In this work,a“cyclopentanone-vanillin”strategy was proposed for the preparation of jet fuel range cycloalkanes from lignocellulose-derived ketones and lignin-derived aldehydes via aldol condensation and hydrodeoxyg...In this work,a“cyclopentanone-vanillin”strategy was proposed for the preparation of jet fuel range cycloalkanes from lignocellulose-derived ketones and lignin-derived aldehydes via aldol condensation and hydrodeoxygenation(HDO).Ethanolamine lactate ionic liquid(LAIL)exhibited excellent catalytic activity in the aldol condensation of cyclopentanone and vanillin.Desired mono-condensation and bicondensation products were obtained with yield of 95.2%at 100℃.It is found that the synergy effects between amino group of ethanolamine and hydroxyl group of lactic acid play a key role in the aldol condensation.The condensation products were converted into cycloalkanes by HDO over 5%Pd/Nb_(2)O_(5)catalyst.The density of the obtained HDO products is 0.89 g/cm^(3)and the freezing point is lower than-60℃.These results suggest that the resulted cycloalkanes can be used as additives to improve the density and low-temperature fluidity of the jet fuels.展开更多
Since the utilization of abundant biomass to develop advanced materials has become an utmost priority in recent years,we developed two sustainable routes(i.e.,the impregnation method and the one-pot synthesis)to prepa...Since the utilization of abundant biomass to develop advanced materials has become an utmost priority in recent years,we developed two sustainable routes(i.e.,the impregnation method and the one-pot synthesis)to prepare the hydrochar-supported catalysts and tested its catalytic performance on the reductive amination.Several techniques,such as TEM,XRD and XPS,were adopted to characterize the structural and catalytic features of samples.Results indicated that the impregnation method favors the formation of outer-sphere surface complexes with porous structure as well as well-distributed metallic nanoparticles,while the one-pot synthesis tends to form the inner-sphere surface complexes with relatively smooth appearance and amorphous metals.This difference explains the better activity of catalysts prepared by the impregnation method which can selectively convert benzaldehyde to benzylamine with an excellent yield of 93.7%under the optimal reaction conditions;in contrast,the catalyst prepared by the one-pot synthesis only exhibits a low selectivity near to zero.Furthermore,the gram-scale test catalyzed by the same catalysts exhibits a similar yield of benzylamine in comparison to its smaller scale,which is comparable to the previously reported heterogeneous noble-based catalysts.More surprisingly,the prepared catalysts can be expediently recycled by a magnetic bar and remain the satisfying catalytic activity after reusing up to five times.In conclusion,these developed catalysts enable the synthesis of functional amines with excellent selectivity and carbon balance,proving cost-effective and sustainable access to the wide application of reductive amination.展开更多
Methanation is an effective way to efficiently utilize product gas generated from the pyrolysis and gasification of organic solid wastes.To deeply study the heat transfer and mass transfer mechanisms in the reactor,a ...Methanation is an effective way to efficiently utilize product gas generated from the pyrolysis and gasification of organic solid wastes.To deeply study the heat transfer and mass transfer mechanisms in the reactor,a successful three-dimensional comprehensive model has been established.Multiphase flow behavior and heat transfer mechanisms were investigated under reference working conditions.Temperature is determined by the heat release of the reaction and the heat transfer of the gas-solid flow.The maximum temperature can reach 951 K where the catalyst gathers.In the simulation,changes in the gas inlet velocity and catalyst flow rate were made to explore their effects on CO conversion rate and temperature for optimization purposes.As the inlet gas velocity increases from 2.78 to 4.79 m/s,the CO conversion rate decreases from 81.6%to 72.4%.However,more heat is removed from the reactor,and the temperature rise increases from 78.03 to 113.49 K.When the catalyst flow rate is increased from 7.18 to 17.96 kg/(m^(2)·s),the mass of the catalyst in the reactor is increased from 0.0019 to 0.0042 kg,and the CO conversion rate is increased from 66.8%to 81.5%.However,this increases the maximum temperature in the reactor from 940.0 to 966.4 K.展开更多
Due to growing concerns regarding climate change and environmental protection,smart power generation has become essential for the economical and safe operation of both conventional thermal power plants and sustainable...Due to growing concerns regarding climate change and environmental protection,smart power generation has become essential for the economical and safe operation of both conventional thermal power plants and sustainable energy.Traditional first-principle model-based methods are becoming insufficient when faced with the ever-growing system scale and its various uncertainties.The burgeoning era of machine learning(ML)and data-driven control(DDC)techniques promises an improved alternative to these outdated methods.This paper reviews typical applications of ML and DDC at the level of monitoring,control,optimization,and fault detection of power generation systems,with a particular focus on uncovering how these methods can function in evaluating,counteracting,or withstanding the effects of the associated uncertainties.A holistic view is provided on the control techniques of smart power generation,from the regulation level to the planning level.The benefits of ML and DDC techniques are accordingly interpreted in terms of visibility,maneuverability,flexibility,profitability,and safety(abbreviated as the“5-TYs”),respectively.Finally,an outlook on future research and applications is presented.展开更多
The paper presents an energy performance assessment of CO2 removal for crude synthetic natural gas (SNG) upgrade by Selexol absorption process. A simplified process simulation of the Selexol process concerning power r...The paper presents an energy performance assessment of CO2 removal for crude synthetic natural gas (SNG) upgrade by Selexol absorption process. A simplified process simulation of the Selexol process concerning power requirement and separation performance was developed. The assessment indicates that less pressure difference between crude SNG and absorption pressure favors the energy performance of CO2 removal process. When both crude SNG and absorption pressures are 20 bar, CO2 removal process has the best energy performance. The optimal specific power consumption of the CO2 removal process is 566 kJ/kg CO2 . The sensitivity analysis shows that the CO2 removal efficiency would significantly influence the total power consumption of the removal process, as well as higher heating value (HHV) and CO2 content in SNG. However, the specific power consumption excluding crude SNG and SNG compressions changes little with the variance of CO2 removal efficiency. If by-product CO2 is compressed for CO2 capture, the process would turn into a CO2 -sink for the atmosphere. Correspondingly, an increase of 281 kJ/kg CO2 in specific power consumption is required for compressing the separated CO2 .展开更多
