Droplet entrainment within the evaporator to the suitable volume-filling ratio of a vertical two-phase closed thermosyphon

Abstract The present study on vertical two-phase closed thermosyphon (TPCT) is aimed to determine the suitable volume-filling ratio, as a function of geometries, heat flux and vapor temperature, in order avoid potential local dryout evaporator section hence maximize performance. In study, droplet entrainment, which caused by internal counter flow during nucleate boiling within falling liquid film section, introduced improve existing TPCT model, so comprehensive model with considering all three transfer regimes further established. suggested lower upper limits ratio (CFR EFR) are then determined utilizing criterias for dryout, flooding limit limit. Furthermore, effects temperature range analyzed details, simplified correlation CFR proposed based numerical modeling results. Particularly, predictions distribution thickness onset validated published experimental data other simulation It also found that entrainment significantly influences film. Increasing inner diameter decreasing length enlarge (between EFR), operation envelope (corresponding limit) TPCT. condenser increases small extent. influence mechanisms optimum filling geometries complicated; however, can be obtained good agreement results ± 30% deviation whole limited scope.