Analysis of a scroll machine for micro ORC applications by means of a RE/CFD methodology

In this paper an integrated Reverse Engineering - Computational Fluid Dynamics (RE/CFD) methodology is applied in order to study the adaptation of a commercial scroll compressor to be used as an expander in a micro ORC system. The analysis consists of the acquisition of a real scroll compressor geometry through an RE procedure, the transient numerical simulation of the scroll in compression and expansion mode and the analysis of the performance in terms of pressure and mass flow rate profiles and volumetric efficiency. In order to set up the numerical strategy, a literature test case is used to perform a sensitivity analysis. The results obtained are: (i) the assessment of a numerical strategy with respect to the most critical parameters of a dynamic mesh-based simulation; (ii) the set up and validation of a Reverse Engineering-based numerical procedure; (iii) the evidence of the different fluid dynamic behavior of the scroll machine in compressor mode compared to the expander mode and (iv) the strong relationship between the volumetric efficiency of the scroll machine and the magnitude of the flank gap.