The microstructures,components,thermal stability,specific heat capacity and thermal conductivity of basalt sample were studied.Besides,as a comprehensive result of thermal expansion and contraction process,both the fr...The microstructures,components,thermal stability,specific heat capacity and thermal conductivity of basalt sample were studied.Besides,as a comprehensive result of thermal expansion and contraction process,both the friction coefficient and wear rate of the basalt sample were also characterized.Our results indicate that basalt is an excellent candidate to be used as thermal energy storage material for concentrated solar power plants,and also provide a strategy for solar energy utilization in volcanic area with excellent geographical environment.展开更多
The heat transfer efficiency of a thermal energy storage unit(TESU)can be improved by the addition of novel longitudinal fins.A series of TESUs are analyzed using the finite volume method(FVM)to determine the effect o...The heat transfer efficiency of a thermal energy storage unit(TESU)can be improved by the addition of novel longitudinal fins.A series of TESUs are analyzed using the finite volume method(FVM)to determine the effect of fin angle on the heat transfer performance.As the fin angle increases,the TES rate first increases,then decreases,reaching a maximum rate at 60°,where the melting time is less by 30.9%,28.58%,21.99%,9.02%,and 18.1%than at 0°,15°,30°,45°,and 80°,respectively.In addition,it is found that the melting time of the phase change material is significantly greater at the bottom of the TESU.The time percentage of this stage decreases as the fin angle increases through these percentages by 7%,14%,23%,33%,and 20%,respectively.Further,the response surface methodology(RSM)is applied to optimize the longitudinal fin by minimizing the total melting time.The analysis concludes that a fin angle of 58.68°reduces the complete melting time of the stearic acid by 44%below the time at 0°.These findings fill a gap in knowledge of the effect on melting performance of the design angle of longitudinal fins and provide a reference for the design of horizontally placed longitudinal finned thermal energy storage units.展开更多
Multiple surface cracks and interfacial delamination are the major failure mechanisms in film/substrate systems.The effect of interlayer upon the failure mechanisms of interfacial delamination concomitant to surface c...Multiple surface cracks and interfacial delamination are the major failure mechanisms in film/substrate systems.The effect of interlayer upon the failure mechanisms of interfacial delamination concomitant to surface crack was explored.Finite element model was developed to obtain the stress and energy release rate(ERR),which governs the propagation of interface cracks.The dependences of delamination upon the geometry and constitutive properties of interlayer were examined.The results indicate that the effect of elastic modulus of interlayer on the steady state ERR is insignificant.In cases of different geometrical parameters,however,the steady ERR decreases with the increase of the interlayer thickness.These findings lead to the conclusion that the interlayer constraint has significant effect on the ERR and thus coating life,which can be adopted to modify the ceramic top coat.展开更多
Peeling-off phenomena in FRP strengthened concrete beams are investigated in this paper. Based on the beam theory and the fracture mechanics, a new theoretical model is proposed to analyze the peeling-off behavior nea...Peeling-off phenomena in FRP strengthened concrete beams are investigated in this paper. Based on the beam theory and the fracture mechanics, a new theoretical model is proposed to analyze the peeling-off behavior near FRP-concrete interfaces, which is governed by residual thermal stresses. Numerical examples are presented to provide a clear insight into the failure mechanism. Some suggestions are provided for the optimal design of FRP strengthened structures.展开更多
新能源接入现有电网将弱化系统的频率稳定性。充分利用调频资源对提升电网稳定性具有重要意义。火电作为当前调频主要资源有着复杂多变的特性,在不同工况下调频能力也会不同;且随着渗透率提高,传统的下垂控制调频方式逐渐不能满足控制...新能源接入现有电网将弱化系统的频率稳定性。充分利用调频资源对提升电网稳定性具有重要意义。火电作为当前调频主要资源有着复杂多变的特性,在不同工况下调频能力也会不同;且随着渗透率提高,传统的下垂控制调频方式逐渐不能满足控制要求。因此,提出一种储能–火电互补频率控制策略,设计了随频率变化自适应调节的出力比重系数,实现了储能出力的自适应调整,并将线性自抗扰控制(Linear active disturbance rejection control,LADRC)应用于火电机组的控制,通过频域法分析典型工业控制对象的LADRC参数调节规律。仿真结果表明,相较于传统下垂控制策略,所提出的储能–火电互补频率控制策略使系统的频率偏差最大值与稳态偏差值显著降低,并且有更好的储能恢复效果。展开更多
Thermal battery plays an important role in renewable energy utilization towards carbon neutrality.The novel absorption thermal battery(ATB)has excellent performance but suffers from serious capacity attenuation.To add...Thermal battery plays an important role in renewable energy utilization towards carbon neutrality.The novel absorption thermal battery(ATB)has excellent performance but suffers from serious capacity attenuation.To address this problem,two capacity regulation methods,i.e.,variable solution flow and variable cooling water flow,are proposed to achieve a demanded discharging rate.The effects of the two regulation strategies on the dynamic discharging characteristics and overall storage performance are comparatively investigated.To demon-strate the adjustability of the output capacity,several stable discharging rates are successfully maintained by the proposed methods.To maintain a higher discharging rate,the stable discharging time has to be sacrificed.As the demanded output increased from 0.5 kW to 6.0 kW,the stable discharging time decreased from 781.8 min to 27.9 min under variable solution flow and from 769.9 min to 30.7 min under variable cooling water flow.With the increase of solution or water flow rate,the energy storage density is improved,while the energy storage efficiency is slightly increased first and decreased later.The regulation method of variable water flow shows relatively lower energy storage efficiency due to the larger pump power.This study could facilitate reasonable development and application of ATB cycles.展开更多
基金Funded by the National Natural Science Foundation of China(Nos.12004150,61674073)the Guangdong Basic and Applied Basic Research Foundation(Nos.2020A1515110998,2022A1515012123)+4 种基金the Science and Technology Planning Project of Guangdong Province(2017A050506056)the College Physics Teaching Team(114961700249)the Key Basic and Applied Research Project of Guangdong Province(2016KZDXM021)the Major Projects of Basic and Application Research in Guangdong Province(2017KZDXM055)the Natural Science Research Youth Project of Lingnan Normal University(QL1404)。
文摘The microstructures,components,thermal stability,specific heat capacity and thermal conductivity of basalt sample were studied.Besides,as a comprehensive result of thermal expansion and contraction process,both the friction coefficient and wear rate of the basalt sample were also characterized.Our results indicate that basalt is an excellent candidate to be used as thermal energy storage material for concentrated solar power plants,and also provide a strategy for solar energy utilization in volcanic area with excellent geographical environment.
