雾化喷射冷却的机理及模型研究

STUDY ON MECHANISMS AND MODEL OF HEAT TRANSFER IN SPRAY COOLING

雾化喷射冷却的换热机理十分复杂,目前其研究还很不成熟。本文从喷射雾滴的特性参数出发,以被冷却表面上形成的喷射液膜为对象,考虑了冷却液体向环境的散热,建立质量、能量守恒方程,得到半经验半解析的雾化喷射换热模型。其中,本文提出真换热系数和显换热系数的概念,认为显换热系数受空间散热影响,而真换热系数只与喷雾动量有关。最后设计了雾化喷射局部换热实验,对模型进行检验,结果表明,该模型能够较好地符合实验所得的换热系数及加热面表面温度沿喷射半径的分布趋势。

The mechanism of heat transfer in spray cooling is complicated, and most theories hitherto are immature. In this paper, according to nozzle spray characteristics, energy and mass balance equations for the liquid film on heated surface were founded, and a half empirical and half analysis model involving the heat dissipation is acquired. The paper presented two heat transfer coefficients： apparent heat transfer coefficient and real heat transfer coefficient. The former is affected by spatial heat dissipation, while the latter is only related to spray momentum. Later, local heat transfer coefficients were acquired through non-boiling spray cooling experiments, and were compared with the computed value to check the heat transfer coefficient models. As a result, the model was proved to accord with the experimental results.