This paper is aimed to investigate the effect of packing material on plasma characteristic from the viewpoint of charge transfer process.Both the charge accumulation and release processes in the dielectric barrier dis...This paper is aimed to investigate the effect of packing material on plasma characteristic from the viewpoint of charge transfer process.Both the charge accumulation and release processes in the dielectric barrier discharge reactor and packed-bed reactor were investigated by measuring voltage and current waveforms and taking ICCD images.The packing material was ZrO2 pellets and the reactors were driven by a parameterized nanosecond pulse source.The quantity of transferred charges in the dielectric barrier discharge reactor was enhanced when decreasing pulse rise time or increasing pulse width(within 150 ns),but reduced when the gas gap was packed with pellets.The quantity of accumulated charges in the primary discharge was larger than the quantity of released charges in the secondary discharges in the dielectric barrier discharge reactor,but they were almost equal in the packed-bed reactor.It indicates that the discharge behavior has been changed from the view of charge transfer process once the gas gap was packed with pellets,and the ICCD images confirmed it.展开更多
Rectangular wave current control of the electrochemical reduction of nitrobenzene im-proves the selectivity for p-aminophenol(PAP) compared to direct current(d.c.) control at thesame average current density in a flow-...Rectangular wave current control of the electrochemical reduction of nitrobenzene im-proves the selectivity for p-aminophenol(PAP) compared to direct current(d.c.) control at thesame average current density in a flow-by packed-bed reactor.Optimal increase in PAP selectivitycan be obtained at about a frequency of 50Hz and a duty cycle of 0.2.A mathematical model isset up to incorporate the effects of mass transfer,hydrogen evolution and double layer charging,and is solved using the Duhamel’s superposition principle and the modified Crank-Nicolson methodwith the upwind scheme.The conventional d.c.control cases are also calculated for comparison.Calculations can be applied to predict the reaction results under periodic current and d.c.control,but both display the same trends compared to experimental data.展开更多
A comprehensive kinetic model of NO formation during coke combustion in packed-bed in presence of noncombustible particles was developed. The detailed homogeneous gas-phase chemistry (including 102 chemical reactions...A comprehensive kinetic model of NO formation during coke combustion in packed-bed in presence of noncombustible particles was developed. The detailed homogeneous gas-phase chemistry (including 102 chemical reactions), heterogeneous gas-solid chemistry (including 11 reactions) of coke combustion and NO formation, and the heat and mass transfer were taken into account in the present model. The governing equations which are strongly coupled, non-linear and unsteady with 26 unknowns in total, were dispersed into differential equations with the finite differential method. Meanwhile, all the differential equations were numerically solved to give the time-histories and space-distributions oftemperatures of the bed and gas phase as well as the concentrations of all the gaseous species. By comparison, the experimental data were explained well by the calculated results. Based on the kinetic and mathematical model, the effects of O2 content of inlet gas, the initial chemical analysis of coke, bed-temperature and local reductive atmosphere (CO/O2) on NO formation during packed-bed coke combustion were numerically discussed. It was found that coke samples with a higher initial content of [N] and volatile matters, combusted under a suitable O2-containing atmosphere produced less NO emission. The reactions between CO and NO, catalyzed by high temperature surface of coke particles may be responsible for efficient reduction of NO.展开更多
In this paper,three dielectric barrier discharge(DBD)configurations,which were plain DBD with no packing,DBD with packed pure quartz fibers and DBD with packed loaded quartz fibers,were employed to investigate the eff...In this paper,three dielectric barrier discharge(DBD)configurations,which were plain DBD with no packing,DBD with packed pure quartz fibers and DBD with packed loaded quartz fibers,were employed to investigate the effect and catalytic mechanism of catalyst materials in a packed-bed ozone generator.From the experimental results,it was clear that the DBD configuration with packed pure fibers and packed loaded fibers promotes ozone generation.For the packed-bed reactor,ozone concentration and ozone yield were enhanced by an increase of electric field in the discharge gap with the packed-bed effect.Meanwhile,the enhancement of ozone concentration and yield for the DBD reactor packed by loaded fibers with silica nanoparticles was due to the catalysis of silica nanoparticles on the fiber surface.The adsorption of silica nanoparticles on the fiber surface can prolong the retention time of active species and enhance surface reactions.展开更多
