Synergistic effect of flow pattern evolution of dispersed and continuous phases in direct-contact heat transfer process

The marker-controlled multiple watershed segmentation are achieved to distinguish darker continuous phase in gas-liquid two-phase flow patterns efficiently. Each plot of the Betti numbers βi is curve-fitted using a four parameter logistics model, for characterizing mixing effects. Similarity between adjacent pixels can be quantified by the distance. The β1 of continuous phase decreases linearly at distance≥2, which can be used to determine the threshold for segmentation. Repeated tests with different pixels and methods are conducted to ensure the repeatability and effectiveness of this model. More interestingly, we find that the rapid increase of β1 of bubbles swarm coincides with the evolution of β1 of continuous phase, and the median of difference of β1 between the two phases in the visible window, as a novel metric of flow regime control is obtained and correlated with average volumetric heat transfer coefficient. This dynamic image analysis method, equipped with computational homology, provides the ability of evaluation of the spatial flow structure from a two-dimensional image and can be used to control the process.