Vaporization transition between mechanical seal faces plays an important role in the operation performance of mechanical seals, which is one of key issues in mechanical seals research and applications.A review on mechanical seals operating with vaporization transition is introduced from the aspects of physical principle, experimental research and theoretical research, respectively.The physical principle and possible damages of film vaporization in mechanical seals are described.The progress from original phenomenon observation to quantitative experiments on steady and transient states and the major achievements are presented.Mathematical models and their development from 2-D axisymmetry models to 3-D models, from steady state to transient state and from discrete boiling models to continuous boiling models are summarized.Based on the above review, the research directions of two-phase mechanical seals are proposed.

Due to the unique features,such as rich self-assembly driving forces,novel self-assembly nanostructures,multiple special capabilities and good biocompatibility,short peptide based self-assembled nanomaterials are extremely attractive as building blocks for nano-biomaterials,skin care and cosmetics,drug delivery,tissue engineering scaffolds and many other applications.Because the self-assembling peptides are constituted by natural amino acids,the self-assembled nanomaterials have low cell toxicity,controlled degradation,reduced of side effects of drugs,high delivery efficiency,enhanced drug targeting property,improved gene transfection efficiency and cellular uptake rate.Therefore,there will be promising prospect for the development of peptides used as drug and gene delivery.Using the peptide based self-assembled nanomaterials as the carrier of hydrophobic anticancer drugs,protein drugs,gene and other therapeutic agents has become the research priorities of biomedical science.The progress and applications of the self-assembled peptide based nanomaterials as a loaded carrier in the biomedical science were reviewed. Moreover,the interaction mechanism and characteristics of some bioactive peptide based materials with the therapeutic agents were also introduced.

A three dimensional numerical model was developed for the description of the physical processes in the electrostatic precipitator(ESP),including fluid flow,corona discharge,particle charging and particle dynamics.Fluid flow was solved using the time-averaged Navier-Stokes equation and the standard κ-ε turbulent model.The electric field generated by corona discharge was solved using an unstructured finite volume method.Particle motion was modeled using the Lagrangian method.Particle charge was calculated by the integration of the charging rate equation.The Rosin-Rammler distribution was used to model particle size distribution.The model was verified by comparing the numerical results with the experimental data of a laboratory scale ESP.The model predictions of plate current density and particle transverse velocity agreed well with the measurements.Finally,the characteristics of fluid flow distribution,particle charging process,particle trajectories and collection efficiency were analyzed.

In a large scale circulating fluidized bed(CFB)device,an experimental study was conducted on the relationship between solids circulating rate and opening rate of plate valve installed in the standpipe under negative pressure gradient.The fluidized patterns and pressure fluctuations above and below the plate valve were measured for analyzing the plate valve operation process.Experimental results showed that there was a critical opening rate of plate valve,which divided the opening of the plate valve into uncontrolled range and controlled range for solids circulating rate regulation.When opening rate was greater than the critical value,the plate valve had no action on solids circulating rate regulation.The fluidized patterns above and below the plate valve were the same,and the pressure fluctuation profiles were similar.When open rate was smaller than the critical value,the plate valve had the function of solids circulating rate regulation.The fluidized pattern above the plate valve was moving bed,and the fluidized pattern was like raining flow below the plate valve.The pressure fluctuation profile above the plate valve was different from that below the plate valve.

Modifications of coherent structures in a turbulent boundary layer of dilute gas-particle horizontal channel flow were experimentally investigated by means of simultaneous two-phase PIV(particle image velocimetry)measurement.The measurements were conducted in the near-wall region at Reynolds number of 430 based on the wall friction velocity and half channel height.Polyethylene beads with the diameter of 110 μm were used as the dispersed phase,and three low mass loading ratios ranging from 10^-4 to 10^-3 were tested.Spatial two-point correlations of fluctuation velocities and quadrant analysis were adopted to examine the change of characteristics of turbulent coherent structures in the lower boundary layer.It was found that the addition of particles noticeably modified the turbulence structures in meso-scale near the wall event at mass loading ratio 0.025%,thereby affected the gas-phase turbulence characteristics in macro-scale,e.g.fluctuation velocities and Reynolds shear stress etc.Particle sedimentation increased the roughness of the bottom wall,which significantly enhanced turbulent bursting in the inner region of the boundary layer.And then the wall-normal fluctuation velocity and Reynolds shear stress were both increased in the viscous sublayer.Under the effect of particle-wall collision,the Q2 events(ejections)of gas-phase were slightly increased by particles,while the Q4 events(sweeps)were obviously decreased.In addition,the spatial scale of the wall structures also remarkably shrink under the intensified crossing-trajectory effects due to particle saltation near the bottom wall.Consequently,the presence of the particles suppressed the turbulent coherent structures in the outer region of the boundary layer,which resulted in significantly decreasing wall-normal fluctuation velocity and Reynolds shear stress of the gas-phase above the viscous sublayer.Particle inertia changed the viscous sublayer of gas turbulence with a smaller thickness and a larger streamwise velocity gradient,which increased the peak value of streamwise fluctuation velocity of the gas-phase with its location shifting to the wall.