To overcome the shortcomings of the energyconsumption prediction models in the application during thedesign stage, a quick prediction model for energy consumptionis proposed based on the decoupling method. Taking typi...To overcome the shortcomings of the energyconsumption prediction models in the application during thedesign stage, a quick prediction model for energy consumptionis proposed based on the decoupling method. Taking typicalresidential and office buildings in hot summer and cold winterzones as research objects, the influence factors on buildingenergy consumption are classified into intrinsic factors andoperational factors on the basis of the heat transfer principle.Then, using the intrinsic factors as the fundamental variablesand operational factors as the modified variables, the quickprediction model for the buildings in typical cold and hot zonesis proposed based on the decoupling method and the accuracyof the proposed model is verified. The results show thatcompared to the simulation results of EnergyPlus, the relativeerror of the prediction model is less than 1.5% ; comparedwith the real operating data of the building, the relative erroris 13.14% in 2011 and 8.56% in 2012 due to the fact that thecoincidence factor becomes larger than the design value about16% in 2011 and 13% in 2012. The finding reveals that theproposed model has the advantages of rapid calculationcompared with EnergyPlus and Design Builder when predictingbuilding energy consumption in building designs. The energyconsumption prediction model is of great practical value inoptimal operation and building designs.展开更多
In this contribution, one-pot tandem conversion of fructose into biofuel components, including 5-ethoxymethylfurfural(EMF), 2,5-(bis(ethoxymethyl)furan(BEMF) and ethyl levulinate(EL), was performed in an in-situ gener...In this contribution, one-pot tandem conversion of fructose into biofuel components, including 5-ethoxymethylfurfural(EMF), 2,5-(bis(ethoxymethyl)furan(BEMF) and ethyl levulinate(EL), was performed in an in-situ generated catalyst system through consecutive dehydration, etherification, and transfer hydrogenation. Specifically, ZrOCl_2·8H_2O was in-situ decomposed into HCl and ZrO(OH)_2 in ethanol, which effectively catalyzed the dehydration/etherification of fructose to 5-ethoxymethylfurfural(EMF) and subsequent reductive etherification of EMF using ethanol as H-donor, respectively. EMF, BEMF and EL were detected as the main products, and total yield of detectable products of up to 65.4% was obtained at 200 ℃ in only 2 h.展开更多
In the present study,two Ni/YSZ anodes with different volume ratios of Ni and YSZ,30:70 and 45:55 vol%,are operated in dry methane under open circuit and polarized conditions.Three-dimensional(3D)Ni/YSZ microstructure...In the present study,two Ni/YSZ anodes with different volume ratios of Ni and YSZ,30:70 and 45:55 vol%,are operated in dry methane under open circuit and polarized conditions.Three-dimensional(3D)Ni/YSZ microstructures after carbon deposition are reconstructed by the focused ion beam-scanning electron microscopy(FIB-SEM)with the help of machine learning segmentation.From the reconstructed mircostructures,volume fraction,connectivity,three phase boundary(TPB)density,and tortuosity are quantified.In addition,local carbon microstructures are quantitatively reconstructed,and the effect of polarization on carbon morphology is investigated.It is demonstrated that Ni surface in the vicinity of active TPB near the electrolyte is free from carbon formation,while remaining Ni surface at some distances from TPB exhibits severe carbon deposition.In average,total amount of carbon deposition is larger near the electrolyte.These observations imply complex interplay between the electrochemical steam generation and methane cracking on Ni surface which take place very locally near the active TPB.展开更多
Organic solid waste(OSW)contains many renewable materials.The pyrolysis and gasification of OSW can realize resource utilization,and its products can be used for methanation reaction to produce synthetic natural gas i...Organic solid waste(OSW)contains many renewable materials.The pyrolysis and gasification of OSW can realize resource utilization,and its products can be used for methanation reaction to produce synthetic natural gas in the specific reactor.In order to understand the dynamic characteristics of the reactor,a three-dimensional numerical model has been established by the method of Computational Fluid Dynamics(CFD).Along the height of the reactor,the particle distribution in the bed becomes thinner and the mean solid volume fraction decreases from 4.18%to 0.37%.Meanwhile,the pressure fluctuation range decreased from 398.76 Pa at the entrance to a much lower value of 74.47 Pa at the exit.In this simulation,three parameters of gas inlet velocity,operating temperature and solid particle diameter are changed to explore their influences on gas-solid multiphase flow.The results show that gas velocity has a great influence on particle distribution.When the gas inlet velocity decreases from 6.51 to 1.98 m/s,the minimum height that particles can reach decreases from 169 to 100 mm.Additionally,as the operating temperature increases,the particle holdup inside the reactor changes from 0.843%to 0.700%.This indicates that the particle residence time reduces,which is not conducive to the follow-up reaction.Moreover,with the increase of particle size,the fluctuation range of the pressure at the bottom of the reactor increases,and its standard deviation increases from 55.34 to 1266.37 Pa.展开更多
Experiments on simultaneous absorption of SO_2 and NO_X from sintering flue gas via a composite absorbent NaClO_2/NaClO were carried out. The effects of various operating parameters such as NaClO_2 concentration(ms), ...Experiments on simultaneous absorption of SO_2 and NO_X from sintering flue gas via a composite absorbent NaClO_2/NaClO were carried out. The effects of various operating parameters such as NaClO_2 concentration(ms), NaClO concentration(mp), molar ratio of NaClO_2/NaClO(M), solution temperature(TR), initial solution pH, gas flow(Vg) and inlet concentration of SO_2(CS) and NO(CN) on the removal efficiencies of SO_2 and NO were discussed. The optimal experimental conditions were determined to be initial solution pH = 6, TR=55 °C and M = 1.3 under which the average efficiencies of desulfurization and denitrification could reach99.7% and 90.8%, respectively. Moreover, according to the analysis of reaction products, it was found that adding NaClO to NaClO_2 aqueous solution is favorable for the generation of ClO_2 and Cl_2 which have significant effect on desulfurization and denitrification. Finally, engineering experiments were performed and obtained good results demonstrating that this method is practicable and promising.展开更多
