Compact hydrogen reformer system utilizing microplasmas

我们的研究目的是开发一种紧凑型氢重整器，用于为便携式电子设备提供电力的燃料电池。我们提出了常压下甲烷在微等离子体中的转化。放电发生在两个电极之间，其中一个是直径为190μm的甲烷流细喷嘴。由于甲烷直接放置在等离子体区域，因此有望实现高效分解。对电极结构为网状或板状。电源频率从500赫兹改为2千赫。在电极的同一位置产生丝状放电。随着频率的增加或甲烷流量的降低，甲烷转化率增加。最大转化率为38.5%。固态碳沉积在电极上，这些电极在几分钟内被桥接起来，以获得超过2 kHz的高频放电。结果，放电被中断。与网状电极和平面电极相比，当流量较大时，网状电极的甲烷转化率较高。由于气体流量较大，抑制了网状电极上的积碳。随着甲烷转化率的提高，氢气产率增加，最大值为26.3%。对氢的选择性约为30%，这与甲烷转化率、甲烷流量、电源频率和对电极的形状无关。在饱和水蒸气中进行甲烷放电以抑制碳沉积。虽然水蒸气的效果很明显，但并没有得到明显的改善。

The aim of our research is to develop a compact hydrogen reformer for fuel cells supplying the electric power of portable electronic equipments. We proposed a methane conversion in microplasmas at atmospheric pressure. The discharge develops between the electrodes, one of which is a thin nozzle of methane flow with a diameter of 190μm. High efficiency decomposition is expected because methane is placed directly in the plasma region. The structure of counter electrode was mesh or plate. The frequency of the power supply was changed from 500Hz to 2kHz. Filamentary discharges developed at the same position of electrodes. With increasing the frequency or decreasing the methane flow-rate, the methane conversion increased. We obtained the maximum conversion of 38.5%. Solid-state carbon is deposited on the electrodes, which were bridged within a couple of minutes for high-frequency discharge over 2kHz. As a result, the discharge was interrupted. In comparison with mesh and plane electrodes, the methane conversion for the mesh electrodes was higher when the flow rate was high. The carbon deposition on the mesh electrode was suppressed because of high gas flow. Hydrogen yield increased and was 26.3% at the maximum when the methane conversion increased. Selectivity to hydrogen is approximately 30% that is independent on the methane conversion, methane flow rate, frequency of the power supply, and shape of the counter electrode. Methane discharge in saturated vapor was done to suppress the carbon deposition. Although the effect of vapor was evident, no appreciable improvement was obtained.