Microcombustion for micro-tubular flame-assisted fuel cell power and heat cogeneration

Abstract

Flame-assisted fuel cell (FFC) studies have been limited to lower fuel-rich equivalence ratios (∼1–1.7, due to the upper flammability limit and sooting limit) where only small concentrations of H2 and CO can be generated in the exhaust. In this work, a non-catalytic microcombustion based FFC is proposed for direct use of hydrocarbons for power generation. The potential for high FFC performance (450 mW cm−2 power density and 50% fuel utilization) in propane/air microcombustion exhaust is demonstrated. The micro flow reactor is investigated as a fuel reformer for equivalence ratios from 1 to 5.5. One significant result is that soot formation in the micro flow reactor is not observed at equivalence ratios from 1 to 5.5 and maximum wall temperatures ranging from 750 to 900 °C. Soot formation is observed at higher wall temperatures of 950 °C and 1000 °C and equivalence ratios above 2.5. H2 and CO concentrations in the exhaust are found to have a strong temperature dependence that varies with the maximum wall temperature and the local flame temperature.