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Numerical study of conduction and radiation heat losses from vacuum annulus in parabolic trough receivers

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Frontiers in Energy 2022年第6期16卷 1048-1059页

作者： dongqiang lei Yucong REN Zhifeng WANG Key Laboratory of Solar Thermal Energy and Photovoltaic System Chinese Academy of SciencesBeijing 100190China Institute of Electrical Engineering Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China Beijing Engineering Research Center of Solar Thermal Power Beijing 100190China

Parabolic trough receiver is a key component to convert solar energy into thermal energy in the parabolic trough solar *** heat loss of the receiver has an important influence on the thermal efficiency and the operating cost of the power *** this paper,conduction and radiation heat losses are analyzed respectively to identify the heat loss mechanism of the receiver.A 2-D heat transfer model is established by using the direct simulation Monte Carlo method for rarefied gas flow and heat transfer within the annulus of the receiver to predict the conduction heat loss caused by residual *** numerical results conform to the experimental results,and show the temperature of the glass envelope and heat loss for various conditions in *** effects of annulus pressure,gas species,temperature of heat transfer fluid,and annulus size on the conduction and radiation heat losses are systematically ***,the main factors that cause heat loss are analyzed,providing a theoretical basis for guiding the improvement of receiver,as well as the operation and maintenance strategy to reduce heat loss.

关键词： parabolic trough receiver vacuum annulus rarefied gas DSMC(direct simulation Monte Carlo) heat loss

基于熔盐介质的大开口槽式集热器光热性能分析

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机械设计与制造工程 2024年第4期53卷 111-115页

作者：郭睿燊雷东强刘汉涛中北大学能源动力工程学院山西太原030051 中国科学院电工研究所北京100190

建立了基于熔盐介质的槽式太阳能集热器的光学仿真模型和传热模型。经验证,传热介质出口温度与实际出口温度误差在±1%以内,周向能流密度误差在4.7%以内,表明所建模型准确性较高。分析了槽式集热器开口弦长、集热管直径、光学误差等对... 详细信息

建立了基于熔盐介质的槽式太阳能集热器的光学仿真模型和传热模型。经验证,传热介质出口温度与实际出口温度误差在±1%以内,周向能流密度误差在4.7%以内,表明所建模型准确性较高。分析了槽式集热器开口弦长、集热管直径、光学误差等对其光学性能的影响,以及法向直接辐照度、熔盐介质流速等对集热系统热性能的影响。结果表明,当开口弦长不变时,选择较大直径的集热管可以提高光学效率与截断因子,使系统热性能略有提高,而入射角和光学误差的增加会降低光学性能;增加法向直接辐照度或传热介质流速可以提高系统热效率。

关键词：太阳能熔盐槽式光学性能热性能

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新型槽式太阳能真空吸热管设计方法及其光学性能研究

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可再生能源 2024年第1期42卷 30-37页

作者：余强单文玺李自豪雷东强中国农业大学信息与电气工程学院北京100083 中国科学院电工研究所北京100190

针对传统槽式太阳能集热系统工质运行温度受限,以及真空吸热管表面能流密度分布不均而引起的热应力过大等问题,文章在不改变聚光器结构的条件下,提出了一种新型的槽式太阳能真空吸热管的设计方法,通过减小金属内管直径、下移金属内管位... 详细信息

针对传统槽式太阳能集热系统工质运行温度受限,以及真空吸热管表面能流密度分布不均而引起的热应力过大等问题,文章在不改变聚光器结构的条件下,提出了一种新型的槽式太阳能真空吸热管的设计方法,通过减小金属内管直径、下移金属内管位置以及在金属内管上方加装双曲线型二次聚光器来提高太阳能聚光比,改善了金属吸热管表面能流密度分布。利用仿真计算方法研究了新型槽式太阳能真空吸热管的光学性能,结果表明:和传统槽式太阳能真空吸热管相比,该新型结构在仅损失1.88%光学效率的情况下将聚光比从62 kW/m^(2)提升至71 kW/m^(2);能流密度分布均匀度改善了55.05%,提升了聚光-吸热系统的整体性能。

关键词：槽式太阳能集热器真空吸热管聚光比能流密度分布光学效率

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具有二次聚光器的新型大开口槽式太阳集热器设计与光学性能分析

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太阳能学报 2022年第8期43卷 245-252页

作者：姚磐雷东强张馨张博王志峰中国科学院太阳能热利用及光伏系统重点实验室北京100190 中国科学院电工研究所北京100190 中国科学院大学北京100049 中北大学电气与控制工程学院太原038507

