Ammonia and nitric acid,versatile industrial feedstocks,and burgeoning clean energy vectors hold immense promise for sustainable development.However,Haber–Bosch and Ostwald processes,which generates carbon dioxide as...Ammonia and nitric acid,versatile industrial feedstocks,and burgeoning clean energy vectors hold immense promise for sustainable development.However,Haber–Bosch and Ostwald processes,which generates carbon dioxide as massive by-product,contribute to greenhouse effects and pose environmental challenges.Thus,the pursuit of nitrogen fixation through carbon–neutral pathways under benign conditions is a frontier of scientific topics,with the harnessing of solar energy emerging as an enticing and viable option.This review delves into the refinement strategies for scale-up mild photocatalytic nitrogen fixation,fields ripe with potential for innovation.The narrative is centered on enhancing the intrinsic capabilities of catalysts to surmount current efficiency barriers.Key focus areas include the in-depth exploration of fundamental mechanisms underpinning photocatalytic procedures,rational element selection,and functional planning,state-of-the-art experimental protocols for understanding photo-fixation processes,valid photocatalytic activity evaluation,and the rational design of catalysts.Furthermore,the review offers a suite of forward-looking recommendations aimed at propelling the advancement of mild nitrogen photo-fixation.It scrutinizes the existing challenges and prospects within this burgeoning domain,aspiring to equip researchers with insightful perspectives that can catalyze the evolution of cutting-edge nitrogen fixation methodologies and steer the development of next-generation photocatalytic systems.展开更多
This study presents a detailed experimental evaluation of a newly developed mechanistic scale-up methodology for gas-solid fluidized beds.Traditional scale-up approaches typically rely on matching global dimensionless...This study presents a detailed experimental evaluation of a newly developed mechanistic scale-up methodology for gas-solid fluidized beds.Traditional scale-up approaches typically rely on matching global dimensionless groups,which often fail to ensure local hydrodynamic similarity.In contrast,the new mechanistic method aims to achieve scale-up by matching the radial profiles of gas holdup between geometrically similar beds at corresponding dimensionless axial positions(z/Dc).This approach is based on the premise that when gas holdup profiles align,other key hydrodynamic parameters—such as solids holdup and particle velocity—also become similar.To validate this methodology,experiments were conducted in two fluidized beds with inner diameters of 14 cm and 44 cm.Optical probes and gamma ray densitometry(GRD)were used to measure local gas holdup,solids holdup,and particle velocity at multiple axial and radial positions.The results show that matched gas holdup profiles led to mean absolute deviations(MAD)below 3%in solids holdup and particle velocity,confirming hydrodynamic similarity.In contrast,unmatched profiles resulted in significant deviations across all parameters.展开更多
The chaotic scale-up approach by matching the Kolmogorov entropy(E_K) proposed by Schouten et al.(1996) was assessed in two geometrically similar gas–solid fluidized bed columns of 0.14 and 0.44 m diameter.We used fo...The chaotic scale-up approach by matching the Kolmogorov entropy(E_K) proposed by Schouten et al.(1996) was assessed in two geometrically similar gas–solid fluidized bed columns of 0.14 and 0.44 m diameter.We used four conditions of our validated new mechanistic scale-up method based on matching the radial profiles of gas holdup where the local dimensionless hydrodynamic parameters were similar as measured by advanced measurement techniques.These experimental conditions were used to evaluate the validity of the chaotic scale-up method,which were selected based on our new mechanistic scale-up methodology.Pressure gauge transducer measurements at the wall and inside the bed at various local radial locations and at three axial heights were used to estimate KE.It was found that the experimental conditions with similar or close radial profiles of the Kolmogorov entropy and with similar or close radial profiles of the gas holdup achieve the similarity in local dimensionless hydrodynamic parameters,and vice versa.展开更多
The production capability of a fermentation process is predominately determined by individual strains,which ultimately affected ultimately by interactions between the scale-dependent flow field developed within biorea...The production capability of a fermentation process is predominately determined by individual strains,which ultimately affected ultimately by interactions between the scale-dependent flow field developed within bioreactors and the physiological response of these strains.Interpreting these complicated interactions is key for better understanding the scale-up of the fermentation process.We review these two aspects and address progress in strategies for scaling up fermentation processes.A perspective on how to incorporate the multiomics big data into the scale-up strategy is presented to improve the design and operation of industrial fermentation processes.展开更多
