Optimal Design of Guide Vane in Tree-Branch Shape Direct Air-Cooled Exhausted Duct System

Research on tree-branch shape direct air-cooled exhausted duct system (DAEDS), which is the invention patent of German GEA Energietechnik GmbH in China, is carried out. The mathematic model for two-phase flow and heat transfer of wet steam in direct air cooled exhausted duct for a 2 × 600 MW power unit in China is constructed. Using the numerical heat transfer (NHT) software called FLUENT, the exhausted steam condition under typical steam turbine modes is simulated. The simulating results, including the flowing field, temperature field and two-phase field of wet steam in 2-dimensional duct are analyzed. The simulation results show that simple geometry principle can not evenly divide the exhausted steam. As for different treelike direct air cooled exhausted duct system, detailed optimal design should be carried out.