A Review on the Preliminary Design of Axial and Radial Turbines for Small-Scale Organic Rankine Cycle

Organic Rankine cycle (ORC) is an effective technology to harness low-grade energy. Turbine, as a key component of ORC, takes advantages its high efficiency and compact size compared with other expanders. Currently, developing suitable turbines performance low cost one the bottlenecks for wide applications various ORCs. In this context, technical progress on radial inflow (RITs), axial (ATs), outflow (ROTs) introduced, loss models used in preliminary design are compared, especially small-scale RIT recommended medium small ORCs expansion pressure ratio <10. The power outs rotational speeds designed RITs spanned ranges 9.3–684 kW 3000–114,000 r/min 56.1–91.75%. comparison, outputs ATs were 3–2446 3000–91,800 63–89.1%. AT large-scale output greater than hundreds kW. However, impulse stages feasible when high, mass flow rate small. ROTs relatively small, at 10–400 speed 7200–42,700 68.7–85%. For organic working fluids large ratio, ROT might be employed. Conventional mean-line may neglect effects supersonic flow, which will encountered many ORC turbines. Therefore, adequate shock need added. Meanwhile, proper multivariable optimization algorithm such gradient-based or stochastic search method should selected. Finally, challenges potential research directions discussed. outcomes can provide some insights development systems.