It is essential to investigate the light field camera parameters for the accurate flame temperature measurement because the sampling characteristics of the flame radiation can be varied with them. In this study, novel...It is essential to investigate the light field camera parameters for the accurate flame temperature measurement because the sampling characteristics of the flame radiation can be varied with them. In this study, novel indices of the light field camera were proposed to investigate the directional and spatial sampling characteristics of the flame radiation. Effects of light field camera parameters such as focal length and magnification of the main lens, focal length and magnification of the microlens were investigated. It was observed that the sampling characteristics of the flame are varied with the different parameters of the light field camera. The optimized parameters of the light field camera were then proposed for the flame radiation sampling. The larger sampling angle(23 times larger) is achieved by the optimized parameters compared to the commercial light field camera parameters. A non-negative least square(NNLS) algorithm was used to reconstruct the flame temperature. The reconstruction accuracy was also evaluated by the optimized parameters. The results suggested that the optimized parameters can provide higher reconstruction accuracy for axisymmetric and non-symmetric flame conditions in comparison to the commercial light field camera.展开更多
With rapid development of 5G communication technologies,electromagnetic interference(EMI)shielding for electronic devices has become an urgent demand in recent years,where the development of corresponding EMI shieldin...With rapid development of 5G communication technologies,electromagnetic interference(EMI)shielding for electronic devices has become an urgent demand in recent years,where the development of corresponding EMI shielding materials against detrimental electromagnetic radiation plays an essential role.Meanwhile,the EMI shielding materials with high flexibility and functional integrity are highly demanded for emerging shielding applications.Hitherto,a variety of flexible EMI shielding materials with lightweight and multifunctionalities have been developed.In this review,we not only introduce the recent development of flexible EMI shielding materials,but also elaborate the EMI shielding mechanisms and the index for"green EMI shielding"performance.In addition,the construction strategies for sophisticated multifunctionalities of flexible shielding materials are summarized.Finally,we propose several possible research directions for flexible EMI shielding materials in near future,which could be inspirational to the fast-growing next-generation flexible electronic devices with reliable and multipurpose protections as offered by EMI shielding materials.展开更多
A quantitative relationship between safety issues and dendritic lithium(Li) has been rarely investigated yet. Herein the thermal stability of Li deposits with distinct surface area against non-aqueous electrolyte in p...A quantitative relationship between safety issues and dendritic lithium(Li) has been rarely investigated yet. Herein the thermal stability of Li deposits with distinct surface area against non-aqueous electrolyte in pouch-type Li metal batteries is probed. The thermal runaway temperatures of Li metal batteries obtained by accelerating rate calorimeter are reduced from 211 ℃ for Li foil to 111 ℃ for cycled Li.The initial exothermic temperature is reduced from 194 ℃ for routine Li foil to 142 ℃ for 49.5 m~2g^(-1) dendrite. Li with different specific surface areas can regulate the reaction routes during the temperature range from 50 to 300 ℃. The mass percent of Li foil and highly dendritic Li reacting with ethylene carbonate is higher than that of moderately dendritic Li. This contribution can strengthen the understanding of the thermal runaway mechanism and shed fresh light on the rational design of safe Li metal batteries.展开更多
The effect of self-reactivation on the CO_(2) capture capacity of the spent calcium based sorbent was investigated in a dual-fixed bed reactor.The sampled sorbents from the dual-fixed bed reactor were sent for XRD,SEM...The effect of self-reactivation on the CO_(2) capture capacity of the spent calcium based sorbent was investigated in a dual-fixed bed reactor.The sampled sorbents from the dual-fixed bed reactor were sent for XRD,SEM and N_2 adsorption analysis to explain the self-reactivation mechanism.The results show that the CaO in the spent sorbent discharged from the calciner absorbs the vapor in the air to form Ca(OH)_(2) and further Ca(OH)_(2)·2 H_(2) O under environmental conditions,during which process the CO_(2) capture capacity of the spent sorbent can be self-reactivated.The microstructure of the spent sorbent is improved by the self-reactivation process,resulting in more porous microstructure,higher BET surface area and pore volume.Compared with the calcined spent sorbent that has experienced 20 cycles,the pore volume and BET surface area are increased by 6.69 times and 56.3% after self-reactivation when φ=170%.The improved microstructure makes it easier for the CO_(2) diffusion and carbonation reaction in the sorbent.Therefore,the CO_(2) capture capacity of the spent sorbent is enhanced by self-reactivation process.A self-reactivation process coupled with calcium looping process was proposed to reuse the discharged spent calcium based sorbent from the calciner.Higher average carbonation conversion and CO_(2) capture efficiency can be achieved when self-reactivated spent sorbent is used as supplementary sorbent in the calciner rather than fresh CaCO_(3) under the same conditions.展开更多
Solid oxide fuel cells (SOFCs) are considered to be one of the most important clean,distributed resources. However,SOFCs present a challenging control problem owing to their slow dynamics,nonlinearity and tight operat...Solid oxide fuel cells (SOFCs) are considered to be one of the most important clean,distributed resources. However,SOFCs present a challenging control problem owing to their slow dynamics,nonlinearity and tight operating constraints. A novel data-driven nonlinear control strategy was proposed to solve the SOFC control problem by combining a virtual reference feedback tuning (VRFT) method and support vector machine. In order to fulfill the requirement for fuel utilization and control constraints,a dynamic constraints unit and an anti-windup scheme were adopted. In addition,a feedforward loop was designed to deal with the current disturbance. Detailed simulations demonstrate that the fast response of fuel flow for the current demand disturbance and zero steady error of the output voltage are both achieved. Meanwhile,fuel utilization is kept almost within the safe region.展开更多
Pyrolysis and heat transfer characteristics of single large biomass particle were investigated using threedimensional unsteady heat transfer model coupled with chemical reactions.The consumption of biomass and the pro...Pyrolysis and heat transfer characteristics of single large biomass particle were investigated using threedimensional unsteady heat transfer model coupled with chemical reactions.The consumption of biomass and the production of products were simulated.Some experiments were designed to provide model parameters for simulation calculations.The simulation was verified by pyrolysis experiments of large biomass particle in a vertical tube furnace.The simulation results show the internal heat and mass transfer law during the pyrolysis of large biomass particle.When the biomass particle diameter is between 10 and 30 mm,for every 5 mm increase in particle diameter,the time required for complete pyrolysis will increase on average by about 50 s.When the pyrolysis temperature is between 673 K and 873 K,a slight decrease in the pyrolysis temperature will cause the time required for the biomass to fully pyrolyze to rise significantly.And the phenomenon is more obvious in the low temperature range.The results indicate that the numerical simulation agrees well with the experimental results.展开更多
