表面活性剂溶液过冷池沸腾中的汽泡穿透行为

Penetration Behavior Between Vapor Bubbles in Subcooled Pool Boiling of Surfactant Solution

沸腾过程中汽泡的演化是决定加热面传热强度的重要参数之一,本文报道一种新的汽泡动力学现象,即在非离子表面活性剂溶液的过冷池沸腾过程中,新成核汽泡与在同一成核点位生成的汽泡相互作用的过程。对于不同的热流及过冷度工况下,其相互作用的过程分别表现为汽泡间的穿入、汽泡间穿透和双汽泡穿透等,汽泡相互穿透的作用速度可达5.01 m·s^(-1)。新成核的汽泡除了对被穿透汽泡的脱离形成一定的加速外,同时,被穿透的汽泡会对新成核的汽泡形成一定的扰动,从而加强对热边界层的扰动,进而增强了汽泡根部的再润湿能力。同时对其产生机理进行了分析,以更好地理解表面活性剂增强沸腾换热的机理。

The evolution of vapor bubbles in a boiling liquid, especially the growth of bubbles, is one of the important parameters that determine the heat transfer performance of a heating surface.This work reports a new phenomenon of vapor bubble dynamics, namely the process of interaction between newly nucleated vapor bubbles, which generated at the same nucleation point during the boiling of the nonionic surfactant solution in the subcooled pool boiling. For different conditions, the interaction process is manifested as bubble-bubble penetration, bubble-bubble piercing, and double penetrations. The interaction speed of vapor bubbles can reach 5.01 m·s^(-1). The newly nucleated bubble not only accelerated the departure of the penetrated bubble, but also generated a certain disturbance to the thermal boundary layer, which enhanced the rewetting ability of the root of the bubble. Moreover, its generation mechanism was analyzed, to help better understand the mechanism of surfactants to enhance boiling heat transfer.