Dynamics of pressure drop oscillations during flow boiling inside minichannel

Abstract

Dynamics of pressure drop oscillations during flow boiling inside minichannel with diameter of 1 mm was experimentally investigated. High speed camera was used to identify two-phase flow patterns. The chaotic pressure drop oscillations occurring with a low and high frequencies were observed. The analysis of the dynamics of chaotic pressure oscillations and recorded videos show that a certain dominant sequences of flow patterns can be identified. These sequences depend on the mean value of pressure drop. The map of dynamical properties of two-phase flow patterns was constructed using the windowed recurrence quantification analysis. The clusters on this map identified the four kinds of dominant sequences of flow patterns. These were: liquid flow - small bubbles flow - confined bubbles flow, small bubbles flow - slug flow - reverse slug flow, churn flow - wavy annular flow - reverse slug flow, churn flow - wavy annular flow. There has been shown that each dominant sequence of flow boiling can exist during a certain time period in the non-stationary flow boiling, therefore such sequence can be treated as temporary boiling pattern.