Laser flash thermal diffusivity and dilatometry of tungsten and tungsten-copper electrodes for magnetohydrodynamic energy conversion
In a magnetohydrodynamic (MHD) generator, the electrode surface temperature strongly influences the electrical charge-transfer across the boundary-layer and direct power extraction efficiency. The thermal transport and thermomechanical properties of potential MHD electrode materials are important material parameters; however, these properties are influenced by the electrode fabrication process and resultant microstructure. We measured the thermal diffusivity and the thermal expansion coefficient of wrought tungsten and copper-tungsten pseudo-alloys electrodes being tested in an oxy-kerosene MHD generator. Scanning electron microscopy and energy-dispersive x-ray spectroscopy were used to examine the microstructure and composition of the electrodes. Using the laser flash and dilatometry data, we then estimated the steady-state surface temperature of an electrode subjected to an oxy-kerosene flame based on finite-element modeling. The surface temperature estimates compare favorably against electrode surface temperatures measured directly through optical pyrometry.
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Peter Hsieh (POC,Primary Presenter,Author), National Energy Technology Laboratory, firstname.lastname@example.org;
Michael Johnson (Co-Author), National Energy Technology Laboratory, email@example.com;
Rigel Woodside (Co-Author), National Energy Technology Laboratory, firstname.lastname@example.org;
Richard Chinn (Co-Author), National Energy Technology Laboratory, Richard.Chinn@netl.doe.gov;