In this study, a hybrid process using non‐thermal plasma (NTP) and photocatalytic oxidation (PCO) was adopted for the degradation of gas‐phase toluene using TiO2 as the photocatalyst. To discover the synergetic effe...In this study, a hybrid process using non‐thermal plasma (NTP) and photocatalytic oxidation (PCO) was adopted for the degradation of gas‐phase toluene using TiO2 as the photocatalyst. To discover the synergetic effect between NTP and PCO, the performances of both sole (O3, UV, NTP, and PCO) and combined (O3 + TiO2, O3 + UV, NTP + UV, O3 + PCO, and NTP + PCO) processes were investigated from different perspectives, such as the toluene removal efficiency, selectivity of COx, mineralization rate, ozone utilization, and the generation of by‐products. The toluene removal efficiency of the combined NTP + PCO process was 80.2%, which was much higher than that of a sole degradation process such as NTP (18.8%) and PCO (13.4%). The selectivity of CO2 and the ozone utilization efficiency also significantly improved. The amount of by‐products in the gas phase and the carbon‐ based intermediates adsorbed on the catalyst surface dramatically reduced. The improvement in the overall performances of the combined NTP + PCO process was mainly ascribed to the efficient utilization of ozone in the photocatalytic oxidation, and the ozone further acting as an electron acceptor and scavenger, generating more hydroxyl radicals and reducing the recombination of electron‐ hole pairs.展开更多
The synergistic effect of high voltage discharge non‐thermal plasma(NTP)and photocatalysts on contaminant removal has repeatedly confirmed by plenty of researches.Most previous plasma‐photocatalyst synergistic syste...The synergistic effect of high voltage discharge non‐thermal plasma(NTP)and photocatalysts on contaminant removal has repeatedly confirmed by plenty of researches.Most previous plasma‐photocatalyst synergistic systems focused on the utilization of the ultraviolet light but ignored the visible light generated by high voltage discharge.Graphitic carbon nitride(g‐C3N4),a metal‐free semiconductor that exhibits high chemical stability,can utilize both the ultraviolet and visible light from high voltage discharge.However,the synergistic system of NTP and g‐C3N4 has been researched little.In this paper,the effect of NTP generated by dielectric barrier discharge(DBD)on g‐C3N4 is studied by comparing the photocatalytic activities,the surface physical structure and the surface chemical characteristics of pristine and plasma treated g‐C3N4.Experimental results indicate that the DBD plasma can change the physical structure and the chemical characteristics and to further affect the photocatalytic activity of g‐C3N4.The effect of NTP on g‐C3N4 is associated with the discharge intensity and the discharge time.For a long time scale,the effect of NTP on g‐C3N4 photocatalysts presents a periodic change trend.展开更多
α‐,β‐,γ‐andδ‐MnO2catalysts were synthesized by a one‐step hydrothermal method,and were utilized for the catalytic oxidation of toluene in a combined plasma‐catalytic process.The relationship between catalyti...α‐,β‐,γ‐andδ‐MnO2catalysts were synthesized by a one‐step hydrothermal method,and were utilized for the catalytic oxidation of toluene in a combined plasma‐catalytic process.The relationship between catalytic performance and MnO2crystal structures was investigated.It was noted that the toluene removal efficiency was32.5%at the specific input energy of160J/L when non‐thermal plasma was used alone.Theα‐MnO2catalyst showed the best activity among the investigated catalysts,yielding a toluene conversion of78.1%at the specific input energy of160J/L.Forβ‐MnO2,γ‐MnO2andδ‐MnO2,removal efficiencies of47.4%,66.1%and50.0%,respectively,were achieved.By powder X‐ray diffraction,Raman spectroscopy,transmission electron microscopy,scanning electron microscopy,Brunauer‐Emmett‐Teller,H2temperature‐programmed reduction and X‐ray photoelectron spectroscopy analyses,it was concluded that the tunnel structure,the stability of the crystal in plasma,the Mn-O bond strength of MnO2and the surface‐chemisorbed oxygen species played important roles in the plasma‐catalytic degradation of toluene.Additionally,the degradation routes of toluene in non‐thermal plasma and in the plasma‐catalytic process were also studied.It was concluded that the introduction of MnO2catalysts enabled O3,O2,electrons and radical species in the gas to be adsorbed on the MnO2surface via a facile interconversion among the Mn4+,Mn3+and Mn2+states.These four species could then be transported to the toluene or intermediate organic by‐products,which greatly improved the toluene removal efficiency and decreased the final output of by‐products.展开更多
Considering Brinkman⁃Forchheimer extended Darcy flow and local thermal non⁃equilibrium effect,a general model of forced convection with viscous dissipation in power⁃law fluid saturated porous media channel was establi...Considering Brinkman⁃Forchheimer extended Darcy flow and local thermal non⁃equilibrium effect,a general model of forced convection with viscous dissipation in power⁃law fluid saturated porous media channel was established.The dimensionless temperature profiles and Nusselt number were numerically solved using the classical fourth⁃order Runge Kutta method under a constant heat flux boundary condition.The conclusion showed that the fluid⁃solid temperature distributions were significantly affected by dimensionless Bi,k,Da,Br,and F,and the effects of power⁃law indexes on convection heat transfer characteristics were also non⁃negligible.展开更多
