Effect of the Hot Gas Composition on a Highly Thermally Loaded Film Cooling System

To reduce the CO₂ emission, three types of the coal-based power generation system are promising: IGCC, the hydrogen-fired turbine cycle and the oxy-fuel cycle. The thermal characteristics of the turbines are expected to be dependent on the different hot and wet gases. For studying the effect of the hot gas composition on the highly thermally loaded cooling system, both the experimental and the numerical studies are carried out in the present work. Five hot gases are focused in the study, which are corresponding to the combustion products of the liquefied petroleum gas, the natural gas, the syngas, the hydrogen and the oxy-fuel gas. A highly thermally loaded film cooling test rig is built up in Tsinghua University. The Discrete Transfer Model (DTM) and the Weighted Sum of Gray Gases (WSGG) spectral model are employed to solve the radiative heat transfer in the multi-composition field. By comparing the experimental and the numerical data, it is resulted that the implemented thermal conduction/convection/radiation method is valid for the studied cases. The results show that the temperature rise on the plate top surface is about 50∼60 K under the condition of the five hot gas compositions due to the radiative heat transfer. The magnitude of the temperature rise is the reverse of the mole fraction of the radiative gases (CO₂+H₂O) in the hot gas. Furthermore, the local temperature gradient is weakened in the five hot gas compositions cases. It means that the thermodynamics of the film cooling system in the multi-composition hot gas has its own characteristics. It may play a role in the future coal-based turbine technology.