Chlorophenols(CPs)are significant refractory pollutants that are highly toxic to humans and other organ-isms.Reactive electrode membranes(REMs)show considerable potential in the electrochemical removal of refractory p...Chlorophenols(CPs)are significant refractory pollutants that are highly toxic to humans and other organ-isms.Reactive electrode membranes(REMs)show considerable potential in the electrochemical removal of refractory pollutants by allowing flow-through operations with convection-enhanced mass transfer.However,relevant studies are commonly performed on the laboratory scale,and there is no straightfor-ward method that guarantees success in scaling up engineered REM reactors.In this study,we demon-strated that a tubular concentric electrode(TCE)configuration with a titanium suboxide ceramic anode and a stainless-steel cathode is suitable for large-scale CPs removal.Both theoretical and experi-mental results showed that the TCE configuration not only allows the electrode surface to be orthogonal to electric field lines everywhere,but also has an ohmic resistance that is inversely proportional to the length of the electrode.In addition,the TCE configuration can be operated in either the anode-to-cathode(AC)or the cathode-to-anode(CA)mode based on the flow direction,creating adjustable condi-tions for selective degradation of CPs.This was confirmed by 98%removal of 2,4-dichlorophenol(2,4-DCP)and 72.5%removal of chemical oxygen demand(COD)in the CA mode,in which the kinetic constant was one order of magnitude higher than that for the AC mode under flow-through single-pass operations.This can be explained by the lower activation energy and free energy in the CA mode,as revealed by the-oretical calculations and experimental measurements.The TCE configuration is also suitable for a numbering-up strategy to scale up the electrochemical reactor without increasing the ohmic resistance or decreasing the specific electrode area,achieving 99.4%removal of 2,4-DCP with an energy consump-tion of 1.5 kW·h·m^(-3) when three TCE modules were employed.This study presents a suitable electrode design configuration for the REM reactor,offering effective strategies to bridge the“Valley of Death”encountered when scaling up the electrochemical removal of CP pollutants.展开更多
The main spatial distribution features of shear rate in a stirred tank operated with five different radial and axial flow impellers were presented with particle image velocimetry(PIV)experiments.Not only the average s...The main spatial distribution features of shear rate in a stirred tank operated with five different radial and axial flow impellers were presented with particle image velocimetry(PIV)experiments.Not only the average shear rate in the whole tank but also the local value in the vicinity of impeller increases linearly with impeller speed.Furthermore,the shear coefficient(Ks,imp)at the impeller outlet is linearly related to the impeller flow number(Nq)and decreases with the increase of Nq in general at the constant power consumption per unit volume(Pv).During scale-up based on the constant Pv and geometric similarity,CFD results show that the volume-averaged shear rate(cavg)for RDT decreases faster than that of other impellers with the impeller tip velocity(Utip).The novel multi-blade combined(MBC)impeller with the increased height-to-diameter ratio of the stirred tank is able to more effectively improve the distribution uniformity of shear rate at the same Pv after scale-up.These studies provide a data basis for selecting the impeller types and improving the shear rate environment in the large-scale stirred tank.展开更多
Covalent organic frameworks(COFs),as a novel class of functional polymers,exhibit versatile applica-tions due to their crystalline porous structures and conjugated skeletons.However,synthesis of COFs with high crystal...Covalent organic frameworks(COFs),as a novel class of functional polymers,exhibit versatile applica-tions due to their crystalline porous structures and conjugated skeletons.However,synthesis of COFs with high crystallinity still faces great challenges,especially for scale-up preparation.Herein we report a two-step solvothermal process to improve crystallinity of COFs.The first step focuses on polycondensa-tion of monomers with no need for optimizing crystallization conditions.In the second step,appropriate solvothermal conditions are used to facilitate crystallization of the COFs through defects correction and structural repairing.Furthermore,this strategy could also be applicable to scale-up synthesis of high qual-ity COFs,which lays a foundation for their practical applications.展开更多
The scale-up synthesis of H2O2 from H2/O2 via a dielectric barrier discharge （DBD） under ambient conditions was studied. A plasma reactor consisting of multiple parallel DBD tubes was designed to scale up the H2O2 s...The scale-up synthesis of H2O2 from H2/O2 via a dielectric barrier discharge （DBD） under ambient conditions was studied. A plasma reactor consisting of multiple parallel DBD tubes was designed to scale up the H2O2 synthesis. The number of tubes had no significant effect on the discharge mode, and no decay occurred in H2O2 selectivity during the scale-up process. These advantages made this technology more stable and efficient. The reactor＇s energy efficiency increased with the number of tubes and reached 136 g H2O2/kWh in the four-tube reaction. The total energy efficiency was limited by the extremely low energy transfer efficiency of power supply, and might be enhanced by optimizing the impedance matching between the power supply and the reactor load. As a result, an assembly of multiple DBD tubes may provide a viable route for the scale-up synthesis of H2O2 by a non-equilibrium plasma.展开更多
A set of hydrodynamic similarity laws is applied to the scale-up of ethylene polymerization fluidized bed reactors(FBRs)under the condensed mode operation.The thermal stability of open-loop controlled FBRs is investig...A set of hydrodynamic similarity laws is applied to the scale-up of ethylene polymerization fluidized bed reactors(FBRs)under the condensed mode operation.The thermal stability of open-loop controlled FBRs is investigated by the homotopy continuation method.And the Hopf bifurcation point is selected as an index of the thermal stability similarity.The simulation results show the similarity in state variables,operation parameters,the space-time yield(STY),and the thermal stability of FBRs with different scales.Furthermore,the thermal stability behaviors and similarity of the closed-loop controlled FBRs with different scales are analyzed.The observed similar trend of Hopf bifurcation curves reveals the similarity in the thermal stability of closed-loop controlled FBRs with different scaling ratios.In general,the results of the thermal stability similarity confirm that the hydrodynamics scaling laws proposed in the work are applicable to the scale-up of FBRs under the condensed mode operation.展开更多
