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Images showing the flow pattern and velocity field in a positive polarity needle-to-plate nonthermal plasma reactor are reported. The images were obtained using the particle image velocimetry. They showed a strong secondary flow, caused by the electrohydrodynamic forces, which transport the working gas also in the upstream main-flow direction. This may influence operation of the nonthermal plasma reactors and affect their capability of gaseous pollutant remediation. Index Terms--Corona discharge, electrohydrodynamic flow, flow visualization, nonthermal plasma, particle image velocimetry.

In this paper, results of hydrogen production via methane pyrolysis in the atmospheric pressure microwave plasma with CH4 swirl are presented. A waveguide-based nozzleless cylinder-type microwave plasma source (MPS) was used to convert methane into hydrogen. The plasma generation was stabilized by a CH4 swirl having a flow rate of 87.5 L min-1. The absorbed microwave power was 1.5–5 kW. The hydrogen production rate and the corresponding energy efficiency were 866 g (H2) h-1 and 577 g (H2) kWh-1 of microwave energy absorbed by the plasma, respectively. These parameters are better than our previous results when nitrogen was used as a swirl gas and much better than those typical for other plasma methods of hydrogen production (electron beam, gliding arc, plasmatron). [ABSTRACT FROM AUTHOR]

The hydrogen production by conversion of liquid compounds containing hydrogen was investigated experimentally. The waveguide-supplied metal cylinder-based microwave plasma source (MPS) operated at frequency of 915 MHz at atmospheric pressure was used. The decomposition of ethanol, isopropanol and kerosene was performed employing plasma dry reforming process. The liquid was introduced into the plasma in the form of vapour. The amount of vapour ranged from 0.4 to 2.4 kg/h. Carbon dioxide with the flow rate ranged from 1200 to 2700 NL/h was used as a working gas. The absorbed microwave power was up to 6 kW. The effect of absorbed microwave power, liquid composition, liquid flow rate and working gas fl ow rate was analysed. All these parameters have a clear influence on the hydrogen production efficiency, which was described with such parameters as the hydrogen production rate [NL(H2)/h] and the energy yield of hydrogen production [NL(H2)/kWh]. The best achieved experimental results showed that the hydrogen production rate was up to 1116 NL(H2)/h and the energy yield was 223 NL(H2) per kWh of absorbed microwave energy. The results were obtained in the case of isopropanol dry reforming. The presented catalyst-free microwave plasma method can be adapted for hydrogen production not only from ethanol, isopropanol and kerosene, but also from different other liquid compounds containing hydrogen, like gasoline, heavy oils and biofuels.