Flow pattern transition instability during flow boiling in a single microchannel
Flow pattern transition instability during flow boiling in a single microchannel
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DOI：
10.1016/j.ijheatmasstransfer.2006.07.027
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发表时间：
2007-03
影响因子：
5.2
通讯作者：
C. Huh;Jeongbae Kim;M. Kim
中科院分区：
文献类型：
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作者：
C. Huh;Jeongbae Kim;M. Kim
研究了单微通道内流动沸腾的特性，包括周期性压降、质量流量和温度波动。利用单水平微通道和去离子水进行了实验，以研究在非常小的质量和热量流量条件下的沸腾不稳定性。聚二甲基硅氧烷（PDMS）矩形单微通道的水力直径为103.5μm，长度为40 mm。在矩形微通道内底壁上制作了一系列分段蛇形铂微加热器，为测试流体提供热能。实时流动可视化的微通道内的流动模式进行同时测量的实验参数。进行了170和360公斤/平方米的质量通量和热通量为200- 530千瓦/平方米的测试。试验结果表明，在不同的工况下，壁温、压降和质量流量都有长周期、大幅度的波动。这些周期性的波动完全匹配的过渡的两个交替的流动模式内的微通道：泡状/段塞流和细长的段塞/半环形流。因此，单微通道内流型转变的不稳定性导致了壁温、压降和质量流量的周期性变化，且周期很长（100- 200 s），幅度很大。
We studied the unique characteristics of flow boiling in a single microchannel, including the periodic pressure drop, mass flow rate, and temperature fluctuations, in terms of a long time period. Experiments were conducted using a single horizontal microchannel and deionized water to study boiling instabilities at very small mass and heat flow rate conditions. A Polydimethylsiloxane (PDMS) rectangular single microchannel had a hydraulic diameter of 103.5μm and a length of 40mm. A series of piecewise serpentine platinum microheaters were fabricated on the inner bottom wall of the rectangular microchannel to supply thermal energy to the test fluid. Real-time flow visualizations of the flow pattern inside the microchannel were performed simultaneously with measurements of the experimental parameters. Tests were performed for mass fluxes of 170 and 360kg/m2s and heat fluxes of 200–530kW/m2. The test results showed that the heated wall temperature, pressure drop, and mass flux all fluctuated with a long period and large amplitude. These periodic fluctuations exactly matched the transition of two alternating flow patterns inside the microchannel: a bubbly/slug flow and an elongated slug/semi-annular flow. Therefore, the flow pattern transition instability in the single microchannel caused a cyclic behavior of the wall temperature, pressure drop, and mass flux, and this behavior had a very long period (100–200s) and large amplitude.