ENERGY BALANCE OF A DIELECTRIC BARRIER DISCHARGE REACTOR FOR HYDROCARBON STEAM REFORMING

Abstract. In the future, hydrogen is supposed to play an important role in the worldwide energy supply. It allows a more efficient utilization of fossil fuels and the reduction of noxious emissions, e. g. by fuel cells or the use of hydrogen enriched fuels in combustion engines or gas turbines. Plasma methods are expected to allow low temperature and fuel flexible on-site hydrogen generation. They are also favorable in terms of a dynamic behavior at load changes, which is particularly important in mobile applications. However, one has to ensure an efficient plasma generation. Experiments on methane steam reforming for hydrogen generation with a dielectric barrier discharge (DBD) reactor were performed. A strong temperature rise of the reactor was observed when the plasma was ignited. To investigate the source of this heating effect, the DBD reactor was furnished with a series of temperature sensors and a constant power electrical heating to determine and quantify the input and output heat fluxes of the reactor. It was possible to strike an energy balance over the reactor including both thermal heat fluxes and the reaction enthalpy. It appears that more than 60 % of the electrical energy input is spent for heating of the dielectric barrier. This effect is independent of the gas type or the presence of chemical conversion, since similar results are obtained when pure nitrogen is fed to the DBD reactor. Nevertheless, it has been demonstrated that steam reforming reactions can be induced by DBD at temperatures below 400 °C, which is not possible with purely catalytic methods. 1