Polymer shells with high sphericity and uniform wall thickness are always needed in the inertial confined fusion(ICF)experiments.Driven by the need to control the shape of water-in-oil(W1/O)compound droplets,the effec...Polymer shells with high sphericity and uniform wall thickness are always needed in the inertial confined fusion(ICF)experiments.Driven by the need to control the shape of water-in-oil(W1/O)compound droplets,the effects of the density matching level,the interfacial tension and the rotation speed of the continuing fluid field on the sphericity and wall thickness uniformity of the resulting polymer shells were investigated and the spherical and concentric mechanisms were also discussed.The centering of W1/O compound droplets,the location and movement of W1/O compound droplets in the external phase(W2)were significantly affected by the density matching level of the key stage and the rotation speed of the continuing fluid field.Therefore,by optimizing the density matching level and rotation speed,the batch yield of polystyrene(PS)shells with high sphericity and uniform wall thickness increased.Moreover,the sphericity also increased by raising the oil/water(O/W2)interfacial tension,which drove a droplet to be spherical.The experimental results show that the spherical driving force is from the interfacial tension affected by the two relative phases,while the concentric driving force,as a resultant force,is not only affected by the three phases,but also by the continuing fluid field.The understanding of spherical and concentric mechanism can provide some guidance for preparing polymer shells with high sphericity and uniform wall thickness.展开更多
The cheap manganese sand was first modified by H2O2 and was further creatively utilized as Ni-based catalyst support.In order to enhance the catalytic performance,Re was added into the Ni-based catalyst and the promot...The cheap manganese sand was first modified by H2O2 and was further creatively utilized as Ni-based catalyst support.In order to enhance the catalytic performance,Re was added into the Ni-based catalyst and the promotion effect of Re on the methanation coupling with water gas shift of biogas was investigated from the perspective of activation energy.It was found that CH4 and CO2 formation rates,which separately represented the reaction rate of methanation and water gas shift,were both enhanced after Re addition compared to non-added catalyst.Two kinetics models including empirical model and K-model were employed and from the results of calculation,it showed that Re selectively decreased the activation energy of methanation reaction and had little impact on the activation energy of water gas shift.The increased CO2 formation rate was owing to the assistance of accelerated H2O production from methanation rather than the activation energy change in water gas shift.展开更多
Chemical looping gasification(CLG)is a promising technology for high-quality syngas production.One key issue to successful CLG is the selection of high-performance oxygen carrier.In this study,several Ca-and Mg-rich s...Chemical looping gasification(CLG)is a promising technology for high-quality syngas production.One key issue to successful CLG is the selection of high-performance oxygen carrier.In this study,several Ca-and Mg-rich steelmaking wastes from steel industry,such as blast furnace slag(BF slag),blast furnace dust(BF dust)and Linz-Donawitz converter slag(LD slag),were used as oxygen carriers in chemical looping gasification of biomass.The results showed that the reducibility of Ca-and Mg-rich waste,especially LD slag and BF dust,was superior to that of hematite.Considering long-term operation,the cyclic stability of steelmaking waste was tested.BF dust showed a poor stability,while the other carrier(hematite,BF slag or LD slag)presented an excellent stability during multiple redox cycles in spite of partial sintering and agglomeration.Moreover,the effects of supply oxygen coefficient(O/B ratio)and reaction temperature on CLG of biomass were investigated.The results revealed that Ca-and Mg-rich waste exhibited a higher syngas production compared to hematite.The higher performance could be attributed to the improved reduction rate of Fe2O3 and gasification rate of biomass by Ca or Mg in steelmaking waste.In addition,LD slag exhibited the higher gas value at the O/B ratio of 1 at 900℃.As a consequence,LD slag was an appropriate oxygen carrier for CLG of biomass in terms of perfect reducibility,superior cyclic stability and high reactivity.展开更多
Phase change materials(PCMs)are important for sustaining energy development.For the thermal performance enhancement,the composite PCM with metal foam reconstructed by the Voronoi method is investigated in this work.Th...Phase change materials(PCMs)are important for sustaining energy development.For the thermal performance enhancement,the composite PCM with metal foam reconstructed by the Voronoi method is investigated in this work.The lattice Boltzmann method(LBM)is used to analyze the melting process on a pore scale.The melting interface evolution and temperature contour of the composite PCM are explored and compared with those of pure PCM.Moreover,structure parameters including the pore density,porosity and irregularity are investigated comprehensively,indicating that the additive of metal foam strengthens the melting performance of PCM obviously.Compared with pure PCM,the composite PCM has quick rates of the melting front evolution and heat transfer.The heat conduction plays a great role in the whole melting process since the convection is weakened for the composite PCM.To improve the melting efficiency,a larger pore density and smaller irregularity are recommended in general.More significantly,a suitable porosity is determined based on the requirement for the balance between the melting rate and heat storage capacity in practical engineering.展开更多
基金funded by grants from the National Natural Science Foundation of China(No.52236010,51876210)the Fundamental Research Funds for the Central Universities(No.2242022R10058)。
文摘In this work,a“cyclopentanone-vanillin”strategy was proposed for the preparation of jet fuel range cycloalkanes from lignocellulose-derived ketones and lignin-derived aldehydes via aldol condensation and hydrodeoxygenation(HDO).Ethanolamine lactate ionic liquid(LAIL)exhibited excellent catalytic activity in the aldol condensation of cyclopentanone and vanillin.Desired mono-condensation and bicondensation products were obtained with yield of 95.2%at 100℃.It is found that the synergy effects between amino group of ethanolamine and hydroxyl group of lactic acid play a key role in the aldol condensation.The condensation products were converted into cycloalkanes by HDO over 5%Pd/Nb_(2)O_(5)catalyst.The density of the obtained HDO products is 0.89 g/cm^(3)and the freezing point is lower than-60℃.These results suggest that the resulted cycloalkanes can be used as additives to improve the density and low-temperature fluidity of the jet fuels.
