute uniformly. After being sintered at 1 460℃C, A4 sample exhibits a better mechanical performance and thermal shock resistance, its loss rate of bending strength after 30 cycles thermal shock is 3.04%, the bulk density and bending strength are 2.86 g.cm^-3 and 139.66 MPa, respectively. The better thermal shock resistance of the sample is closely related to the effect of zirconium silicate, such as its uniform distribution, nested growth with mullite, low thermal expansion coefficient, high thermal conductivity, etc. This ceramic can be widely used as one of potential thermal storage materials of solar thermal power generation system.展开更多
A simple, convenient and efficient method for the synthesis of 1,2,4,5-tetrasubstituted imidazole derivatives using benzoin, an aromatic aldehyde, an aromatic amine in the presence of ammonium acetate catalyzed by hig...A simple, convenient and efficient method for the synthesis of 1,2,4,5-tetrasubstituted imidazole derivatives using benzoin, an aromatic aldehyde, an aromatic amine in the presence of ammonium acetate catalyzed by high surface area SiO2 and induced by free solar thermal energy was reported. C 2009 Kamal User Sadek. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.展开更多
In view of the high cost of solar thermal power generation in China,it is difficult to realize large-scale production in engineering and industrialization.Non-dominated sorting genetic algorithm II(NSGA-II)is applied ...In view of the high cost of solar thermal power generation in China,it is difficult to realize large-scale production in engineering and industrialization.Non-dominated sorting genetic algorithm II(NSGA-II)is applied to optimize the levelling cost of energy(LCOE)of the solar thermal power generation system in this paper.Firstly,the capacity and generation cost of the solar thermal power generation system are modeled according to the data of several sets of solar thermal power stations which have been put into production abroad.Secondly,the NSGA-II genetic algorithm and particle swarm algorithm are applied to the optimization of the solar thermal power station LCOE respectively.Finally,for the linear Fresnel solar thermal power system,the simulation experiments are conducted to analyze the effects of different solar energy generation capacities,different heat transfer mediums and loan interest rates on the generation price.The results show that due to the existence of scale effect,the greater the capacity of the power station,the lower the cost of leveling and electricity,and the influence of the types of heat storage medium and the loan on the cost of leveling electricity are relatively high.展开更多
Using solar energy to produce syngas via the endothermic reforming of methane has been extensively inves- tigated at the laboratory- and pilot plant-scales as a promising method of storing solar energy. One of the cha...Using solar energy to produce syngas via the endothermic reforming of methane has been extensively inves- tigated at the laboratory- and pilot plant-scales as a promising method of storing solar energy. One of the challenges to scaling up this process in a tubular reformer is to improve the reactor＇s performance, which is limited by mass and heat transfer issues. High thermal conductivity Cu foam was therefore used as a sub-strate to improve the catalyst＇s thermal conductivity during solar reforming. We also developed a method to coat the foam with the catalytically active component NiMg3AlOx. The Cu foam-based NiMg3AlOx performs better than catalysts supported on SiSiC foam, which is currently used as a substrate for solar-reforming cat- alysts, at high gas hourly space velocity （≥400,000 mL/（g.h）） or at low reaction temperatures （≤ 720 ℃）. The presence of a γ-Al2O3 intermediate layer improves the adhesion between the catalyst and substrate as well as the catalytic activity.展开更多
The energy storage mechanism of azobenzene is based on the transformation of molecular cis and trans isomerization,while NBD/QC,DHA/VHF,and fulvalene dimetal complexes realize the energy storage function by changing t...The energy storage mechanism of azobenzene is based on the transformation of molecular cis and trans isomerization,while NBD/QC,DHA/VHF,and fulvalene dimetal complexes realize the energy storage function by changing the molecular structure.Acting as“molecular batteries,”they can exhibit excellent charging and discharging behavior by converting between trans and cis isomers or changing molecular structure upon absorption of ultraviolet light.Key properties determining the performance of STFs are stored energy,energy density,half-life,and solar energy conversion efficiency.This review is aiming to provide a comprehensive and authoritative overview on the recent advancements of azobenzene molecular photoswitch system in STFs fields,including derivatives and carbon nano-templates,which is emphasized for its attractive performance.Although the energy storage performance of Azo-STFs has already reached the level of commercial lithium batteries,the cycling capability and controllable release of energy still need to be further explored.For this,some potential solutions to the cycle performance are proposed,and the methods of azobenzene controllable energy release are summarized.Moreover,energy stored by STFs can be released in the form of mechanical energy,which in turn can also promote the release of thermal energy from STFs,implying that there could be a relationship between mechanical and thermal energy in Azo-STFs,providing a potential direction for further research on Azo-STFs.展开更多
