Design and performance prediction of radial ORC turboexpanders

Finally, starting from the developed design tool, an off-design analysis of turbo-expanders is presented. Once the design data are available, the characteristic curves of the expander at variable temperature, pressure and fluid mass flowrate at the expander inlet for different values of the specific speed are built. It is thus possible to evaluate the performance of the radial expanders when working far from design point. This analysis, demonstrated for R134a, shows that the total to static efficiency has a relatively modest sensitivity to the off design of the expansion ratio, especially at corrected speed below the design value.