Electrocatalytic urea synthesis provides a favorable strategy for conventional energy-consuming urea synthesis,but achieving large-scale catalyst synthesis with high catalytic efficiency remains challenging.Herein,we ...Electrocatalytic urea synthesis provides a favorable strategy for conventional energy-consuming urea synthesis,but achieving large-scale catalyst synthesis with high catalytic efficiency remains challenging.Herein,we developed a simple method for the preparation of a series of FeNi-alloy-based catalysts,named FeNi@nC-T(n represents the content of nanoporous carbon as 1,3,5,7 or 9 g and T=900,950,1000 or 1100°C),for highly performed urea synthesis via NO_(3)−and CO_(2)co-reduction.The FeNi@7C-1000 achieved a high urea yield of 1041.33 mmol h^(−1)gFeNi^(−1)with a Faradaic efficiency of 15.56%at–1.2 V vs.RHE.Moreover,the scale-up synthesized FeNi@7C-950-S(over 140 g per batch)was achieved with its high catalytic performance and high stability maintained.Mechanism investigation illuminated that the Ni and Fe sites catalyze and stabilize the key*CO and*N intermediates and minimize the C–N coupling reaction barriers for highly efficient urea synthesis.展开更多
Study of the effect of dissolved oxygen and shear stress on rifamycin B fermentation with A. mediterranei XC 9-25 showed that rifamycin B fermentation with Amycolatoposis mediterranei XC 9-25 needs high dissolved oxyg...Study of the effect of dissolved oxygen and shear stress on rifamycin B fermentation with A. mediterranei XC 9-25 showed that rifamycin B fermentation with Amycolatoposis mediterranei XC 9-25 needs high dissolved oxygen and is not very sensitive to shearing stress. The scale-up ofrifamycin B fermentation withA, mediterranei XC 9-25 from a shaking flask to a 15 L fermentor was realized by controlling the dissolved oxygen to above 25% of saturation in the fermentation process, and the potency of rifamycin B fermentation in the 15 L fermentor reached 10 g/L after 6-day batch fermentation. By continuously feeding glucose and ammonia in the fermentation process, the potency of rifamycin B fermentaion in the 15 L fermentor reached 18.67 g/L, which was 86.65% higher than that of batch fermentation. Based on the scale-up principle of constantly aerated agitation power per unit volume, the scale-up of rifamycin B fed-batch fermentation with continuous feed from a 15 L fermentor to a 7 m^3 fermentor and further to a 60 m^3 fermentor was realized successfully. The potency of rifamycin B fermentation in the 7 m^3 fermentor and in the 60 m^3 fermentor reached 17.25 g/L and 19.11 g/L, respectively.展开更多
In the present work, steady state heat transfer experiments were conducted in the upper splash region of three cold circulating fluidized beds （CFB）, B 1, B2 and B3, with height of each 2.85 m and bed cross sections...In the present work, steady state heat transfer experiments were conducted in the upper splash region of three cold circulating fluidized beds （CFB）, B 1, B2 and B3, with height of each 2.85 m and bed cross sections of 0.15 m × 0.15 m, 0.20 m × 0.20 m and 0.25 m × 0.25 m, respectively. Experiments were conducted under similar operating conditions on all the three CFt3 setups for two different non-dimensional air velocities （U＊ = 5 and 8） and two different sand inventories with average particles size of 460 μm. Effect of cross section of riser on heat transfer characteristics was studied. Bed temperature distribution across the heater placed in the upper splash region of riser was measured at two sections, at a height of 1.96 m and 2.24 m above the distributor plate. Axial distribution of local heat transfer coefficients along the height of heater were evaluated and compared for different bed cross sections. Results obtained were compared with the available literatures.展开更多
Experiments and simulations were conducted for bubble columns with diameter of 0.2 m(180 mm i.d.), 0.5 m(476 mm i.d.) and 0.8 m(760 mm i.d.) at high superficial gas velocities(0.12–0.62 m·s-1) and high solid con...Experiments and simulations were conducted for bubble columns with diameter of 0.2 m(180 mm i.d.), 0.5 m(476 mm i.d.) and 0.8 m(760 mm i.d.) at high superficial gas velocities(0.12–0.62 m·s-1) and high solid concentrations(0–30 vol%). Radial profiles of time-averaged gas holdup, axial liquid velocity, and turbulent kinetic energy were measured by using in-house developed conductivity probes and Pavlov tubes. Effects of column diameter, superficial gas velocity, and solid concentration were investigated in a wide range of operating conditions. Experimental results indicated that the average gas holdup remarkably increases with superficial gas velocity, and the radial profiles of investigated flow properties become steeper at high superficial gas velocities. The axial liquid velocities significantly increase with the growth of the column size, whereas the gas holdup was slightly affected. The presence of solid in bubble columns would inhibit the breakage of bubbles, which results in an increase in bubble rise velocity and a decrease in gas holdup, but time-averaged axial liquid velocities remain almost the same as that of the hollow column. Furthermore, a 2-D axisymmetric k–ε model was used to simulate heterogeneous bubbly flow using commercial code FLUENT 6.2. The lateral lift force and the turbulent diffusion force were introduced for the determination of gas holdup profiles and the effects of solid concentration were considered as the variation of average bubble diameter in the model. Results predicted by the CFD simulation showed good agreement with experimental data.展开更多