Post-combustion amine absorption and stripping can remove 90% of the CO2 from power plant flue gas, but systems can reduce electrical output by approximately 30% due to energy requirements for stripping CO2 from solve...Post-combustion amine absorption and stripping can remove 90% of the CO2 from power plant flue gas, but systems can reduce electrical output by approximately 30% due to energy requirements for stripping CO2 from solvent and CO2 compression. The CO2 capture energy penalty can be reduced while developing renewable energy technologies by meeting CO2 capture energy requirements with a solar thermal energy system, particularly when electricity demand and prices are the highest. This study presents an initial review of solar thermal technologies for supplying CO2 capture energy, with a focus on high temperature systems. Parabolic troughs and central receivers are technically able to provide energy for CO2 capture. However, the solar system＇s capital costs would be roughly half that of the base coal-fired plant with CO2 capture, and high electricity prices are required to offset the costs of operating the solar thermal system. For high temperature solar thermal systems, direct electricity generation is likely a more efficient way to use solar energy to replace output lost to CO2 capture energy. However, low temperature solar thermal systems might integrate better with solvent stripping equipment, and more rigorous analysis is required to definitively assess the feasibility of using solar energy for CO2 capture.展开更多
To this day, only two types of solar power plants have been proposed and built: high temperature thermal solar one and photovoltaic one. It is here proposed a new type of solar thermal plant using glass-top flat surfa...To this day, only two types of solar power plants have been proposed and built: high temperature thermal solar one and photovoltaic one. It is here proposed a new type of solar thermal plant using glass-top flat surface solar collectors, so working at low temperature (i.e., below 100°C). This power plant is aimed at warm countries, i.e., the ones mainly located between -40° and 40° latitude, having available space along their coast. This land based plant, to install on the seashore, is technologically similar to the one used for OTEC (Ocean Thermal Energy Conversion). This plant, apart from supplying electricity with a much better thermodynamic efficiency than OTEC plants, has the main advantage of providing desalinated water for drinking and irrigation. This plant is designed to generate electricity (and desalinated water) night and day and all year round, by means of hot water storage, with just a variation of the power delivered depending on the season.展开更多
In this research, the performance of the solar thermal powered systems (STPS) is analyzed with different models (without inserts, with inserts and with Nano fluids with different concentrations) and its impact on the ...In this research, the performance of the solar thermal powered systems (STPS) is analyzed with different models (without inserts, with inserts and with Nano fluids with different concentrations) and its impact on the Electric load in a residential/Institutional Electrical Distribution system. For this purpose, the electrical and solar thermal water heater is tested and validated. Solar thermal powered systems and its impact on the Institutional electrical distribution feeders are tested and compared with the energy efficiency (EE) and cost optimization. The goal of this paper is to analyze the impact of solar thermal energy on electrical energy consumption in the electrical distribution feeder level. The electrical system cost and energy consumptions are tabulated and observed that there is a considerable savings.展开更多
The target of the National Solar Mission is to build up India as a worldwide pioneer in solar energy generation. Solar power can be transmitted through grid either from solar photovoltaic or solar thermal technology. ...The target of the National Solar Mission is to build up India as a worldwide pioneer in solar energy generation. Solar power can be transmitted through grid either from solar photovoltaic or solar thermal technology. As compared to solar photovoltaic, solar thermal installations are less studied, especially regarding energy estimation and performance analysis. For estimating the potential of CSP plants, it is planned to simulate a power plant. We have marginally modified the design of 1 MW operational power plant installed at Gurgaon using Parabolic Trough Collector (PTC) technology. The results are compared with the expected output of Gurgaon power plant and also 50 MW power plant at Rajasthan. Our results have closely matched with a small deviation of 3.1% and 3.6% for Gurgaon and Rajasthan plants, respectively. Our developed model is also validated with 18 different solar power plants in different parts of the world by slightly modifying the parameters according to the plant capacity without changing major changes to the plant design. Difference between our results and the expected energy generation varied from 0.4% to 13.7% with an average deviation of 6.8%. As our results show less than 10% deviation as compared to the actual generation, an attempt has been made here to estimate the potential for the entire nation. For this modelling has been carried out for every grid station of 0.25° × 0.25° interval in India. Our results show that annual solar thermal power plant of 1 MW<sub>e</sub> capacity potential varies from 900 to 2700 MWh. We have also compared our results with previous studies and discussed.展开更多
