Radiative cooling can achieve cooling effect without consuming any energy by delivering energy into outer space(3K) through"atmospheric window"(8–13 μm). Conventional radiative cooling coating with multi-l...Radiative cooling can achieve cooling effect without consuming any energy by delivering energy into outer space(3K) through"atmospheric window"(8–13 μm). Conventional radiative cooling coating with multi-layer structure was severely restricted during application due to its complex preparation process and high cost. In this study, a single-layer radiative cooling coating with mixture of TiO_(2) particles and SiO_(2) particles was proposed. The algorithm for calculating the radiative properties of the multi-particle system was developed. Monte Carlo ray-tracing method combined with that algorithm was used to solve the radiative transfer equation(RTE) of the single-layer radiative cooling coating with mixture of TiO_(2) particles and SiO_(2) particles.The effects of particle diameter, volume fraction and coating thickness on radiative cooling performance were analyzed to obtain the best radiative cooling performance. The numerical results indicated that the average reflectivity of the single-layer radiative cooling coating with mixture of TiO_(2) particles and SiO_(2) particles in the solar spectrum can reach 95.6%, while and the average emissivity in the "atmospheric window" spectrum can reach 94.9% without additional silver-reflectance layer. The average reflectivity in the solar spectrum and average emissivity in the "atmospheric window" spectrum of the single-layer radiative cooling coating with mixture of TiO_(2) particles and SiO_(2) particles can increase 4.6% and 4.8% compared to the double-layer radiative cooling coating. This numerical research results can provide a theoretical guidance for design and optimization of single-layer radiative cooling coatings containing mixed nanoparticles.展开更多
Selective absorptive nanofluid can pre-absorb certain sunlight wavelength that cannot be used by PV and transmits remaining sunlight to the surface of PV,which can decouple PV from the thermal receiver spatially.In or...Selective absorptive nanofluid can pre-absorb certain sunlight wavelength that cannot be used by PV and transmits remaining sunlight to the surface of PV,which can decouple PV from the thermal receiver spatially.In order to improve the harvesting of electricity and high-temperature thermal nanofluid,it is important to design an optimal optical filter window(transmit sunlight with wavelengths of 732-1067 nm to the surface of the photovoltaic cell and absorb the remaining sunlight).However,designing optimal optical filter is facing following challenges:(1) inherently narrow selective absorptivity property of single nanoparticle;(2) simplified numerical calculation method calculating transmittance;(3) ignoring the shape of the nanoparticle.In this study,the idea of using multiple nanoparticles coupling effect to design an optical filter is proposed,which can superimpose the narrow absorption bandwidth of different nanoparticles to obtain a wide absorption bandwidth of the whole system.In addition,an improved transmission method considering light-matter interaction at air/vessel and liquid/vessel interfaces is adopted to compute the transmittance.The results calculated by improved transmission method are more accurate than widely used traditional Lambert-Beer law,which is verified by experimental test.Furthermore,the effect of nanoparticle shape on spectral transmittance is also investigated,which shows that spiny Ag can approximately extend absorbance from 400 nm to 600 nm compared to nanosphere silver.Finally,the results show that optical filter efficiency of nanofluids with multiple nanoparticles coupling(Ag,spiny Ag,ZnO,ITO) can reached up to 35%.展开更多
Passive daytime radiative cooling(PDRC)technology has great potential in reducing cooling energy consumption.In order to further improve the spectral performance of PDRC coatings,current researchers mostly focus on th...Passive daytime radiative cooling(PDRC)technology has great potential in reducing cooling energy consumption.In order to further improve the spectral performance of PDRC coatings,current researchers mostly focus on the selection and size design of functional particles,while ignoring the optical properties enhancement effect caused by the interlayer binder.In this study,based on the principle that the refractive index difference between layers enhanced the backscattering performance of the solar spectrum,we proposed and manufactured a double-layer PDRC coating with polyvinylidene difluoride(PVDF)as the filmforming material in the upper layer and polydimethylsiloxane(PDMS)as the film-forming material in the lower layer,both filled with Al_(2)O_(3) and SiO_(2) particles.The double-layer PDRC coating exhibited excellent spectral performance that a high solar reflectivity of 98%and an emissivity of 0.95 at the“atmospheric window”band.In comparison,the solar spectrum reflectivity of the single-layer PDRC coatings based on PVDF and PDMS of the same thickness was 95%and 94.7%,respectively.Outdoor tests showed that the PDRC coating achieved a temperature decrease of up to 7.1℃ under direct sunlight at noon time.In addition,the PDRC coating had excellent weather resistance,water resistance,and other basic properties.This article opens up a new idea and provides methodological guidance for the design of double-layer PDRC coatings.展开更多
文摘为探究蓼属植物叶绿体基因组的结构、功能和进化特征,利用CodonW、SPSS软件和在线程序Galaxy、Genepioneer生信云、mVISTA、GENE DENOVO等工具,对28种蓼属植物叶绿体基因组的密码子使用偏好性和系统发育关系进行分析。结果表明,28种蓼属植物叶绿体基因组的密码子适应指数(codon adaptation index,CAI)和有效密码子数(effective number of codon,ENC)均较低,说明其密码子使用偏好性较弱,且主要受自然选择影响;密码子第3位碱基以A/U结尾为主,且叶绿体基因组的9个最优密码子均以A/U结尾;密码子不同位置的GC含量和ENC与密码子GC3s、GC3、GC2之间的相关性分析揭示,蓼属植物叶绿体基因组的密码子偏好性弱,且密码子偏好性主要受第3位碱基组成的影响,叶绿体基因序列长度对碱基组成和密码子偏好性影响较小;基于同义密码子相对使用度(relative synonymous codon usage,RSCU)的系统发育树与基于matk和rbcl基因序列的系统发育树结果相似,28种蓼属植物均被划分为3个类群,但内部存在部分差异,如长戟叶蓼基于matk序列时与蓼蓝聚为一个类群,而基于rbcl序列时与丛枝蓼聚为一个类群。以上研究结果为蓼属植物的资源利用、系统发育和叶绿体基因工程研究提供了参考和依据。