A three-dimensional geometric model of the oxidative coupling of methane （OCM） packed-bed reactor loaded with Na2WO4-Mn/SiO2 partic- ulate catalyst was set up, and an improved Stansch kinetic model was established t...A three-dimensional geometric model of the oxidative coupling of methane （OCM） packed-bed reactor loaded with Na2WO4-Mn/SiO2 partic- ulate catalyst was set up, and an improved Stansch kinetic model was established to calculate the OCM reactions using the computational fluid dynamics method and Fluent software. The simulation conditions were completely the same with the experimental conditions that the volume velocity of the reactant was 80 mL/min under standard state, the ratio of CH4/O2 was 3, the temperature and pressure were 800 ℃ and 1 atm, respectively. The contour of the characteristics parameters in the catalyst bed was analyzed, such as the species mass fractions, temperature, the heat flux on side wall surface, pressure, fluid density and velocity. The results showed that the calculated values matched well with the experimental values on the conversion of CH4 and the selectivity to products （C2H6, C2H4, CO2, CO） in the reactor outlet with an error range of 4-2%. The mass fractions of CH4 and O2 decreased from 0.6 and 0.4 in the catalyst bed inlet to 0.436 and 0.142 in the outlet, where the mass fractions of C2H6, C2H4, CO and CO2 were 0.035, 0.061, 0.032 and 0.106, respectively. Due to the existence of laminar boundary layer, the contours of each component bent upwards in the vicinity of the boundary layer. This OCM reaction was volume increase reaction and the total moles of products were greater than those of reactants. The flow field in the catalyst bed maintained constant temperature and pressure. The fluid density decreased gradually from 2.28 kg/m3 in the inlet of the catalyst bed to 2.22 kg/m3 in the outlet of the catalyst bed, while the velocity increased from 0.108 m/s to 0.115 m/s.展开更多
The effects of nitrogen on ozone synthesis are studied in a coaxial cylinder generator with dielectric barrier discharge（DBD） and pack-bed dielectric barrier discharge（PB-DBD）.A series of 10 h discharge experiment...The effects of nitrogen on ozone synthesis are studied in a coaxial cylinder generator with dielectric barrier discharge（DBD） and pack-bed dielectric barrier discharge（PB-DBD）.A series of 10 h discharge experiments are conducted adopting a bare stainless electrode and bare copper electrode.Results show that the material of the electrode can affect the ozone synthesis.It is inferred that the ozone zero phenomenon（OZP） may be induced from ozone decomposing by metallic oxide catalysis.Packing dielectric particles can reduce the OZP.Adding a certain amount of nitrogen into the oxygen feed gas can further eliminate the OZP,and increase the ozone concentration significantly,but decreases the maximum energy efficiency of ozone generators.Initial analysis indicates that the optimal proportion of nitrogen addition is inversely related to the average reduced electric field strength in the discharge region.展开更多
Establishing reliable technological information on the safety of biofertilizers produced from a bioreactor composting technique is a must prior to its commercialization. A phytotoxicity study of biofertilizer made fro...Establishing reliable technological information on the safety of biofertilizers produced from a bioreactor composting technique is a must prior to its commercialization. A phytotoxicity study of biofertilizer made from the bioreactor composting technology at Aklan State University, Banga, Aklan, Philippines was conducted for fourteen (14) days using commercially available lettuce seeds (Lactuca sativa L.). Standard phytotoxicity attributes such as hypocotyl length, radicle length, relative germination percentage, and relative radicle growth observed during the germination stage were evaluated. Results revealed no significant difference in the radicle lengths of the germinated lettuce seeds as affected by the varying levels of biofertilizer dilution at H(3) = 10.567, p = 0.061 > 0.05. On the other hand, the hypocotyl length of the lettuce showed significant differences in response to varying levels of biofertilizer dilution with Welch’s F(5, 5.163) = 8.175, p = 0.017 < 0.05. Also, the different levels of biofertilizer affected significantly the germination percentage of lettuce seeds F(5, 12) = 5.822, p = 0.006 < 0.05. All levels of biofertilizer treatments indicated a decrease in relative germination percentage. However, those seeds applied with 10% biofertilizer have the highest reduction of germination percentage, equivalent to 86.9% (RGP = 13.10%). All levels of biofertilizer showed an increase in radicle growth in contrast to the negative control plant except for the one given a 10% level of biofertilizer. Seeds that received 10% biofertilizer showed an extremely high reduction in radicle growth, equivalent to 72.22% (RRG = 27.78%). The study shows that applying low levels of the bioreactor-produced biofertilizer will observably reduce the measure of the germination characteristics of lettuce seeds, but not necessarily low enough to be considered phytotoxic. However, the application of at least 10% bioreactor-produced biofertilizer can presumptively lead to phytotoxicity.展开更多
