Boiling Synchronization in Two Parallel Minichannels—Image Analysis

Gabriela Rafałko,Iwona Zaborowska,Hubert Grzybowski,Romuald Mosdorf

doi:10.3390/en13061409

Abstract

In this paper, the boiling synchronization of two-phase flow patterns in two parallel minichannels of 1 mm in diameter with connected compressible volumes was analyzed. The analysis was performed using images recorded with a high-speed camera. The degree of synchronization between channels was evaluated by assessing the presence of liquid flow in the small part of the minichannels. It can be concluded that boiling is synchronized when small bubble flow or wavy annular flow occur in neighboring channels. The occurrence of slug flow in one channel causes the boiling in neighboring channels to become unsynchronized. The result of the image analysis shows that the correlation coefficient based on the evaluation of the presence of liquid flow in the small part of the minichannels over a long enough time period allows for the detection of boiling synchronization.

Highlights

The continuous formation of different flow patterns that change during two-phase flow with boiling leads to the occurrence of numerous instabilities
The images recorded with a high-speed camera in each parallel minichannel were processed using image analysis
The smoothed function of r was greater than 0. This was because the channels were filled with wavy annular flow, which indicated that the boiling processes occurring in neighboring channels were synchronized

Summary

Introduction

The continuous formation of different flow patterns that change during two-phase flow with boiling leads to the occurrence of numerous instabilities. Several instabilities happen simultaneously in the system [4] This occurs when instability of one type causes an oscillation that is overlapped by another oscillation caused by a different instability. In the field of image analysis, coefficients or thresholds are often introduced in order to classify the observed flow patterns [1,15]. In this this paper, paper, the the synchronization synchronization of of boiling boiling in in two two parallel parallel minichannels minichannels was was determined determined using using image image analysis. Presence of liquid flow in the small part of the minichannels over a long time period

Methods

Test Conditions and Procedures

Detecting the Presence of Water Using Image Analysis

Results and Discussion

Conclusions