Flow pattern visualization and definition of transition criteria for two-phase flow in Chevron-type corrugated channels

This study aims to highlight the factors influencing flow patterns in Plate Heat Exchangers (PHEs) operated with two-phase flows. Our focus is on providing precise definitions of flow regimes and proposing transition boundaries by comparing diverse experimental datasets. To accomplish this, we designed an experimental apparatus for flow visualization through high-speed videos. The videos clarify flow patterns in an upward-flowing air-water mixture within a chevron-type plate heat exchanger. We introduce a new, clearly defined nomenclature and present the results in the form of a flow regime map. Moreover, we reclassify previously documented flow patterns in the literature using our established nomenclature, creating a unified and comparable database of visualization data. Subsequently, we explore semi-theoretical transition criteria and establish new transition boundaries based on the compiled experimental data. These newly determined transition lines are integrated into a comprehensive global flow regime map, advancing our understanding of two-phase flow behavior in PHEs.