This scale-up study demonstrated the feasibility of an ionic liquid(IL)pretreatment process at 40 kg scale,using the IL 1-ethyl-3-methylimidazolium acetate([C2C1Im][OAc])as the solvent.The pretreatment was followed by...This scale-up study demonstrated the feasibility of an ionic liquid(IL)pretreatment process at 40 kg scale,using the IL 1-ethyl-3-methylimidazolium acetate([C2C1Im][OAc])as the solvent.The pretreatment was followed by enzymatic hydrolysis through which the process efficiency for biomass conversion to monomeric sugars was determined.The results show that 43 wt%of switchgrass was dissolved in IL after 2 h of pretreatment at 160℃ with 15 wt%solid loading.A 120 h enzymatic hydrolysis of the pretreated switchgrass results in 96%glucan and 98%xylan conversion.[C2C1Im][OAc]pretreatment has been successfully scaled up to 40 kg with improved sugar titers and yields relative to bench scale(6 kg).The mass flow of the overall process was established and the major scale-up challenges of the process were identified.展开更多
The scale-up effect, which is a key factor controlling the performance of industrial cyclones, is conventionally estimated through grade efficienty curves. A new principle based on the centrifugal separation factor (C...The scale-up effect, which is a key factor controlling the performance of industrial cyclones, is conventionally estimated through grade efficienty curves. A new principle based on the centrifugal separation factor (CSF) is proposed to improve the scale-up procedure in designing industrial cyclones.展开更多
Interest in the technology for producing alternative proteins is rapidly increasing,driven by the need to find new ways to produce and consume protein for the global population.This technology involves growing differe...Interest in the technology for producing alternative proteins is rapidly increasing,driven by the need to find new ways to produce and consume protein for the global population.This technology involves growing different microorganisms and animal cells under controlled conditions to ensure their viability and efficient growth.The cultivation process takes place in different types of bioreactors,from traditional models to innovative new designs,each offering unique features and capabilities.The most commonly used bioreactors are stirred tank reactors,which are mechanically agitated,and airlift or bubble column bioreactors,which are pneumatically agitated.These bioreactors are often adapted or modified to optimize the production of cultured meat.Essential to the process are microcarriers or scaffolds that support cell adhesion and proliferation.Other bioreactor models,such as hollow fiber and packed bed bioreactors,are also being explored.The trend towards single-use technology is growing due to benefits like easier cleaning and sterilization,and reduced operation times,though it does raise concerns about plastic waste.This review not only describes various bioreactor models but also discusses instrumentation and control systems.It aims to present the main bioreactor models currently in use for cultivated meat production,detailing their features,advantages,disadvantages,and the technological challenges that need to be addressed.展开更多
Supercritical water gasification is a promising method for efficient hydrogen production.Among various reactor designs,fluidized bed reactors demonstrate strong industrial potential due to their plugging resistance an...Supercritical water gasification is a promising method for efficient hydrogen production.Among various reactor designs,fluidized bed reactors demonstrate strong industrial potential due to their plugging resistance and favorable hydrodynamic properties.However,scaling up the reactor to industrial applications disrupts the mass transfer-reaction matching relationship established at the particle level,making it challenging to replicate the performance of smaller reactors.To mitigate the scale-up effect of the reactor,a fundamental understanding of particle-scale mechanisms is essential.In this study,high-resolution numerical simulations are employed to investigate particle dynamics across both reactor and particle scales.To enhance computational efficiency,adaptive mesh refinement and heterogeneous computing are utilized.The scale-up laws governing the internal flow structures and chemical reaction performance within the reactor are analyzed.The temperature,diffusion,and chemical reaction performance at the particle level are tracked,and statistical analyses are performed to elucidate the mechanisms driving the scale-up effects.Results reveal that the two scaling approaches affect reactor performance through different mechanisms.Radial scaling has minimal impact on particle mixing and reaction rates,whereas axial scaling reduces particle reaction rates;however,this reduction is compensated by an increased particle count,ultimately enhancing overall hydrogen yield.Additionally,higher superficial velocity enhances feedstock mixing and thermal uniformity,resulting in more uniform particle reactions,although it may hinder homogeneous reactions.These findings offer new insights into reactor scale-up effects and hold promise for guiding optimal and detailed design of future industrial-scale reactors.展开更多
基金financially supported by the National Natural Science Foundation of China(No.21675131)the Volkswagen Foundation(Freigeist Fellowship No.89592)+1 种基金the Natural Science Foundation of Chongqing(No.2020jcyj-zdxmX0003,CSTB2023NSCQ-MSX0924)the National Research Foundation,Singapore,and A*STAR(Agency for Science Technology and Research)under its LCER Phase 2 Programme Hydrogen&Emerging Technologies FI,Directed Hydrogen Programme(Award No.U2305D4003).