基金This work was supported financially by the National Key R&D Program of China(2018YFB1501500)National Natural Science Foundation of China(51976225).
文摘Since the utilization of abundant biomass to develop advanced materials has become an utmost priority in recent years,we developed two sustainable routes(i.e.,the impregnation method and the one-pot synthesis)to prepare the hydrochar-supported catalysts and tested its catalytic performance on the reductive amination.Several techniques,such as TEM,XRD and XPS,were adopted to characterize the structural and catalytic features of samples.Results indicated that the impregnation method favors the formation of outer-sphere surface complexes with porous structure as well as well-distributed metallic nanoparticles,while the one-pot synthesis tends to form the inner-sphere surface complexes with relatively smooth appearance and amorphous metals.This difference explains the better activity of catalysts prepared by the impregnation method which can selectively convert benzaldehyde to benzylamine with an excellent yield of 93.7%under the optimal reaction conditions;in contrast,the catalyst prepared by the one-pot synthesis only exhibits a low selectivity near to zero.Furthermore,the gram-scale test catalyzed by the same catalysts exhibits a similar yield of benzylamine in comparison to its smaller scale,which is comparable to the previously reported heterogeneous noble-based catalysts.More surprisingly,the prepared catalysts can be expediently recycled by a magnetic bar and remain the satisfying catalytic activity after reusing up to five times.In conclusion,these developed catalysts enable the synthesis of functional amines with excellent selectivity and carbon balance,proving cost-effective and sustainable access to the wide application of reductive amination.
基金supported by the National Key Research and Development Program of China[Grant Number 2019YFC1906802].
文摘Methanation is an effective way to efficiently utilize product gas generated from the pyrolysis and gasification of organic solid wastes.To deeply study the heat transfer and mass transfer mechanisms in the reactor,a successful three-dimensional comprehensive model has been established.Multiphase flow behavior and heat transfer mechanisms were investigated under reference working conditions.Temperature is determined by the heat release of the reaction and the heat transfer of the gas-solid flow.The maximum temperature can reach 951 K where the catalyst gathers.In the simulation,changes in the gas inlet velocity and catalyst flow rate were made to explore their effects on CO conversion rate and temperature for optimization purposes.As the inlet gas velocity increases from 2.78 to 4.79 m/s,the CO conversion rate decreases from 81.6%to 72.4%.However,more heat is removed from the reactor,and the temperature rise increases from 78.03 to 113.49 K.When the catalyst flow rate is increased from 7.18 to 17.96 kg/(m^(2)·s),the mass of the catalyst in the reactor is increased from 0.0019 to 0.0042 kg,and the CO conversion rate is increased from 66.8%to 81.5%.However,this increases the maximum temperature in the reactor from 940.0 to 966.4 K.
文摘Due to growing concerns regarding climate change and environmental protection,smart power generation has become essential for the economical and safe operation of both conventional thermal power plants and sustainable energy.Traditional first-principle model-based methods are becoming insufficient when faced with the ever-growing system scale and its various uncertainties.The burgeoning era of machine learning(ML)and data-driven control(DDC)techniques promises an improved alternative to these outdated methods.This paper reviews typical applications of ML and DDC at the level of monitoring,control,optimization,and fault detection of power generation systems,with a particular focus on uncovering how these methods can function in evaluating,counteracting,or withstanding the effects of the associated uncertainties.A holistic view is provided on the control techniques of smart power generation,from the regulation level to the planning level.The benefits of ML and DDC techniques are accordingly interpreted in terms of visibility,maneuverability,flexibility,profitability,and safety(abbreviated as the“5-TYs”),respectively.Finally,an outlook on future research and applications is presented.
基金supported by the Special Fund for Major State Basic Research Projects of China(2010CB732206)
文摘The paper presents an energy performance assessment of CO2 removal for crude synthetic natural gas (SNG) upgrade by Selexol absorption process. A simplified process simulation of the Selexol process concerning power requirement and separation performance was developed. The assessment indicates that less pressure difference between crude SNG and absorption pressure favors the energy performance of CO2 removal process. When both crude SNG and absorption pressures are 20 bar, CO2 removal process has the best energy performance. The optimal specific power consumption of the CO2 removal process is 566 kJ/kg CO2 . The sensitivity analysis shows that the CO2 removal efficiency would significantly influence the total power consumption of the removal process, as well as higher heating value (HHV) and CO2 content in SNG. However, the specific power consumption excluding crude SNG and SNG compressions changes little with the variance of CO2 removal efficiency. If by-product CO2 is compressed for CO2 capture, the process would turn into a CO2 -sink for the atmosphere. Correspondingly, an increase of 281 kJ/kg CO2 in specific power consumption is required for compressing the separated CO2 .
