Robust and Computationally Efficient Dynamic Simulation of ORC Systems: The ThermoCycle Modelica Library

The ThermoCycle library, an open-source library for dynamic modeling of ORC systems, has been recently developed in the Modelica language and is presented in this paper. Special attention has been paid to robustness and to simulation speed. Dynamic simulations are indeed often limited by numerical constraints and failures, either during initialization or during integration. Furthermore, the use of complex equations of state (EOS) to compute thermodynamic properties dramatically decreases the simulation speed. In this paper, the different numerical methods developed to overcome these limitations are presented and discussed and the proposed models are then benchmarked against alternative simulation tools.