In order to meet the growing global energy demand and fulfill energy conservation and emission reduction goals, the efficient utilization of solar energy is becoming increasingly critical. However, the effects of high...In order to meet the growing global energy demand and fulfill energy conservation and emission reduction goals, the efficient utilization of solar energy is becoming increasingly critical. However, the effects of high temperatures on solar absorption are rarely considered in practical research. Therefore, this study presents a porous zinc and silver sulfide solar absorber with high-temperature radiative cooling capabilities. The solar absorption rate and radiative cooling efficiency in the high-temperature range(636 K–1060 K) are computed using the finite-difference time-domain method. Furthermore, the impact of parameters such as characteristic length, porosity, incident angle, and pore shape factor on both the absorption rate and efficiency of the solar absorber is analyzed. The mechanism is further examined from the perspective of microscopic thermal radiation. The results show that, in the high-temperature range, the solar absorption rate increases with higher porosity and incident angles, reaching its peak when the characteristic length is 1 μm. These findings highlight the significant potential of the solar absorber for efficient solar energy harvesting in photo-thermal conversion applications within a specific high-temperature range.展开更多
Prolonged exposure to hot weather and direct sunlight can lead to heat exhaustion and skin irritation,which reduces the productivity of outdoor workers and increases health risks.This study has developed a polylactic ...Prolonged exposure to hot weather and direct sunlight can lead to heat exhaustion and skin irritation,which reduces the productivity of outdoor workers and increases health risks.This study has developed a polylactic acid/boron nitride nanosheet composite fabric by electrospinning.Being selectively modified for hydrophilicity,the fabric has combined passive radiative cooling,thermal conductivity and directional sweat wicking to improve thermal comfort in outdoor environments.Compared to conventional cotton fabrics,the composite fibric exhibits excellent solar reflectance(96%)and infrared heat emissivity(93%),along with high thermal conductivity(0.38 W·m^(−1)·K^(−1)).In outdoor experiments,the composite fabric lowers skin temperature by 2.0℃ under direct sunlight during the day and by 3.8℃ at night relative to bare skin.The composite fabric features a directional perspiration function and an impressive sweat evaporation rate of 1.67 g·h^(−1),which can efficiently transport sweat and heat to the fiber membrane surface to keep the skin dry and cool.This work should advance human thermal management strategies for high-temperature outdoor environments.展开更多
Passive radiative cooling is widely recognized as an environmentally sustainable method for achieving significant cooling effects.However,the mechanical properties and environmental adaptability of current radiative c...Passive radiative cooling is widely recognized as an environmentally sustainable method for achieving significant cooling effects.However,the mechanical properties and environmental adaptability of current radiative cooling materials are not sufficient to maintain high cooling performance in external environments.Here we reported an environment-adaptive phase-separation-porous fluorofilm for high-performance passive radiation cooling.Compared to the homogenous fluoro-porous network with limited scattering efficiencies,we modulated the porous structure of the fluorofilm to achieve a strong emissivity of 95.2%(8-13μm)and a high reflectivity of 97.1%(0.3-2.5μm).The fluorofilm demonstrates a temperature drop of 10.5°C and an average cooling power of 81 W·m^(−2)under a sunlight power of 770 W·m^(−2).The high mechanical performance and environmental adaptability of fluorofilms are also exhibited.Considering its significant radiative cooling capability and robust environmental adaptability,the fluorofilm is expected to have a promising future in radiative temperature regulation.展开更多
In order to improve the heat dissipation capability of motor controller for new energy vehicles,the water cooled radiator with multiple channels is optimized in this paper.The heat conduction between the heat source I...In order to improve the heat dissipation capability of motor controller for new energy vehicles,the water cooled radiator with multiple channels is optimized in this paper.The heat conduction between the heat source IGBT and the radiator,the convective heat transfer between the radiator and the coolant,the mechanical strength and the manufacturing cost are comprehensively considered during the optimization process.The power loss and thermal resistance of the IGBT unit are calculated at first,and finite element model of the radiator is established.On this basis,multi-physics coupling analysis of the water cooled radiator is carried out.Secondly,the sensitivity analysis is applied to verify the influence of structural parameters on the heat dissipation performance of the radiator system.The influence of coolant inlet velocity v,number of cooling ribs n,height of radiator ribs H on the maximum temperature rise T,the temperature difference ΔT between phase U and W,and the coolant pressure lossΔP are analyzed in depth,and the optimal range of the structural parameters for heat dissipation is obtained.Finally,an experimental platform was set up to verify the performance of the proposed structure of water cooled radiator for motor controller of new energy vehicle.The results show that the heat dissipation capability of the proposed radiator is improved compared with the initial design.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No. 52406102)Shandong Provincial Natural Science Foundation (Grant No. ZR2023QE258)。
文摘In order to meet the growing global energy demand and fulfill energy conservation and emission reduction goals, the efficient utilization of solar energy is becoming increasingly critical. However, the effects of high temperatures on solar absorption are rarely considered in practical research. Therefore, this study presents a porous zinc and silver sulfide solar absorber with high-temperature radiative cooling capabilities. The solar absorption rate and radiative cooling efficiency in the high-temperature range(636 K–1060 K) are computed using the finite-difference time-domain method. Furthermore, the impact of parameters such as characteristic length, porosity, incident angle, and pore shape factor on both the absorption rate and efficiency of the solar absorber is analyzed. The mechanism is further examined from the perspective of microscopic thermal radiation. The results show that, in the high-temperature range, the solar absorption rate increases with higher porosity and incident angles, reaching its peak when the characteristic length is 1 μm. These findings highlight the significant potential of the solar absorber for efficient solar energy harvesting in photo-thermal conversion applications within a specific high-temperature range.