文摘Ammonia and nitric acid,versatile industrial feedstocks,and burgeoning clean energy vectors hold immense promise for sustainable development.However,Haber–Bosch and Ostwald processes,which generates carbon dioxide as massive by-product,contribute to greenhouse effects and pose environmental challenges.Thus,the pursuit of nitrogen fixation through carbon–neutral pathways under benign conditions is a frontier of scientific topics,with the harnessing of solar energy emerging as an enticing and viable option.This review delves into the refinement strategies for scale-up mild photocatalytic nitrogen fixation,fields ripe with potential for innovation.The narrative is centered on enhancing the intrinsic capabilities of catalysts to surmount current efficiency barriers.Key focus areas include the in-depth exploration of fundamental mechanisms underpinning photocatalytic procedures,rational element selection,and functional planning,state-of-the-art experimental protocols for understanding photo-fixation processes,valid photocatalytic activity evaluation,and the rational design of catalysts.Furthermore,the review offers a suite of forward-looking recommendations aimed at propelling the advancement of mild nitrogen photo-fixation.It scrutinizes the existing challenges and prospects within this burgeoning domain,aspiring to equip researchers with insightful perspectives that can catalyze the evolution of cutting-edge nitrogen fixation methodologies and steer the development of next-generation photocatalytic systems.
文摘This study presents a detailed experimental evaluation of a newly developed mechanistic scale-up methodology for gas-solid fluidized beds.Traditional scale-up approaches typically rely on matching global dimensionless groups,which often fail to ensure local hydrodynamic similarity.In contrast,the new mechanistic method aims to achieve scale-up by matching the radial profiles of gas holdup between geometrically similar beds at corresponding dimensionless axial positions(z/Dc).This approach is based on the premise that when gas holdup profiles align,other key hydrodynamic parameters—such as solids holdup and particle velocity—also become similar.To validate this methodology,experiments were conducted in two fluidized beds with inner diameters of 14 cm and 44 cm.Optical probes and gamma ray densitometry(GRD)were used to measure local gas holdup,solids holdup,and particle velocity at multiple axial and radial positions.The results show that matched gas holdup profiles led to mean absolute deviations(MAD)below 3%in solids holdup and particle velocity,confirming hydrodynamic similarity.In contrast,unmatched profiles resulted in significant deviations across all parameters.
基金the Multiphase Reactors Engineering and Applications Laboratory(mReal) for funding and support
文摘The chaotic scale-up approach by matching the Kolmogorov entropy(E_K) proposed by Schouten et al.(1996) was assessed in two geometrically similar gas–solid fluidized bed columns of 0.14 and 0.44 m diameter.We used four conditions of our validated new mechanistic scale-up method based on matching the radial profiles of gas holdup where the local dimensionless hydrodynamic parameters were similar as measured by advanced measurement techniques.These experimental conditions were used to evaluate the validity of the chaotic scale-up method,which were selected based on our new mechanistic scale-up methodology.Pressure gauge transducer measurements at the wall and inside the bed at various local radial locations and at three axial heights were used to estimate KE.It was found that the experimental conditions with similar or close radial profiles of the Kolmogorov entropy and with similar or close radial profiles of the gas holdup achieve the similarity in local dimensionless hydrodynamic parameters,and vice versa.
基金The authors would like to acknowledge the Projects 21776082 and 21978085 supported by National Natural Science Foundation of ChinaProject 22221818014 supported by the Fundamental Research Funds for the Central Universities.
文摘The production capability of a fermentation process is predominately determined by individual strains,which ultimately affected ultimately by interactions between the scale-dependent flow field developed within bioreactors and the physiological response of these strains.Interpreting these complicated interactions is key for better understanding the scale-up of the fermentation process.We review these two aspects and address progress in strategies for scaling up fermentation processes.A perspective on how to incorporate the multiomics big data into the scale-up strategy is presented to improve the design and operation of industrial fermentation processes.
基金supported by the National Natural Science Foun-dation of China(U21A20161 and 51822806)State Key Laboratory of Urban Water Resource and Environment,China(Harbin Institute of Technology)(2020DX07)Heilongjiang Touyan Innovation Team Program,China(HIT-SE-01).