The flow and heat transfer characteristics over solid wavy surface and flexible wavy surface are investigated with large eddy simulation.For the solid wavy surface,it is found that smaller wave amplitude of wavy surface does not form the recirculation in the valley.When a/λ is increased to 0.03,the flow separation appears in the valley,and the range of recirculation area becomes broader as the amplitude increases.The spindle-shaped spots with higher Nusselt number value are observed in the up-slope of the wavy surface.As the value of a/λ varies from 0.01 to 0.04,the local time-averaged Nusselt number is enhanced about 63.5% and comprehensive coefficient is increased by 0.5112.For the flexible wavy surface,the results indicate that periodic fluctuation of the wavy surface induces a periodic variation of pressure.It is also found that the spindle-shaped spots with higher Nusselt number value appear in the up-slope part of the wavy surface.When the value of a/λ varies from 0.01 to 0.04,the time-averaged local Nusselt number and comprehensive coefficient are increased by 173.1% and 1.1232,respectively. Compared with the solid wavy surface,the flexible wavy wall will remarkably enhance the heat transfer in the same amplitude and consumption of fluid pumping power.

The two-phase pressure drop characteristics of R410A flow boiling inside tubes filled with metal foams were investigated experimentally.The test sections are two tubes of 13.8 mm inner diameter filled with 5 PPI/95% porosity and 10 PPI/95% porosity metal foams separately.Experimental conditions include saturation pressure of 995 kPa,mass flux from 30 to 90 kg穖^-2穝^-1,heat flux from 5.9 to 16.5 kW穖^-2,and inlet vapor quality from 0.175 to 0.775.The experimental results are as follows.Metal foams always increase the pressure drop of flow boiling,and the pressure drop reaches 56 kPa穖^-1 at vapor quality of 0.775 and mass flux of 90 kg穖^-2穝^-1. The pressure drop increases with the value of PPI,and the pressure drop with 10 PPI metal foams can be as much as 1.2 times that with 5 PPI metal foams under the same working condition.A pressure drop correlation for the 13.8 mm tube filled with metal foams was developed based on the experimental data,and 90% of the predicted results agree with the experimental data within a deviation of ?15%.

To analyze the evaporation characteristics of single water droplet in low temperature and low humidity ratio air in ice production system with evaporative supercooled water,a mathematical model of evaporative supercooling process of single water droplet was proposed.The evaporation process of droplet in supercooling stage was simulated with theoretical model and the results are basically consistent with the experiment on suspended single water droplet,so it is feasible to predict the evaporative supercooling characteristics of small water droplet by the mathematical model.The influence of initial diameter and temperature of water droplet,air temperature,humidity ratio of air,and air velocity on the temperature of water droplet during its evaporative supercooling process was analyzed.The numerical results show that smaller diameter and lower temperature of water droplet and larger air velocity can increase the cooling rate of water droplet and shorten the supercooling time reaching steady state evaporation stage.Additionally,lowering the temperature or humidity ratio of air can not only improve the cooling rate of water droplet,but also increase the supercooling degree of water droplet reaching steady state evaporation stage.The investigation of evaporative supercooling process of water droplet can provide a foundation for improving the efficiency of ice production and optimal design for ice-making system with evaporative supercooled water.

