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Analysis of radiation heat transfer and temperature distributions of solar thermochemical reactor for

Bachirou GUENE LOUGOU, Yong SHUAI, Xiang CHEN, Yuan YUAN, Heping TAN, Huang XING

《能源前沿(英文)》 2017年 第11卷 第4期   页码 480-492 doi: 10.1007/s11708-017-0506-2

摘要: This paper investigated radiation heat transfer and temperature distributions of solar thermochemical reactor for syngas production using the finite volume discrete ordinate method (fvDOM) and P1 approximation for radiation heat transfer. Different parameters including absorptivity, emissivity, reflection based radiation scattering, and carrier gas flow inlet velocity that would greatly affect the reactor thermal performance were sufficiently investigated. The fvDOM approximation was used to obtain the radiation intensity distribution along the reactor. The drop in the temperature resulted from the radiation scattering was further investigated using the P1 approximation. The results indicated that the reactor temperature difference between the P1 approximation and the fvDOM radiation model was very close under different operating conditions. However, a big temperature difference which increased with an increase in the radiation emissivity due to the thermal non-equilibrium was observed in the radiation inlet region. It was found that the incident radiation flux distribution had a strong impact on the temperature distribution throughout the reactor. This paper revealed that the temperature drop caused by the boundary radiation heat loss should not be neglected for the thermal performance analysis of solar thermochemical reactor.

关键词: solar thermochemical reactor     incident radiation flux     temperature distribution     radiation absorptivity     radiation emissivity     thermal performance analysis    

A method of determining flame radiation fraction induced by interaction burning of tri-symmetric propane

Jie JI, Junrui DUAN, Huaxian WAN

《能源前沿(英文)》 2022年 第16卷 第6期   页码 1017-1026 doi: 10.1007/s11708-020-0716-x

摘要: The interaction of multiple fires may lead to a higher flame height and more intense radiation flux than a single fire, which increases the possibility of flame spread and risks to the surroundings. Experiments were conducted using three burners with identical heat release rates (HRRs) and propane as the fuel at various spacings. The results show that flames change from non-merging to merging as the spacing decreases, which result in a complex evolution of flame height and merging point height. To facilitate the analysis, a novel merging criterion based on the dimensionless spacing / was proposed. For non-merging flames ( / >0.368), the flame height is almost identical to a single fire; for merging flames ( / ≤0.368), based on the relationship between thermal buoyancy and thrust (the pressure difference between the inside and outside of the flame), a quantitative analysis of the flame height, merging point height, and air entrainment was formed, and the calculated merging flame heights show a good agreement with the measured experimental values. Moreover, the multi-point source model was further improved, and radiation fraction of propane was calculated. The data obtained in this study would play an important role in calculating the external radiation of propane fire.

关键词: flame interaction     air entrainment     flame height     multi-point source model     thermal radiation    

Effects of radiation and heat source/sink on unsteady MHD boundary layer flow and heat transfer over

Krishnendu Bhattacharyya

《化学科学与工程前沿(英文)》 2011年 第5卷 第3期   页码 376-384 doi: 10.1007/s11705-011-1121-0

摘要: In this paper, an investigation is made to study the effects of radiation and heat source/sink on the unsteady boundary layer flow and heat transfer past a shrinking sheet with suction/injection. The flow is permeated by an externally applied magnetic field normal to the plane of flow. The self-similar equations corresponding to the velocity and temperature fields are obtained, and then solved numerically by finite difference method using quasilinearization technique. The study reveals that the momentum boundary layer thickness increases with increasing unsteadiness and decreases with magnetic field. The thermal boundary layer thickness decreases with Prandtl number, radiation parameter and heat sink parameter, but it increases with heat source parameter. Moreover, increasing unsteadiness, magnetic field strength, radiation and heat sink strength boost the heat transfer.

