Simulation of Condensation Processes in Turbines including Impurity Effects

Condensation processes are important for many technical applications such as in transsonic low pressure steam turbines. Impurities like dust particles or chemical deposits significantly affect the condensation process. Depending on the expansion rate the condensate formation is controlled by homogeneous or heterogeneous nucleation. Technical steam for example, used in power processes, typically consists of several impurities, which change due to lower expansion rates the condensation behaviour, so that a large fraction of the condensate mass is formed heterogeneously. Numerical parameter variations in the nozzle BA-1 were performed to study as how to the number of particles influences the condensation onset and the total amount of formed condensate mass. In comparison to the homogeneous case, a smaller supersaturation is reached if heterogeneous condensation dominates. The condensation occurs close to the equilibrium state and reduces losses caused by the pure non-equilibrium process.