文摘Chlorophenols(CPs)are significant refractory pollutants that are highly toxic to humans and other organ-isms.Reactive electrode membranes(REMs)show considerable potential in the electrochemical removal of refractory pollutants by allowing flow-through operations with convection-enhanced mass transfer.However,relevant studies are commonly performed on the laboratory scale,and there is no straightfor-ward method that guarantees success in scaling up engineered REM reactors.In this study,we demon-strated that a tubular concentric electrode(TCE)configuration with a titanium suboxide ceramic anode and a stainless-steel cathode is suitable for large-scale CPs removal.Both theoretical and experi-mental results showed that the TCE configuration not only allows the electrode surface to be orthogonal to electric field lines everywhere,but also has an ohmic resistance that is inversely proportional to the length of the electrode.In addition,the TCE configuration can be operated in either the anode-to-cathode(AC)or the cathode-to-anode(CA)mode based on the flow direction,creating adjustable condi-tions for selective degradation of CPs.This was confirmed by 98%removal of 2,4-dichlorophenol(2,4-DCP)and 72.5%removal of chemical oxygen demand(COD)in the CA mode,in which the kinetic constant was one order of magnitude higher than that for the AC mode under flow-through single-pass operations.This can be explained by the lower activation energy and free energy in the CA mode,as revealed by the-oretical calculations and experimental measurements.The TCE configuration is also suitable for a numbering-up strategy to scale up the electrochemical reactor without increasing the ohmic resistance or decreasing the specific electrode area,achieving 99.4%removal of 2,4-DCP with an energy consump-tion of 1.5 kW·h·m^(-3) when three TCE modules were employed.This study presents a suitable electrode design configuration for the REM reactor,offering effective strategies to bridge the“Valley of Death”encountered when scaling up the electrochemical removal of CP pollutants.
基金National Key Research and Development Program (2020YFA0906800)the National Natural Science Foundation of China (21808221, 91934301, 21961160745)+2 种基金External Cooperation Program of BIC, Chinese Academy of Sciences (122111KYSB20190032)the Key Research Program of Nanjing IPE Institute of Green Manufacturing Industry (No. E0010719)Innovation Academy for Green Manufacture, Chinese Academy of Sciences (IAGM2020C06)
文摘The main spatial distribution features of shear rate in a stirred tank operated with five different radial and axial flow impellers were presented with particle image velocimetry(PIV)experiments.Not only the average shear rate in the whole tank but also the local value in the vicinity of impeller increases linearly with impeller speed.Furthermore,the shear coefficient(Ks,imp)at the impeller outlet is linearly related to the impeller flow number(Nq)and decreases with the increase of Nq in general at the constant power consumption per unit volume(Pv).During scale-up based on the constant Pv and geometric similarity,CFD results show that the volume-averaged shear rate(cavg)for RDT decreases faster than that of other impellers with the impeller tip velocity(Utip).The novel multi-blade combined(MBC)impeller with the increased height-to-diameter ratio of the stirred tank is able to more effectively improve the distribution uniformity of shear rate at the same Pv after scale-up.These studies provide a data basis for selecting the impeller types and improving the shear rate environment in the large-scale stirred tank.
基金the National Natural Science Foundation of China(No.21632004)the Science and Technology Commission of Shang-hai Municipality(No.19XD1404900)for financial support.
文摘Covalent organic frameworks(COFs),as a novel class of functional polymers,exhibit versatile applica-tions due to their crystalline porous structures and conjugated skeletons.However,synthesis of COFs with high crystallinity still faces great challenges,especially for scale-up preparation.Herein we report a two-step solvothermal process to improve crystallinity of COFs.The first step focuses on polycondensa-tion of monomers with no need for optimizing crystallization conditions.In the second step,appropriate solvothermal conditions are used to facilitate crystallization of the COFs through defects correction and structural repairing.Furthermore,this strategy could also be applicable to scale-up synthesis of high qual-ity COFs,which lays a foundation for their practical applications.
基金supported by National Natural Science Foundation of China (No. 20233050)
文摘The scale-up synthesis of H2O2 from H2/O2 via a dielectric barrier discharge （DBD） under ambient conditions was studied. A plasma reactor consisting of multiple parallel DBD tubes was designed to scale up the H2O2 synthesis. The number of tubes had no significant effect on the discharge mode, and no decay occurred in H2O2 selectivity during the scale-up process. These advantages made this technology more stable and efficient. The reactor＇s energy efficiency increased with the number of tubes and reached 136 g H2O2/kWh in the four-tube reaction. The total energy efficiency was limited by the extremely low energy transfer efficiency of power supply, and might be enhanced by optimizing the impedance matching between the power supply and the reactor load. As a result, an assembly of multiple DBD tubes may provide a viable route for the scale-up synthesis of H2O2 by a non-equilibrium plasma.
基金financial supports from the Project of the National Natural Science Foundation of China(22178304,22108239)the Start-up Funding of Ningbo Research Institute of Zhejiang University(20201207Z0204).
