Evaluating the Performance of a Rotary Vane Expander for Small Scale Organic Rankine Cycles Using CFD tools

AbstractThis work proposes a focus on the simulation of a rotative volumetric expander via a CFD code. A customized application of OpenFOAMOR has been developed to handle the particular motion of the calculation grid. In particular, a prescribed shape of the stator has been defined in order to adapt the motion of the vanes along the whole cycle. The model uses a mesh to mesh interpolation technique, switching from a calculation grid to the new one on the basis of dynamic mesh quality considerations.This particular approach allows to account for the presence of leakages occurring between the stator and vane tips and also occurring at the top and bottom of the vanes. The fluid considered is the refrigerant R245fa, whose particular properties have been determined resorting to the NIST database. Experimental data, measured at different conditions of mass flow and fluid temperature, are compared to calculation results. Moreover, the CFD analysis has allowed the estimation of the influence of the leakage mass flow occurring at the tip of the vanes on the overall machine performances