doiSerbia

Analysis of the energetic/environmental performances of gas turbine plant: Effect of thermal barrier coatings and mass of cooling air

Ion Ion V. ('Dunarea de Jos' University of Galati, Thermodynamics and Heat Engines Department, Galati, Romania)
Portinha Anibal (University of Minho, Physics Department, GRF-Functional Coatings Group, Campus de Azurém, Guimarães, Portugal)
Martins Jorge (University of Minho, Mechanical Engineering Department Campus de Azurém, Guimarães, Portugal)
Teixeira Vasco (University of Minho, Physics Department, GRF-Functional Coatings Group, Campus de Azurém, Guimarães, Portugal)
Carneiro Joaquim (University of Minho, Physics Department, GRF-Functional Coatings Group, Campus de Azurém, Guimarães, Portugal)

Zirconia stabilized with 8 wt.% Y2O3 is the most common material to be applied in thermal barrier coatings owing to its excellent properties: low thermal conductivity, high toughness and thermal expansion coefficient as ceramic material. Calculation has been made to evaluate the gains of thermal barrier coatings applied on gas turbine blades. The study considers a top ceramic coating Zirconia stabilized with 8 wt.% Y2O3 on a NiCoCrAlY bond coat and Inconel 738LC as substrate. For different thickness and different cooling air flow rates, a thermodynamic analysis has been performed and pollutants emissions (CO, NOx) have been estimated to analyze the effect of rising the gas inlet temperature. The effect of thickness and thermal conductivity of top coating and the mass flow rate of cooling air have been analyzed. The model for heat transfer analysis gives the temperature reduction through the wall blade for the considered conditions and the results presented in this contribution are restricted to a two considered limits: (1) maximum allowable temperature for top layer (1200ºC) and (2) for blade material (1000ºC). The model can be used to analyze other materials that support higher temperatures helping in the development of new materials for thermal barrier coatings.

Keywords: thermal barrier coatings, zirconia, gas turbines, heat transfer, thermal and exergetic efficiency, irreversibility, pollutant emissions