An analytical approach for designing turbo expanders for organic rankine cycle

Abstract

ORCs (Organic Rankine Cycles) are becoming widely attractive for waste heat use since they facilitate power generation from low thermal content supplies. ORC may be optimized in various ways after determining the appropriate operating working fluid and design parameters. This article introduces a new design approach to produce a turbo expander demonstrated for a 1kW ORC utilizing R245fa as the working fluid. The obtained initial dimensions of the rotor were evaluated using performance criteria commonly used in turbo-machinery designing and the best results were selected after conducting several iterations. The inlet tip speed U 5 is considered as the primary design variable since it is restricted by mechanical stress considerations. The results obtained from the rotor analytical study are then utilized for stator, volute, and diffuser designs.