Predictable modelling of heat transfer coefficient between spraying water and a hot surface above the Leidenfrost temperature
Predictable modelling of heat transfer coefficient between spraying water and a hot surface above the Leidenfrost temperature
复制标题
喷水与高于莱顿弗罗斯特温度的热表面之间的传热系数的可预测建模
DOI：
10.2355/isijinternational.37.492
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发表时间：
1997
期刊：
影响因子：
--
通讯作者：
Toshie Hashimoto
中科院分区：
文献类型：
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作者：
H. Fujimoto;N. Hatta;Hiroyoshi Asakawa;Toshie Hashimoto
为了评估莱顿弗罗斯特温度以上水喷雾撞击热金属表面的冷却强度，将强制对流沸腾区的传热系数公式化为液滴尺寸、撞击速度和液滴数密度的函数，这些参数彼此独立。到目前为止，已经进行了许多关于雾/喷雾冷却过程的工作，特别是从实验的角度进行的工作。然而，由于影响喷雾冷却过程的参数很多，因此尚未建立能够评估热金属表面与水喷雾之间传热速率的通用程序。然后，我们通过实验推导了一个由上述三个参数组成的新公式，以决定喷雾冷却过程中的传热率。将加热至约 900°C 的不锈钢表面通过~20°C 的喷水冷却，并测量表面温度的时间历程。我们选取了平均液滴直径、流速、水通量分布等特性各不相同的几种实心锥形喷嘴，并对其进行了冷却试验。最后，提出了最适合实验结果的公式。从实验的角度讨论了喷雾特性对传热速率的影响。
In order to evaluate the cooling intensity of water spray impacting on a hot metallic surface above the Leidenfrost temperature, the formulation of heat transfer coefficient in the forced convection boiling region has been made as a function of the droplet size, the impinging velocity and the number density of droplets whose parameters are independent of each other. So far, many works on the mist/spray cooling process have been made, in particular, from an experimental point of view. However, the general procedure capable of evaluating heat transfer rate between a hot metallic surface and water spray has not been established yet, because there are a large number of parameters affecting the spray cooling process. Then, we have experimentally derived a new formula consisting of the above three parameters to be dominant for heat transfer rate in the spray cooling process. The stainless steel surface heated to about 900°C has been cooled by water spray of ∼20°C and the time history of the surface temperature has been measured. We have selected some kinds of full cone nozzles whose characteristics such as the average droplet diameter, the velocity and the distribution of water flux have been different from each other, and performed the cooling tests using them. Finally, the formula capable of giving best-fit to the experimental results has been proposed. The effect of the spraying characteristics on the heat transfer rate has been discussed from an experimental point of view.