Fluid dynamic design of Organic Rankine Cycle turbines

Successful Organic Rankine Cycle (ORC) power systems demand highly efficient turbo-expanders. In order to meet this goal, a sound strategy for the fluid-dynamic design of the turbine is necessary. The key point of this strategy is the integration of preliminary design methods based on mean-line and throughflow models with the most advanced shape optimization techniques exploiting Computational Fluid-Dynamics (CFD). After an overview on present-day ORC turbine architectures, this chapter discusses the rational connection amongst the various steps of the fluid-dynamic design process, supplementing the dissertation with several applicable examples. Specific design remarks for ORC turbines are highlighted throughout the discussion, and emerging and future trends in the ORC framework are considered.