基金supported by the China National Key Research and Development Plan Project (Grant No.2018YFA0702300)the National Natural Science Foundation of China (Grant No.51676061)the Taishan Scholars of Shandong Proviance (Grant No.tsqn201812105)。
文摘Radiative cooling can achieve cooling effect without consuming any energy by delivering energy into outer space(3K) through"atmospheric window"(8–13 μm). Conventional radiative cooling coating with multi-layer structure was severely restricted during application due to its complex preparation process and high cost. In this study, a single-layer radiative cooling coating with mixture of TiO_(2) particles and SiO_(2) particles was proposed. The algorithm for calculating the radiative properties of the multi-particle system was developed. Monte Carlo ray-tracing method combined with that algorithm was used to solve the radiative transfer equation(RTE) of the single-layer radiative cooling coating with mixture of TiO_(2) particles and SiO_(2) particles.The effects of particle diameter, volume fraction and coating thickness on radiative cooling performance were analyzed to obtain the best radiative cooling performance. The numerical results indicated that the average reflectivity of the single-layer radiative cooling coating with mixture of TiO_(2) particles and SiO_(2) particles in the solar spectrum can reach 95.6%, while and the average emissivity in the "atmospheric window" spectrum can reach 94.9% without additional silver-reflectance layer. The average reflectivity in the solar spectrum and average emissivity in the "atmospheric window" spectrum of the single-layer radiative cooling coating with mixture of TiO_(2) particles and SiO_(2) particles can increase 4.6% and 4.8% compared to the double-layer radiative cooling coating. This numerical research results can provide a theoretical guidance for design and optimization of single-layer radiative cooling coatings containing mixed nanoparticles.
基金supported by the National Natural Science Foundation of China (Grant No.52076064)the Taishan Scholars of Shandong Province (tsqn 201812105)+1 种基金China Scholarship Council (202106120157)CSC grant for LIANG Huaxu's scholarship of research visiting at Nanyang Technological University, Singapore。
文摘Selective absorptive nanofluid can pre-absorb certain sunlight wavelength that cannot be used by PV and transmits remaining sunlight to the surface of PV,which can decouple PV from the thermal receiver spatially.In order to improve the harvesting of electricity and high-temperature thermal nanofluid,it is important to design an optimal optical filter window(transmit sunlight with wavelengths of 732-1067 nm to the surface of the photovoltaic cell and absorb the remaining sunlight).However,designing optimal optical filter is facing following challenges:(1) inherently narrow selective absorptivity property of single nanoparticle;(2) simplified numerical calculation method calculating transmittance;(3) ignoring the shape of the nanoparticle.In this study,the idea of using multiple nanoparticles coupling effect to design an optical filter is proposed,which can superimpose the narrow absorption bandwidth of different nanoparticles to obtain a wide absorption bandwidth of the whole system.In addition,an improved transmission method considering light-matter interaction at air/vessel and liquid/vessel interfaces is adopted to compute the transmittance.The results calculated by improved transmission method are more accurate than widely used traditional Lambert-Beer law,which is verified by experimental test.Furthermore,the effect of nanoparticle shape on spectral transmittance is also investigated,which shows that spiny Ag can approximately extend absorbance from 400 nm to 600 nm compared to nanosphere silver.Finally,the results show that optical filter efficiency of nanofluids with multiple nanoparticles coupling(Ag,spiny Ag,ZnO,ITO) can reached up to 35%.
基金supported by the National Natural Science Foundation of China(Grant Nos.52306078 and 52211530089)Taishan Scholars of Shandong Province(Grant No.tsqn201812105)+1 种基金the Natural Science Foundation of Shandong Province(Grant No.ZR2023QE141)the Royal Society(Grant No.IEC\NSFC\211210)。
文摘Passive daytime radiative cooling(PDRC)technology has great potential in reducing cooling energy consumption.In order to further improve the spectral performance of PDRC coatings,current researchers mostly focus on the selection and size design of functional particles,while ignoring the optical properties enhancement effect caused by the interlayer binder.In this study,based on the principle that the refractive index difference between layers enhanced the backscattering performance of the solar spectrum,we proposed and manufactured a double-layer PDRC coating with polyvinylidene difluoride(PVDF)as the filmforming material in the upper layer and polydimethylsiloxane(PDMS)as the film-forming material in the lower layer,both filled with Al_(2)O_(3) and SiO_(2) particles.The double-layer PDRC coating exhibited excellent spectral performance that a high solar reflectivity of 98%and an emissivity of 0.95 at the“atmospheric window”band.In comparison,the solar spectrum reflectivity of the single-layer PDRC coatings based on PVDF and PDMS of the same thickness was 95%and 94.7%,respectively.Outdoor tests showed that the PDRC coating achieved a temperature decrease of up to 7.1℃ under direct sunlight at noon time.In addition,the PDRC coating had excellent weather resistance,water resistance,and other basic properties.This article opens up a new idea and provides methodological guidance for the design of double-layer PDRC coatings.
