Search

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.

River water cleaning from microorganisms using electrohydraulic discharges and ozonation was investigated. The processed water was highly polluted with the total number of microorganisms (70  400 cfu/mL) and total Escherichia coli bacteria (280 cfu/mL). The processing was conducted in a tube reactor with a hollow needle-rod electrode configuration. A 400-mL sample of river water was treated at different flow rates. Ozonation was performed in a washing bottle with an ozone concentration of 20 \g/m^3. The corona discharge treatment showed a steady decrease of bacteria and microorganisms but did not kill them completely. Spark discharge killed the bacteria and microorganisms completely; however, its energy efficiency was much lower than that of ozonation. The ozone treatment decreased the concentration of microorganisms and coli bacteria down to 785 and 10 cfu/mL, respectively, in 45 s which resulted in higher energy efficiency than processing using corona and spark discharges. The NPOC analysis of the treated samples showed its concentration of 5 \pm 0, 4 ppm in all samples. [ABSTRACT FROM AUTHOR]

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 efficiency of hydrogen production from ethanol in the atmospheric pressure plasma generated in waveguide-supplied metal-cylinder-based microwave plasma source (MPS) was investigated experimentally. The tested parameters of hydrogen production efficiency were: hydrogen production rate in NL(H 2 )/h, energy yield of hydrogen production in NL(H 2 )/kWh, ethanol conversion degree in % and volume concentration of hydrogen in the outlet gas in %. Two ethanol based methods of hydrogen production were performed, namely ethanol dry and steam reforming. The best achieved experimental results showed that the energy yield of hydrogen production was about 78 NL(H 2 ) per kWh of absorbed microwave energy in the case of ethanol dry reforming and about 257 NL(H 2 )/kWh in the case of ethanol steam reforming. Presented microwave plasma method can be successfully used for hydrogen production not only from ethanol, but also from different liquid compounds like gasoline, heavy oils and biofuels. [ABSTRACT FROM AUTHOR]

In contrast to conventional technologies of hydrogen production like water electrolysis or coal gasification we propose a method based on the atmospheric pressure microwave plasma. In this paper we present results of the experimental investigations of the hydrogen production from ethanol in the atmospheric pressure plasma generated in waveguide-supplied cylindrical type nozzleless microwave (915 MHz and 2.45 GHz) plasma source (MPS). Argon, nitrogen and carbon dioxide were used as a working gas. All experimental tests were performed with the working gas flow rate Q ranged from 1500 to 3900 NL/h and absorbed microwave power P A up to 6 kW. Ethanol was introduced into the plasma as vapours carried with the working gas. The process resulted in the ethanol conversion rate greater than 99%. The hydrogen production rate was up to 210 NL[H 2 ]/h and the energy efficiency was 77 NL[H 2 ] per kWh of absorbed microwave energy. [ABSTRACT FROM AUTHOR]

Abstract: Nowadays hydrogen is considered as a clean energy carrier and fuel of the future. That is why the interest in production and storage of hydrogen is still increasing. One of the promising technology is using microwave plasma for hydrogen production. In this study we propose two types of an atmospheric pressure microwave plasma source (MPS) for hydrogen production via methane conversion. The first one was a nozzleless waveguide-supplied coaxial-line-based. The second one was a nozzleless waveguide-supplied metal-cylinder-based. They can be operated with microwave frequency of 2.45 GHz and power up to a few kW with a high gas flow rates (up to several thousands l/h). We present experimental results concerning electrical properties of the MPS, plasma visualization, spectroscopic diagnostics and hydrogen production. The experiment was carried out with methane flow rate up to 12,000 l/h. An additional nitrogen or carbon dioxide swirl flow was used. The absorbed microwave power was up to 5000 W. Our experiments show that MPSs presented in this paper have a high potential for hydrogen production via hydrocarbon conversion. [Copyright &y& Elsevier]