文摘Prolonged exposure to hot weather and direct sunlight can lead to heat exhaustion and skin irritation,which reduces the productivity of outdoor workers and increases health risks.This study has developed a polylactic acid/boron nitride nanosheet composite fabric by electrospinning.Being selectively modified for hydrophilicity,the fabric has combined passive radiative cooling,thermal conductivity and directional sweat wicking to improve thermal comfort in outdoor environments.Compared to conventional cotton fabrics,the composite fibric exhibits excellent solar reflectance(96%)and infrared heat emissivity(93%),along with high thermal conductivity(0.38 W·m^(−1)·K^(−1)).In outdoor experiments,the composite fabric lowers skin temperature by 2.0℃ under direct sunlight during the day and by 3.8℃ at night relative to bare skin.The composite fabric features a directional perspiration function and an impressive sweat evaporation rate of 1.67 g·h^(−1),which can efficiently transport sweat and heat to the fiber membrane surface to keep the skin dry and cool.This work should advance human thermal management strategies for high-temperature outdoor environments.
基金the National Natural Science Foundation of China(Nos.22035008,22275183,21972155,and 21988102)the National Key R&D Program of China(Nos.2019YFA0709300 and 2022YFE0201200)International Partnership Program of Chinese Academy of Sciences(No.1A1111KYSB20200010).
文摘Passive radiative cooling is widely recognized as an environmentally sustainable method for achieving significant cooling effects.However,the mechanical properties and environmental adaptability of current radiative cooling materials are not sufficient to maintain high cooling performance in external environments.Here we reported an environment-adaptive phase-separation-porous fluorofilm for high-performance passive radiation cooling.Compared to the homogenous fluoro-porous network with limited scattering efficiencies,we modulated the porous structure of the fluorofilm to achieve a strong emissivity of 95.2%(8-13μm)and a high reflectivity of 97.1%(0.3-2.5μm).The fluorofilm demonstrates a temperature drop of 10.5°C and an average cooling power of 81 W·m^(−2)under a sunlight power of 770 W·m^(−2).The high mechanical performance and environmental adaptability of fluorofilms are also exhibited.Considering its significant radiative cooling capability and robust environmental adaptability,the fluorofilm is expected to have a promising future in radiative temperature regulation.
基金supported in part by the National Natural Science Foundation of China(61503132)。
文摘In order to improve the heat dissipation capability of motor controller for new energy vehicles,the water cooled radiator with multiple channels is optimized in this paper.The heat conduction between the heat source IGBT and the radiator,the convective heat transfer between the radiator and the coolant,the mechanical strength and the manufacturing cost are comprehensively considered during the optimization process.The power loss and thermal resistance of the IGBT unit are calculated at first,and finite element model of the radiator is established.On this basis,multi-physics coupling analysis of the water cooled radiator is carried out.Secondly,the sensitivity analysis is applied to verify the influence of structural parameters on the heat dissipation performance of the radiator system.The influence of coolant inlet velocity v,number of cooling ribs n,height of radiator ribs H on the maximum temperature rise T,the temperature difference ΔT between phase U and W,and the coolant pressure lossΔP are analyzed in depth,and the optimal range of the structural parameters for heat dissipation is obtained.Finally,an experimental platform was set up to verify the performance of the proposed structure of water cooled radiator for motor controller of new energy vehicle.The results show that the heat dissipation capability of the proposed radiator is improved compared with the initial design.