Solar thermal and photovoltaic applications are the most w idely used and the most successful w ay of commercial development in solar energy applications. Observation and assessment of solar thermal and photovoltaic r...Solar thermal and photovoltaic applications are the most w idely used and the most successful w ay of commercial development in solar energy applications. Observation and assessment of solar thermal and photovoltaic resources are the basis and key of their large-scale development and utilization. Using the observational data carried out from Beijing southern suburbs observation station of China M eteorological Administration in summer of 2009,preliminary solar thermal and photovoltaic resources characteristics for different w eather conditions,different angle and different directions are analyzed. The results show that:(1) In sunny,cloudy or rainy w eather conditions,both of solar thermal and photovoltaic sensors daily irradiance have consistent change in trend. Solar thermal irradiance is larger than photovoltaic. Under sunny conditions,solar thermal global radiation has about 2.7%higher than the photovoltaic global radiation. Under cloudy w eather conditions,solar thermal global radiation has about 3. 9%higher than the photovoltaic. Under rainy w eather conditions,solar thermal global radiation has about 20% higher than the photovoltaic.(2) For different inclined plane daily global radiation,southern latitude-15 °incline is the maximum and southern vertical surface is the minimum. The order from large to small is southern latitude-15 ° incline,southern latitude incline,southern latitude+15 °incline,horizontal surface and southern vertical surface. Southern latitude-15 °incline global radiation has about 41% higher than the southern vertical surface.(3) For different orientation vertical surface daily global radiation,southern vertical surface is the maximum and w estern vertical surface is the minimum,w hich eastern vertical surface is in the middle. Southern vertical surface global radiation has about 20% higher than the w estern vertical surface.展开更多
This paper describes how to achieve an efficient design and management of a tele-monitoring system of several solar thermal plants. The system will be able to make an analysis that assures a more efficient management ...This paper describes how to achieve an efficient design and management of a tele-monitoring system of several solar thermal plants. The system will be able to make an analysis that assures a more efficient management of each plant and of the whole system. In the first part of this study, the features of the monitoring system that allows to monitor the operating parameters and to discover the issues before they actually become dangerous for the plant have been identified. The data collected in the different solar thermal systems realized in Italian jails have been analyzed. The results of these elaborations allowed us both to find out some anomalies of functioning of the plants, and to optimize the management of the whole plant in a more efficient way.展开更多
A system of energy storage for solar thermal air conditioning combined with ejector cooling system for residential is determined in this paper. The purpose of this study is to design the energy storage system for heat...A system of energy storage for solar thermal air conditioning combined with ejector cooling system for residential is determined in this paper. The purpose of this study is to design the energy storage system for heating the water in a storage tank to reach the required temperature for exchanging heat with the refrigerant of cooling system. The design from calculation of thermal energy storage system that proper with the solar flat plate collector area results are 70 m2, and the hot water temperature is over than 80 ℃. A cooling system is selected for refrigerant of R141b from the solar air conditioning system of 10.5 kW, and the energy source is solar thermal energy from the collector that there is an efficiency of 0.46 approximately. This storage system for the electric solar cooling system can be reduced the problem of the intermittent of energy source with the constant generating temperature to run the cooling system continuously.展开更多
Mullite and corundum co-bonded SiC-based composite ceramics(SiC-mullite-Al2O3)were prepared by using SiC,calcined bauxite and kaolin via pressureless carbon-buried sintering.The low-cost SiC-based composite ceramics d...Mullite and corundum co-bonded SiC-based composite ceramics(SiC-mullite-Al2O3)were prepared by using SiC,calcined bauxite and kaolin via pressureless carbon-buried sintering.The low-cost SiC-based composite ceramics designed in this study are expected to be used as thermal storage materials in solar thermal power generation based on the high density and excellent thermal shock resistance.The influences of calcined bauxite addition and sintering temperature on the microstructures,phase compositions,and physical properties of the samples were investigated.Results demonstrated that the introduction of calcined bauxite containing two bonding phases greatly reduced the lowest sintering temperature to 1400℃.The SiC-mullite Al2O3 composite with 40 wt%calcined bauxite sintered at 1500℃exhibited optimum performance.The density and bending strength were 2.27 g·cm^-3 and 77.05 MPa.The bending strength increased by 24.58%and no cracks were observed after 30 thermal shock cycles,while general clay would reduce the thermal shock resistance of SiC.The SiC-mullite-Al2O3 composites with satisfied performance are expected to be used as thermal storage materials in solar thermal power generation systems.展开更多
基金funding from the National Natural Science Foundation of China(No.22268025)China Postdoctoral Science Foundation(NO.2022MD713757)+2 种基金Yunnan Provincial Postdoctoral Science Foundation(NO.34Y2022)Yunnan Province Joint Special Project for Enterprise Fundamental Research and Applied Basic Research(No.202101BC070001-016)Guangdong Basic and Applied Basic Research Foundation(No.2023A1515011985).
