An image analysis method of liquid phase distribution during boiling in parallel minichannels

Abstract

Due to miniaturisation and fast development of heat exchangers, flow maldistribution studies are of common interest. However, there is still a lack of non-invasive methods dedicated for comparing results gained from different experiments. In the paper, two-phase flow in parallel minichannels with separate and common inlet plenum was analysed. The data was recorded by a high speed camera in two different experimental stands. The aim of the paper was to study the liquid phase distribution in parallel minichannels based on the analysis of the recorded images. In the analysis, the correlation during time between changes of pixel brightness in the parts of video frames was analysed. The histograms of correlation coefficient enabled the identification of two types of liquid phase occurrence: synchronized (liquid phase filling at least half of both parts in neighbouring minichannels) and asynchronized (liquid phase occurring alternately in both parts of neighbouring minichannels). The statistical analysis of correlation coefficient enabled determining the probability of two-phase flow patterns synchronization and its intensity. It was observed that during two-phase flow with separate inlet solution a synchronized type of liquid phase distribution is more likely to occur. In the case of common inlet both types of liquid phase occurrence are likely to occur.