The research on heat transfer gives a rough conclusion that vibration can enhance heat transfer near the vibrating surface,and its mechanism basically depends on the boundary layer theory that vibration reduces the thickness of boundary layer.Field synergism theory in convective transfer interprets convective enhancement approach by the maxing principle and matching principle with quantitative indicators.In this study,the convective heat transfer characteristics of vibrating cylinder is investigated using maxing principle and matching principle of field synergism.The properties of working fluid are similar to those of water,the cylinder vibrates in simple harmonic vibration with frequency of 15 Hz,the amplitude is 1 mm,and the turbulence model is RNG k-ε model.The study shows that the relation between heat transfer and synergism performance interprets the enhancement of heat transfer outside the vibrating cylinder.The matching principle and maxing principle in synergism theory shows that the improvement is from the increase of heat transfer coefficient.Synergism angle cosine has maximum values on position phase 0° and 180° and minimum values on 90° and 270°,and increases when the time phase is close to the equilibrium moment.The synergism matching performance corresponds to the angle cosine value. Heat transfer coefficient distribution pattern is consistent with the angle cosine value and matching coefficient.

The structure and characteristics of the two-phase closed thermosyphon with working trap are described.A mathematical model is presented to calculate the unsteady-state start-up process of a room temperature heat pipe.The model is based on the special structure and operation conditions of the heat pipe,which is simplified to that the steam temperature in the tube changes with time only.The relation of steam temperature and time is obtained by numerical calculation and used as the temperature boundary condition of the measurement trap.The temperature,velocity and pressure distribution in the working trap are then solved by FLUENT.The main effect of ambient air on the thermometer well occurs at the orifice,while the temperature is uniform at other locations.The calculation is in good agreement with experimental data,and the maximum deviation is 3.7 K when the start-up time is 100 s.The simulation and experiments indicate that water fluid filling volume has little effect on the start-up performance of the heat pipe.The mathematical model and the research methods provide a new approach for the study of special heat pipes.

Regeneration of dehumidification solution is necessary to maintain the continuous dehumidifying process,whose efficiency directly affects the performance of whole system.The size,mass,and temperature of droplets during the flash evaporation were analyzed based on droplet flash theory,and the factors affecting the efficiency of flash evaporation were tested through preliminary experiments.The results show that pressure is the key factor affecting the efficiency of the flash evaporation.Flash evaporation may proceed only if the steam is removed timely.The mixed ratio of different solutions is relevant to the efficiency of flash evaporation.The initial temperature of droplet has little effect on the efficiency.The experimental values of temperature are higher than the theoretical values,so the physical properties need to be modified if the flash evaporation theory of droplet is adopted according to droplets flash evaporation of mixed dehumidification solutions.

The flow behavior of dense non-Newtonian slurry in a hydrocyclone was described by a viscosity correction model.Combined with the Reynolds stress model,the mixture multiphase model and the stochastic Lagrangian particle tracking model,a comprehensive computational fluid dynamics model was established to simulate the multiphase non-Newtonian flow in a hydrocyclone.The validity of the proposed model was verified by the reasonably good agreement between measured and predicted results with the deviation less than 10%.The results showed that the spatial distribution of slurry viscosity was similar to that of slurry density.The particles at a specific size range with zero radial resultant forces had high-speed rotational movement around the locus of zero vertical velocity(LZVV),resulting in a high density ring in the body.The spatial distribution of dispersed phase depended on the forces applied.For the particles of various sizes,the magnitude of outward centrifugal force was twice that of inward pressure gradient force.The large particles would enter the downward flow and be collected at the underflow.As particle size decreased,the overall inward drag force with varying direction increased exponentially.As a result,some relatively fine particles were pushed towards the air core and escaped from the overflow with the upward flow. Meanwhile,the randomness of such particle movement was enhanced.When particle size was below a critical value,which meant that the fluid drag force on the particles was much larger than centrifugal force and pressure gradient force,the randomness of particle movement was very strong,resulting in a macroscopically uniform distribution.

Phase transition heat exchange is widely used in heat transfer.The thick liquid film formed during phase transition is the reason for worsening condensation heat transfer.The passive phase separation concept using mesh construction on the pipe wall was proposed to modulate the flow pattern for the first time.In order to verify the novel concept,air-water two-phase flow experiment was performed.It was found that part of the liquid could be separated and removed from the pipe and the contact area between air and tube wall was increased.The length ratio of gas and liquid increased oscillatorily after multi-stage modulation,and furthermore,slug flow pattern changed to stratified flow.With the decrease of liquid velocity or the increase of gas velocity the modulation effect was enhanced.According to the result of the adiabatic two-phase flow pattern modulation,it was expected that the structure would significantly enhance phase transition heat transfer performance.

