PDSim: A general quasi-steady modeling approach for positive displacement compressors and expanders

A novel generalized framework is presented that can be used to simulate the quasi-steady-state performance of a wide range of positive displacement compressors and expanders (scroll, piston, screw, rotary, spool, etc.). The complete simulation algorithm is described, and an emphasis is placed on the numerical methods required to obtain robust behavior of the simulation. This formulation has been implemented into an open-source software package entitled PDSim written in the Python language. PDSim is the first open-source generalized compressor and expander simulation package and the complete source code is included in the Supplemental material. A piston expander is used as an example of the utilization of this framework. The framework has been applied to several positive displacement machines in the companion paper in order to demonstrate the flexibility of the approach (Ziviani et al., 2019).