Numerical Investigation of Geothermal Steam-Water Two-Phase Flow in Horizontal Pipes

Abstract

Two-phase flow is commonly encountered in various industrial and technological processes, including geothermal systems. The flow pattern, pressure drop, and water holdup of two-phase flow formation are critical parameters that affect the efficiency and safety of geothermal systems. This study employed CFD simulations with both 2D and 3D approaches. The inner diameter of the pipe was set to 26 mm, and the length was set to 1000 mm. The superficial velocities of steam (J_S) ranged from 6 to 30 m/s, and for water (J_W) from 0.02 to 0.2 m/s. The operating conditions were at temperature of 443.15 K and pressure of 791 kPa. Validation was performed by comparing the simulation results with experimental data. The findings indicated that the flow pattern, pressure drop, and water holdup were significantly influenced by the superficial velocities of steam and water. The flow patterns observed in this study include stratified wavy, annular, and mist flow. Stratified wavy flow is considered a safe flow pattern, especially in the context of steam-water flow in geothermal systems. Moreover, the results show that both pressure drops and water holdup (at a fixed J_W) increased as J_S increased. A 3D approach provides more realistic results, while the 2D approach is recommended for faster simulations of simpler models. This research contributes to improving the design quality and optimizing the operation of geothermal systems.