A design method for right angle die with non-symmetric flow channels for double-lumen micro-tubes was presented by using flow balance of polymers.First,based on the flow balance of polymers,a relationship among the structural parameters of non-symmetric flow channels in the right angle die was built.Second,in the opposite direction of extrusion,the lengths of the flow channels that were created by the relationship were calculated,and the ends of the lengths were fitted.Then,there was an objective function for the structural optimization of the flow channel in the right angle die to be established through the fitting deviations.Finally,the non-symmetric flow channels in the right angle die were designed and manufactured according to the optimization results.The experimental results of extrusion indicated that the design for the non-symmetric flow channels of extrusion die was reasonable and the design method for right angle extrusion die of polymeric double-lumen micro-tube according to the non-symmetric flowing balance was correct and effective.

The dynamics Shannon entropy H_kof the signal of time series is applied to nonlinear time series analysis because of less data demand and simpler calculation.It was used to analyze the signals of two-phase flow conductance.Firstly,the selection criteria of the parameters were analyzed through the application in white Gaussian noise.Secondly,the effect of different parameters in the two-phase flow pattern identification was discussed,and the H_k-up of flow pattern were compared with three typical simulated signals.Finally,the signals of two-phase flow conductance were analyzed by calculating the segmented H_k-up,and the evolutions of various flow patterns were analyzed.The dynamics Shannon entropy was an effective method for the analysis of two-phase flow conductance signals,different flow patterns could be distinguished and the evolution characteristics of different flow patterns could be identified.

To quantitatively control the aspect ratio of hollow glass microspheres(HGMs)for inertial confinement fusion(ICF)targets,a model was developed to describe the relationship between HGM aspect ratios and compositions and pressures of furnace gas,based on the process analysis of transformation mechanism from gel microspheres to HGMs in the drop-tower furnace.Furthermore,the mean diameters and aspect ratios of HGM batches under different compositions and pressures of furnace gas were experimentally investigated.The results showed that the shell-blowing process from the initial molten glass bubble to the resulting liquid HGM could be regulated by the partial pressures of argon gas in the furnace atmosphere,and therefore the diameters and aspect ratios of HGMs could be quantitatively controlled by the partial pressure of argon gas in the furnace atmosphere.However,it was infeasible to produce large-diameter HGMs with target quality by simply reducing the partial pressures of argon gas to zero.To meet the stringent requirements of ICF targets,special furnace gases with enough partial pressures of helium gas must be used to obtain high quality HGMs with good sphericity,surface finish and high yield.Except for the extreme operation conditions of excessively high(>0.08 MPa)or low(<0.01 MPa)partial pressures of argon gas in the furnace atmosphere,the predicted values of the model proposed in this work agreed well with the experimental results.

Diffusion filtration combustion is a new combustion technology,which combines some characteristics of diffusion combustion and premixed filtration combustion.A numerical study of diffusion filtration flame characteristics in a nitrogen diluted CH₄+N₂/O₂ co-flow plane-parallel is conducted using a two-dimensional two-temperature model with a simple reaction rate mechanism.Both thermal and species dispersion effects are taken into account.The effects of pellet diameter(d),gas mixture velocity(u_g)and mass fraction of CH₄(Y_CH4),etc.on the flame shape and flame height are investigated.Results show that high gas and solid temperature zones exist at different locations compared to the premixed filtration combustion,and that in the area aside of the high temperature zone the differences between the gas and porous solid temperatures are very small.Flame height increases from 0.048 m to 0.12 m as d decreases from 6.66 mm to 2.02 mm.Increases in u_g and Y_CH4 reduce the flame width and flame height.The calculated result is verified by experimental data.