关键词: MHD boundary layer     unsteady flow     heat transfer     thermal radiation     heat source/sink     shrinking sheet     suction/injection    

细水雾与热烟气相互作用数值模拟研究

叶栋,蒋勇

《中国工程科学》 2007年 第9卷 第2期   页码 84-89

摘要:

使用CFD软件Fluent对火灾中热烟气与细水雾的相互作用过程进行了数值模拟研究。比较了灭火过 程中不同粒径细水雾在流场中的运动及其对灭火效果的影响,并研究了细水雾对着火房间火焰辐射的散射作用 及细水雾的聚合破碎过程对灭火效果的影响。模拟结果表明辐射是火灾中主要的热传递过程,粒径较大的水雾 比较容易离开回流区到达燃烧反应区。房间细水雾的通过吸收和散射作用减弱辐射强度,水雾在喷射初期可能 使燃烧速率增大,这些结果与实验事实相符

关键词: 细水雾     Fluent     热辐射     散射     聚合     破碎    

动态热过程分析用建筑几何模型的构建

丁力行,何立群,陈祖铭,刘仙萍,季杰

《中国工程科学》 2010年 第12卷 第8期   页码 88-93

摘要:

建筑墙体表面的太阳直射辐射投影及辐射强度随时间发生很大变化,该变化在已有的动态热过程算法框架内很难直接计算。根据建筑传热模型特点和计算机图形学原理,构建了动态热过程的建筑几何模型,该模型将建筑空间抽象为由矢量平面围成的空间区域的集合;提出了建筑几何模型的核心计算方法,即三维空间内直线与表面的矢量运算。该建筑几何模型能解决建筑动态热过程中直接计算建筑墙体表面之间的太阳直射辐射换热和太阳直射辐射投影等问题,并对空气流通、楼房之间的相互遮阳和光污染等问题的研究也具有实际意义。

关键词: 建筑热过程     几何模型     太阳辐射    

Design and analysis of electrothermal metasurfaces

Xiu LIU, Zhuo LI, Zexiao WANG, Hyeong Seok YUN, Sheng SHEN

《能源前沿(英文)》 2023年 第17卷 第1期   页码 134-140 doi: 10.1007/s11708-022-0841-9

摘要: Electrothermal metasurfaces have garnered considerable attention owing to their ability to dynamically control thermal infrared radiation. Although previous studies were mainly focused on metasurfaces with infinite unit cells, in practice, the finite-size effect can be a critical design factor for developing thermal metasurfaces with fast response and broad temperature uniformity. Here, we study the thermal metasurfaces consisting of gold nanorods with a finite array size, which can achieve a resonance close to that of the infinite case with only several periods. More importantly, such a small footprint due to the finite array size yields response time down to a nanosecond level. Furthermore, the number of the unit cells in the direction perpendicular to the axis of nanorods is found to be insensitive to the resonance and response time; thus, providing a tunable aspect ratio that can boost the temperature uniformity in the sub-Kelvin level.

关键词: modulated thermal infrared radiation     metasurface     nanosecond response time     sub-Kelvin temperature uniformity     finite size     aspect ratio    

Particle therapy for cancers: a new weapon in radiation therapy

null

《医学前沿(英文)》 2012年 第6卷 第2期   页码 165-172 doi: 10.1007/s11684-012-0196-4

摘要:

Particle irradiation started to draw attention in the past decade and has now become a hotspot in the radiation oncology community. This article reviews the most advanced developments in particle irradiation, focusing on the characteristics of proton and carbon ions in radiation physics and radiobiology. The Bragg peak of physical dose distribution causes proton and carbon beams to optimally meet the requirement for cancer irradiation because the Bragg peak permits the accurate concentration of the dose on the tumor, thus sparing the adjacent normal tissues. Moreover, carbon ion has more radiobiological benefits than photon and proton beams. These benefits include stronger sterilization effects on intrinsic radio-resistant tumors and more effective killing of hypoxic, G0, and S phase cells. Compared with the most advanced radiation techniques using photon, such as three-dimensional conformal radiation therapy and intensity-modulated radiation therapy, proton therapy has yielded more promising outcomes in local control and survival for head and neck cancers, prostate carcinoma, and pediatric cancers. Carbon therapy in Japan showed even more promising results than proton therapy. The local controls and overall survivals were as good as that treated by surgery in early stages of non-small cell lung cancer, hepatocellular carcinoma, prostate carcinoma, and head and neck cancers, especially for such highly resistant tumors as melanoma. The non-invasive nature of particle therapy affords more patients with chances to receive and benefit from treatment. Particle therapy is gradually getting attention from the oncology community. However, the cost of particle therapy facilities has limited the worldwide use of this technology.

