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
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
In this paper,CPCM(Composite Phase Change Material)was manufactured with metal foam matrix used as filling material.The temperature curves were obtained by experiment.The performance of heat transfer was analyzed.The ...In this paper,CPCM(Composite Phase Change Material)was manufactured with metal foam matrix used as filling material.The temperature curves were obtained by experiment.The performance of heat transfer was analyzed.The experimental results show that metal foam matrix can improve temperature uniformity in phase change thermal storage material and enhance heat conduction ability.The thermal performance of CPCM is significantly improved.The efficiency of temperature control can be obviously improved by adding metal foam in phase change material.CPCM is in solid-liquid two-phase region when temperature is close to phase change point of paraffin.An approximate plateau appears.The plateau can be considered as the temperature control zone of CPCM.Heat can be transferred fiom hot source and be uniformly spread in thermal storage material by using metal foam matrix since thermal storage material has the advantage of strong heat storage capacity and disadvantage of poor heat conduction ability.Natural convection promotes the melting of solid-liquid phase change material.Good thermal conductivity of foam metal accelerates heat conduction of solid-liquid phase change material.The interior temperature difference decreases and the whole temperature becomes more uniform.For the same porosity with a metal foam,melting time of solid-liquid phase change material decreases.Heat conduction is enhanced and natural convection is suppressed when pore size of metal foam is smaller.The thermal storage time decreases and heat absorption rate increases when the pore size of metal foam reduces.The research results can be used to guide fabricating the CPCM.展开更多
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
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.
基金Support provided by National Basic Research Program of China(Grant No.2012CB933200)National Natural Science Foundation of China(Grant No:51161140332,Grant No.51476172)
文摘In this paper,CPCM(Composite Phase Change Material)was manufactured with metal foam matrix used as filling material.The temperature curves were obtained by experiment.The performance of heat transfer was analyzed.The experimental results show that metal foam matrix can improve temperature uniformity in phase change thermal storage material and enhance heat conduction ability.The thermal performance of CPCM is significantly improved.The efficiency of temperature control can be obviously improved by adding metal foam in phase change material.CPCM is in solid-liquid two-phase region when temperature is close to phase change point of paraffin.An approximate plateau appears.The plateau can be considered as the temperature control zone of CPCM.Heat can be transferred fiom hot source and be uniformly spread in thermal storage material by using metal foam matrix since thermal storage material has the advantage of strong heat storage capacity and disadvantage of poor heat conduction ability.Natural convection promotes the melting of solid-liquid phase change material.Good thermal conductivity of foam metal accelerates heat conduction of solid-liquid phase change material.The interior temperature difference decreases and the whole temperature becomes more uniform.For the same porosity with a metal foam,melting time of solid-liquid phase change material decreases.Heat conduction is enhanced and natural convection is suppressed when pore size of metal foam is smaller.The thermal storage time decreases and heat absorption rate increases when the pore size of metal foam reduces.The research results can be used to guide fabricating the CPCM.
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.
