Performance enhancement of flat plate solar collectors is an endless research direction as it represents the most used solar technology.The enhancement could be achieved via design alteration,absorber-installed protru...Performance enhancement of flat plate solar collectors is an endless research direction as it represents the most used solar technology.The enhancement could be achieved via design alteration,absorber-installed protrusions,and integration with thermal energy storage.The objective of the current research is to evaluate a compacted solar collector integrated with octadecane organic paraffin PCM(phase change materials)as a thermal energy storage medium.The investigations have been performed numerically utilizing ANSYS software.Thermal storage contains the PCM securely encased behind the absorbent plate of the collector in four packing containers.The investigations have been performed without thermal energy storage and with nanoencapsulated thermal energy storage at 5%and 10%volume fractions.The optimal blend for the ongoing inquiry comprises two constituents:particulate octadecane and water as the primary fluid of operation.The findings suggest that in the morning,the nano-encapsulated PCM falls somewhere in the middle,between the absorbent copper plate’s temperature and the fluid temperature flowing out of the collector.However,the collector’s heat output is insufficient tomelt this thermal energy storagewhen its temperature drops overnight.5%by volume of nanoparticles was determined to be the ideal concentration.While increasing the volume percentage of nanoparticles inside PCM can sometimes boost the temperature of the fluid exiting,it does not necessarily improve performance.展开更多
Phase Change Material(PCM)-based cold energy storage system(CESS)can effectively utilize the peak and valley power resources to reduce the excessive dependence on the power grid.In this study,a PCM-based CESS was desi...Phase Change Material(PCM)-based cold energy storage system(CESS)can effectively utilize the peak and valley power resources to reduce the excessive dependence on the power grid.In this study,a PCM-based CESS was designed for cold storage applications.The optimal number of PCM plates was determined through numerical simulations to meet the required cold storage temperature and control time.Additionally,the air temperature field,flow field,and melting characteristics of the PCMplates during the cooling release process were analyzed.The effects of plate positioning and thickness on the cooling release performance were further investigated.The results indicated that when 64PCMplateswere used,the duration formaintaining temperatures below−18℃increased from0.6 h to approximately 16.94 h.During the cooling release process,the temperature field in the cold storage exhibited stratification,and the melting of the PCM plates was non-uniform.Placing the PCM plates at the top or within the interlayers without cargo above proved more effective,with their cooling release power being approximately twice that of the PCM plates placed in the interlayers with cargo above.Furthermore,reducing the thickness of the PCMplates from15 to 7.5mmresulted in a 3.6-h increase in the time below−18℃and a 4.5-h reduction in the time required to reach 80%liquid phase fraction.展开更多
文摘Performance enhancement of flat plate solar collectors is an endless research direction as it represents the most used solar technology.The enhancement could be achieved via design alteration,absorber-installed protrusions,and integration with thermal energy storage.The objective of the current research is to evaluate a compacted solar collector integrated with octadecane organic paraffin PCM(phase change materials)as a thermal energy storage medium.The investigations have been performed numerically utilizing ANSYS software.Thermal storage contains the PCM securely encased behind the absorbent plate of the collector in four packing containers.The investigations have been performed without thermal energy storage and with nanoencapsulated thermal energy storage at 5%and 10%volume fractions.The optimal blend for the ongoing inquiry comprises two constituents:particulate octadecane and water as the primary fluid of operation.The findings suggest that in the morning,the nano-encapsulated PCM falls somewhere in the middle,between the absorbent copper plate’s temperature and the fluid temperature flowing out of the collector.However,the collector’s heat output is insufficient tomelt this thermal energy storagewhen its temperature drops overnight.5%by volume of nanoparticles was determined to be the ideal concentration.While increasing the volume percentage of nanoparticles inside PCM can sometimes boost the temperature of the fluid exiting,it does not necessarily improve performance.
基金supported by National Natural Science Foundation of China(Nos.51806092,52201410)Non-Carbon Energy Conversion and Utilization Institute under the Shanghai Class IV Peak Disciplinary Development Program,High-End Foreign Experts Recruitment Plan of China(G2022013028L).
文摘Phase Change Material(PCM)-based cold energy storage system(CESS)can effectively utilize the peak and valley power resources to reduce the excessive dependence on the power grid.In this study,a PCM-based CESS was designed for cold storage applications.The optimal number of PCM plates was determined through numerical simulations to meet the required cold storage temperature and control time.Additionally,the air temperature field,flow field,and melting characteristics of the PCMplates during the cooling release process were analyzed.The effects of plate positioning and thickness on the cooling release performance were further investigated.The results indicated that when 64PCMplateswere used,the duration formaintaining temperatures below−18℃increased from0.6 h to approximately 16.94 h.During the cooling release process,the temperature field in the cold storage exhibited stratification,and the melting of the PCM plates was non-uniform.Placing the PCM plates at the top or within the interlayers without cargo above proved more effective,with their cooling release power being approximately twice that of the PCM plates placed in the interlayers with cargo above.Furthermore,reducing the thickness of the PCMplates from15 to 7.5mmresulted in a 3.6-h increase in the time below−18℃and a 4.5-h reduction in the time required to reach 80%liquid phase fraction.
文摘针对采用单一冷却方式的锂离子电池模组LIBM(lithium-ion battery module)冷却效果不佳的问题,提出了1种相变材料PCM(phase change material)风冷耦合电池冷却系统。讨论了不同入口空气风速IAV(inlet air velocity)、不同电池间隙BG(battery gap)和不同入口空气温度IAT(inlet air temperature)对LIBM内最高温度和最大温差的影响;以IAV、BG和IAT为设计变量,以最高温度和最大温差为目标函数,通过响应面模型对设计变量与目标函数进行了数值拟合;采用非支配排序遗传算法对响应面模型进行了优化预测;利用计算流体力学仿真对优化预测结果进行了验证。结果表明,经过优化后的冷却系统能将LIBM内的最高温度降低4.68℃(13.8%),最大温差降低0.57℃(30.3%)。