文摘Phase change materials(PCMs)offer a promising solution to address the challenges posed by intermittency and fluctuations in solar thermal utilization.However,for organic solid-liquid PCMs,issues such as leakage,low thermal conductivity,lack of efficient solar-thermal media,and flamma-bility have constrained their broad applications.Herein,we present an innova-tive class of versatile composite phase change materials(CPCMs)developed through a facile and environmentally friendly synthesis approach,leveraging the inherent anisotropy and unidirectional porosity of wood aerogel(nanowood)to support polyethylene glycol(PEG).The wood modification process involves the incorporation of phytic acid(PA)and MXene hybrid structure through an evaporation-induced assembly method,which could impart non-leaking PEG filling while concurrently facilitating thermal conduction,light absorption,and flame-retardant.Consequently,the as-prepared wood-based CPCMs showcase enhanced thermal conductivity(0.82 W m^(-1)K^(-1),about 4.6 times than PEG)as well as high latent heat of 135.5 kJ kg^(-1)(91.5%encapsula-tion)with thermal durability and stability throughout at least 200 heating and cooling cycles,featuring dramatic solar-thermal conversion efficiency up to 98.58%.In addition,with the synergistic effect of phytic acid and MXene,the flame-retardant performance of the CPCMs has been significantly enhanced,showing a self-extinguishing behavior.Moreover,the excellent electromagnetic shielding of 44.45 dB was endowed to the CPCMs,relieving contemporary health hazards associated with electromagnetic waves.Overall,we capitalize on the exquisite wood cell structure with unidirectional transport inherent in the development of multifunctional CPCMs,showcasing the operational principle through a proof-of-concept prototype system.
基金supported by the National Natural Science Foundation of China(No.52104265)。
文摘The conversion and storage of photothermal energy using phase change materials(PCMs)represent an optimal approach for harnessing clean and sustainable solar energy.Herein,we encapsulated polyethylene glycol(PEG)in montmorillonite aerogels(3D-Mt)through vacuum impregnation to prepare 3D-Mt/PEG composite PCMs.When used as a support matrix,3D-Mt can effectively prevent PEG leakage and act as a flame-retardant barrier to reduce the flammability of PEG.Simultaneously,3D-Mt/PEG demonstrates outstanding shape retention,increased thermal energy storage density,and commendable thermal and chemical stability.The phase transition enthalpy of 3D-Mt/PEG can reach 167.53 J/g and remains stable even after 50 heating-cooling cycles.Furthermore,the vertical sheet-like structure of 3D-Mt establishes directional heat transport channels,facilitating efficient phonon transfer.This configuration results in highly anisotropic thermal conductivities that ensure swift thermal responses and efficient heat conduction.This study addresses the shortcomings of PCMs,including the issues of leakage and inadequate flame retardancy.It achieves the development and design of 3D-Mt/PEG with ultrahigh strength,superior flame retardancy,and directional heat transfer.Therefore,this work offers a design strategy for the preparation of high-performance composite PCMs.The 3D-Mt/PEG with vertically aligned and well-ordered array structure developed in this research shows great potential for thermal management and photothermal conversion applications.