In order to evaluate the performance of on-line particles test equipment at high temperature,an optical on-line particle size analyzer was used to test catalyst particles concentration and particle size distribution(PSD)downstream of a fluid catalytic cracking(FCC)flue gas filtration test facility.At the same time,an off-line sampling system tested catalyst particles concentration both upstream and downstream of the facility.Catalyst PSD and microstructure were measured with Coulter counter particle size analyzer and scanning electron microscopy(SEM).The off-line test results agreed well with the results of on-line particle size analyzer.Experimental results showed that the on-line test equipment had high accuracy when operating pressure was 0.21 MPa and operating temperature ranged from 320℃ to 465℃.Experimental and simulation results showed that operating temperature almost had no influence on test measurement.On this basis,aiming at real condition of coal chemical industry,an iterated method was developed to correct on-line measurement results,which could provide a guideline to determine the particulate matter in high temperature pipeline in coal chemical industry.

In double dielectric barrier discharge aqueous electrodes reactor(DDBD),hydrogen peroxide was prepared in a mixture of hydrogen and oxygen by using DBD discharge with inert gas(Ar,He and N₂)as additive gas.The influence of different inert gases on the breakdown voltage and energy efficiency of H₂O₂ synthesis was studied.The results showed that breakdown voltage,conversion of O₂,selectivity of H₂O₂,yield of H₂O₂ and energy efficiency were obviously affected by different inert gases.The breakdown voltage could be reduced with He and Ar as additive gas,however,it became higher when N₂ was the additive gas.On the other hand,energy efficiency of H₂O₂ synthesis was reduced dramatically with N₂ as the additive gas,and little changed with He as the additive gas.However,energy efficiency of H₂O₂ synthesis increased markedly with Ar as the additive gas.When Ar flow rate was 56.6 ml穖in^-1,breakdown voltage could be reduced from 11.8 kV to 10.2 kV;energy efficiency of H₂O₂ synthesis increased by about 51%,from 3.45 g?(kW穐)^-1 to 5.20 g?(kW穐)^-1(100% H₂O₂).Therefore,the addition of Ar could not only reduce breakdown voltage,but also increase energy efficiency of H₂O₂ synthesis.The optical emission spectra revealed that Penning ionization effects of metastable state Ar species(696.5,794.8,811.5 nm)existing in H₂-O₂-Ar discharge system might be responsible for the decrease of breakdown voltage.From the waveform of discharge current,the addition of Ar increased electron density,which obviously facilitated the increase of O₂ conversion and energy efficiency of H₂O₂ synthesis at the same power.

Carbon dioxide methanation catalyst Ni/Al₂O₃ was prepared by the impregnation method using Al₂O₃ as carrier and Ni as active component.The catalytic performance in the methanation of carbon dioxide in high purity hydrogen chloride was evaluated in an isothermal fixed-bed reactor.The influence of temperature,pressure,hydrogen chloride volume space velocity and molar ratio of hydrogen to carbon dioxide on the conversion of CO₂ over the Ni/Al₂O₃ catalyst was investigated and the catalyst stability and regeneration performance of the catalyst were evaluated.The results showed that the methanation conversion of CO₂ was about 90% under the optimal process condition as follows:temperature 250℃,pressure 4.0 MPa,hydrogen chloride volume space velocity 100 h^-1 and H₂/CO₂ molar ratio 500:1,promising satisfactory removal of trace amount of CO₂ from high purity hydrogen chloride.The catalyst would rapidly deactivate after the reaction when temperature was higher than 300℃ and catalyst regeneration could only partially restore catalyst activity.

A new technology of synthesis of poly(ethylene glycol succinate)(PES)oligomers and dimethyl carbonate(DMC)by coupling reaction of ethylene carbonate(EC)and dimethyl succinate(DMSu)over ZnO was studied.The effect of calcination temperature of ZnO catalysts on catalytic activity was investigated and ZnO catalysts were characterized with XRD,BET and NH₃-TPD.PES oligomers were characterized with FTIR and ¹H NMR.The preferable reaction conditions were as follows:reaction temperature 225-235℃,molar ratio of EC to DMSu 2,molar ratio of catalyst to the total mass of EC and DMSu 0.005,reaction time 3 h.Under these conditions,the yield of DMC was 59.7%,the intrinsic viscosity of PES oligomer was 0.3857dl·g^-1.The catalytic activity of coupling reaction was affected possibly by the degree of crystallization and the weak acid sites on the surface of ZnO.

