Testing Microtubular SOFCs in Unmanned Air Vehicles (UAVs)
SOLID OXIDE FUEL CELLS 13 (SOFC-XIII)
Authors: Meadowcroft, A. D.; Howroyd, S.; Kendall, K.; Kendall, M.
Abstract
Unmanned Air Vehicles (UAVs) powered by microtubular SOFCs (mSOFCs) are described for comparison with polymer fuel cells (PEFCs). Using propane as fuel, 7mm diameter mSOFCs have been tested in a 2m wingspan aircraft with a total weight of 6kg. The start-up time was 12 minutes to deliver 250W in a fuel cell/battery hybrid drive system. Tubes were YSZ cermet anode supported, with 10 mu m YSZ electrolyte, 6 mu m SDC interlayer coated with 50 mu m LSCF cathode. Silver wires were used as interconnects. Pure propane fuel gas was mixed with air in a CPOX reactor using catalytic fuel processing mesh. A polymeric fuel inlet manifold gave cold sealing at the tube inlet ends which projected out of the hot box. Cathode air was provided in counterflow, preheated over an anode off-gas catalyst. The fuel utilization was 55%, output power of 250W. The fuel cell was incorporated in a hybrid electrical system with lithium polymer battery and inserted in a Skywalker X8 UAV with 500g of propane in an aluminum tank.
Study on the Fuel-Reforming-Assisted Hydrocarbon Selective Catalytic Reduction over Silver/Alumina Catalyst
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
Authors: Lee, Jaewook; Song, Soonho; Chun, Kwang Min
Abstract
This study aims to assess the feasibility of fuel-reforming-assisted hydrocarbon selective catalytic reduction (HC-SCR) over 2 wt % Ag/Al2O3 catalyst. For this purpose, the effects of reduction agents and the presence of hydrogen on NOx reduction over silver catalyst were tested, and, after catalytic partial oxidation (CPOx) reforming performances were studied, the DeNO(x) performance of reformate-assisted HC-SCR was investigated. Although normal heptane/octane/dodecane showed better NOx reduction rates at 300 and 350 degrees C than the other C-2-C-4 range hydrocarbons, the performances were still unpractical at the temperature range similar to actual diesel exhaust. To enhance the low temperature activity of the Ag/Al2O3 catalyst, CPOx reforming was tested and applied in the SCR system. By the addition of CPOx products to the HC-SCR reactor, NOx reduction performance was increased to a great extent especially in the low temperature range between 200 and 400 degrees C. For the reductant condition of C/N = 6 + CPOx/N = 6 without water, about 52.5% of NOx reduction was recorded over C3H6-SCR at 300 degrees C, whereas nearly zero DeNO, efficiency was measured when only C3H6 was present in the reactants. Also, it was found that C/N = 6 + CPOx/N = 6 showed the better NOx reduction efficiency than C/N = 3 + CPOx/N = 9. Together with the hydrogen model gas tests results, it implies that there is an optimum hydrogen to hydrocarbon ratio in terms of low-temperature activity enhancement assuming that the total amount of fuel used in CPOx-assisted HC-SCR is the same. In addition, inhibition effect by water was reduced to an extent by CPOx products. C3H6-SCR was deactivated so seriously that no NOx conversions were measured at 300 and 400 degrees C in the presence of water vapor. However, through the addition of CPOx products to the C3H6-SCR reactants, NOx reduction was increased to 20% at 300 degrees C and 25% at 400 degrees C.