Modelling the two-phase flow of propane in a capillary tube: Investigating and modelling the metastable flow and hysteresis effect.

• Thorough investigations on the propane flow through a capillary tube. • Investigations include the hysteresis effect on the flow of the refrigerant. • Proposition of a modelling approach to capture and predict the hysteresis effect. • Comparison between the experimental and numerical data show good results. In this paper the two-phase propane flow through a copper capillary tube with an inner diameter of 1.1799 mm is thoroughly investigated according to metastable flow and hysteresis effects of the flow. The hysteresis effect causes ambiguity in experimental data of the two-phase pressure drop or mass flow. It is assumed that the hysteresis effect occurs when metastable flow is developed. As cause for the development of the metastable flow, the wetting ratio of the capillary tube is derived. The wetting ratio is considered to be the ratio of the length of the capillary that is covered by liquid flow only and the total capillary length. The findings are transferred into a mathematical description and supplemented into an existing homogeneous flow model. The extended model is able to simulate the general course of observed hysteresis courses and shows improvement in predicting the overall data base of previous work by being able to predict ambiguous data. [ABSTRACT FROM AUTHOR]