基金supported by the National Science Fund for Distinguished Young Scholars(No.51925703)National Natural Science Foundation of China(Nos.51637010,51707186 and 51807190)。
文摘This paper is aimed to investigate the effect of packing material on plasma characteristic from the viewpoint of charge transfer process.Both the charge accumulation and release processes in the dielectric barrier discharge reactor and packed-bed reactor were investigated by measuring voltage and current waveforms and taking ICCD images.The packing material was ZrO2 pellets and the reactors were driven by a parameterized nanosecond pulse source.The quantity of transferred charges in the dielectric barrier discharge reactor was enhanced when decreasing pulse rise time or increasing pulse width(within 150 ns),but reduced when the gas gap was packed with pellets.The quantity of accumulated charges in the primary discharge was larger than the quantity of released charges in the secondary discharges in the dielectric barrier discharge reactor,but they were almost equal in the packed-bed reactor.It indicates that the discharge behavior has been changed from the view of charge transfer process once the gas gap was packed with pellets,and the ICCD images confirmed it.
基金Supported by the State Key Laboratory of Chemical Engineering,National Nature Science Foundation of China,and China Petrochemical Corporation.
文摘Rectangular wave current control of the electrochemical reduction of nitrobenzene im-proves the selectivity for p-aminophenol(PAP) compared to direct current(d.c.) control at thesame average current density in a flow-by packed-bed reactor.Optimal increase in PAP selectivitycan be obtained at about a frequency of 50Hz and a duty cycle of 0.2.A mathematical model isset up to incorporate the effects of mass transfer,hydrogen evolution and double layer charging,and is solved using the Duhamel’s superposition principle and the modified Crank-Nicolson methodwith the upwind scheme.The conventional d.c.control cases are also calculated for comparison.Calculations can be applied to predict the reaction results under periodic current and d.c.control,but both display the same trends compared to experimental data.
文摘A comprehensive kinetic model of NO formation during coke combustion in packed-bed in presence of noncombustible particles was developed. The detailed homogeneous gas-phase chemistry (including 102 chemical reactions), heterogeneous gas-solid chemistry (including 11 reactions) of coke combustion and NO formation, and the heat and mass transfer were taken into account in the present model. The governing equations which are strongly coupled, non-linear and unsteady with 26 unknowns in total, were dispersed into differential equations with the finite differential method. Meanwhile, all the differential equations were numerically solved to give the time-histories and space-distributions oftemperatures of the bed and gas phase as well as the concentrations of all the gaseous species. By comparison, the experimental data were explained well by the calculated results. Based on the kinetic and mathematical model, the effects of O2 content of inlet gas, the initial chemical analysis of coke, bed-temperature and local reductive atmosphere (CO/O2) on NO formation during packed-bed coke combustion were numerically discussed. It was found that coke samples with a higher initial content of [N] and volatile matters, combusted under a suitable O2-containing atmosphere produced less NO emission. The reactions between CO and NO, catalyzed by high temperature surface of coke particles may be responsible for efficient reduction of NO.
基金supported by National Natural Science Foundation of China(No.51867018)Jiangxi Province’s Major Subject Academic and Technical Leader Training ProgramLeading Talent Project(No.20204BCJ22016)the Innovation Fund Designed for Graduate Students of Jiangxi Province,China(No.YC2020-S118)。
文摘In this paper,three dielectric barrier discharge(DBD)configurations,which were plain DBD with no packing,DBD with packed pure quartz fibers and DBD with packed loaded quartz fibers,were employed to investigate the effect and catalytic mechanism of catalyst materials in a packed-bed ozone generator.From the experimental results,it was clear that the DBD configuration with packed pure fibers and packed loaded fibers promotes ozone generation.For the packed-bed reactor,ozone concentration and ozone yield were enhanced by an increase of electric field in the discharge gap with the packed-bed effect.Meanwhile,the enhancement of ozone concentration and yield for the DBD reactor packed by loaded fibers with silica nanoparticles was due to the catalysis of silica nanoparticles on the fiber surface.The adsorption of silica nanoparticles on the fiber surface can prolong the retention time of active species and enhance surface reactions.