文摘A set of hydrodynamic similarity laws is applied to the scale-up of ethylene polymerization fluidized bed reactors(FBRs)under the condensed mode operation.The thermal stability of open-loop controlled FBRs is investigated by the homotopy continuation method.And the Hopf bifurcation point is selected as an index of the thermal stability similarity.The simulation results show the similarity in state variables,operation parameters,the space-time yield(STY),and the thermal stability of FBRs with different scales.Furthermore,the thermal stability behaviors and similarity of the closed-loop controlled FBRs with different scales are analyzed.The observed similar trend of Hopf bifurcation curves reveals the similarity in the thermal stability of closed-loop controlled FBRs with different scaling ratios.In general,the results of the thermal stability similarity confirm that the hydrodynamics scaling laws proposed in the work are applicable to the scale-up of FBRs under the condensed mode operation.
文摘Electrocatalytic urea synthesis provides a favorable strategy for conventional energy-consuming urea synthesis,but achieving large-scale catalyst synthesis with high catalytic efficiency remains challenging.Herein,we developed a simple method for the preparation of a series of FeNi-alloy-based catalysts,named FeNi@nC-T(n represents the content of nanoporous carbon as 1,3,5,7 or 9 g and T=900,950,1000 or 1100°C),for highly performed urea synthesis via NO_(3)−and CO_(2)co-reduction.The FeNi@7C-1000 achieved a high urea yield of 1041.33 mmol h^(−1)gFeNi^(−1)with a Faradaic efficiency of 15.56%at–1.2 V vs.RHE.Moreover,the scale-up synthesized FeNi@7C-950-S(over 140 g per batch)was achieved with its high catalytic performance and high stability maintained.Mechanism investigation illuminated that the Ni and Fe sites catalyze and stabilize the key*CO and*N intermediates and minimize the C–N coupling reaction barriers for highly efficient urea synthesis.
文摘Study of the effect of dissolved oxygen and shear stress on rifamycin B fermentation with A. mediterranei XC 9-25 showed that rifamycin B fermentation with Amycolatoposis mediterranei XC 9-25 needs high dissolved oxygen and is not very sensitive to shearing stress. The scale-up ofrifamycin B fermentation withA, mediterranei XC 9-25 from a shaking flask to a 15 L fermentor was realized by controlling the dissolved oxygen to above 25% of saturation in the fermentation process, and the potency of rifamycin B fermentation in the 15 L fermentor reached 10 g/L after 6-day batch fermentation. By continuously feeding glucose and ammonia in the fermentation process, the potency of rifamycin B fermentaion in the 15 L fermentor reached 18.67 g/L, which was 86.65% higher than that of batch fermentation. Based on the scale-up principle of constantly aerated agitation power per unit volume, the scale-up of rifamycin B fed-batch fermentation with continuous feed from a 15 L fermentor to a 7 m^3 fermentor and further to a 60 m^3 fermentor was realized successfully. The potency of rifamycin B fermentation in the 7 m^3 fermentor and in the 60 m^3 fermentor reached 17.25 g/L and 19.11 g/L, respectively.
文摘In the present work, steady state heat transfer experiments were conducted in the upper splash region of three cold circulating fluidized beds （CFB）, B 1, B2 and B3, with height of each 2.85 m and bed cross sections of 0.15 m × 0.15 m, 0.20 m × 0.20 m and 0.25 m × 0.25 m, respectively. Experiments were conducted under similar operating conditions on all the three CFt3 setups for two different non-dimensional air velocities （U＊ = 5 and 8） and two different sand inventories with average particles size of 460 μm. Effect of cross section of riser on heat transfer characteristics was studied. Bed temperature distribution across the heater placed in the upper splash region of riser was measured at two sections, at a height of 1.96 m and 2.24 m above the distributor plate. Axial distribution of local heat transfer coefficients along the height of heater were evaluated and compared for different bed cross sections. Results obtained were compared with the available literatures.
基金Supported by the National High Technology Research and Development Program of China(2011AA05A205)the National Natural Science Foundation of China(U1162125,U1361112)
文摘Experiments and simulations were conducted for bubble columns with diameter of 0.2 m(180 mm i.d.), 0.5 m(476 mm i.d.) and 0.8 m(760 mm i.d.) at high superficial gas velocities(0.12–0.62 m·s-1) and high solid concentrations(0–30 vol%). Radial profiles of time-averaged gas holdup, axial liquid velocity, and turbulent kinetic energy were measured by using in-house developed conductivity probes and Pavlov tubes. Effects of column diameter, superficial gas velocity, and solid concentration were investigated in a wide range of operating conditions. Experimental results indicated that the average gas holdup remarkably increases with superficial gas velocity, and the radial profiles of investigated flow properties become steeper at high superficial gas velocities. The axial liquid velocities significantly increase with the growth of the column size, whereas the gas holdup was slightly affected. The presence of solid in bubble columns would inhibit the breakage of bubbles, which results in an increase in bubble rise velocity and a decrease in gas holdup, but time-averaged axial liquid velocities remain almost the same as that of the hollow column. Furthermore, a 2-D axisymmetric k–ε model was used to simulate heterogeneous bubbly flow using commercial code FLUENT 6.2. The lateral lift force and the turbulent diffusion force were introduced for the determination of gas holdup profiles and the effects of solid concentration were considered as the variation of average bubble diameter in the model. Results predicted by the CFD simulation showed good agreement with experimental data.
