Heat transfer analysis of stratified flow in rotating heat pipes with cylindrical and stepped walls

This paper deals with the flow behavior and the related heat transfer characteristics of stratified Row in axially rotating heat pipes with cylindrical and stepped wall configurations. Flow patterns are presented with existing experimental data of heat transfer in cylindrical and stepped wall rotating heat pipes. Theoretical and semi-empirical models for calculation of the condensation and evaporation heat transfer coefficients are developed. Key dimensionless numbers such as Froude, Galileo, G and zeta-number are identified. Existing experimental data from a rotating cylindrical heat pipe are analyzed and used for regression based on semi-empirical models. Good agreement between the predicted results and experimental data was obtained. Comparison between the present heat transfer models rotating cylindrical wall heat pipes and experimental data from a stepped wall heat pipe shows that the present models can be used to predict the condensation and evaporation heat transfer coefficients in a rotating stepped wall heat pipe. (C) 1997 Elsevier Science Ltd.