| Abstract |
The Organic Rankine Cycle (ORC) has been considered to be the most feasible technology among the existing approaches to convert low grade heat source (such as geothermal energy and industrial waste heat) into electricity. Due to the main features of low mass flow rate and high pressure ratio, radial inflow turbines are applied more often than other types of turbines in small scale ORC systems with a general power range of 50kW to 500kW, because they are more efficient, adaptable, stable and cost-effective. When developing such a turbine, the aerodynamic design and the stress analysis are the steps of vital importance. This paper presents the detailed information of the aerodynamic design and the stress analysis of a 100kW radial inflow turbine, including preliminary design, three dimensional modelling of blades and volute, performance evaluation by using Computational Fluid Dynamics (CFD) and stress analysis based on Finite Element Method (FEM). In the step of aerodynamic design, ANSYS turbomachinery module and in-house code are used to design the turbine geometry. The scalloped design of the rotor and the balance piton on the shaft were carried out to reduce the turbine thrust load and match with the requirement of the magnetic bearings. The performance evaluation of the turbine is conducted by using ANSYS CFX, where R245fa was used as the working fluid. Detailed analyses of the flow features across the turbine stage and the volute are presented. In the stress analysis step, the material selection of each component of turbine is completed and the simulation results in terms of equivalent stress and deformation of turbine blades are analysed to confirm the safety of turbine during its operation. |