【摘要】 本文对流体沿水平表面受迫对流时的层流膜沸腾进行了分析,探讨了压力沿流动方向的变化、主要是两相边界层由于密度差所引起的压力梯度的影响,建立了相应的数学模型.对远离临界态、Pr将近Ⅰ的低粘性流体求得传热的近似解.分析表明:在边界层层流范围内,考虑气、液两相密度差所引起的压力沿流动方向的变化,将使预示的传热强度显著加大而更接近于实际值。更多还原

【Abstract】 In this paper, the forced-convective film boiling in laminar boundary-layer flow along a horizontal flat plate is discussed. Based on the analytical model shown in Fig. 1, a mathematical model is presented to cover the effect of pressure gredient caused by the increasing in vapor film thickness along flow direction. Approximate heat transfer solution, Eq. (45), is obtained analytically for laminar film boiling of a liquid deviated greatly from its critical state. For saturated film boiling, Eq. (45) can be simplified to the form of Eq. (46) which is plotted as in Fig. 2. The effect of subcooling of liquid on laminar film boiling heat transfer is shown in Fig. 3. It is concluded that, the heat transfer rate thus calculated may be obviously improved as compared with the results from Eq. (1) reported in literature, especially for the region of low flow velocity.更多还原