Study of boiljing phenomena at high heat flues focusing on evaporation in interline region

以行间区域蒸发为重点的高温烟道沸腾现象研究

基本信息

批准号：
10450080
负责人：
NISHIO Shigefumi
金额：
$ 10.37万
依托单位：
University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-10450080/
关键词：
Thermal Engineering Heat Transfer Phase Change Contact-line Evaporation Boiling Critical Heat Flux Microgroove

项目摘要

The present project aimed at obtaining better understanding of the mechanism of phase change at high heat fluxes by combining the following two phase change systems ; a pseudo-two-dimensional boiling system in which information about the relation between bubble structure and contact-line-length density (CLD) is obtained, and a mirogoove evaporation system in which evaporation in the interline region plays an important role in the total heat transfer rate.The results obtained in the present project are summarized as follows.(1) The dryout heat flux in the microgroove evaporation system reaches a maximum at a groove width and it is comparable with the critical heat flux (CHF) in pool boiling.(2) The bubble departure period (BDP) under microgravity conditions can be markedly shortened by using ribbed surface. In addition, the product of CHF and BDP is almost constant and thus shortening of BDP under microgravity conditions results in the increase of CHF.(3) The dependence of CLD on surface superheat is very similar to the boiling curve. CLD and the number density of dry area on the boiling surface at the critical heat flux (CHF) in saturated boiling are almost independent of the kind of liquid. In particular, the number density of dry area in the large dry-are region is independent of subcooling.(4) In high heat-flux boiling, liquid-solid contact take the liquid network pattern like canals. The base areas of bubbles are almost dry and liquid-solid contact is localized in the spaces between bubbles. These situations bring about the liquid network pattern at CHF.

本项目旨在通过结合以下两个相变系统来更好地理解高热通量下的相变机理。伪两维沸腾系统，其中获得有关气泡结构与接触线长度密度（CLD）之间关系的信息，以及一个Mirogoove蒸发系统，该系统在中间区域中的蒸发在总的热传输速率中起着重要作用。当前项目中所获得的最大效果是遵循的，以下是在Out fluds中，以下是在悬空中。宽度且与池沸腾中的临界热通量（CHF）相当。（2）在微重力条件下的气泡出发周期（BDP）可以通过使用肋骨表面明显缩短。另外，CHF和BDP的乘积几乎是恒定的，因此在微重力条件下BDP的缩短导致CHF的增加。（3）CLD对表面过热的依赖性与沸腾曲线非常相似。 CLD和饱和沸腾的临界热通量（CHF）在沸腾表面上的干燥面积的数量密度几乎与液体类型无关。特别是，大型干燥区域的干燥面积的数量密度与亚冷水无关。（4）在高热量沸腾的液态固体接触中，在运河中采用液体网络模式。气泡的基本区域几乎是干燥的，液态固体接触位于气泡之间的空间中。这些情况带来了CHF的液体网络模式。