Geothermal-Flowloop (GFL): Investigating multiphase flows under geothermal conditions

The design and operation of geothermal wells, pipelines, and associated infrastructure depend on accurate analysis and understanding of multiphase flow behavior. While a variety of multiphase flow models are available, most are based on experimental data obtained under near-ambient conditions for air–water or oil–gas systems. Applying these models to high-temperature geothermal fluids potentially results in substantial inaccuracies, highlighting the need to investigate multiphase flow under conditions relevant to geothermal applications. Here we introduce the Geothermal-Flowloop (GFL)—a novel, purpose-built facility for direct observation and analysis of multiphase flow in geothermal fluids at representative temperatures and pressures. The system enables controlled multiphase flow experiments with water or brine and gases at temperatures up to 200 °C and pressures up to 40 bar. Equipped with an optical window, hydrophone, and gamma densitometers, the GFL allows real-time and direct visualization of fluid flow behavior including identification of flow regimes, cavitation, slip, liquid holdup and void fraction determination. The GFL also offers a platform for evaluating emerging technologies with potential geothermal applications. By facilitating detailed investigations under realistic operating conditions, the facility contributes to the advancement of geothermal infrastructure design and performance optimization.