文摘A three-dimensional geometric model of the oxidative coupling of methane （OCM） packed-bed reactor loaded with Na2WO4-Mn/SiO2 partic- ulate catalyst was set up, and an improved Stansch kinetic model was established to calculate the OCM reactions using the computational fluid dynamics method and Fluent software. The simulation conditions were completely the same with the experimental conditions that the volume velocity of the reactant was 80 mL/min under standard state, the ratio of CH4/O2 was 3, the temperature and pressure were 800 ℃ and 1 atm, respectively. The contour of the characteristics parameters in the catalyst bed was analyzed, such as the species mass fractions, temperature, the heat flux on side wall surface, pressure, fluid density and velocity. The results showed that the calculated values matched well with the experimental values on the conversion of CH4 and the selectivity to products （C2H6, C2H4, CO2, CO） in the reactor outlet with an error range of 4-2%. The mass fractions of CH4 and O2 decreased from 0.6 and 0.4 in the catalyst bed inlet to 0.436 and 0.142 in the outlet, where the mass fractions of C2H6, C2H4, CO and CO2 were 0.035, 0.061, 0.032 and 0.106, respectively. Due to the existence of laminar boundary layer, the contours of each component bent upwards in the vicinity of the boundary layer. This OCM reaction was volume increase reaction and the total moles of products were greater than those of reactants. The flow field in the catalyst bed maintained constant temperature and pressure. The fluid density decreased gradually from 2.28 kg/m3 in the inlet of the catalyst bed to 2.22 kg/m3 in the outlet of the catalyst bed, while the velocity increased from 0.108 m/s to 0.115 m/s.
基金supported by National Natural Science Foundation of China(No.11675177)Anhui Province ST program(No.1604a0902)
文摘The effects of nitrogen on ozone synthesis are studied in a coaxial cylinder generator with dielectric barrier discharge（DBD） and pack-bed dielectric barrier discharge（PB-DBD）.A series of 10 h discharge experiments are conducted adopting a bare stainless electrode and bare copper electrode.Results show that the material of the electrode can affect the ozone synthesis.It is inferred that the ozone zero phenomenon（OZP） may be induced from ozone decomposing by metallic oxide catalysis.Packing dielectric particles can reduce the OZP.Adding a certain amount of nitrogen into the oxygen feed gas can further eliminate the OZP,and increase the ozone concentration significantly,but decreases the maximum energy efficiency of ozone generators.Initial analysis indicates that the optimal proportion of nitrogen addition is inversely related to the average reduced electric field strength in the discharge region.
文摘Establishing reliable technological information on the safety of biofertilizers produced from a bioreactor composting technique is a must prior to its commercialization. A phytotoxicity study of biofertilizer made from the bioreactor composting technology at Aklan State University, Banga, Aklan, Philippines was conducted for fourteen (14) days using commercially available lettuce seeds (Lactuca sativa L.). Standard phytotoxicity attributes such as hypocotyl length, radicle length, relative germination percentage, and relative radicle growth observed during the germination stage were evaluated. Results revealed no significant difference in the radicle lengths of the germinated lettuce seeds as affected by the varying levels of biofertilizer dilution at H(3) = 10.567, p = 0.061 > 0.05. On the other hand, the hypocotyl length of the lettuce showed significant differences in response to varying levels of biofertilizer dilution with Welch’s F(5, 5.163) = 8.175, p = 0.017 < 0.05. Also, the different levels of biofertilizer affected significantly the germination percentage of lettuce seeds F(5, 12) = 5.822, p = 0.006 < 0.05. All levels of biofertilizer treatments indicated a decrease in relative germination percentage. However, those seeds applied with 10% biofertilizer have the highest reduction of germination percentage, equivalent to 86.9% (RGP = 13.10%). All levels of biofertilizer showed an increase in radicle growth in contrast to the negative control plant except for the one given a 10% level of biofertilizer. Seeds that received 10% biofertilizer showed an extremely high reduction in radicle growth, equivalent to 72.22% (RRG = 27.78%). The study shows that applying low levels of the bioreactor-produced biofertilizer will observably reduce the measure of the germination characteristics of lettuce seeds, but not necessarily low enough to be considered phytotoxic. However, the application of at least 10% bioreactor-produced biofertilizer can presumptively lead to phytotoxicity.