文摘This study is focused on the simulation and optimization of packed-bed solar thermal energy storage by using sand as a storage material and hot-water is used as a heat transfer fluid and storage as well.The analysis has been done by using the COMSOL multi-physics software and used to compute an optimization charging time of the storage.Parameters that control this optimization are storage height,storage diameter,heat transfer fluid flow rate,and sand bed particle size.The result of COMSOL multi-physics optimized thermal storage has been validated with Taguchi method.Accordingly,the optimized parameters of storage are:storage height of 1.4m,storage diameter of 0.4 m,flow rate of 0.02 kg/s,and sand particle size 12 mm.Among these parameters,the storage diameter result is the highest influenced optimized parameter of the thermal storage fromthe ANOVA analysis.For nominal packed bed thermal storage,the charging time needed to attain about 520 K temperature is more than 3500 s,while it needs only about 2000 s for the optimized storage which is very significant difference.Average charging energy efficiency of the optimized is greater than the nominal and previous concrete-based storage by 13.7%,and 13.1%,respectively in the charging time of 2700 s.
基金Funded by the Major State Basic Research Development Program of China(973 Program)(No.2010CB227105)
文摘In order to improve the thermal shock resistance of solar thermal heat transfer tube material, the mullite-cordierite composite ceramic as solar thermal heat transfer tube material were fabricated by pressureless sintering using a-Al203, Suzhou kaolin, talc, and feldspar as starting materials. The important parameter for solar thermal transfer tube such as water absorption （W）, bulk density （Db）, and the mechanical properties were investigated. The phase composition and microstructure of the composite ceramics were analyzed by XRD and SEM. The experimental results show that the B3 sintered at 1 300 ℃ and holding for 3 h has an optimum thermal shock resistance. The bending strength loss rate of B3 is only 2% at 1 100℃ by air quenching-strength test and the sample can endure 30 times thermal shock cycling, and the water absorption, the bulk density and the bending strength are 0.32%, 2.58 g·cm-3, and 125.59 MPa respectively. The XRD analysis indicated that the phase compositions of the sample were mullite, cordierite, corundum, and spinel. The SEM images illustrate that the cordierite is prismatic grain and the mullite is nano rod, showing a good thermal shock resistance for composite ceramics as potential solar thermal power material.
文摘Thermodynamic analysis of the reforming of methane with carbon dioxide alone （＂dry reforming＂） and with carbon dioxide and steam together （＂mixed reforming＂） is performed as part of a project which investigates the suitability of these endothermic reactions for the storage of solar thermal energy. The Gibbs free energy minimization method was employed to identify thermodynamically optimal operating conditions for dry reforming as well as mixed reforming with a desired H2/CO molar ratio of 2. The non-stoichiometric equilibrium model was developed using FactSage software to conduct the thermodynamic calculations for carbon formation, H2/CO ratio, CH4 conversion and H2 yield as a function of reaction temperature, pressure and reactant molar ratios. Thermodynamic calculations demonstrate that in the mixed reforming process, optimal operating conditions in a carbon-free zone are under H2O/CH4 /CO2 =1.0/1.0/0.5, p = 1 to 10 bar and T = 800 to 850℃ for the production of syngas with a H2 /CO molar ratio of 2. Under the optimal conditions, the maximum H2 yield of 88.0% is achieved at 1 bar and 850℃ with a maximum CH4 conversion of 99.3%. In the dry reforming process, a carbon formation regime is always present at a CO2/CH4 molar ratio of 1 for T = 700 1000℃ and p = 1-30 bar, whereas a carbon-free regime can be obtained at a CO2/CH4 molar ratio greater than 1.5 and T≥800℃.
文摘The Al2O3-ZrO2（3Y）-SiC composite ceramics used in solar thermal power were prepared by micrometric Al2O3,nano-ZrO2 and SiC powders under the condition of pressureless sintering.The bulk density and bending strength of samples with 10vol% nano-ZrO2 sintered at 1480℃ were 3.222 g/cm3 and 160.4MPa,respectively.The bending strength of samples after 7 times thermal shock tests （quenching from 1000℃ to 25℃ in air medium） is 132.0MPa,loss rate of bending strength is only 17%.The effect of nano-ZrO2 content on the microstructure and performance of Al2O3-ZrO2（3Y）-SiC composite ceramic was investigated.The experimental results show that the bending strength of samples with above 10vol% nano-ZrO2 content has decreased,because the volume expansion resulting from t-ZrO2 to m-ZrO2 phase transformation is excessive;Adding proper nano-ZrO2 would be contributed to improve the thermal shock resistance of the composite ceramics.The Al2O3-ZrO2（3Y）-SiC composite ceramic has promising potential application in solar thermal power.
