Over the past few decades, high-performance heat-transfer devices have been studied for numerous applications. Boiling flow in such confined spaces induces high-frequency flow instabilities that directly influence the heat-transfer performances. A small-scale water vaporizer with 10 millimeter-sized channels is experimentally studied over a wide range of vapor quality (0.05 – 1). The peculiarity of the setup is a transparent window that allows for high speed imaging of the boiling flow up to 5 bars. This work focuses on a post-processing method based on spatio-temporal diagrams. Hydrodynamics of the boiling flow can be observed on the diagrams enabling to understand the boiling mechanisms and the flow regimes inside the channels. Four regimes are observed, namely bubbly, slug, churn and annular flow. Diagrams are also used to estimate the local mean void fraction over time in channels, the local vapor quality, the slip ratio and a flow-regime map. For qualities under 10%, the bubbly flow is predominant in channel. For higher qualities, if the specific mass flow rate of water is below 37 kg/s/m², only the slug flow and the annular flow are observed, whereas the churn flow is also observed for larger flow rates.

在过去的几十年中，高性能传热设备已被研究用于许多应用。在这种密闭空间中的沸腾流动会引起高频流动不稳定性，直接影响传热性能。实验研究了一种具有10毫米大小通道的小型水蒸发器，其蒸发质量范围很广（0.05 – 1）。装置的独特之处在于它是一个透明窗口，可对高达5巴的沸腾流进行高速成像。这项工作着重于基于时空图的后处理方法。可以在图中观察到沸腾流动的流体力学，从而能够了解沸腾机理和通道内部的流动方式。观察到四种状态，即气泡状，团状，搅动和环形流动。图表还用于估算通道中随时间变化的局部平均空隙率，局部蒸气质量，滑移率和流态图。对于低于10％的质量，通道中的气泡流占主导地位。为了获得更高的质量，如果水的比质量流量低于37 kg / s /m²，则仅会观察到团状流和环形流，而对于较大的流速，还会观察到搅动流。