Effects and limitations of superhydrophobic surfaces on the heat transfer performance of a two-phase closed thermosyphon

•Internal flow pattern and condensation behavior of a superhydrophobic surface in a TPCT were investigated by the change of heat flux.•Stepwise propagation of local surface flooding induced by the repetitive liquid collision was systematically analyzed.•An entrainment effect of growing and jumping droplets caused by counter-current vapor flow was visually studied.•Effects and limitations of the superhydrophobic condenser on the heat transfer performance of the TPCT were demonstrated using experiments and analytical models.