文摘To overcome the shortcomings of the energyconsumption prediction models in the application during thedesign stage, a quick prediction model for energy consumptionis proposed based on the decoupling method. Taking typicalresidential and office buildings in hot summer and cold winterzones as research objects, the influence factors on buildingenergy consumption are classified into intrinsic factors andoperational factors on the basis of the heat transfer principle.Then, using the intrinsic factors as the fundamental variablesand operational factors as the modified variables, the quickprediction model for the buildings in typical cold and hot zonesis proposed based on the decoupling method and the accuracyof the proposed model is verified. The results show thatcompared to the simulation results of EnergyPlus, the relativeerror of the prediction model is less than 1.5% ; comparedwith the real operating data of the building, the relative erroris 13.14% in 2011 and 8.56% in 2012 due to the fact that thecoincidence factor becomes larger than the design value about16% in 2011 and 13% in 2012. The finding reveals that theproposed model has the advantages of rapid calculationcompared with EnergyPlus and Design Builder when predictingbuilding energy consumption in building designs. The energyconsumption prediction model is of great practical value inoptimal operation and building designs.
基金financial support from the National Natural Science Foundation of China (Grant Nos.21706223 21776234+7 种基金 21676223 21506177)the Fundamental Research Funds for the Central Universities (Grant Nos. 20720160087 20720160077)the Natural Science Foundation of Fujian Province of China (Grant Nos. 2016J01077 2015J05034 2014J01209)the Education Department of Fujian Province (Grant No. JZ160398)
文摘In this contribution, one-pot tandem conversion of fructose into biofuel components, including 5-ethoxymethylfurfural(EMF), 2,5-(bis(ethoxymethyl)furan(BEMF) and ethyl levulinate(EL), was performed in an in-situ generated catalyst system through consecutive dehydration, etherification, and transfer hydrogenation. Specifically, ZrOCl_2·8H_2O was in-situ decomposed into HCl and ZrO(OH)_2 in ethanol, which effectively catalyzed the dehydration/etherification of fructose to 5-ethoxymethylfurfural(EMF) and subsequent reductive etherification of EMF using ethanol as H-donor, respectively. EMF, BEMF and EL were detected as the main products, and total yield of detectable products of up to 65.4% was obtained at 200 ℃ in only 2 h.
基金partly supported by the New Energy and Industrial Technology Development Organization(NEDO)by the Japan Society for the Promotion of Science KAKENHI(21K14090)+3 种基金the National Key R&D Program of China(2019YFE0122000)the Scientific Research Foundation of Graduate School of Southeast University(YBPY2106)the China Scholarship Councilby the Advanced Research Infrastructure for Materials and Nanotechnology in Japan(ARIM Japan)sponsored by the Ministry of Education,Culture,Sport,Science and Technology(MEXT),Japan。
文摘In the present study,two Ni/YSZ anodes with different volume ratios of Ni and YSZ,30:70 and 45:55 vol%,are operated in dry methane under open circuit and polarized conditions.Three-dimensional(3D)Ni/YSZ microstructures after carbon deposition are reconstructed by the focused ion beam-scanning electron microscopy(FIB-SEM)with the help of machine learning segmentation.From the reconstructed mircostructures,volume fraction,connectivity,three phase boundary(TPB)density,and tortuosity are quantified.In addition,local carbon microstructures are quantitatively reconstructed,and the effect of polarization on carbon morphology is investigated.It is demonstrated that Ni surface in the vicinity of active TPB near the electrolyte is free from carbon formation,while remaining Ni surface at some distances from TPB exhibits severe carbon deposition.In average,total amount of carbon deposition is larger near the electrolyte.These observations imply complex interplay between the electrochemical steam generation and methane cracking on Ni surface which take place very locally near the active TPB.
基金Funding Statement:This work was supported by the National Key Research and Development Program of China[Grant No.2019YFC1906802].
文摘Organic solid waste(OSW)contains many renewable materials.The pyrolysis and gasification of OSW can realize resource utilization,and its products can be used for methanation reaction to produce synthetic natural gas in the specific reactor.In order to understand the dynamic characteristics of the reactor,a three-dimensional numerical model has been established by the method of Computational Fluid Dynamics(CFD).Along the height of the reactor,the particle distribution in the bed becomes thinner and the mean solid volume fraction decreases from 4.18%to 0.37%.Meanwhile,the pressure fluctuation range decreased from 398.76 Pa at the entrance to a much lower value of 74.47 Pa at the exit.In this simulation,three parameters of gas inlet velocity,operating temperature and solid particle diameter are changed to explore their influences on gas-solid multiphase flow.The results show that gas velocity has a great influence on particle distribution.When the gas inlet velocity decreases from 6.51 to 1.98 m/s,the minimum height that particles can reach decreases from 169 to 100 mm.Additionally,as the operating temperature increases,the particle holdup inside the reactor changes from 0.843%to 0.700%.This indicates that the particle residence time reduces,which is not conducive to the follow-up reaction.Moreover,with the increase of particle size,the fluctuation range of the pressure at the bottom of the reactor increases,and its standard deviation increases from 55.34 to 1266.37 Pa.
基金Supported by the National Science Foundation of China for Distinguished Young Scholars(No.51325601)Major Program of National Science Foundation of China(No.51390492)Joint Funds of National Science Foundation of China(No.U1560205)
文摘Experiments on simultaneous absorption of SO_2 and NO_X from sintering flue gas via a composite absorbent NaClO_2/NaClO were carried out. The effects of various operating parameters such as NaClO_2 concentration(ms), NaClO concentration(mp), molar ratio of NaClO_2/NaClO(M), solution temperature(TR), initial solution pH, gas flow(Vg) and inlet concentration of SO_2(CS) and NO(CN) on the removal efficiencies of SO_2 and NO were discussed. The optimal experimental conditions were determined to be initial solution pH = 6, TR=55 °C and M = 1.3 under which the average efficiencies of desulfurization and denitrification could reach99.7% and 90.8%, respectively. Moreover, according to the analysis of reaction products, it was found that adding NaClO to NaClO_2 aqueous solution is favorable for the generation of ClO_2 and Cl_2 which have significant effect on desulfurization and denitrification. Finally, engineering experiments were performed and obtained good results demonstrating that this method is practicable and promising.
