The profiles of the local void fraction close to the heated wall in the subcooled flow boiling

Abstract

Flow boiling in the subcooled liquid condition is characterized by the complex interplay of phenomena such as bubble detachment from the wall, condensation in the flow, and the interaction between bubbles on which non-drag forces are exerted. However, the fundamental characteristics of the flow boiling in the subcooled liquid condition remain uncharted. In particular, a distribution of the bubbles close to the heated wall is not well understood. Here, we measure the void fraction in the steam-water mixture which is representing the distribution of bubbles by using a single sensor optical fiber probe with fine radial spacing in the close vicinity of the heated wall. We show that the profile of the void fraction along the radial direction of the flow channel is altered by the flow condition. In particular, the peak of the void fraction can be shifted towards the heated wall when there are fast bubbles close to the heated wall. © 2020 Elsevier Ltd