Abstract In this study, the combined effect of nanostructure and inlet restrictor on reducing the instabilities during flow boiling in parallel microchannel heat sinks is investigated experimentally. Four types of microchannel heat sinks are considered; plain microchannel, microchannel with inlet restrictor, nanostructured microchannel, and nanostructured microchannel with inlet restrictor. Different flow regimes such as bubbly flow, slug flow, annular flow, and partial dry out are observed with the variation in applied heat flux and mass flux. The fluctuations in pressure, temperature, and mass flux are characterised in each regime. It is found that the fluctuations increase with power input, which is primarily due to backflow of vapour in the upstream direction of flow. The microchannel with inlet restrictor is more effective in reducing fluctuations and result in less surface temperature compared to the baseline case of plain microchannel without restrictor at the same mass flux. Moreover, if the nanostructured surface is added to the plain microchannel with inlet restrictor, the effectiveness in reducing fluctuations increases at higher heat flux and also produces less surface temperature compared to other types of microchannels.

中文翻译：

---

入口限流器和纳米结构对平行微通道散热器两相流性能的综合影响

摘要 在本研究中，通过实验研究了纳米结构和入口限流器对降低并联微通道散热器流动沸腾过程中不稳定性的联合作用。考虑了四种类型的微通道散热器；普通微通道、带入口限流器的微通道、纳米结构微通道和带入口限流器的纳米结构微通道。随着施加的热通量和质量通量的变化，观察到不同的流态，例如气泡流、段塞流、环形流和部分干涸。压力、温度和质量通量的波动在每个状态中都有特征。发现波动随着功率输入的增加而增加，这主要是由于蒸汽在上游流动方向上的回流。在相同质量通量下，与没有限流器的普通微通道的基线情况相比，带有入口限流器的微通道在减少波动方面更有效，并导致更低的表面温度。此外，如果将纳米结构表面添加到带有入口限流器的普通微通道中，与其他类型的微通道相比，在更高的热通量下减少波动的有效性增加，并且产生的表面温度也更低。