| Budget Amount *help |
¥12,290,000 (Direct Cost: ¥11,300,000、Indirect Cost: ¥990,000)
Fiscal Year 2007: ¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000)
Fiscal Year 2006: ¥8,000,000 (Direct Cost: ¥8,000,000)
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| Research Abstract |
A ceria-based oxygen permeable membrane was mounted on a stainless-steel separator to be a module and to optimize its mixed conductivity in the context of achieving high system efficiency for hydrogen production. For FY2006, 1) fabrication of the oxygen permeable membrane module and their methane reforming properties, and 2) mixed oxide-ion and electronic conductivity of the membrane were investigated. Expected amount of hydrogen was obtained by operating the module at around 780 to 950℃. The mixed ionic and electronic conductivities were separated by means of the Hebb-Wagner polarization technique; at 900℃, major carrier was found to be switched from oxide-ion to electron at an oxygen partial pressure of 10^<-7> bar by reducing the pressure from air. For FY2007, 1) heat balance of the oxygen permeable membrane module, and 2) exergy analysis of co-production system of hydrogen and electricity based on solid-oxide electrolytes were examined. Based on the mixed conductivity mentioned above, under an operating condition at 780℃ and a rate of 150 sccm methane input, the membrane module was found to emit a heat of 8.4 W. As a solid-oxide fuel cell system, 20mol%Sm-doped CeO_2, Ba_<0.5>Sr_<0.5>Co_<0.8>Sr_<0.2>O_<3-δ>, (Ce_<0.8>Sm_<0.2>)O_2-50vol%NiO were used as an electrolyte, cathode and anode, respectively. By supplying Ar-10%CH_4 as a fuel, the highest power density of 131 mW/cm^2 was attained at a current density of 288 mA/cm^2 at 700℃. Based on these value, an exergy compass diagram was constructed; under the optimum condition, an exergy efficiency reached to 46.7%. On the other hand, under short-circuited mode, which corresponds to an oxygen permeable membrane, the efficiency was 22.8%.
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