文摘Green conditions have been developed for the synthesis of substituted 2-aminothiophenes employing multicomponent reactions of a ketone with active methylene nitrile and elemental sulphur induced by free solar thermal energy.
基金Funded by the Major State Basic Research Development Program of China(973 Program)(No.2010CB227105)Self-determined and Innovative Research Funds of WUT(No.44420520001)
文摘High-temperature thermal storage material is one of the critical materials of solar thermal power generation system. Andalusite, kaolin, talc, γ-Al2O3 and partially stabilized zireonia were used as the raw materials, and in-situ synthesis of cordierite was adopted to fabricate thermal storage material for solar thermal power generation via pressureless sintering. The phase compositions, microstructures and thermal shock resistances of the sintered samples were analyzed by XRD, SEM and EDS, and the corresponding mechanical properties were measured. The results show that the major phases of the samples are mullite and zirconium silicate, and the pores distribute uniformly. After being sintered at 1 460℃C, A4 sample exhibits a better mechanical performance and thermal shock resistance, its loss rate of bending strength after 30 cycles thermal shock is 3.04%, the bulk density and bending strength are 2.86 g.cm^-3 and 139.66 MPa, respectively. The better thermal shock resistance of the sample is closely related to the effect of zirconium silicate, such as its uniform distribution, nested growth with mullite, low thermal expansion coefficient, high thermal conductivity, etc. This ceramic can be widely used as one of potential thermal storage materials of solar thermal power generation system.
文摘A simple, convenient and efficient method for the synthesis of 1,2,4,5-tetrasubstituted imidazole derivatives using benzoin, an aromatic aldehyde, an aromatic amine in the presence of ammonium acetate catalyzed by high surface area SiO2 and induced by free solar thermal energy was reported. C 2009 Kamal User Sadek. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
基金National Natural Science Foundation of China(No.519667013)
文摘In view of the high cost of solar thermal power generation in China,it is difficult to realize large-scale production in engineering and industrialization.Non-dominated sorting genetic algorithm II(NSGA-II)is applied to optimize the levelling cost of energy(LCOE)of the solar thermal power generation system in this paper.Firstly,the capacity and generation cost of the solar thermal power generation system are modeled according to the data of several sets of solar thermal power stations which have been put into production abroad.Secondly,the NSGA-II genetic algorithm and particle swarm algorithm are applied to the optimization of the solar thermal power station LCOE respectively.Finally,for the linear Fresnel solar thermal power system,the simulation experiments are conducted to analyze the effects of different solar energy generation capacities,different heat transfer mediums and loan interest rates on the generation price.The results show that due to the existence of scale effect,the greater the capacity of the power station,the lower the cost of leveling and electricity,and the influence of the types of heat storage medium and the loan on the cost of leveling electricity are relatively high.
基金supported by the CSIRO Energy Flagship and the Chinese Scholarship Council
文摘Using solar energy to produce syngas via the endothermic reforming of methane has been extensively inves- tigated at the laboratory- and pilot plant-scales as a promising method of storing solar energy. One of the challenges to scaling up this process in a tubular reformer is to improve the reactor＇s performance, which is limited by mass and heat transfer issues. High thermal conductivity Cu foam was therefore used as a sub-strate to improve the catalyst＇s thermal conductivity during solar reforming. We also developed a method to coat the foam with the catalytically active component NiMg3AlOx. The Cu foam-based NiMg3AlOx performs better than catalysts supported on SiSiC foam, which is currently used as a substrate for solar-reforming cat- alysts, at high gas hourly space velocity （≥400,000 mL/（g.h）） or at low reaction temperatures （≤ 720 ℃）. The presence of a γ-Al2O3 intermediate layer improves the adhesion between the catalyst and substrate as well as the catalytic activity.
