Investigating the entropy generation in condensing steam flow in turbine blades with volumetric heating

Abstract

In the last stages of steam turbines, the existence of the liquid phase results in wetness losses. This study intends to analyze the effect of volumetric heating on condensing steam flow in the stationary cascade of turbine blades and the losses associated with wetness. Numerical simulation of a turbulent flow of wet steam in the cascade of turbine blades was conducted based on two phase Eulerian-Eulerian description and SST k - ω turbulence model. Numerical solution results show a consistency with experimental data in the adiabatic cases. An agreement was also shown between the numerical solution and analytical solution results in the presence of heat transfer. The numerical results proposed that by applying volumetric heating to the convergent section, the wetness fraction in the cascade of turbine blades can be reduced which prevent corrosion losses. As volumetric heating is increased to 2.0 × 105(kWm2), the entropy generation is ascending; while as the liquid phase disappears and the entropy generated from the liquid is eliminated at 3.55 × 105(kWm2), the entropy generation shows a descending trend which ascends again by increasing volumetric heating. Hence, applying an appropriate volumetric heating can prevent the corrosion associated with the liquid phase and control total entropy generation.