In the early weeks of the FlexGeo project, TUM has successfully achieved the first operational hours of its reversible ORC test rig at the TUM campus in Garching, Germany. A major focus during the commissioning phase was controller tuning, along with several minor hardware upgrades to optimize various parts of the setup. TUM is now conducting test campaigns, which have already yielded promising preliminary data, setting the stage for a thorough characterization of the system in the coming weeks.

The test rig is powered by a 200 kW hot water heating circuit, designed to represent a geothermal source as the primary heat supply. At its core is a fully reversible 20 kW twin-screw machine, capable of operating in both ORC and HTHP modes. An intermediate closed-loop cooling circuit simulates a district heating network, adjusting temperature levels and mass flow rates during HTHP operation. In ORC mode, the heat source operates at temperatures between 90°C and 140°C, while in HTHP mode, the system handles heat sink temperatures from 80°C to 120°C, with a heat source range of 40°C to 90°C.

The initial results mark a significant step forward, and the upcoming experiments will provide deeper insights into the system’s capabilities as the FlexGeo project continues to advance.

A first preprint of a journal paper with the detailed characterization of the test rig and first lessons learned is planned to be published by the end of the year.