A Highly Flexible Approach on the Steady-State Analysis of Innovative Micro Gas Turbine Cycles

Steady-state simulation is an important method to investigate thermodynamic processes. This is especially true for innovative micro gas turbine (MGT)-based cycles as the complexity of such systems grows. Therefore, steady-state simulation tools are required that ensure large flexibility and computation robustness. As the increased system complexity result often in more extensive parameter studies also a fast computation speed is required. While a number of steady-state simulation tools for MGT-based systems are described and applied in literature, the solving process of such tools is rarely explained. However, this solving process is crucial to achieve a robust and fast computation within a physically meaningful range. Therefore, a new solver routine for a steady-state simulation tool developed at the DLR Institute of Combustion Technology is presented in detail in this paper. The solver routine is based on Broyden's method. It considers boundaries during the solving process to maintain a physically and technically meaningful solution process. Supplementary methods are implemented and described which improve the computation robustness and speed. Furthermore, some features of the resulting steady-state simulation tool are presented. Exemplary applications of a hybrid power plant (HyPP), an inverted Brayton cycle (IBC), and an aircraft auxiliary power unit (APU) show the capabilities of the presented solver routine and the steady-state simulation tool. It is shown that the new solver routine is superior to the standard Simulink algebraic solver in terms of system evaluation and robustness for the given applications.