Boiling Heat Transfer of Binary Mixture in a Tube

二元混合物在管内的沸腾传热

基本信息

批准号：
62550157
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：
1987
资助国家：
日本
起止时间：
1987 至 1988
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-62550157/
关键词：
Binary Mixture Flow Boiling in Tube Boiling Heat Transfer フロン系混合液核沸騰熱伝達

项目摘要

1. Boiling heat transfer of Freon R11-R113 mixture flowing a uniformly heated vertical tube was experimented under various combinations of composition of mixture, pressure, mass velocity, heat flux and inlet condition. The test tube was heated by passing direct current through the tube which resulted in an excessive voltage drop across thermocouple junctions welded on the outer surface of the tube. Correcting method for this voltage drop was proposed and found to provide accurate wall temperature.2. Both the tube wall temperature and the bulk fluid temperature increase linearly in parallel along the tube length before the incipience of boiling. Heat Transfer coefficients in this non-boiling forced convection region are correlated well with Dittus and Boelter's Formula.3. At the point where boiling is initialed, wall temperature abruptly falls and hence heat transfer coefficient abruptly rises from the level of forced convection without phase change.4. Heat transfer coefficients in nucleate boiling regime at relatively low quality are independent to mass velocity. Heat transfer coefficients of mixture in this regime are found to become lower compared to the coefficients linearly interpolated by weighing the mole fraction on their single-component values. Proposed correlating methods for pool boiling of binary mixture are found to fail to correlate the data for flow boiling.Heat transfer coefficients in two-phase forced convection regime at relatively high quality are rather a weak function of local quality.6. For further detailed consideration to be performed on heat transfer characteristics of binary mixture, there are urgently required not only thermodynamic properties but transport properties for binary mixture.

1.在混合物组成、压力、质量速度、热通量和入口条件的各种组合下，对氟利昂R11-R113混合物在均匀加热的立管中流动的沸腾传热进行了实验。通过使直流电流过试管来加热试管，这导致焊接在试管外表面的热电偶接头上产生过大的电压降。提出了对该电压降的校正方法，并发现可以提供准确的壁温。 2．在沸腾开始之前，管壁温度和本体流体温度均沿管长度平行线性增加。该非沸腾强制对流区域的传热系数与 Dittus 和 Boelter 公式 3 密切相关。在沸腾开始点，壁温突然下降，因此传热系数从无相变的强制对流水平突然上升。4．相对较低质量的核态沸腾状态下的传热系数与质量速度无关。发现与通过权衡单组分值的摩尔分数线性插值的系数相比，该状态下混合物的传热系数变得更低。所提出的二元混合物池沸腾的关联方法被发现无法关联流动沸腾的数据。在相对高质量的两相强制对流状态下的传热系数是局部质量的弱函数。6．为了对二元混合物的传热特性进行更详细的考虑，不仅迫切需要二元混合物的热力学性质，而且还需要二元混合物的传输性质。