Accurate fitting formulae to the synchrotron function, F（x）, and its com- plementary function, G（x）, are performed and presented. The corresponding relative errors are less than 0.26% and 0.035% for F（x） and G（...Accurate fitting formulae to the synchrotron function, F（x）, and its com- plementary function, G（x）, are performed and presented. The corresponding relative errors are less than 0.26% and 0.035% for F（x） and G（x）, respectively. To this end we have, first, fitted the modified Bessel functions, Ks/3（x） and K2/3（x）. For all the fitted functions, the general fit expression is the same, and is based on the well known asymptotic forms for low and large values of z for each function. It consists of multi- plying each asymptotic form by a function that tends to unity or zero for low and large values of z. Simple formulae are suggested in this paper, depending on adjustable parameters. The latter have been determined by adopting the Levenberg-Marquardt algorithm. The proposed formulae should be of great utility and simplicity for com- puting spectral powers and the degree of polarization for synchrotron radiation, both for laboratory and astrophysical applications.展开更多
In the present work, forced convection heat transfer in plate channels filled with metallic or non metallic particles (packed beds) or sintered porous media is simulated numerically using a thermal non equilibrium...In the present work, forced convection heat transfer in plate channels filled with metallic or non metallic particles (packed beds) or sintered porous media is simulated numerically using a thermal non equilibrium model. The numerical simulation results are compared with experimental data. The difference between convection heat transfer in packed beds and in sintered porous media and the effects of the boundary condition assumptions are investigated. The results show that the numerical simulation of convection heat transfer of air or water in packed beds using the local thermal non equilibrium model and the variable porosity model agrees well with the experimental data. The convection heat transfer coefficient in sintered porous media is much higher than that in packed beds. In the numerical simulation of convection heat transfer in sintered porous media, the boundary conditions on the wall should be that the particle temperatures are equal to the fluid temperature.展开更多
基金supported by the National Key Research and Development Plan of China (2016YFC0204700)National Natural Science Foundation of China (NSFC-51578488)+3 种基金Zhejiang Provincial "151" Talents Program (2013)Key Project of Zhejiang Provincial Science and Technology Programthe Program for Zhejiang Leading Team of S&T Innovation (2013TD07)the Changjiang Scholar Incentive Program (2009)~~
文摘In this study, a hybrid process using non‐thermal plasma (NTP) and photocatalytic oxidation (PCO) was adopted for the degradation of gas‐phase toluene using TiO2 as the photocatalyst. To discover the synergetic effect between NTP and PCO, the performances of both sole (O3, UV, NTP, and PCO) and combined (O3 + TiO2, O3 + UV, NTP + UV, O3 + PCO, and NTP + PCO) processes were investigated from different perspectives, such as the toluene removal efficiency, selectivity of COx, mineralization rate, ozone utilization, and the generation of by‐products. The toluene removal efficiency of the combined NTP + PCO process was 80.2%, which was much higher than that of a sole degradation process such as NTP (18.8%) and PCO (13.4%). The selectivity of CO2 and the ozone utilization efficiency also significantly improved. The amount of by‐products in the gas phase and the carbon‐ based intermediates adsorbed on the catalyst surface dramatically reduced. The improvement in the overall performances of the combined NTP + PCO process was mainly ascribed to the efficient utilization of ozone in the photocatalytic oxidation, and the ozone further acting as an electron acceptor and scavenger, generating more hydroxyl radicals and reducing the recombination of electron‐ hole pairs.
文摘The synergistic effect of high voltage discharge non‐thermal plasma(NTP)and photocatalysts on contaminant removal has repeatedly confirmed by plenty of researches.Most previous plasma‐photocatalyst synergistic systems focused on the utilization of the ultraviolet light but ignored the visible light generated by high voltage discharge.Graphitic carbon nitride(g‐C3N4),a metal‐free semiconductor that exhibits high chemical stability,can utilize both the ultraviolet and visible light from high voltage discharge.However,the synergistic system of NTP and g‐C3N4 has been researched little.In this paper,the effect of NTP generated by dielectric barrier discharge(DBD)on g‐C3N4 is studied by comparing the photocatalytic activities,the surface physical structure and the surface chemical characteristics of pristine and plasma treated g‐C3N4.Experimental results indicate that the DBD plasma can change the physical structure and the chemical characteristics and to further affect the photocatalytic activity of g‐C3N4.The effect of NTP on g‐C3N4 is associated with the discharge intensity and the discharge time.For a long time scale,the effect of NTP on g‐C3N4 photocatalysts presents a periodic change trend.
