Heat Transfer in Post Dryout and Its Augmentation

干燥后的传热及其增强

基本信息

批准号：
01550184
负责人：
FUJITA Yasunobu
金额：
$ 1.28万
依托单位：
Kyushu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1989
资助国家：
日本
起止时间：
1989 至 1990
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-01550184/
关键词：
Forced Convective Boiling Boiling in a Tube Nucleate Boiling Two-Phase Convective Boiling Post-Dryout Freon Enhancement ポストドライアウト熱伝達

项目摘要

1. Boiling heat transfer coefficient for flow boiling in a uniformly heated vertical tube was measured for freon 11, freon 113 and their mixture in the various range of pressure, mass velocity, inlet subcooling, and heat flux.2. Heat transfer coefficient in the regions of nucleate boiling and two-phase forced convection was not predicted well by the available correlations proposed so far. In the two-phase forced convection region in particular, there was not observed an appreciable increase of heat transfer coefficient with increasing quality, as in the case of water.3. A semi-empirical correlation was proposed for heat transfer coefficient in the regions of nucleate boiling and two-phase forced convection.4. A transition from the two-phase forced convection to the post dry out region resulted in an abrupt increase of tube wall temperature. The heat flux and quality for this transition were well predicted from the Katto correlation for the critical heat flux.5. Wall temperature in the post dry out region increased abruptly right after the dry out and thereafter asymptotically approached to the wall temperature predicted for pure vapor, while the pattern of wall temperature in this process depended upon mass velocity, heat flux, and a distance from the dry point.6. Heat transfer coefficient was greatly degradated in the post dry out region. Thus an augmentation of heat transfer coefficient in this region is very important from the practical point of view.

1。测量弗莱恩11，弗雷恩113及其混合物在各种压力，质量速度，入口亚冷却和热通量的范围内测量均匀加热的垂直管中流量沸腾系数。2。到目前为止，提出的可用相关性无法很好地预测核沸腾区域和两相强迫对流区域中的传热系数。特别是在两相强制对流区域中，没有观察到随着水的质量提高，传热系数的增加，如水。3。提出了半经验相关性，用于在核沸腾区域和两相强迫对流区域中进行传热系数。4。从两相强迫对流到干燥区域的过渡导致管壁温度突然升高。通过临界热通量的katto相关性很好地预测了这种过渡的热通量和质量。5。柱中的壁温干燥区域在干燥后突然增加，此后渐近地接近预测纯蒸气的壁温，而此过程中壁温的模式取决于质量速度，热量通量，距离干点的距离为6。在干燥的区域中，传热系数大大降解。因此，从实际的角度来看，该区域中传热系数的增强非常重要。