Electrical properties of gadolinia-doped ceria for electrodes for magnetohydrodynamic energy systems
- PDF / 2,006,583 Bytes
- 9 Pages / 595.276 x 790.866 pts Page_size
- 61 Downloads / 171 Views
Electrical properties of gadolinia‑doped ceria for electrodes for magnetohydrodynamic energy systems Michael S. Bowen1,2 · Michael Johnson1,2 · Ryan McQuade2 · Bryce Wright1,2 · Kyei‑Sing Kwong1 · Peter Y. Hsieh1 · David P. Cann1,2 · C. Rigel Woodside1 Received: 5 April 2020 / Accepted: 28 July 2020 © This is a U.S. Government work and not under copyright protection in the U.S.; foreign copyright protection may apply 2020
Abstract High temperature conducting ceramics are of current interest for use as electrode materials for magnetohydrodynamic (MHD) power generation systems for their high conductivity values and their excellent stability under extreme conditions including operating temperatures above 2000 °C. Ceria doped with Gd (GDC) has been extensively studied for intermediate temperature applications and shows promise as an efficient electrode material. A summary of the current understanding of the electrical properties of GDC is provided with an emphasis on the higher temperature limits. Experiments to further validate the conclusions drawn in the literature review confirm that with electrical conductivities near 10 S/m at 1100 °C make GDC a good candidate electrode material for an MHD power generator. Keywords Magnetohydrodynamics · Energy materials · Doped ceria · Energy conversion · Electroceramics
1 Introduction Research and development of a direct power extraction concept using magnetohydrodynamics (MHD) is motivated by the fact that this technology can provide a significant increase in energy efficiency for chemical-toelectrical energy conversion by enabling the operation of power plants at higher temperatures [1]. By utilizing high temperature gases as a working fluid in a MHD topping unit, a combined-cycle coal-fired power plant could eventually lead to plant thermal efficiencies above 60% [2]. While the thermodynamic advantages of a MHD system have been known for years, legacy US Department of Energy (DOE) research was impeded by challenges in the supporting technology and unfavorable techno-economics. Fortunately, technological advancements in magnets, materials, and thermal fluids have improved since
previous DOE research efforts, improving the viability of MHD power generation. More recently, interest in using oxy-fuel combustion to enable carbon dioxide capture has renewed R&D into MHD topping cycles especially with the increased use of high temperature oxy-fuel combustion [3]. Thus, implementation of MHD technology has the potential to significantly reduce fossil fuel consumption and reduce greenhouse gas emissions. A great challenge in development of a functional generator is material selection. The working fluid of a MHD generator creates an extreme environment with combustion temperatures as high as 3000 °C, gas velocities up to mach-2, and the presence of ionizable species, specifically potassium vapor. Materials are functionally exposed to less intense conditions at the boundary layer, with temperatures up to 2400 °C [3, 4]. Previous versions of MHD generators used cold electrodes whi
Data Loading...
