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首页> 外文期刊>International Journal of Heat and Mass Transfer >Numerical analysis of the flow and heat transfer in cylindrical clothing microclimates - Influence of the microclimate thickness ratio
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Numerical analysis of the flow and heat transfer in cylindrical clothing microclimates - Influence of the microclimate thickness ratio

机译：圆柱衣物微气候中流动和传热的数值分析-微气候厚度比的影响

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摘要

Clothing microclimates, i.e. the space between the skin and the clothing, can play a central role in the heat and mass exchanges from or to the body. This is especially true for protective clothing, where microclimates are generally thicker and natural convection is more likely to occur. We used a computational fluid dynamics approach to perform numerical studies of fluid flow and heat transfer across cylindrical clothing microclimates for Reynolds number of 3900. Transient simulations were performed for three different values of microclimate thickness to diameter ratio (0.05, 0.10 and 0.25), considering a two-dimensional cross-section of a human limb surrounded by a porous fabric and exposed to cool external air (10 ℃). The obtained local heat transfer along the skin shows that increasing the microclimate thickness ratio from 0.05 to 0.25 decreases the convective heat fluxes by up to 100% in the upstream regions of the microclimate, and increases them up to 190% in the downstream regions. This asymmetry, which indicates an increasingly important role of natural convection as the microclimate thickness ratio is increased, is often overlooked in space-averaged approaches due to the opposite changes in the different regions of the microclimate. Local variations in temperature along the outer fabric and in convective fluxes along the skin were significant, reaching up to 14 K and 90%, respectively. The critical thickness ratio above which natural convection should not be ignored was found to be 0.1 (e.g. corresponding to a microclimate thicknesses of 11 mm or 8 mm, around an upper arm or forearm, respectively).
机译：衣物的小气候，即皮肤和衣物之间的空间，可以在与人体之间的热量和质量交换中发挥中心作用。对于防护服而言尤其如此，在防护服中，小气候通常较厚，自然对流的可能性更大。我们使用计算流体动力学方法对3900雷诺数的圆柱衣物微气候上的流体流动和传热进行了数值研究。考虑到三种不同的微气候厚度与直径比（0.05、0.10和0.25），进行了瞬态模拟。被多孔织物包围并暴露于凉爽的外部空气（10℃）的人肢的二维横截面。沿皮肤获得的局部热传递表明，将微气候厚度比从0.05增加到0.25时，对流热通量在微气候的上游区域减少了高达100％，在下游区域将对流热通量增加了多达190％。这种不对称性表明随着自然气候对流的增加，随着微气候厚度比的增加，自然对流的作用日益重要。由于微气候不同区域的相反变化，这种方法在空间平均方法中经常被忽略。沿外层织物的温度局部变化以及沿皮肤的对流通量的局部变化很大，分别达到14 K和90％。发现不应该忽略自然对流的临界厚度比为0.1（例如，分别对应于上臂或前臂周围的11mm或8mm的微气候厚度）。

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  • 作者

    M.S. Santos; D. Oliveira; J.B.LM. Campos; T.S. Mayor;

  • 作者单位

    CEFT, Transport Phenomena Research Center, Chemical Engineering Department, Engineering Faculty of Porto University, Rua Roberto Frias, 4200-465 Porto, Portugal,Empa, Swiss Federal Laboratories for Materials Science and Technology, Lerchenfeldstrasse 5, 9014 St. Callen, Switzerland;

    CEFT, Transport Phenomena Research Center, Chemical Engineering Department, Engineering Faculty of Porto University, Rua Roberto Frias, 4200-465 Porto, Portugal,Empa, Swiss Federal Laboratories for Materials Science and Technology, Lerchenfeldstrasse 5, 9014 St. Callen, Switzerland;

    CEFT, Transport Phenomena Research Center, Chemical Engineering Department, Engineering Faculty of Porto University, Rua Roberto Frias, 4200-465 Porto, Portugal;

    CEFT, Transport Phenomena Research Center, Chemical Engineering Department, Engineering Faculty of Porto University, Rua Roberto Frias, 4200-465 Porto, Portugal,Empa, Swiss Federal Laboratories for Materials Science and Technology, Lerchenfeldstrasse 5, 9014 St. Callen, Switzerland;

  • 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

    Clothing microclimates; Natural convection; Air flow; Turbulence; CFD; Protective clothing;

    机译：服装小气候;自然对流;空气流动;湍流差价合约防护服;

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