Experimental study of heat transfer in oscillatory gas flow inside a parallel-plate channel with imposed axial temperature gradient
Experimental study of heat transfer in oscillatory gas flow inside a parallel-plate channel with imposed axial temperature gradient
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DOI：
10.1016/j.ijheatmasstransfer.2014.06.031
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发表时间：
2014-10
影响因子：
5.2
通讯作者：
Zhibin Yu;Xiaoan Mao;A. Jaworski
中科院分区：
文献类型：
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作者：
Zhibin Yu;Xiaoan Mao;A. Jaworski
了解固体边界和振荡气体流动之间的传热过程对于热声和斯特林热力机器中的热交换器，蓄热器和热缓冲管等内部部件的设计非常重要，其中流动振荡是电力生产或传递过程的一部分。本文通过实验和数值方法研究了冷热板排列形成平行板通道时流动与通道间的换热问题。这里，特别关注的是发生在热边界层和粘性边界层内的过程。并结合速度场对测得的相位相关温度场进行了详细的研究。当气体从通道的冷到热或从热到冷部分移动时，可以观察到近壁温度的最小值和最大横截面温度分布。它们分别被称为“温度过低”和“温度过高”。这些温度极小值和极大值的存在导致了向壁面垂直方向存在较大的局部温度梯度，从而导致气层之间在向壁面垂直方向存在较大的热扩散。观察到流动历史对温度场有很强的影响。这使所谓的“井口假说”失效，根据井口假说，稳定流动的传热数据被应用于振荡流动条件。讨论了用于热声器件的热交换器设计的一般准则。
Understanding of heat transfer processes between a solid boundary and an oscillatory gas flow is important for the design of internal components such as heat exchangers, regenerators and thermal buffer tubes in thermoacoustic and Stirling thermodynamic machines where the flow oscillations are part of the power production or transfer processes. The heat transfer between the flow and an arrangement of hot and cold plates forming a parallel-plate channel is studied experimentally and numerically. Here, the particular focus is on the processes occurring within the thermal and viscous boundary layers. The measured phase-dependent temperature fields combined with the velocity fields are studied in detail. Near wall temperature minima and maxima of the cross sectional temperature profiles are observed when the gas moves from cold to hot or from hot to cold parts of the channel. They are referred to as “temperature undershoot” and “overshoot”, respectively. The existence of these temperature minima and maxima causes large local temperature gradients in the direction normal to the wall, which result in large heat diffusion between gas layers in the direction normal to the wall. It is observed that the flow history has a strong impact on the temperature fields. This invalidates the so-called “Iguchi hypothesis”, based on which the heat transfer data for steady flows is being applied to oscillatory flow conditions. General guidelines for the design of heat exchangers used in thermoacoustic devices are discussed.