The Use of Real Gas Properties for Design and Flow Field Simulations of a Small Centripetal Steam Turbine

In this paper, the applied design procedure for generation of a small-capacity ORC centripetal steam turbine working with the fluid 1, 1, 1, 3, 3-Pentafluoropropane (R245fa) is described with consideration of real gas effects. After specification of the turbine geometry in an iterative process using different commercial design tools which have been enhanced in order to work with real gas conditions, CFD simulations based on the real gas properties of the fluid have been conducted for the originated geometry. The simulations are performed by using the CFD code ANSYS-CFX11 with a pre-prepared real gas property (RGP) table, which comprises the required gas properties at different discrete pressure and temperature values. In addition, the flow fields inside the turbine obtained from the real gas model is compared to those flow fields which are obtained by the ideal gas model and also by the Redlich-Kwong model.