This work describes the experimental setup, method, and results of utilizing a micrometer to move an adjustable orifice immediately in front of an array of microchannels. Research by others indicates potential for significant improvement in delaying critical heat flux and increasing heat transfer coefficients when placing an orifice in front of each individual channel of a microchannel array. The experimental setup in this work allows incremental orifice size changes. This ability allows the experimentalist to find which orifice size provides enough pressure drop immediately in front of the channels to reduce oscillations. The design also allows for rapid change of orifice size without having to remove and replace any components of the test setup. Signal analysis methods were used to identify frequency and amplitude of pressure and temperature oscillations. Low mass flux experiments (300 kg m~(-2) s~(-1) and 600 kg m~(-2) s~(-1) of Rl 34a in a pumped loop) showed reduced channel wall temperatures with smaller orifice sizes. The orifice concept was found to be more effective at reducing oscillations for the higher 600 kg m~(-2) s~(-1) flow rate.
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机译:这项工作描述了利用测微计将可调节孔口立即移动到微通道阵列前面的实验装置,方法和结果。其他人的研究表明,当在微通道阵列的每个单独通道的前面放置孔口时,可以显着改善延迟临界热通量和增加传热系数的潜力。在这项工作中的实验设置允许增加孔口尺寸的变化。这种能力使实验人员能够找到哪个孔尺寸立即在通道前提供足够的压降,以减少振荡。该设计还允许快速更改孔口尺寸,而不必拆卸和更换测试装置的任何组件。信号分析方法用于识别压力和温度振荡的频率和幅度。低质量通量实验(泵回路中Rl 34a的300 kg m〜(-2)s〜(-1)和600 kg m〜(-2)s〜(-1))显示出孔壁较小时通道壁温度降低了大小。人们发现,节流孔的概念对于降低600 kg m〜(-2)s〜(-1)流量时的振动更为有效。
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