Mesoporous sulfated Zr-PHTS(SO₄^2-/Zr-PHTS)solid acid was prepared by using P123(EO₂₀PO₇₀EO₂₀)as a structure directing agent via the one-pot hydrothermal process in lower concentration sulfuric acid solution.These prepared samples were characterized by powder X-ray diffraction(XRD),TEM,N₂ sorption isotherms,Py-FTIR spectra,and NH₃-TPD.The characterization results showed that the obtained samples possessed well-ordered hexagonal mesostructure,and all the samples had weak and medium acidity dominated by Lewis acid sites according to the analysis of pyridine adsorption and NH₃-TPD.With the increase of Si/Zr molar ratio,specific surface areas relatively little varied and acidity was obviously reduced,but pore volume and pore diameter were not severely affected.In addition,the SO₄^2-/Zr-PHTS catalyst showed good performance in the THF polymerization reaction,and such result could be related to the mesoporous structure and surface acidity.

Decabromodiphenyl ether(decaBDE)is one of the most popular flame retardants used with polystyrene.The interest in the thermal decomposition of decaBDE has intensified due to its potential production of polybrominated dibenzo-p-dioxins(PBDD)or dibenzofurans(PBDF)in the thermal recycle of plastic waste.Kinetics of thermal decomposition of decaBDE was studied by non-isothermal thermogravimetric analysis(TGA).The three-dimensional diffusion model was found to be the best correlation of TGA data by the general integration method.The activity energy and logarithmic pre-exponential factor were found to be 122.7 kJ·mol^-1 and 74.3 s^-1 in TGA of decaBDE.In the process of thermal decomposition of decaBDE in the atmosphere of nitrogen,solid decaBDE melt at 306℃ and then vaporized in the temperature range of 400-450℃.When PS was blended with decaBDE,the decomposition temperature of the mixture was lower than that of virgin PS and a higher temperature was needed to complete pyrolysis.The infrared spectral characteristics of 1,3-diphenylbutane was detected in the pyrolysis vapor-phase products of the mixture,whereas styrene was usually found in the pyrolysis product of PS.It indicated that the active groups released from decaBDE changes the path of depolymerization in thermal decomposition of PS.

Solvent extraction based on aliphatic 1,3-diols is a promising technique for the recovery of boric acid from salt lake brine.In this work,two diols,2-ethyl-1,3-hexanediol(EHD)and 2-butyl-2-ethyl-1,3-propanediol(BEPD),were selected as extractants and toluene was used as diluent.The effects of extractant concentration,pH of brine,initial boric acid concentration,magnesium chloride concentration,and temperature on the distribution coefficients of boric acid were systematically investigated.Distribution coefficients of boric acid up to 9.43 and 8.25 were obtained from the boric acid aqueous solutions with the initial concentration of 0.0185 mol稬^-1 when using toluene containing 0.4 mol稬^-1 EHD and BEPD,respectively,as organic phases at 303.15 K.Higher extractant concentration or lower pH is favorable to the extraction.However,the distribution coefficients decrease gradually with the increase of boric acid concentration and temperature.The extraction of boric acid with aliphatic 1,3-diols is an exothermic process.The salting-out effect of magnesium chloride enhances the extraction performance.

The critical particle size model was developed through analyzing the forces acting on a single particle with axial,radial and circumferential directions considered.The effects of feed temperature,cross-flow velocity and permeate flux on the critical particle size were investigated theoretically and experimentally,and the mechanism of particle deposition was discussed.Both simulation and measured results show that the membrane thickness becomes larger with the decrease of feed temperature and increase of trans-membrane pressure difference,and smaller with the increase of cross-flow velocity.Because of the net gravity,there exists a dynamic layer of non-uniform thickness along the circumference direction in the horizontal tube.This non-uniformity can be reduced evidently as the cross-velocity increases.The model calculation is in good agreement with the experimental results.

In recent years,the electrodeionization(EDI)and some integrated processes derived from EDI play important roles in some fields such as desalination,ion concentrating and chemical synthesis,but it is still needed to explore the mechanism of water decomposition at the membrane-liquid interface of ion-exchange membranes.In this study,the degradation of anion exchange membrane in EDI process and its effects on water decomposition were examined and analyzed through experiments.The phenomenon of partial degradation of the anion exchange membrane from quarternary ammonium to tertiary amine is confirmed through the tests for permselectivity,exchange capacity,conductivity and infrared spectroscopy analysis.Furthermore,based on the investigation on the characteristic curves of the EDI process,it is validated that the weakly basic tertiary amine group has a catalytic effect on the water decomposition at the membrane-solution interface of the anion exchange membrane.The results are helpful for the design and improvement of the EDI and EDI-based electro-membrane processes,so that the water decomposition can be well controlled to achieve some specific separation.

