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首页> 外文期刊>Journal of Heat Transfer >Estimating the Thermal Radiative Properties of Shading Nets Under Natural Outdoor Conditions
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Estimating the Thermal Radiative Properties of Shading Nets Under Natural Outdoor Conditions

机译：估算室外自然条件下遮阳网的热辐射特性

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摘要

The perforated nature of nets makes it impossible to measure the thermal radiative properties (emittance, ε_n, transmittance, τ_n, and reflectance, ρ_n) correctly by using any measuring device under natural conditions. In this study, a theoretical model was developed and validated to predict ε_n, τ_n, and ρ_n precisely by solving the model equations simultaneously. The net was tacked onto a wooden frame; thermal radiation balance was applied below and above the net surfaces and above a black substrate underneath the frame. The downward and upward thermal radiation fluxes were measured below and above the net to be used as input parameters to the simulation. Nets with different porosities (Φ) and colors were used for the study. The results showed that the estimated ε_n ranged from 0.41 to 0.82 and τ_n ranged from 0.16 to 0.55 for the nets tested, whereas the reflectances were very low (ρ_n ≤ 0.08). The color and porosity together affect the properties of the net. Even though under equilibrium conditions of a net with the surrounding environment, the emittance of the net is equal to its absorptance. However, the absorbed thermal radiation by the net dose not equal to the emitted radiation and the difference is a convected heat.
机译：网的穿孔性质使得不可能在自然条件下使用任何测量设备正确地测量热辐射特性（发射率ε_n，透射率τ_n和反射率ρ_n）。在这项研究中，通过同时求解模型方程，开发并验证了理论模型以精确预测ε_n，τ_n和ρ_n。网被钉在木框上。热辐射平衡施加在网面的下方和上方以及框架下方的黑色基材上方。在网的下方和上方测量了向下和向上的热辐射通量，以用作模拟的输入参数。使用具有不同孔隙率（Φ）和颜色的网进行研究。结果表明，对于所测试的网，估计的ε_n在0.41至0.82的范围内，τ_n在0.16至0.55的范围内，而反射率非常低（ρ_n≤0.08）。颜色和孔隙度共同影响网的性能。即使在网与周围环境达到平衡的条件下，网的发射率也等于其吸收率。但是，吸收的热辐射的净剂量不等于发射的辐射，而差是对流热。

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  • 来源
    《Journal of Heat Transfer》 |2016年第9期|091004.1-091004.6|共6页
  • 作者

    Ahmed M. Abdel-Ghany; Ibrahim M. Al-Helal; M. R. Shady;

  • 作者单位

    Department of Agricultural Engineering, College of Food and Agriculture Sciences, King Saud University, P.O. Box 2460, Riyadh 11451, Saudi Arabia;

    Department of Agricultural Engineering, College of Food and Agriculture Sciences, King Saud University, P.O. Box 2460, Riyadh 11451, Saudi Arabia;

    Department of Agricultural Engineering, College of Food and Agriculture Sciences, King Saud University, P.O. Box 2460, Riyadh 11451, Saudi Arabia;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    plastic nets; heat transfer; arid climate; thermal radiative properties;

    机译：塑料网;传播热量;干旱气候散热性能;

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