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首页> 外文期刊>International Journal of Heat and Mass Transfer >Modulated heat transfer tube with short conical-mesh inserts: A linking from microflow to macroflow
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Modulated heat transfer tube with short conical-mesh inserts: A linking from microflow to macroflow

机译：带短圆锥形插入件的模块化传热管：从微流到大流的链接

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摘要

This paper creates new method that uses microflows through mesh pores to modulate flow and temperature fields. Modulated heat transfer tube (MHTT) was constructed by suspending consecutive conical-mesh inserts in a tube. Because there are too many 3D mesh pores (10-100 μm size) for a conical mesh insert, numerical simulations in laminar flow regime were performed by an 3D to 2D conversion of mesh pores applying equal equivalent diameter criterion and total flow area criterion of mesh pores. The multiscale grid generation linked micron scale of mesh pores and macroscale of the tube. Covering the present data ranges, MHTT had Nusselt numbers which are 1.4-4.1 times of that in a bare tube, PEC (performance evaluation criterion) was up to 2.2, demonstrating excellent heat transfer enhancement at low flow rate pumping cost. The perfect MHTT performance comes from the distinct flow field: an attached hydraulic boundary layer having large velocity and its gradient near the tube wall, a weak circulating flow region upstream of the mesh insert and a weakly positive flow region downstream of the mesh insert. A thin thermal boundary layer on the tube wall was reached to enhance heat transfer. The periodic unit length S and diameter of the conical mesh insert d were optimized. The varied slopes of Nu versus Re were found and explained while increasing Re. There are best matches of PPI (pores per inch) and Re (Reynolds number). Low PPI mesh insert was suggested at low Re, high PPI mesh insert deformed streamlines to deviate from the perfect flow and temperature fields. Meanwhile, high PPI mesh insert had better performance at high Re. Low PPI mesh insert had good performance, which can be further improved by raising PPI. Because metallic mesh screen is commercialized and cheap, MHTT has wide potential engineering applications.
机译：本文创建了一种新方法，该方法使用通过网孔的微流来调节流场和温度场。调制传热管（MHTT）是通过将连续的圆锥形网状插入物悬挂在管中而构造的。因为圆锥形网格插入物的3D网格孔太多（尺寸为10-100μm），所以层流状态下的数值模拟是通过使用相等的等效直径准则和网格的总流动面积准则对网格孔隙进行3D到2D转换来进行的毛孔。多尺度网格生成将网孔的微米尺度与管的宏观尺度联系起来。在当前数据范围内，MHTT的努塞尔数是裸管的1.4-4.1倍，PEC（性能评估标准）高达2.2，表明在低流量泵送成本下具有出色的传热效果。完美的MHTT性能来自于独特的流场：在管壁附近具有较大速度和梯度的附着水力边界层，网状插件上游的弱循环流区域和网状插件下游的弱正流区域。在管壁上达到了薄的热边界层，以增强热传递。优化了圆锥形网状插入物d的周期单位长度S和直径。发现并解释了增加Re时Nu与Re的变化斜率。 PPI（每英寸的孔数）和Re（雷诺数）是最好的匹配。建议在低Re，高PPI网格插入物变形流线下使用低PPI网格插入物，以偏离理想的流场和温度场。同时，高PPI网格插入物在高Re下具有更好的性能。低PPI网格插入具有良好的性能，可以通过提高PPI进一步改进。由于金属丝网的商品化和价格便宜，因此MHTT具有广泛的工程应用潜力。

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