水平微肋管内基于分层流流型的沸腾传热理论模型

本文提出了基于气液分层流的水平螺旋微肋管内沸腾传热理论预测模型。在模型建立过程中,采用了与开发微肋管冷凝分层流模型类似的理论处理方法。在气液分界面以上区域,相邻微肋之间的沟槽内的半月形液面形状取决于重力和表面张力之间的静力平衡关系,其中半月形液面中的薄液膜区域的传热特性由先前提出的薄液膜蒸发模型预测;分层流液体中的传热特性由Mori等建立的基于实验数据的关联式确定。将模型理论预测值与已由的四种不同结构的微肋管、三种有机工质下得到的实验数据进行了比较,结果表明,只要不发生管内部分烧涸现象,在Fr0<2.5时,理论预测值和实验数据符合得相当好。

THEORETICAL MODEL OF EVAPORATION HEAT TRANSFER BASED ON STRATIFIED FLOW OF HORIZONTAL MICRO-FIN TUBE

The stratified flow model of evaporation heat transfer in helically grooved, horizontal micro-fin tubes has been developed. The profile of stratified liquid was determined by a theoretical model previously developed for condensation in horizontal micro-fin tubes. For the region above the stratified liquid, the meniscus profile in the groove between adjacent fins wad determined by a force balance between the gravity and surface tension forces. The thin film evaporation model in the thin film region of the meniscus previously proposed by the authors was applied. Heat transfer through the stratified liquid was estimated by using an empirical correlation proposed by Mori et al. The theoretical predictions of the circumferential average heat transfer coefficient were compared with available experimental data for four tubes and three refrigerants. A good agreement was obtained for the region Fr0 < 2.5 as long as partial dry-out of tube surface did not occur.