权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Enhancement of Liguid-Solid Contact in Miniaturization Phenomena

微型化现象中液固接触的增强

基本信息

批准号：
07650236
负责人：
INADA Shigeaki
金额：
$ 1.6万
依托单位：
GUNMA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

项目摘要

This research concerns with augmentation of liquid-solid contact in two boiling phenomena : minute bubble emission boiling and miniaturization boiling of droplets. In the former, vapor phase generated on a heating surface, instead of covering the surface, appear in many minute-size vapor bubbles ejecting into subcooled liquid, in a subcooled pool boiling.In the latter, however, a liquid volume, upon its impingement upon a heating surface, produces numerous minute-size droplets dispersing into the atmosphere, referred to as liquid droplet boiling. Enhancements in liquid-solid Contact are achieved through disturbances due to the ejection of minute bubbles and dispersion of minute droplets which were measured by means of the void probe and piezoelectric potential methods, respectively. The periods of bubble ejection and droplet dispersion were compared. In the miniaturization boiling case, the timewise variation of heating surface temperature was monitored using thermocouples that were embedded underneath the heating surface, from which the time-wise average surface temperature and heat flux during miniaturization process were evaluated and compared with steady-state pool boiling curve of the minute bubble emission boiling process.In connection with the liquid-solid contact boiling, the liquid-liquid, direct-contact boiling was performed at steady state by placeing a molten ally of low melting point into a pool filled with water. The boiling curve was obtained in the range of the superheat from 20 to 200K.It was disclosed that the heat flux was under 1 MW/m^2, although a violent interaction was observed between the melt and the water.It is concluded from a comparison based on these measured results that the three miniaturized boiling phenomena occur at the same threshold temperature, in the range of about 180 to 210ﾟC with miniaturization taking place under the same mechanism.

本文研究了微气泡发射沸腾和液滴小型化沸腾两种沸腾现象中的液固接触增强现象。在前者中，在加热表面上产生的汽相不是覆盖在表面上，而是在过冷池沸腾中以许多微小尺寸的汽泡喷射到过冷液体中。而在后者中，液体体积撞击加热表面时，会产生许多微小尺寸的液滴分散到大气中，称为液滴沸腾。液固接触的强化是通过微气泡的喷射和微滴的分散而实现的，这两种扰动分别用空穴探头和压电位法测量。比较了气泡喷发和液滴分散的周期。在微型化沸腾的情况下，利用埋置在受热面下的热电偶监测受热面温度的时间变化，计算微型化过程中受热面的时间平均温度和热流密度，并与微气泡发射沸腾过程的稳态池沸腾曲线进行比较。对于液-固接触沸腾，通过将低熔点的熔体放置在充满水的水池中，实现液-液直接接触沸腾。在20~200K的过热度范围内，得到了沸腾曲线，热流密度在1 mW/m~2以下，但熔体与水之间存在强烈的相互作用。根据这些测量结果的比较，得出三种小型化沸腾现象发生在相同的阈值温度，在约180~210ﾟC的范围内，在相同的机理下发生小型化。