Meanline design of a 250 kW radial inflow turbine stage using R245fa working fluid and waste heat from a refinery process

Abstract

The purpose of this research is to develop a meanline simulation model that provides a good starting point for the detail design of radial inflow turbine stages and then demonstrate the application of the model to the design of a turbine stage. This study begins with a thermodynamic design of an organic Rankine cycle power plant with the working fluid R245fa utilizing waste heat from a refinery process. The thermodynamic cycle analysis gives the design point of a turbine expander suitable for generating a net power of 250 kWe in the power plant. Empirical data and correlations, based on the performance measurements of a large number of turbines, from literature provide a base to determine both geometric and aerodynamic parameters of rotor blades and nozzle vanes. The efficiency of the designed turbine stage is estimated by using flow loss models for the rotor. Preliminary blade stress and modal analysis is also carried out. The numerical model is validated by comparing simulation results with published data of a gas turbine. The designed radial inflow turbine has a rotor inlet diameter of 37.2 cm and a rotational speed of 7000 r/min with a total-to-static efficiency of 87.3% predicted.