关键词: radiation therapy     particle therapy     proton     carbon     cancer    

Security of solar radiation management geoengineering

Andrew LOCKLEY

《工程管理前沿(英文)》 2019年 第6卷 第1期   页码 102-116 doi: 10.1007/s42524-019-0008-5

摘要:

Solar Radiation Management (SRM) geoengineering is a proposed response to anthropogenic global warming (AGW) (National Academy of Sciences, 2015). There may be profound – even violent – disagreement on preferred temperature. SRM disruption risks dangerous temperature rise (termination shock). Concentrating on aircraft-delivered Stratospheric Aerosol Injection (SAI), we appraise threats to SRM and defense methodologies. Civil protest and minor cyberattacks are almost inevitable but are manageable (unless state-sponsored). Overt military attacks are more disruptive, but unlikely – although superpowers’ symbolic overt attacks may deter SRM. Unattributable attacks are likely, and mandate use of widely-available weapons. Risks from unsophisticated weapons are therefore higher. An extended supply chain is more vulnerable than a secure airbase – necessitating supply-chain hardening. Recommendations to improve SRM resilience include heterogeneous operations from diverse, secure, well-stocked bases (possibly ocean islands or aircraft carriers); and avoidance of single-point-of-failure risks (e.g. balloons). A distributed, civilian-operated system offers an alternative strategy. A multilateral, consensual SRM approach reduces likely attack triggers.

关键词: security     geoengineering     solar radiation ma-nagement     SRM    

用于个人降温和保暖的具有定制热传导和热辐射特性的双功能非对称织物 Article

Yucan Peng, Hiang Kwee Lee, David S. Wu, Yi Cui

《工程(英文)》 2022年 第10卷 第3期   页码 167-173 doi: 10.1016/j.eng.2021.04.016

摘要:

为了让人体感到热舒适,同时节约能源,个人热管理正逐渐成为一种颇有前景的策略。通过更好地控制人体散热,个人热管理可以实现有效的个人降温和保暖。本文提出了一种简单的表面改性方法,在商用织物的基础上定制热传导和热辐射特性,以便更好地管理从人体到环境的整个传热路径。本文对一种同时具有降温和保暖效果的双功能非对称织物(BAF)进行论证。凭借粗糙度不对称和表面改性等优点,BAF在降温模式下通过增强热传导和热辐射表现出显著的降温效果;在保暖模式下,两条路径的散热都减少,从而实现个人保暖。结果表明,在BAF的降温和保暖模式下测得的皮肤温差可达4.6 ℃,表明一件BAF衣服可以扩大人体的热舒适区。希望本研究可为用于个人热管理的织物的设计提供新的视角,并为现有的用于个人降温和保暖的织物的简单改性提供新的解决方案。

关键词: 织物     个人热管理     双功能非对称织物     热传导     热辐射    

Distributed governance of Solar Radiation Management geoengineering: A possible solution to SRM’s “free-driver

Andrew LOCKLEY

《工程管理前沿(英文)》 2019年 第6卷 第4期   页码 551-556 doi: 10.1007/s42524-019-0055-y

摘要: Geoengineering (deliberate climate modification) is a possible way to limit Anthropogenic Global Warming (AGW) (Shepherd, 2009; National Research Council, 2015). Solar Radiation Management geoengineering (SRM) offers relatively inexpensive, rapid temperature control. However, this low cost leads to a risk of controversial unilateral intervention—the “free-driver” problem (Weitzman, 2015). Consequently, this creates a risk of counter-geoengineering (deliberate warming) (Parker et al., 2018), resulting in governance challenges (Svoboda, 2017) akin to an arms race. Free-driver deployment scenarios previously considered include the rogue state, Greenfinger (Bodansky, 2013), or power blocs (Ricke et al., 2013), implying disagreement and conflict. We propose a novel distributed governance model of consensually-constrained unilateralism: Countries’ authority is limited to each state’s fraction of the maximum realistic intervention (e.g., pre-industrial temperature). We suggest a division of authority based on historical emissions (Rocha et al., 2015)—noting alternatives (e.g., population). To aid understanding, we offer an analogue: An over-heated train carriage, with passenger-controlled windows. We subsequently discuss the likely complexities, notably Coasian side-payments. Finally, we suggest further research: Algebraic, bot and human modeling; and observational studies.

