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首页> 外文期刊>International Journal of Heat and Mass Transfer >Microtube liquid single-phase heat transfer in laminar flow
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Microtube liquid single-phase heat transfer in laminar flow

机译：层流中的微管液体单相传热

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摘要

One of the main applications of microscale flow is miniature, high-efficiency heat transfer. The most simple and immediate solution to the problem of concentrated heat exchange is the use of small diameter channels with single-phase water flow, but there is a lack of publicised knowledge about the heat transfer performance in these conditions. In this article, an experimental investigation is reported to accurately characterize the diabatic behaviour of single-phase laminar flow in circular microducts, ranging in diameter from 528 down to 120 μm. The experiments on a capillary of 50 μm ID proved upon analysis to be unaccountable due to the intrinsic error contained in the set-up, which is tied to the large inertia of the pipe wall, etc. in proportion to the small passage of flow at this diameter. The vacuum environment in which experiments were carried out ensured a test section free of convective losses, so that measurements are provided as precise as possible within the geometry of the microchannel. The possible occurrence of scaling effects such as axial conduction in the walls, viscous heating of the fluid and thermal entrance length effects was studied and criteria were established which have been validated by the measurements. Results show a decrease of Nusselt number with decreasing diameter, an axial dependence that is linked to thermal entrance effects and a dependence of the Nusselt number also on Reynolds number, whence the large conductive losses from the test section can be deduced, not necessarily restricted to axial redistribution of the heat flux in the wall only.
机译：微型流量的主要应用之一是微型高效传热。解决集中热交换问题的最简单，直接的方法是使用具有单相水流的小直径通道，但是在这些情况下，缺乏有关传热性能的公开知识。在本文中，据报道进行了一项实验研究，以准确表征圆形微管中单相层流的绝热行为，其直径范围从528到120μm。在分析中证明，在50μm内径的毛细管上进行的实验由于设置中包含的固有误差而无法解释，该固有误差与管壁的大惯性等相关，而与管壁处的小流量通道成比例。这个直径。进行实验的真空环境确保了测试部分没有对流损失，因此在微通道的几何形状内提供了尽可能精确的测量。研究了可能发生的结垢效应，例如壁中的轴向传导，流体的粘性加热和热入口长度效应，并建立了已通过测量验证的标准。结果表明，随着直径的减小，Nusselt数减少，与热入射效应相关的轴向依赖性，以及Nusselt数也对雷诺数的依赖性，从而可以推断出测试部分的较大导电损耗，而不必局限于壁中的热通量仅在轴向上重新分布。

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