基金supported by the National Natural Science Foundation of China(No.51766012)the Inner Mongolia Science and Technology Major Project(No.2020ZD0017)+1 种基金the Science and Technology Research Project of Inner Mongolia Autonomous Region(No.2021GG0252)the Basic research business fund projects for Universities directly under the Inner Mongolia Autonomous Region(No.JY20220107)。
文摘The heat transfer efficiency of a thermal energy storage unit(TESU)can be improved by the addition of novel longitudinal fins.A series of TESUs are analyzed using the finite volume method(FVM)to determine the effect of fin angle on the heat transfer performance.As the fin angle increases,the TES rate first increases,then decreases,reaching a maximum rate at 60°,where the melting time is less by 30.9%,28.58%,21.99%,9.02%,and 18.1%than at 0°,15°,30°,45°,and 80°,respectively.In addition,it is found that the melting time of the phase change material is significantly greater at the bottom of the TESU.The time percentage of this stage decreases as the fin angle increases through these percentages by 7%,14%,23%,33%,and 20%,respectively.Further,the response surface methodology(RSM)is applied to optimize the longitudinal fin by minimizing the total melting time.The analysis concludes that a fin angle of 58.68°reduces the complete melting time of the stearic acid by 44%below the time at 0°.These findings fill a gap in knowledge of the effect on melting performance of the design angle of longitudinal fins and provide a reference for the design of horizontally placed longitudinal finned thermal energy storage units.
基金Project(2013CB035700) supported by the National Basic Research Program of ChinaProjects(11272259,11321062,11002104) supported by the National Natural Science Foundation of China
文摘Multiple surface cracks and interfacial delamination are the major failure mechanisms in film/substrate systems.The effect of interlayer upon the failure mechanisms of interfacial delamination concomitant to surface crack was explored.Finite element model was developed to obtain the stress and energy release rate(ERR),which governs the propagation of interface cracks.The dependences of delamination upon the geometry and constitutive properties of interlayer were examined.The results indicate that the effect of elastic modulus of interlayer on the steady state ERR is insignificant.In cases of different geometrical parameters,however,the steady ERR decreases with the increase of the interlayer thickness.These findings lead to the conclusion that the interlayer constraint has significant effect on the ERR and thus coating life,which can be adopted to modify the ceramic top coat.
基金supported by the National Basic Research Program of China(No.2007CB714102)the National Natural Science Foundation of China(No.50979048)
文摘Peeling-off phenomena in FRP strengthened concrete beams are investigated in this paper. Based on the beam theory and the fracture mechanics, a new theoretical model is proposed to analyze the peeling-off behavior near FRP-concrete interfaces, which is governed by residual thermal stresses. Numerical examples are presented to provide a clear insight into the failure mechanism. Some suggestions are provided for the optimal design of FRP strengthened structures.
文摘新能源接入现有电网将弱化系统的频率稳定性。充分利用调频资源对提升电网稳定性具有重要意义。火电作为当前调频主要资源有着复杂多变的特性,在不同工况下调频能力也会不同;且随着渗透率提高,传统的下垂控制调频方式逐渐不能满足控制要求。因此,提出一种储能–火电互补频率控制策略,设计了随频率变化自适应调节的出力比重系数,实现了储能出力的自适应调整,并将线性自抗扰控制(Linear active disturbance rejection control,LADRC)应用于火电机组的控制,通过频域法分析典型工业控制对象的LADRC参数调节规律。仿真结果表明,相较于传统下垂控制策略,所提出的储能–火电互补频率控制策略使系统的频率偏差最大值与稳态偏差值显著降低,并且有更好的储能恢复效果。
基金The authors gratefully acknowledge the supports from the Research Grants Council of Hong Kong(Project number:CityU 21201119,CityU 11212620,CityU 11215621)City University of Hong Kong(Project number:9610408).
文摘Thermal battery plays an important role in renewable energy utilization towards carbon neutrality.The novel absorption thermal battery(ATB)has excellent performance but suffers from serious capacity attenuation.To address this problem,two capacity regulation methods,i.e.,variable solution flow and variable cooling water flow,are proposed to achieve a demanded discharging rate.The effects of the two regulation strategies on the dynamic discharging characteristics and overall storage performance are comparatively investigated.To demon-strate the adjustability of the output capacity,several stable discharging rates are successfully maintained by the proposed methods.To maintain a higher discharging rate,the stable discharging time has to be sacrificed.As the demanded output increased from 0.5 kW to 6.0 kW,the stable discharging time decreased from 781.8 min to 27.9 min under variable solution flow and from 769.9 min to 30.7 min under variable cooling water flow.With the increase of solution or water flow rate,the energy storage density is improved,while the energy storage efficiency is slightly increased first and decreased later.The regulation method of variable water flow shows relatively lower energy storage efficiency due to the larger pump power.This study could facilitate reasonable development and application of ATB cycles.
