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首页> 外文期刊>International Journal of Heat and Mass Transfer >Numerical studies on heat transfer and friction factor characteristics of a tube fitted with helical screw-tape without core-rod inserts
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Numerical studies on heat transfer and friction factor characteristics of a tube fitted with helical screw-tape without core-rod inserts

机译：装有无芯棒插入件的螺旋螺旋胶带的管的传热和摩擦系数特性的数值研究

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摘要

The principle of heat transfer enhancement in the core flow of tube has been proposed to improve the temperature uniformity and reduce flow resistance, which is different from that of heat transfer enhancement in the boundary flow of tube. Helical screw-tape inserts with four different widths (w = 7.5 mm, 12 mm, 15 mm and 20 mm) have been investigated for different inlet volume-flow rates ranging from 200 L/h to 500 L/h. A three-dimensional turbulence analysis of heat transfer and fluid flow is performed by numerical simulation. The simulation results show that the average overall heat transfer coefficients in circular plain tubes are enhanced with helical screw-tape of different widths by as much as 212 ~ 351% at a constant tube-side temperature and the friction factor are enhanced by as much as 33% to 1020%. The PEC value of the helical screw-tape inserts of different width varies between 1.58 and 2.35. Physical quantity synergy analysis is performed to investigate the mechanism of heat transfer enhancement. The synergy angles α, β, γ, θ and η are calculated, and the numerical results verify the synergy regulation among physical quantities of fluid particle in the flow field of convective heat transfer, which can guide the optimum design for better heat transfer units and high-efficiency heat exchangers. Entropy generation analysis is also performed to explain how to get the optimum helical screw-tape.
机译：为了提高温度均匀性并减小流阻，提出了增强管芯流动中传热的原理，这与增强管芯边界流中传热的原理不同。研究了具有四种不同宽度（w = 7.5 mm，12 mm，15 mm和20 mm）的螺旋形胶带，其入口流量范围为200 L / h至500 L / h。通过数值模拟对传热和流体流动进行了三维湍流分析。仿真结果表明，在管侧温度恒定的情况下，使用不同宽度的螺旋带将圆形普通管的平均总传热系数提高212〜351％，并且将摩擦系数提高多达33％至1020％。不同宽度的螺旋胶带的PEC值在1.58和2.35之间变化。进行物理量协同分析以研究传热增强的机理。计算了协同角α，β，γ，θ和η，数值结果验证了对流传热流场中流体颗粒物理量之间的协同规律，可为优化传热单元和优化设计提供指导。高效热交换器。还进行了熵产生分析，以解释如何获得最佳的螺旋螺旋胶带。

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