Flow boiling in a network of heated parallel channels is prone to instabilities that can cause uneven flow distribution, thereby degrading the heat transfer performance of the system and limiting predictability. This study experimentally investigates flow maldistribution between two parallel microchannels that arises due to the Ledinegg instability. The channels are heated uniformly and are thermally isolated from each other, such that both channels are subjected to the same input power regardless of the flow distribution. The channels are hydrodynamically connected in parallel and deionized water is delivered at a constant total flow rate shared by both channels. Direct measurements of the flow rate, wall temperature, and pressure drop in individual channels are performed simultaneously with flow visualization. At low power levels, when both channels remain in the single-phase liquid regime, the flow is evenly distributed between the channels and they attain the same wall temperature. As the power is increased, boiling incipience in one of the channels triggers the Ledinegg instability, which causes the flow to become maldistributed and induces a temperature difference between the channels. The severity of flow maldistribution, as well as the temperature difference between the channels, grows with increasing power. In the most extreme condition measured in this study, 96.5% of the total flow rate is directed to the channel operating in the single-phase liquid regime, while the boiling channel is starved and receives just 3.5% of the flow. The quantitative account of the flow maldistribution and temperature non-uniformity presented here provides a mechanistic understanding of the effects of Ledinegg instability-induced flow maldistribution on the heat transfer characteristics of thermally isolated parallel microchannels.

在加热的平行通道网络中的流动沸腾容易造成不稳定，从而可能导致流量分布不均，从而降低系统的传热性能并限制可预测性。这项研究实验研究了由于Ledinegg不稳定性而引起的两个平行微通道之间的流量分配不均。通道被均匀地加热并且彼此热隔离，使得两个通道都受到相同的输入功率，而与流量分布无关。这些通道在流体动力学上并联，并且去离子水以两个通道共享的恒定总流量输送。流量可视化的同时，可以直接测量各个通道中的流速，壁温和压降。在低功率水平下，当两个通道都保持为单相液体状态时，流量在两个通道之间均匀分布，并且达到相同的壁温。随着功率的增加，通道之一中的沸腾开始会触发Ledinegg不稳定性，从而导致流量分布不均，并在通道之间引起温差。流量分配不均的严重程度以及通道之间的温差会随着功率的增加而增加。在本研究中测量的最极端条件下，总流量的96.5％定向到在单相液体状态下运行的通道，而沸腾通道却饿了，仅接收了3.5％的流量。