Organic Rankine cycle allow the conversion of low heat sources into electricity. Although the technology is not new, the increase demand in energy and the requirement for CO2 emission reduction create new opportunities to harvest low great heat sources such as waste residual heat.

Radial turbines have a simple construction, they are robust and they are not very sensitive to geometry inaccuracies. Most of the radial inflow turbine used for ORC application feature a vaned diffuser ensuring the appropriate distribution angle at the rotor inlet. In this work, vaneless diffuser are considered. They are supposed to be more flexible when varying operating conditions and to maintain higher efficiency at off-design.

This paper presents a design methodology for such turbines using a combination of meanline loss models enhanced with real gas fluid properties. Then, a turbine is designed for a low temperature ORC. Its performances are predicted using the loss models and compared with the 3D CFD computations, which take into account the entire turbomachine including the single suction volute, the vaneless diffusor, the runner and the axial discharge pipe.

A deep insight of the flow field through the turbomachine is carried out with a particular focus on the entropy field in order to evaluate the losses repartition between the diffuser and the runner, hence validating the results of the meanline loss model.


Meanline Analysis and CFD Study of a Radial Inflow Turbine With Vaneless Distributor for Low Temperature Organic Rankine Cycle

Division / Sponsor:
International Gas Turbine Institute (IGTI)

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2020/volume/84058

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