针对大开口和更高运行温度的槽式太阳能热发电系统,提出一种可实现高聚光比、低辐射热损及能流密度均匀的新型槽式太阳集热器,即在集热管内放置外壁具有太阳选择吸收膜层和内壁具有反射膜层二次聚光器的大开口槽式太阳集热器。建立圆弧... 详细信息

针对大开口和更高运行温度的槽式太阳能热发电系统,提出一种可实现高聚光比、低辐射热损及能流密度均匀的新型槽式太阳集热器,即在集热管内放置外壁具有太阳选择吸收膜层和内壁具有反射膜层二次聚光器的大开口槽式太阳集热器。建立圆弧为微元段的自适应设计新方法,提出3种典型的二次聚光器面型,利用蒙特卡洛光线追迹方法仿真新型集热器的能流密度分布特性,验证该光学仿真方法,分析影响集热器光学性能的各种因素。结果表明,该集热器可显著提升集热效率。

关键词：槽式太阳集热器二次聚光器光学性能能流

基于混合神经网络的槽式太阳能集热场出口温度预测研究

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太阳能学报 2023年第5期44卷 265-273页

作者：闫露雷东强李晓徐立董军王志峰中北大学电气与控制工程学院太原030051 中国科学院电工研究所北京100190 中国科学院大学北京100049 中广核太阳能开发有限公司北京100070

为解决槽式太阳能集热场实际现场工况难以满足现有热性能测试标准的难题,提出一种基于混合神经网络(ALSTM)模型预测槽式太阳能集热场出口温度的方法。首先对中国科学院电工研究所延庆、常州龙腾乌拉特中旗、中广核德令哈、中船乌拉特中... 详细信息

为解决槽式太阳能集热场实际现场工况难以满足现有热性能测试标准的难题,提出一种基于混合神经网络(ALSTM)模型预测槽式太阳能集热场出口温度的方法。首先对中国科学院电工研究所延庆、常州龙腾乌拉特中旗、中广核德令哈、中船乌拉特中旗4处槽式太阳能集热场动态热性能实验数据和气象数据进行预处理与相关性分析,形成训练样本数据和验证样本数据;其次对该网络模型进行训练与优化,最后进行验证,得出上述4处集热场实际出口温度与预测出口温度的最大相对误差分别为3.00%、0.31%、1.45%、1.95%。证明了该模型的预测精度较高,为槽式太阳能集热场实际现场热性能预测与评价提供了一种新的方法。

关键词：槽式太阳能热发电系统集热场出口温度混合神经网络

Metarelation2vec:A Metapath-Free Scalable Representation Learning Model for Heterogeneous Networks

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Tsinghua Science and Technology 2024年第2期29卷 553-575页

作者： lei Chen Yuan Li Yong lei Xingye Deng School of Information and Electrical Engineering Hunan University of Science and TechnologyXiangtan 411201China School of Computer Science and Engineering Hunan University of Science and TechnologyXiangtan 411201China

Metapaths with specific complex semantics are critical to learning diverse semantic and structural information of heterogeneous networks(HNs)for most of the existing representation learning ***,any metapaths consisting of multiple,simple metarelations must be driven by domain *** sensitive,expensive,and limited metapaths severely reduce the flexibility and scalability of the existing models.A metapath-free,scalable representation learning model,called Metarelation2vec,is proposed for HNs with biased joint learning of all metarelations in a bid to address this ***,a metarelation-aware,biased walk strategy is first designed to obtain better training samples by using autogenerating cooperation probabilities for all metarelations rather than using expert-given ***,grouped nodes by the type,a common and shallow skip-gram model is used to separately learn structural proximity for each node ***,grouped links by the type,a novel and shallow model is used to separately learn the semantic proximity for each link ***,supervised by the cooperation probabilities of all meta-words,the biased training samples are thrown into the shallow models to jointly learn the structural and semantic information in the HNs,ensuring the accuracy and scalability of the *** experimental results on three tasks and four open datasets demonstrate the advantages of our proposed model.