基金financially supported by the State Key Program of National Natural Science Foundation of China (No. 51633007 and 52130303)the National Natural Science Foundation of China (Nos. 51803151, 51973152, 51973151 and 51773147)
文摘The energy storage mechanism of azobenzene is based on the transformation of molecular cis and trans isomerization,while NBD/QC,DHA/VHF,and fulvalene dimetal complexes realize the energy storage function by changing the molecular structure.Acting as“molecular batteries,”they can exhibit excellent charging and discharging behavior by converting between trans and cis isomers or changing molecular structure upon absorption of ultraviolet light.Key properties determining the performance of STFs are stored energy,energy density,half-life,and solar energy conversion efficiency.This review is aiming to provide a comprehensive and authoritative overview on the recent advancements of azobenzene molecular photoswitch system in STFs fields,including derivatives and carbon nano-templates,which is emphasized for its attractive performance.Although the energy storage performance of Azo-STFs has already reached the level of commercial lithium batteries,the cycling capability and controllable release of energy still need to be further explored.For this,some potential solutions to the cycle performance are proposed,and the methods of azobenzene controllable energy release are summarized.Moreover,energy stored by STFs can be released in the form of mechanical energy,which in turn can also promote the release of thermal energy from STFs,implying that there could be a relationship between mechanical and thermal energy in Azo-STFs,providing a potential direction for further research on Azo-STFs.
文摘Post-combustion amine absorption and stripping can remove 90% of the CO2 from power plant flue gas, but systems can reduce electrical output by approximately 30% due to energy requirements for stripping CO2 from solvent and CO2 compression. The CO2 capture energy penalty can be reduced while developing renewable energy technologies by meeting CO2 capture energy requirements with a solar thermal energy system, particularly when electricity demand and prices are the highest. This study presents an initial review of solar thermal technologies for supplying CO2 capture energy, with a focus on high temperature systems. Parabolic troughs and central receivers are technically able to provide energy for CO2 capture. However, the solar system＇s capital costs would be roughly half that of the base coal-fired plant with CO2 capture, and high electricity prices are required to offset the costs of operating the solar thermal system. For high temperature solar thermal systems, direct electricity generation is likely a more efficient way to use solar energy to replace output lost to CO2 capture energy. However, low temperature solar thermal systems might integrate better with solvent stripping equipment, and more rigorous analysis is required to definitively assess the feasibility of using solar energy for CO2 capture.
文摘To this day, only two types of solar power plants have been proposed and built: high temperature thermal solar one and photovoltaic one. It is here proposed a new type of solar thermal plant using glass-top flat surface solar collectors, so working at low temperature (i.e., below 100°C). This power plant is aimed at warm countries, i.e., the ones mainly located between -40° and 40° latitude, having available space along their coast. This land based plant, to install on the seashore, is technologically similar to the one used for OTEC (Ocean Thermal Energy Conversion). This plant, apart from supplying electricity with a much better thermodynamic efficiency than OTEC plants, has the main advantage of providing desalinated water for drinking and irrigation. This plant is designed to generate electricity (and desalinated water) night and day and all year round, by means of hot water storage, with just a variation of the power delivered depending on the season.
文摘In this research, the performance of the solar thermal powered systems (STPS) is analyzed with different models (without inserts, with inserts and with Nano fluids with different concentrations) and its impact on the Electric load in a residential/Institutional Electrical Distribution system. For this purpose, the electrical and solar thermal water heater is tested and validated. Solar thermal powered systems and its impact on the Institutional electrical distribution feeders are tested and compared with the energy efficiency (EE) and cost optimization. The goal of this paper is to analyze the impact of solar thermal energy on electrical energy consumption in the electrical distribution feeder level. The electrical system cost and energy consumptions are tabulated and observed that there is a considerable savings.
文摘The target of the National Solar Mission is to build up India as a worldwide pioneer in solar energy generation. Solar power can be transmitted through grid either from solar photovoltaic or solar thermal technology. As compared to solar photovoltaic, solar thermal installations are less studied, especially regarding energy estimation and performance analysis. For estimating the potential of CSP plants, it is planned to simulate a power plant. We have marginally modified the design of 1 MW operational power plant installed at Gurgaon using Parabolic Trough Collector (PTC) technology. The results are compared with the expected output of Gurgaon power plant and also 50 MW power plant at Rajasthan. Our results have closely matched with a small deviation of 3.1% and 3.6% for Gurgaon and Rajasthan plants, respectively. Our developed model is also validated with 18 different solar power plants in different parts of the world by slightly modifying the parameters according to the plant capacity without changing major changes to the plant design. Difference between our results and the expected energy generation varied from 0.4% to 13.7% with an average deviation of 6.8%. As our results show less than 10% deviation as compared to the actual generation, an attempt has been made here to estimate the potential for the entire nation. For this modelling has been carried out for every grid station of 0.25° × 0.25° interval in India. Our results show that annual solar thermal power plant of 1 MW<sub>e</sub> capacity potential varies from 900 to 2700 MWh. We have also compared our results with previous studies and discussed.
