Enhancement of Fluid-to-Fluid Scaling Criteria for Modeling Condensation in Horizontal Tubes Under Stratified Flow Conditions

Fluid-to-fluid scaling criteria for modeling high-pressure steam condensation have been developed. It was shown that to guarantee the similarity between the prototype and the model, the liquid-to-vapor density ratio, the Froude number, and the vapor Reynolds number should be preserved. Preserving those three non-dimensional numbers allows quantities allows having control of the four degrees of freedom usually available during experimentation, the mass flux, temperature, pressure, and geometry. The gravity dominated flow, or the stratified or the stratified-wavy flow, is characterized by a thick condensate layer flowing along the bottom of the tube, while a thin liquid film forms on the wall in the upper part. For this flow regime, the heat transfer coefficient is characterized to be dependent on the temperature difference between the flow and the tube inner wall. For the shear dominated flow, or the annular flow, which is characterized by the axial flow of the condensate along the channel. The forced convective condensation is the dominant heat transfer mode, and the heat transfer coefficient is characterized by the dependence on the mass flux and the flow quality. In this paper, the improvement of the application of the developed scaling criteria on the gravity dominated flow (the stratified flow) regime will be discussed. It was shown that approach B of the heat flux scaling criterion had shown better matching between the prototypes and the models in terms of the Nusselt number. A further study will be conducted which include more benchmark problems and experimental data for the scaling criteria validation.