基金the funding support from The Bioenergy Technologies Office (BETO) within the US DOE’s Office of Energy Efficiency and Renewable Energythe funding support from the American Recovery and Reinvestment Actsupported by the US DOE’s Office of Science, Biological and Environmental Research program through contract DE-AC02-05CH11231 between Lawrence Berkeley National Laboratory and the U.S. Department of Energy
文摘This scale-up study demonstrated the feasibility of an ionic liquid(IL)pretreatment process at 40 kg scale,using the IL 1-ethyl-3-methylimidazolium acetate([C2C1Im][OAc])as the solvent.The pretreatment was followed by enzymatic hydrolysis through which the process efficiency for biomass conversion to monomeric sugars was determined.The results show that 43 wt%of switchgrass was dissolved in IL after 2 h of pretreatment at 160℃ with 15 wt%solid loading.A 120 h enzymatic hydrolysis of the pretreated switchgrass results in 96%glucan and 98%xylan conversion.[C2C1Im][OAc]pretreatment has been successfully scaled up to 40 kg with improved sugar titers and yields relative to bench scale(6 kg).The mass flow of the overall process was established and the major scale-up challenges of the process were identified.
文摘The scale-up effect, which is a key factor controlling the performance of industrial cyclones, is conventionally estimated through grade efficienty curves. A new principle based on the centrifugal separation factor (CSF) is proposed to improve the scale-up procedure in designing industrial cyclones.
基金Conselho Nacional de Desenvolvimento Científico e Tecnológico,Process 440080/2022-3Luciana Porto de Souza Vandenberghe,409337/2023-4Luciana Porto de Souza Vandenberghe,Coordenação de Aperfeiçoamento de Pessoal de Nível Superior,CAPES-PROEX,Ariane Fátima Murawski de Mello。
文摘Interest in the technology for producing alternative proteins is rapidly increasing,driven by the need to find new ways to produce and consume protein for the global population.This technology involves growing different microorganisms and animal cells under controlled conditions to ensure their viability and efficient growth.The cultivation process takes place in different types of bioreactors,from traditional models to innovative new designs,each offering unique features and capabilities.The most commonly used bioreactors are stirred tank reactors,which are mechanically agitated,and airlift or bubble column bioreactors,which are pneumatically agitated.These bioreactors are often adapted or modified to optimize the production of cultured meat.Essential to the process are microcarriers or scaffolds that support cell adhesion and proliferation.Other bioreactor models,such as hollow fiber and packed bed bioreactors,are also being explored.The trend towards single-use technology is growing due to benefits like easier cleaning and sterilization,and reduced operation times,though it does raise concerns about plastic waste.This review not only describes various bioreactor models but also discusses instrumentation and control systems.It aims to present the main bioreactor models currently in use for cultivated meat production,detailing their features,advantages,disadvantages,and the technological challenges that need to be addressed.
基金the support of the Basic Science Center Program for Ordered Energy Conversion of the National Natural Science Foundation of China(grant No.52488201).
文摘Supercritical water gasification is a promising method for efficient hydrogen production.Among various reactor designs,fluidized bed reactors demonstrate strong industrial potential due to their plugging resistance and favorable hydrodynamic properties.However,scaling up the reactor to industrial applications disrupts the mass transfer-reaction matching relationship established at the particle level,making it challenging to replicate the performance of smaller reactors.To mitigate the scale-up effect of the reactor,a fundamental understanding of particle-scale mechanisms is essential.In this study,high-resolution numerical simulations are employed to investigate particle dynamics across both reactor and particle scales.To enhance computational efficiency,adaptive mesh refinement and heterogeneous computing are utilized.The scale-up laws governing the internal flow structures and chemical reaction performance within the reactor are analyzed.The temperature,diffusion,and chemical reaction performance at the particle level are tracked,and statistical analyses are performed to elucidate the mechanisms driving the scale-up effects.Results reveal that the two scaling approaches affect reactor performance through different mechanisms.Radial scaling has minimal impact on particle mixing and reaction rates,whereas axial scaling reduces particle reaction rates;however,this reduction is compensated by an increased particle count,ultimately enhancing overall hydrogen yield.Additionally,higher superficial velocity enhances feedstock mixing and thermal uniformity,resulting in more uniform particle reactions,although it may hinder homogeneous reactions.These findings offer new insights into reactor scale-up effects and hold promise for guiding optimal and detailed design of future industrial-scale reactors.
