The year 2023 was the year of gradual commissioning of all experimental expanders in the Dexpand project. The last in the series is a rotary vane expander (RVE) for testing oil-free operation. While the CTU team has extensive experience in operating RVE in ORC systems with MM and a few percent of dissolved oil in it (for pump lubrication and for the expander itself), the use of the RVE in oil-free systems is under research and development. The original planned outcome of the project was a vane expander for the EXPAND system working with isobutane. However, due to complications with this system, a design change was necessary and the result was modified to an expander simulating the conditions of operation in an isobutane rig but operated on an air rig.
The resulting expander is designed for powers of around 1 kW, ideal for variability for different experiments. However, a similar size may also find application in microgeneration applications. The system has been successfully commissioned on an air experimental rig and the main characteristics have been obtained. Planned future activities now include verification of long-term operation to predict the lifetime of the machine.