关键词: geoengineering     Solar Radiation Management     governance     decentralised    

Theoretical study on flow and radiation in tubular solar photocatalytic reactor

《能源前沿(英文)》 2021年 第15卷 第3期   页码 687-699 doi: 10.1007/s11708-021-0773-9

摘要: In this paper, based on the mixture flow model, an optimized six-flux model is first established and applied to the tubular solar photocatalytic reactor. Parameters influencing photocatalyst distribution and radiation distribution at the reactor outlet, viz. catalyst concentration and circulation speed, are also analyzed. It is found that, at the outlet of the reactor, the optimized six-flux model has better performances (the energy increase by 1900% and 284%, respectively) with a higher catalyst concentration (triple) and a lower speed (one third).

关键词: photocatalytic hydrogen photoreactor     nume- rical simulation     solar energy     flow model     radiation model    

Performance improvement of a pulse tube cryocooler with a single compressor through cascade utilization of cold energy

Xuming LIU, Xiafan XU, Biao YANG, Xiaotong XI, Liubiao CHEN, Junjie WANG, Yuan ZHOU

《能源前沿(英文)》 2021年 第15卷 第2期   页码 345-357 doi: 10.1007/s11708-020-0708-x

摘要: The high-frequency pulse tube cryocooler (HPTC) has been attracting increasing and widespread attention in the field of cryogenic technology because of its compact structure, low vibration, and reliable operation. The gas-coupled HPTC, driven by a single compressor, is currently the simplest and most compact structure. For HPTCs operating below 20 K, in order to obtain the mW cooling capacity, hundreds or even thousands of watts of electrical power are consumed, where radiation heat leakage accounts for a large proportion of their cooling capacity. In this paper, based on SAGE10, a HPTC heat radiation calculation model was first established to study the effects of radiation heat leakage on apparent performance parameters (such as temperature and cooling capacity), and internal parameters (such as enthalpy flow and gas distribution) of the gas-coupled HPTC. An active thermal insulation method of cascade utilization of the cold energy of the system was proposed for the gas-coupled HPTC. Numerical simulations indicate that the reduction of external radiation heat leakage cannot only directly increase the net cooling power, but also decrease the internal gross losses and increase the mass and acoustic power in the lower-temperature section, which further enhances the refrigeration performance. The numerical calculation results were verified by experiments, and the test results showed that the no-load temperature of the developed cryocooler prototype decreased from 15.1 K to 6.4 K, and the relative Carnot efficiency at 15.5 K increased from 0.029% to 0.996% when substituting the proposed active method for the traditional passive method with multi-layer thermal insulation materials.

关键词: radiation heat leakage     active thermal insulation     cascade utilization     cold energy     performance improvement     cryocooler    

Design and analysis of Salisbury screens and Jaumann absorbers for solar radiation absorption

Xing FANG, C. Y. ZHAO, Hua BAO

《能源前沿(英文)》 2018年 第12卷 第1期   页码 158-168 doi: 10.1007/s11708-018-0542-6

摘要: Two types of resonance absorbers, i.e., Salisbury screens and Jaumann absorbers are systematically investigated in solar radiation absorption. Salisbury screen is a metal-dielectric-metal structure which overcomes the drawback of bulky thickness for solar spectrum. Such structures have a good spectral selective absorption property, which is also insensitive to incident angles and polarizations. To further broaden absorption bandwidth, more metal and dielectric films are taken in the structure to form Jaumann absorbers. To design optimized structural parameters, the admittance matching equations have been derived in this paper to give good initial structures, which are valuable for the following optimization. Moreover, the analysis of admittance loci has been conducted to directly show the effect of each layer on the spectral absorptivity, and then the effect of thin films is well understood. Since the fabrication of these layered absorbers is much easier than that of other nanostructured absorbers, Salisbury screen and Jaumann absorbers have a great potential in large-area applications.

