Duc Ba Nguyen

Comparison of different applied voltage waveforms on CO2 reforming of CH4 in an atmospheric plasma system

Sinusoidal and pulse waveforms of applied voltage were employed for CO2 reforming of CH4 to syngas in an atmospheric dielectric barrier discharge reactor. The discharge power of a pulse waveform was higher than that of sinusoidal waveform at the same applied voltage. The plasma reaction by a pulse waveform enhanced the conversion of CO2 and CH4 and the selectivity of H2 and CO. It was confirmed that CO2 reforming of CH4 can be improved by the adaption of pulse-type power supply in a dielectric barrier discharge reactor immersed in an electrically insulating oil bath.

Process conditions for complete decomposition of CHF3 in a dielectric barrier discharge reactor

Plasma decomposition of CHF3 was investigated using a dielectric barrier discharge immersed in an electrically insulating oil bath in a mixture of CHF3, O2, and N2. CHF3 was well decomposed under a relatively high applied voltage in an atmospheric pressure plasma system. The main by-product was CO2 and its selectivity increased with a decrease in the CHF3 concentration in the feed. Complete decomposition of CHF3 was achieved at a typical process range: an applied voltage ≥7.0 kVp, an initial CHF3 flow rate of 3ml/min, and a total flow rate of 500ml/min. The value of energy efficiency and energy density at the center range for the complete decomposition of CHF3 was 0.01 mmol/kJ and 6.00kWh/Nm3, respectively.

Analytical Approach to estimate and Predict the CO2 Reforming of CH4 in a Dielectric Barrier Discharge

CO2 reforming of CH4 to syngas was investigated in a coaxial dielectric barrier discharge reactor immersed in an oil bath. An analytical model was suggested to estimate and predict the reaction phenomena. The model had input parameters as predictor variables (applied voltage, ratio of CH4/CO2, and total flow rate in the feed), output parameters as observed variables, the molar flow rates of reactants (CH4, CO2, CO, H2, and by-products), and energy efficiencies. More than 70% of the output parameters variance could be explained by the input parameter. The model for the CO2 reforming of CH4 in a dielectric barrier discharge reactor would be useful to optimize the experiments. A comparison between input parameters suggests that the reaction should be performed under high total flow rate or low applied voltage to obtain greater energy efficiency; whereas at high applied voltage and total flow rate, the reaction obtains a greater absolute amount of reactant conversion and products, but lower energy efficiency.

Analysis of Plasma Reaction for Decomposition of CHF3 in a Dielectric Barrier Discharge

The decomposition of CHF3 in a mixture with O2 and Ar was investigated in a coaxial dielectric barrier discharge at atmospheric pressure. CHF3 decomposition increased linearly in regard to specific energy input (SEI), whereas energy efficiency decreased. The main product was CO2, and its selectivity increased with high SEI and the presence of O2 in the feed, but an increase of O2 in the feed led to a decrease in decomposition rate. An increase in total flow rate led to an increase of the absolute amount of CHF3 decomposition and energy efficiency; however, the decomposition of CHF3 decreased. A complete CHF3 decomposition occurred under an SEI of 1.54 kJ/L with the selectivity of CO2 and CO as 89.87% and 7.00%, respectively. Optical emission spectroscopic analysis could explain the available reaction pathways for CHF3 decomposition in the CHF3/O2/Ar atmospheric plasma and show the possibility of F2 and HF formation.