关键词： metarelation random walk heterogeneous network metapath representation learning

Two-Stage Online Debiased Lasso Estimation and Inference for High-Dimensional Quantile Regression with Streaming Data

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Journal of Systems Science & Complexity 2024年第3期37卷 1251-1270页

作者： PENG Yanjin WANG lei School of Statistics and Data Science KLMDASRLEBPS and LPMCNankai UniversityTianjin 300071China

In this paper,the authors propose a two-stage online debiased lasso estimation and statistical inference method for high-dimensional quantile regression(QR)models in the presence of streaming *** the first stage,the authors modify the QR score function based on kernel smoothing and obtain the online lasso smoothed QR estimator through iterative *** estimation process only involves the current data batch and specific historical summary statistics,which perfectly accommodates to the special structure of streaming *** the second stage,an online debiasing procedure is carried out to eliminate biases caused by the lasso penalty as well as the accumulative approximation error so that the asymptotic normality of the resulting estimator can be *** authors conduct extensive numerical experiments to evaluate the performance of the proposed *** experiments demonstrate the effectiveness of the proposed method and support the theoretical *** application to the Beijing PM2.5 Dataset is also presented.

关键词： Adaptive tuning asymptotic normality debiased lasso online updating quantile regres-sion

Structural energy storage composites based on modified carbon fiber electrode with metal-organic frame enhancing layered double hydroxide

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Nano Research 2024年第3期17卷 1552-1563页

作者： Jinrui Ye Zhongbao Wang Qin lei lei Sun Jinfeng Gu School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China Tangshan Research Institute Beijing Institute of TechnologyTangshan 063000China School of Materials Science and Engineering Shenyang Jianzhu UniversityShenyang 110168China Department of Stomatology PLA Strategic Support Force Characteristic Medical CenterBeijing 100101China Beijing Electromechanical Engineering Research Institute Beijing 100074China

Structural energy storage composites present advantages in simultaneously achieving structural strength and electrochemical *** of carbon fiber electrodes and resin structural electrolytes in energy storage composite poses challenges in maintaining good mechanical and electrochemical properties at reasonable cost and ***,we report a simple method to fabricate structural supercapacitor using carbon fiber electrodes(modified by Ni-layered double hydroxide(Ni-LDH)and in-situ growth of Co-metal-organic framework(Co-MOF)in a two-step process denoted as Co-MOF/Ni-LDH@CF)and bicontinuous-phase epoxy resin-based structural ***-MOF/Ni-LDH@CF as electrode material exhibits improved specific capacity(42.45 F·g^(-1))and cycle performance(93.3%capacity retention after 1000 cycles)in a three-electrode *** bicontinuous-phase epoxy resin-based structural electrolyte exhibits an ionic conductivity of 3.27×10^(-4) S·cm^(-1).The fabricated Co-MOF/Ni-LDH@CF/SPE-50 structural supercapacitor has an energy density of 3.21 Wh·kg^(-1) at a power density of 42.25 W·kg^(-1),whilst maintaining tensile strength and modulus of 334.6 MPa and 25.2 *** results show practical potential of employing modified commercial carbon fiber electrodes and epoxy resin-based structural electrolytes in structural energy storage applications.

关键词： carbon fiber electrode structural electrolyte structural energy storage composites supercapacitor

基于火花放电的抛物面槽式太阳能集热管环形空间气体压强与成分实验研究

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真空科学与技术学报 2022年第3期42卷 209-216页

作者：张博雷东强李晓张馨王志峰中北大学电气与控制工程学院太原030051 中国科学院电工研究所北京100190 中国科学院大学北京100049 中国科学院太阳能热利用及光伏系统重点实验室北京100190

集热管的真空失效一直是抛物面槽式太阳能电站中存在的主要问题,其真空性能的优劣直接影响了整个系统的效率和经济性。本文提出一种新型基于火花放电和发射光谱法的便携式无损检测方法去评估集热管真空性能。针对集热管环形空间中最常... 详细信息

集热管的真空失效一直是抛物面槽式太阳能电站中存在的主要问题,其真空性能的优劣直接影响了整个系统的效率和经济性。本文提出一种新型基于火花放电和发射光谱法的便携式无损检测方法去评估集热管真空性能。针对集热管环形空间中最常出现的四种高纯气体(氢气、氦气、氮气、氩气)以及其混合气体,检测其放电特性与光谱特性,得出各气体特征峰光谱强度与气压的拟合规律并进行验证。结果表明:利用此方法可以准确获得气体种类和压力并将气压测量范围延伸至0.5 Pa。整套检测装置轻便易携带,适合在槽式太阳能集热系统或发电系统中在线应用。通过该装置对集热管进行无损真空性能测试,将为提高系统效率和降低运行维护成本起着重要指导意义。

关键词：真空性能火花放电发射光谱无损检测