In order to research its natural circulation, the downcomer part and the riser part is distinguished, where there are no mass and energy transferred between them.

• 该模型为体现其自然循环的特性，将下降段与上升段区分开，并假定两者之间不存在质量和能量的交换。在处理两相流区域时采用比较准确的漂移流模型。