Condensation heat transfer regarding hysteretic annular flow in a rotating stepped wall heat pipe

Hysteresis effects of annular flow in rotating stepped wall heat pipes are addressed based on visualization and systematic experiments. The region of hysteretic annular flow is defined. Experimental data for the annular flow condensation heat transfer in a rotating stepped wall heat pipe are presented. A model for predicting the condensation heat transfer coefficient is proposed. The theoretical results are compared with experimental data. The effect of vapor shear drag on the condensation heat transfer is discussed.