TWO PHASE FLOW PATTERNS DURING CONDENSATION OF STEAM IN MICRO-TUBES

Flow visualization of two phase flow pattern of steam during condensation process in separate horizontal quartz micro-tubes with inner diameter ranging from 70-675Pm was conducted. Two main kinds of flow patterns were observed: annular flow and slug flow, which both were nearly symmetrical. The annular flow also can be divided into two kinds: annular flow and annular-wave flow. The effects of tube diameter and mass flux on the two phase flow pattern were discussed and the characteristics of two phase flow in micro-tubes were analyzed. The experimental results were compared with the criteria for two phase flow pattern transition in traditional large diameter tubes and the results indicated that the present data has a good agreement with Mandhane(1974) map, but the ranges of slug flow predicted by Taitel and Dukler(1976) model are obviously narrow and the stratified flow predicted by these three maps was not found at present experiments.