文摘Solar thermal and photovoltaic applications are the most w idely used and the most successful w ay of commercial development in solar energy applications. Observation and assessment of solar thermal and photovoltaic resources are the basis and key of their large-scale development and utilization. Using the observational data carried out from Beijing southern suburbs observation station of China M eteorological Administration in summer of 2009,preliminary solar thermal and photovoltaic resources characteristics for different w eather conditions,different angle and different directions are analyzed. The results show that:(1) In sunny,cloudy or rainy w eather conditions,both of solar thermal and photovoltaic sensors daily irradiance have consistent change in trend. Solar thermal irradiance is larger than photovoltaic. Under sunny conditions,solar thermal global radiation has about 2.7%higher than the photovoltaic global radiation. Under cloudy w eather conditions,solar thermal global radiation has about 3. 9%higher than the photovoltaic. Under rainy w eather conditions,solar thermal global radiation has about 20% higher than the photovoltaic.(2) For different inclined plane daily global radiation,southern latitude-15 °incline is the maximum and southern vertical surface is the minimum. The order from large to small is southern latitude-15 ° incline,southern latitude incline,southern latitude+15 °incline,horizontal surface and southern vertical surface. Southern latitude-15 °incline global radiation has about 41% higher than the southern vertical surface.(3) For different orientation vertical surface daily global radiation,southern vertical surface is the maximum and w estern vertical surface is the minimum,w hich eastern vertical surface is in the middle. Southern vertical surface global radiation has about 20% higher than the w estern vertical surface.
文摘This paper describes how to achieve an efficient design and management of a tele-monitoring system of several solar thermal plants. The system will be able to make an analysis that assures a more efficient management of each plant and of the whole system. In the first part of this study, the features of the monitoring system that allows to monitor the operating parameters and to discover the issues before they actually become dangerous for the plant have been identified. The data collected in the different solar thermal systems realized in Italian jails have been analyzed. The results of these elaborations allowed us both to find out some anomalies of functioning of the plants, and to optimize the management of the whole plant in a more efficient way.
文摘A system of energy storage for solar thermal air conditioning combined with ejector cooling system for residential is determined in this paper. The purpose of this study is to design the energy storage system for heating the water in a storage tank to reach the required temperature for exchanging heat with the refrigerant of cooling system. The design from calculation of thermal energy storage system that proper with the solar flat plate collector area results are 70 m2, and the hot water temperature is over than 80 ℃. A cooling system is selected for refrigerant of R141b from the solar air conditioning system of 10.5 kW, and the energy source is solar thermal energy from the collector that there is an efficiency of 0.46 approximately. This storage system for the electric solar cooling system can be reduced the problem of the intermittent of energy source with the constant generating temperature to run the cooling system continuously.
基金Funded by the National Key Research and Development Program of Science and Technology of China(No.2018YFB1501002).
文摘Mullite and corundum co-bonded SiC-based composite ceramics(SiC-mullite-Al2O3)were prepared by using SiC,calcined bauxite and kaolin via pressureless carbon-buried sintering.The low-cost SiC-based composite ceramics designed in this study are expected to be used as thermal storage materials in solar thermal power generation based on the high density and excellent thermal shock resistance.The influences of calcined bauxite addition and sintering temperature on the microstructures,phase compositions,and physical properties of the samples were investigated.Results demonstrated that the introduction of calcined bauxite containing two bonding phases greatly reduced the lowest sintering temperature to 1400℃.The SiC-mullite Al2O3 composite with 40 wt%calcined bauxite sintered at 1500℃exhibited optimum performance.The density and bending strength were 2.27 g·cm^-3 and 77.05 MPa.The bending strength increased by 24.58%and no cracks were observed after 30 thermal shock cycles,while general clay would reduce the thermal shock resistance of SiC.The SiC-mullite-Al2O3 composites with satisfied performance are expected to be used as thermal storage materials in solar thermal power generation systems.
