Abstract Two-phase flow boiling is susceptible to the Ledinegg instability, which can result in non-uniform flow distribution between parallel channels and thereby adversely impact the heat transfer performance. This study experimentally assesses the effect of thermal coupling between the parallel channels on flow maldistribution caused by the Ledinegg instability and compares the results to our prior theoretical predictions. A system with two parallel microchannels is investigated using water as the working fluid. The channels are hydrodynamically connected via common inlet/outlet plenums and supplied with a constant total flow rate. The channels are uniformly subjected to the same input power (which is increased in steps). Two separate configurations are evaluated to assess drastically different levels of thermal coupling between the channels, namely thermally isolated and thermally coupled channels. Synchronized measurements of the flow rate in each individual channel, wall temperature, and pressure drop are performed along with flow visualization to compare the thermal-hydraulic characteristics of these two configurations. Thermal coupling is shown to reduce the wall temperature difference between the channels and dampen flow maldistribution. Specifically, the range of input power over which flow maldistribution occurs is noticeably smaller and the maximum severity of flow maldistribution is reduced in thermally coupled channels. The data provide a quantitative account of the effect of lateral thermal coupling in moderating flow maldistribution, which is corroborated by comparison to predictions from our two-phase flow distribution model. This combined experimental and theoretical evidence demonstrates that, under extreme conditions when one channel is significantly starved of flow rate and risks dryout, channel-to-channel thermal coupling can redistribute the heat load from the flow-starved channel to the channel with excess flow. Due to such a possibility of heat redistribution, the coupled channels are significantly less prone to flow maldistribution compared to thermally isolated channels.

中文翻译：

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沸腾平行微通道间热耦合对莱丁格不稳定性引起的流动分布不均影响的实验研究

摘要 两相流沸腾易受Ledinegg不稳定性影响，导致平行通道间流动分布不均匀，从而对传热性能产生不利影响。这项研究通过实验评估了平行通道之间的热耦合对由 Ledinegg 不稳定性引起的流动分布不均的影响，并将结果与​​我们先前的理论预测进行了比较。使用水作为工作流体研究了具有两个平行微通道的系统。这些通道通过共同的入口/出口压力通风系统以流体动力学方式连接，并提供恒定的总流量。通道均匀地承受相同的输入功率（逐步增加）。评估了两种不同的配置，以评估通道之间截然不同的热耦合水平，即热隔离和热耦合通道。每个单独通道中的流速、壁温和压降的同步测量与流动可视化一起执行，以比较这两种配置的热工水力特性。显示热耦合可减少通道之间的壁温差并抑制流动分布不均。具体而言，发生流量分布不均的输入功率范围明显更小，并且热耦合通道中流量分布不均的最大严重程度降低。数据提供了横向热耦合在缓和流动分布不均中的影响的定量说明，通过与我们的两相流动分布模型的预测进行比较证实了这一点。这一结合的实验和理论证据表明，在极端条件下，当一个通道严重缺乏流速并有干涸风险时，通道到通道的热耦合可以将热负荷从缺乏流动的通道重新分配到流量过多的通道。由于这种热重新分布的可能性，与热隔离通道相比，耦合通道明显更不容易发生流动分布不均。