Aerothermal Challenges in Syngas, Hydrogen-Fired, and Oxyfuel Turbines—Part II: Effects of Internal Heat Transfer

Abstract

Future advanced turbine systems for electric power generation, based on coal-gasified fuels with CO2 capture and sequestration, are aimed for achieving higher cycle efficiency and near-zero emission. The most promising operating cycles being developed are hydrogen-fired cycle and oxyfuel cycle. Both cycles will likely have turbine working fluids significantly different from that of conventional air-based gas turbines. In addition, the oxyfuel cycle will have a turbine inlet temperature target at approximately 2030 K (1760°C), significantly higher than the current level. This suggests that aerothermal control and cooling will play a critical role in realizing our nation’s future fossil power generation systems. This paper provides a computational analysis in comparing the internal cooling performance of a double-wall or skin-cooled airfoil to that of an equivalent serpentine-cooled airfoil. The present results reveal that the double-wall or skin-cooled approach produces superior performance than the conventional serpentine designs. This is particularly effective for the oxyfuel turbine with elevated turbine inlet temperatures. The effects of coolant-side internal heat transfer coefficient on the airfoil metal temperature in both hydrogen-fired and oxyfuel turbines are evaluated. The contribution of thermal barrier coatings toward overall thermal protection for turbine airfoil cooled under these two different cooling configurations is also assessed.