| Abstract: |
Thermal barrier coatings (TBCs) are commonly used in turbine engines for increasing the fuel combustion temperature. Typically, these coatings are composed of a ceramic component (zirconia) that slows down the heat transfer from the hot gases to the engine components. As in the case of all thermal engines, the overall efficiency, that is the ratio of the produced power to the power chemically stored in the fuel, depends on the temperature of operation. By raising this temperature, the TBC makes the engine thermodynamically more efficient, producing more power per unit of fuel burned. As it is normal, however, there is a tradeoff in the use of TBCs; which have a manufacturing cost. Normally, it is known that a TBC treatment is convenient in economic terms, but the question being asked in the present work is how the treatment's performance can be measured in energy terms. That is, manufacturing a TBC requires energy for a variety of operations that start with the mining of the minerals used for it, processing, the related equipment and other factors. The energy cost of these factors can be determined by well known LCA (Life cycle assessment) procedures. Knowing this energy cost, it is possible to determine the ratio of the extra energy produced by the TBC and the energy needed to manufacture it. This ratio is termed sometimes EROEI (Energy return on energy invested). We will show in this paper that the EROEI of TBC can be approximately determined and that it is large, in the range of a few hundreds. TBCs are therefore an efficient way to improve the energy efficiency of thermal engines.
|
|