基金supported by the National Key Research and Development Plan of China(2016YFC0204700)Zhejiang Provincial"151"Talents Program(2013)+2 种基金Key Project of Zhejiang Provincial Science and Technology Program,the Program for Zhejiang Leading Team of S&T Innovation(2013TD07)Special Program for Social Development of Key Science and Technology Project of Zhejiang Province(2014C03025)Changjiang Scholar Incentive Program(2009)~~
文摘α‐,β‐,γ‐andδ‐MnO2catalysts were synthesized by a one‐step hydrothermal method,and were utilized for the catalytic oxidation of toluene in a combined plasma‐catalytic process.The relationship between catalytic performance and MnO2crystal structures was investigated.It was noted that the toluene removal efficiency was32.5%at the specific input energy of160J/L when non‐thermal plasma was used alone.Theα‐MnO2catalyst showed the best activity among the investigated catalysts,yielding a toluene conversion of78.1%at the specific input energy of160J/L.Forβ‐MnO2,γ‐MnO2andδ‐MnO2,removal efficiencies of47.4%,66.1%and50.0%,respectively,were achieved.By powder X‐ray diffraction,Raman spectroscopy,transmission electron microscopy,scanning electron microscopy,Brunauer‐Emmett‐Teller,H2temperature‐programmed reduction and X‐ray photoelectron spectroscopy analyses,it was concluded that the tunnel structure,the stability of the crystal in plasma,the Mn-O bond strength of MnO2and the surface‐chemisorbed oxygen species played important roles in the plasma‐catalytic degradation of toluene.Additionally,the degradation routes of toluene in non‐thermal plasma and in the plasma‐catalytic process were also studied.It was concluded that the introduction of MnO2catalysts enabled O3,O2,electrons and radical species in the gas to be adsorbed on the MnO2surface via a facile interconversion among the Mn4+,Mn3+and Mn2+states.These four species could then be transported to the toluene or intermediate organic by‐products,which greatly improved the toluene removal efficiency and decreased the final output of by‐products.
基金Sponsored by the Liaoning Provincial Doctoral Initiation Fund Project(Grant No.2019-BS-030).
文摘Considering Brinkman⁃Forchheimer extended Darcy flow and local thermal non⁃equilibrium effect,a general model of forced convection with viscous dissipation in power⁃law fluid saturated porous media channel was established.The dimensionless temperature profiles and Nusselt number were numerically solved using the classical fourth⁃order Runge Kutta method under a constant heat flux boundary condition.The conclusion showed that the fluid⁃solid temperature distributions were significantly affected by dimensionless Bi,k,Da,Br,and F,and the effects of power⁃law indexes on convection heat transfer characteristics were also non⁃negligible.
基金supported by the National Administration of Scientific Research NASR-DZ, of Algeria, in the framework of National Projects of Research (NPR)
文摘Accurate fitting formulae to the synchrotron function, F（x）, and its com- plementary function, G（x）, are performed and presented. The corresponding relative errors are less than 0.26% and 0.035% for F（x） and G（x）, respectively. To this end we have, first, fitted the modified Bessel functions, Ks/3（x） and K2/3（x）. For all the fitted functions, the general fit expression is the same, and is based on the well known asymptotic forms for low and large values of z for each function. It consists of multi- plying each asymptotic form by a function that tends to unity or zero for low and large values of z. Simple formulae are suggested in this paper, depending on adjustable parameters. The latter have been determined by adopting the Levenberg-Marquardt algorithm. The proposed formulae should be of great utility and simplicity for com- puting spectral powers and the degree of polarization for synchrotron radiation, both for laboratory and astrophysical applications.
基金Supported by the National Outstanding Youth Fundfrom the National Natural Science Foundation of China( No.5 0 0 2 5 617) and the Major State Basic ResearchDevelopment Program( No.G19990 3 3 10 6)
文摘In the present work, forced convection heat transfer in plate channels filled with metallic or non metallic particles (packed beds) or sintered porous media is simulated numerically using a thermal non equilibrium model. The numerical simulation results are compared with experimental data. The difference between convection heat transfer in packed beds and in sintered porous media and the effects of the boundary condition assumptions are investigated. The results show that the numerical simulation of convection heat transfer of air or water in packed beds using the local thermal non equilibrium model and the variable porosity model agrees well with the experimental data. The convection heat transfer coefficient in sintered porous media is much higher than that in packed beds. In the numerical simulation of convection heat transfer in sintered porous media, the boundary conditions on the wall should be that the particle temperatures are equal to the fluid temperature.
