Application of a Similarity Criteria approach for centrifugal compressor design in high temperature heat pumps with overheated water vapor

Kurzfassung

This work presents the application of a mean-line centrifugal compressor design for high temperature heat pumps with overheated water vapor, focused on a low mass flow operating range. The preliminary mean-line design provides the calculation of 0D and 2D blade profile parameters for centrifugal compressors. Because the design is correlated for air as a gas, valid similarity criterion between air and water vapor need to be defined. In order to estimate the accuracy of the mean-line design, CFD calculations based on 3D-RANS are proceeded. To reach this CFD calculation, a process chain has been setup, where the 3D profile of the blades is created using mean-line design obtained values. Afterwards, the 3D meshing of the impeller geometry is generated, followed by CFD Pre-processing. To establish an optimization process chain for the engineering of centrifugal compressor design, a structural-mechanical consideration of the impeller blade and the rotating disk is also investigated. The obtained results suggest that during the simulations based on mean-line design values, the similarity criteria usage allows to replace, in a very precise way the steam boundaries by air. With the proposed optimization process, the compressor pressure ratio has been increased up to 2 and the efficiency up to 0.87.