微尺度流动沸腾不稳定性的控制策略

Controlling Strategies for Flow Boiling Instability in Microchannels

微尺度流动沸腾不稳定性是发生在换热微通道内的一种复杂现象,其不稳性流动与传热给热控对象带来有害振动,使局部热力过程发生变化,导致传热恶化,产生不均匀的热应力,造成设备疲劳损坏。因此,如何有效抑制此类不稳定性的发生,以提高相变传热效率十分重要。针对目前国内外学者提出的沸腾不稳定性控制策略进行论述,这些策略大致可以分为主动式与被动式两大类。主动控制方法包括加种子汽泡、注入空气、用纳米流体三类;被动控制方法包括做入口节流装置、人工核化穴、用拓展通道等。文中对每种方法的原理、技术手段及其性能与优缺点等进行深入细致的阐述、对比与讨论,并对其未来的发展趋势作了展望。论述内容对微通道相变换热系统的设计、控制及运行有重要指导意义。

Microscale flow-boiling instability is an intriguing phenomenon in heat-transfer microchannels.The instable flow and heat transfer induces harmful vibration to the thermal equipment,and shifts the thermal dynamic process,resulting in inefficient heat transfer and non-uniform thermal stress,creating fatigue damage to the equipment.It is thus important to suppress such instability and improve the efficiency of phase change heat transfer.In this article,the control strategies for flow boiling instability in microchannel are summarized.These strategies can bedivided into two categories:active and passive schemes.The active-controlling methods include seed bubble technology,air bubble injection,nanofluids.The passive-controlling methods involve introducing inlet throttling device,fabrication of nucleation cavity,using expanding channels etc.This paper describes the principle,technicalroutes and performance of each kind of the methods.The advantages and disadvantages of the proposed approaches are compared and discussed.Future research directions are additional targeted.The result of this study provides guidance of the design,control and operation of micro-heat transfer system.