Porous resins(hypercrosslinked resin MN-202,aminated polystyrene resin MN-150,and macroporous resin XAD-4)and carboxylated multiwall carbon nanotube C-MWCNT were used to remove ciprofloxacin from aqueous solutions.Similar patterns of pH-dependent adsorption show that the adsorption amounts of ciprofloxacin increase with the increase of their percentages of zwitterionic form,implying the importance of zwitterionic form.Ciprofloxacin adsorption to the three resins exhibits similar ionic strength dependence,consistent with the positive contribution of hydrophobic effect and the negative contribution of electrostatic interaction.The amounts of ciprofloxacin adsorbed decrease much more in the presence of CaCl₂ on the surface of C-MWCNT than with NaCl because of the dominant contribution of electrostatic interaction.The adsorption kinetics of the four adsorbents follow the pseudo-second order model while the adsorption isotherm data fit well to the Langmuir models,indicating the coverage of the surface by a mono-molecular layer.The apparent temperature influence on the adsorption process demonstrates that hydrophobic effect is dominant mechanism responsible for ciprofloxacin removal by XAD-4, while micropore-filling is likely the main mechanism for the adsorption by MN-202 and MN-150,with the aid of hydrophobic effect,electrostatic interaction,H-bond and π-π electron-donor-acceptor interactions.

It is accepted in the world that the quality and the quantity of desalination could be improved under the hybrid desalination system,at the same time the energy cost would be decreased greatly.The superstructure model of hybrid multistage flash(MSF)/reverse osmosis(RO)desalination system is presented based on the blend note and the distribution note which aims to minimize the total annual cost.The ratio of RO and MSF product rate R is introduced as an optimum variable.The modified genetic algorithm(MGA)is adopted to solve the problem and the optimum structure and the operation condition are obtained.The results showed that the cost of water of hybrid desalination system is lower than that of the independent MSF and RO.The optimal value of R is 0.45 for the example and the optimal configuration is MSF-RO.

Temperature and pressure reducers are widely used in the steam power system of petrochemical plants,which can transfer higher pressure steam to lower pressure steam for different grades of heat demands.Otherwise,generally in summer there is abundant low pressure steam in plants.Using back-pressure turbines to replace temperature and pressure reducer,as well as condensing steam turbines to recover the energy of the abundant low pressure steam are effective energy-saving methods.In this paper,an economic evaluation model is proposed for determining the critical economic point for back-pressure and condensing steam turbines.The effect of steam price or the price ratio of electricity to heat on the critical point is discussed.The results for an industrial case show that the critical powers of steam turbine are relatively low,which means that in most industrial cases,using steam turbines to save energy is beneficial.This paper provides guidance in selection of suitable steam turbine for energy saving in petrochemical plants.

Model predictive control(MPC),as an advanced control strategy,has been widely applied to process industry.But the soft constrain limits of MPC is often set in a conservative way in industrial application,which leads to poor economic performance.For MPC system,the quadratic economic performance index is used to assess the economic performance in the paper.After that the problem of solving the optimal solution is transformed into a typical linear programming problem with constraints.Then according to the historical data and optimal operation results obtained from quadratic economic performance function,evidential network modeling of multivariable MPC can be built.Through reasoning and decision-making,the reason which causes the system performance decline can be got.The strategy to improve the control system performance is proposed.Finally,the effectiveness of assessment economic performance based on evidential network is verified through the simulation experiments.

This paper developed a new kinetic model for catalytic reforming reactions based on the lumping theory and catalytic reforming reaction mechanisms.The developed model thoroughly analyzed the mutual reaction relationships among paraffin,cycloparaffin and aromatics,and covered most related reactions included in the continuous catalytic reforming progress.In order to resolve the challenges of the parameter estimation,the number of estimated parameters was decreased to 99 through reasonable supposition and the originally complex reaction network was split into several simpler sub-networks according to the number of carbon atoms.An iteration method combined of BFGS and SQP algorithms was then implemented to increase the accuracy of the parameter estimation.The developed model was used to simulate a continuous catalytic reforming reactor for verifying the model accuracy.And the simulation result showed that the model successfully predicted the reformate composition in the reactor and was proved to be able to meet the accuracy requirement of the industrial applications.