基金supported by the National Natural Science Foundation of China(Grant Nos.51676044 and 51327803)the Social Development Project of Jiangsu Province,China(Grant No.BE20187053)+1 种基金the Postgraduate Research and Practice Innovation Program of Jiangsu Province,China(Grant No.KYCX170081)China Scholarship Council
文摘It is essential to investigate the light field camera parameters for the accurate flame temperature measurement because the sampling characteristics of the flame radiation can be varied with them. In this study, novel indices of the light field camera were proposed to investigate the directional and spatial sampling characteristics of the flame radiation. Effects of light field camera parameters such as focal length and magnification of the main lens, focal length and magnification of the microlens were investigated. It was observed that the sampling characteristics of the flame are varied with the different parameters of the light field camera. The optimized parameters of the light field camera were then proposed for the flame radiation sampling. The larger sampling angle(23 times larger) is achieved by the optimized parameters compared to the commercial light field camera parameters. A non-negative least square(NNLS) algorithm was used to reconstruct the flame temperature. The reconstruction accuracy was also evaluated by the optimized parameters. The results suggested that the optimized parameters can provide higher reconstruction accuracy for axisymmetric and non-symmetric flame conditions in comparison to the commercial light field camera.
基金This work was financially supported by the National Natural Science Foundation of China(51725101,11727807,51672050,61790581,52102368,52101213)the Ministry of Science and Technology of China(973 Project No.2018YFA0209102)+6 种基金University Development Fund(UDF0100152)the Program for Guangdong Introducing Innovative and Entrepreneurial Teams(Grant No.2017ZT07C291)Shenzhen Science and Technology Program(Grant No.KQTD20170810141424366)China Postdoctoral Science Foundation(Grant No.2020M680085)Regional Joint Fund for Basic Research and Applied Basic Research of Guangdong Province(No.2020SA001515110905)Science and Technology Department of Jiangsu Province of China(Grant No.BK20210261)Open access funding provided by Shanghai Jiao Tong University
文摘With rapid development of 5G communication technologies,electromagnetic interference(EMI)shielding for electronic devices has become an urgent demand in recent years,where the development of corresponding EMI shielding materials against detrimental electromagnetic radiation plays an essential role.Meanwhile,the EMI shielding materials with high flexibility and functional integrity are highly demanded for emerging shielding applications.Hitherto,a variety of flexible EMI shielding materials with lightweight and multifunctionalities have been developed.In this review,we not only introduce the recent development of flexible EMI shielding materials,but also elaborate the EMI shielding mechanisms and the index for"green EMI shielding"performance.In addition,the construction strategies for sophisticated multifunctionalities of flexible shielding materials are summarized.Finally,we propose several possible research directions for flexible EMI shielding materials in near future,which could be inspirational to the fast-growing next-generation flexible electronic devices with reliable and multipurpose protections as offered by EMI shielding materials.
基金supported by the National Key Research and Development Program(2021YFB2500300)the National Natural Science Foundation of China(22179070,22109084,22075029,and U1932220)+1 种基金the China Postdoctoral Science Foundation(2021TQ0161 and 2021M691709)the Beijing Natural Science Foundation(JQ20004)。
文摘A quantitative relationship between safety issues and dendritic lithium(Li) has been rarely investigated yet. Herein the thermal stability of Li deposits with distinct surface area against non-aqueous electrolyte in pouch-type Li metal batteries is probed. The thermal runaway temperatures of Li metal batteries obtained by accelerating rate calorimeter are reduced from 211 ℃ for Li foil to 111 ℃ for cycled Li.The initial exothermic temperature is reduced from 194 ℃ for routine Li foil to 142 ℃ for 49.5 m~2g^(-1) dendrite. Li with different specific surface areas can regulate the reaction routes during the temperature range from 50 to 300 ℃. The mass percent of Li foil and highly dendritic Li reacting with ethylene carbonate is higher than that of moderately dendritic Li. This contribution can strengthen the understanding of the thermal runaway mechanism and shed fresh light on the rational design of safe Li metal batteries.
基金supported by the National Natural Science Foundation of China (51706094)。
文摘The effect of self-reactivation on the CO_(2) capture capacity of the spent calcium based sorbent was investigated in a dual-fixed bed reactor.The sampled sorbents from the dual-fixed bed reactor were sent for XRD,SEM and N_2 adsorption analysis to explain the self-reactivation mechanism.The results show that the CaO in the spent sorbent discharged from the calciner absorbs the vapor in the air to form Ca(OH)_(2) and further Ca(OH)_(2)·2 H_(2) O under environmental conditions,during which process the CO_(2) capture capacity of the spent sorbent can be self-reactivated.The microstructure of the spent sorbent is improved by the self-reactivation process,resulting in more porous microstructure,higher BET surface area and pore volume.Compared with the calcined spent sorbent that has experienced 20 cycles,the pore volume and BET surface area are increased by 6.69 times and 56.3% after self-reactivation when φ=170%.The improved microstructure makes it easier for the CO_(2) diffusion and carbonation reaction in the sorbent.Therefore,the CO_(2) capture capacity of the spent sorbent is enhanced by self-reactivation process.A self-reactivation process coupled with calcium looping process was proposed to reuse the discharged spent calcium based sorbent from the calciner.Higher average carbonation conversion and CO_(2) capture efficiency can be achieved when self-reactivated spent sorbent is used as supplementary sorbent in the calciner rather than fresh CaCO_(3) under the same conditions.
基金Projects(51076027,51036002) supported by the National Natural Science Foundation of ChinaProject(20090092110051) supported by the Doctoral Fund of Ministry of Education of China
文摘Solid oxide fuel cells (SOFCs) are considered to be one of the most important clean,distributed resources. However,SOFCs present a challenging control problem owing to their slow dynamics,nonlinearity and tight operating constraints. A novel data-driven nonlinear control strategy was proposed to solve the SOFC control problem by combining a virtual reference feedback tuning (VRFT) method and support vector machine. In order to fulfill the requirement for fuel utilization and control constraints,a dynamic constraints unit and an anti-windup scheme were adopted. In addition,a feedforward loop was designed to deal with the current disturbance. Detailed simulations demonstrate that the fast response of fuel flow for the current demand disturbance and zero steady error of the output voltage are both achieved. Meanwhile,fuel utilization is kept almost within the safe region.