关键词: thin films     admittance loci     solar absorber    

Gain-enhanced reconfigurable radiation array with mechanically driven system and directive elements

《机械工程前沿(英文)》 2022年 第17卷 第4期 doi: 10.1007/s11465-022-0716-0

摘要: In the artificial intelligence-driven modern wireless communication system, antennas are required to be reconfigurable in terms of size according to changing application scenarios. However, conventional antennas with constant phase distributions cannot achieve enhanced gains in different reconfigurable sizes. In this paper, we propose a mechanically reconfigurable radiation array (RRA) based on miniaturized elements and a mechanically reconfigurable system to obtain gain-enhanced antennas in compact and deployed states. A five-element RRA with a phase-reconfigurable center element is designed and analyzed theoretically. The experimental sample has been fabricated, driven by a deployable frame with only one degree of freedom to realize the size and phase distribution reconfiguration simultaneously to validate the enhanced gains of RRA. The proposed RRA can be tessellated into larger arrays to achieve higher gains in other frequency regimes, such as terahertz or photonics applications with nanometer fabrication technology.

关键词: mechanism     reconfigurable radiation array (RRA)     compact state     deployed state     enhanced gain    

The effect of orbital radiation therapy on thyroid-associated orbitopathy complicated with dysthyroid

null

《医学前沿(英文)》 2017年 第11卷 第3期   页码 359-364 doi: 10.1007/s11684-017-0528-5

摘要:

Thyroid-associated orbitopathy (TAO) is an inflammatory autoimmune disorder. The most serious complication of TAO is dysthyroid optic neuropathy (DON), which can lead to permanent vision loss because of volume expansion in the orbital apex. Orbital radiation therapy (ORT) is an anti-inflammatory treatment used in the treatment of active TAO. Clinical studies support radiotherapy as having a modest effect on DON, and early radiotherapy may protect against disease progression to DON. Current studies suggest that radiotherapy is generally safe. However, risks still exist in some cases. The possible effects of radiotherapy on TAO, especially complicated with DON, are reviewed. The effects of radiotherapy on DON are not completely known, and evidence from standardized, prospective, and multicenter clinical trials is still lacking.

关键词: thyroid-associated orbitopathy     dysthyroid optic neuropathy     orbital radiation therapy    

标题 作者 时间 类型 操作

Analysis of radiation heat transfer and temperature distributions of solar thermochemical reactor for

Bachirou GUENE LOUGOU, Yong SHUAI, Xiang CHEN, Yuan YUAN, Heping TAN, Huang XING

期刊论文

A method of determining flame radiation fraction induced by interaction burning of tri-symmetric propane

Jie JI, Junrui DUAN, Huaxian WAN

期刊论文

Effects of radiation and heat source/sink on unsteady MHD boundary layer flow and heat transfer over

Krishnendu Bhattacharyya

期刊论文

细水雾与热烟气相互作用数值模拟研究

叶栋,蒋勇

期刊论文

动态热过程分析用建筑几何模型的构建

丁力行,何立群,陈祖铭,刘仙萍,季杰

期刊论文

Design and analysis of electrothermal metasurfaces

Xiu LIU, Zhuo LI, Zexiao WANG, Hyeong Seok YUN, Sheng SHEN

期刊论文

Particle therapy for cancers: a new weapon in radiation therapy

null

期刊论文

Security of solar radiation management geoengineering

Andrew LOCKLEY

期刊论文

用于个人降温和保暖的具有定制热传导和热辐射特性的双功能非对称织物

Yucan Peng, Hiang Kwee Lee, David S. Wu, Yi Cui

期刊论文

Distributed governance of Solar Radiation Management geoengineering: A possible solution to SRM’s “free-driver

Andrew LOCKLEY

期刊论文

Theoretical study on flow and radiation in tubular solar photocatalytic reactor

期刊论文

Performance improvement of a pulse tube cryocooler with a single compressor through cascade utilization of cold energy

Xuming LIU, Xiafan XU, Biao YANG, Xiaotong XI, Liubiao CHEN, Junjie WANG, Yuan ZHOU

期刊论文

Design and analysis of Salisbury screens and Jaumann absorbers for solar radiation absorption

Xing FANG, C. Y. ZHAO, Hua BAO

期刊论文

Gain-enhanced reconfigurable radiation array with mechanically driven system and directive elements

期刊论文

The effect of orbital radiation therapy on thyroid-associated orbitopathy complicated with dysthyroid

null

期刊论文