Simulation von Strömungsvorgängen in einem Dampfexpander zur Abwärmenutzung

In industrial processes, large amounts of waste heat are generated, which are often lost to the environment without suitable recuperation. The optimum conversion of this thermal energy into mechanical work and ultimately into electrical power promises a significant improvement in energy utilization, the efficiency of the overall system and thus the cost-effectiveness. Here, the use of a Rankine cycle is an already established technical process. A novel expansion machine is considered to be integrated into a steam cycle process to convert the heat energy into mechanical work. A first prototype has already been set up on a test bench at the Institute of Internal Combustion Engines and Thermodynamics at Graz University of Technology and provides initial insights.

Primarily, this master thesis deals with the thermodynamic and fluid dynamic investigation, as well as the simulation of this expansion machine, which is based on the principle of a rotary piston machine. The aim is to develop, analyze and optimize components. For the analysis, a Computational Fluid Dynamics (CFD) model is created, which should correspond as closely as possible to the requirements and geometries of the real working machine. With the help of this simulation model, for the given boundary conditions, such as revolution speed, inlet and exhaust pressure, the port timing can be optimized and improvements can be made to the geometry of the expansion machine. The calculation model is validated by means of existing measurements from the test bench operation with the working medium compressed air. The model is used for a performance and efficiency estimation of the expander.