基金supported by the National Key Research and Development Program of China (Grand No. 2019YFD1100602)the National Natural Science Fund for Excellent Young Scholar of China (Grant No. 51822604)+1 种基金the National Natural Foundation of China (Grand No. 51676045)the Natural Science Fund of Jiangsu Province for Distinguished Young Scholar (Grand No. BK20180014)。
文摘Pyrolysis and heat transfer characteristics of single large biomass particle were investigated using threedimensional unsteady heat transfer model coupled with chemical reactions.The consumption of biomass and the production of products were simulated.Some experiments were designed to provide model parameters for simulation calculations.The simulation was verified by pyrolysis experiments of large biomass particle in a vertical tube furnace.The simulation results show the internal heat and mass transfer law during the pyrolysis of large biomass particle.When the biomass particle diameter is between 10 and 30 mm,for every 5 mm increase in particle diameter,the time required for complete pyrolysis will increase on average by about 50 s.When the pyrolysis temperature is between 673 K and 873 K,a slight decrease in the pyrolysis temperature will cause the time required for the biomass to fully pyrolyze to rise significantly.And the phenomenon is more obvious in the low temperature range.The results indicate that the numerical simulation agrees well with the experimental results.
基金the China Academy of Engi-neering Physics for financial support(2014B0302052)National Natural Science Foundation of China(U1530260).
文摘Polymer shells with high sphericity and uniform wall thickness are always needed in the inertial confined fusion(ICF)experiments.Driven by the need to control the shape of water-in-oil(W1/O)compound droplets,the effects of the density matching level,the interfacial tension and the rotation speed of the continuing fluid field on the sphericity and wall thickness uniformity of the resulting polymer shells were investigated and the spherical and concentric mechanisms were also discussed.The centering of W1/O compound droplets,the location and movement of W1/O compound droplets in the external phase(W2)were significantly affected by the density matching level of the key stage and the rotation speed of the continuing fluid field.Therefore,by optimizing the density matching level and rotation speed,the batch yield of polystyrene(PS)shells with high sphericity and uniform wall thickness increased.Moreover,the sphericity also increased by raising the oil/water(O/W2)interfacial tension,which drove a droplet to be spherical.The experimental results show that the spherical driving force is from the interfacial tension affected by the two relative phases,while the concentric driving force,as a resultant force,is not only affected by the three phases,but also by the continuing fluid field.The understanding of spherical and concentric mechanism can provide some guidance for preparing polymer shells with high sphericity and uniform wall thickness.
基金Supported by the International S&T Cooperation Program of China(ISTCP,2014DFE70150)the National Key R&D Program of China(2018YFC1901200)+1 种基金the Scientific Research Foundation of Graduate School of Southeast University(YBJJ1803)the UK-China Joint Research and Innovation Partnership Fund provided by China Scholarship Council and The British Council(201703780063)。
文摘The cheap manganese sand was first modified by H2O2 and was further creatively utilized as Ni-based catalyst support.In order to enhance the catalytic performance,Re was added into the Ni-based catalyst and the promotion effect of Re on the methanation coupling with water gas shift of biogas was investigated from the perspective of activation energy.It was found that CH4 and CO2 formation rates,which separately represented the reaction rate of methanation and water gas shift,were both enhanced after Re addition compared to non-added catalyst.Two kinetics models including empirical model and K-model were employed and from the results of calculation,it showed that Re selectively decreased the activation energy of methanation reaction and had little impact on the activation energy of water gas shift.The increased CO2 formation rate was owing to the assistance of accelerated H2O production from methanation rather than the activation energy change in water gas shift.
基金supported by the National Natural Science Foundation of China(Grant No.52006104)the Fundamental Research Funds for the Central Universities(No.30919011237)。
文摘Chemical looping gasification(CLG)is a promising technology for high-quality syngas production.One key issue to successful CLG is the selection of high-performance oxygen carrier.In this study,several Ca-and Mg-rich steelmaking wastes from steel industry,such as blast furnace slag(BF slag),blast furnace dust(BF dust)and Linz-Donawitz converter slag(LD slag),were used as oxygen carriers in chemical looping gasification of biomass.The results showed that the reducibility of Ca-and Mg-rich waste,especially LD slag and BF dust,was superior to that of hematite.Considering long-term operation,the cyclic stability of steelmaking waste was tested.BF dust showed a poor stability,while the other carrier(hematite,BF slag or LD slag)presented an excellent stability during multiple redox cycles in spite of partial sintering and agglomeration.Moreover,the effects of supply oxygen coefficient(O/B ratio)and reaction temperature on CLG of biomass were investigated.The results revealed that Ca-and Mg-rich waste exhibited a higher syngas production compared to hematite.The higher performance could be attributed to the improved reduction rate of Fe2O3 and gasification rate of biomass by Ca or Mg in steelmaking waste.In addition,LD slag exhibited the higher gas value at the O/B ratio of 1 at 900℃.As a consequence,LD slag was an appropriate oxygen carrier for CLG of biomass in terms of perfect reducibility,superior cyclic stability and high reactivity.
基金supported by the National Natural Science Foundation of China(Grant Nos.51876184,51725602,and 51806147)the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20180102).
文摘Phase change materials(PCMs)are important for sustaining energy development.For the thermal performance enhancement,the composite PCM with metal foam reconstructed by the Voronoi method is investigated in this work.The lattice Boltzmann method(LBM)is used to analyze the melting process on a pore scale.The melting interface evolution and temperature contour of the composite PCM are explored and compared with those of pure PCM.Moreover,structure parameters including the pore density,porosity and irregularity are investigated comprehensively,indicating that the additive of metal foam strengthens the melting performance of PCM obviously.Compared with pure PCM,the composite PCM has quick rates of the melting front evolution and heat transfer.The heat conduction plays a great role in the whole melting process since the convection is weakened for the composite PCM.To improve the melting efficiency,a larger pore density and smaller irregularity are recommended in general.More significantly,a suitable porosity is determined based on the requirement for the balance between the melting rate and heat storage capacity in practical engineering.