To solve the problem of unacceptable execution time for solving large-scale and complex mixed integer non-linear programming problems by using deterministic algorithms,a paralleled sequential quadratic programming algorithm on the basis of GPU acceleration was proposed,in which a thorough analysis of the SQP algorithm and the framework of GPU was made.In the proposed method,enumeration algorithm was used to deal with binary variables,and the CPU +GPU strategy and the GPU in parallel were used to accelerate convergence rate.Numerical experiments show that compared to the typical serial algorithm,the proposed algorithm possesses a better convergence performance for solving MINLP problems with more binary variables and less constraints.

The utilization of heat of reaction and energy optimization within ethoxylation reactive distillation(ERD)column,which involves reactions with highly thermal effect,was studied by using the mathematical model and simulation method.A typical ethoxylation system,the synthesis of ethylene glycol monobutyl ether(EGMBE)from ethylene oxide(EO)and n-butanol was employed as example. Firstly,the conventional column design,into which a reactive section was superimposed onto a stripping section,was used as a base case for analysis,and detailed simulations were carried out to investigate the influence of heat of reaction on the process performance.The results obtained showed that,by the adoption of the conventional design of ERD column,the heat of reaction was finally removed from condenser by cooling medium,i.e.,the heat of reaction could not be directly utilized in ERD column for improving the separation operation or reducing the heat duty of reboiler.Based on this,the approaches to utilizing heat of reaction was analyzed,and an internally heat-integrated ethoxylation reactive distillation structure,IHIERD,was proposed to maximize the energy efficiency of system,into which the reactive section and stripping section was partitioned into two parts with different operating pressures.In such arrangement,the heat of reaction can be allowed as heat resource to be drawn from reactive section to supply stripping section,and therefore the heat duty of reboiler in IHIERD can be reduced.The saving effectiveness of different designs was analyzed and compared by using simulations.The results obtained demonstrated that the IHIERD leads to a reduction of the reboiler temperature from 462.5 K to 420.0 K,a reduction of the heat duties of condenser and the total energy input by 11% and 14%,respectively,which indicated that the energy saving was obvious.

Two general approaches are adopted in solving dynamic optimization problems in biochemical processes,namely,the analytical and numerical methods.The numerical method based on heuristic algorithms has been widely used,but it is likely to converge to local optimum at a slow convergence speed. An improved differential evolution algorithm(IDEA)was proposed to solve dynamic optimization problems in this paper.In IDEA,a novel representation of the control variables was proposed for effectively solving dynamic optimization problems.A local search vector was designed in IDEA to enhance the local search ability of the algorithm.The efficiency and robustness of the algorithm was illustrated by solving several challenging case studies regarding the optimal control of fed-batch bioreactors.In order to fairly evaluate their advantages,a careful and critical comparison with several other direct approaches was provided.The results indicated that the proposed approach presented the best compromise between robustness and efficiency.

Fermentation process is characterized by high non-linearity,time-delay and uncertainty,which directly influence the control performance of the fermentation system.In this paper,a fed-batch fermentation process predictive control method based on non-linear quadratic Gaussian(NLQG)was proposed.The method was composed of an extended Kalman filter(EKF)and non-linear quadratic regulator(NLQR)connected in series.In order to realize the dynamic predictive control of fed-batch fermentation process,the optimal state estimation and the real-time state feedback of the controlled variable were realized by EKF and NLQR respectively.The NLQG controller was designed in the LabVIEW by the strategy using ActiveX to invoke the COM components which were compiled and generated in MATLAB.The controller was applied to the predictive control of the dissolved oxygen concentration in penicillin fed-batch fermentation process.The experiments showed that the proposed fed-batch fermentation process predictive control method had good tracking for the change of set value,high control accuracy and good robustness in different noisy environments.

Organic corrosion inhibitors of aluminum alloy are widely studied and used in sea water environment.Seven organic compounds were chosen and their inhibiting effects on corrosion of 7075 aluminum alloy in 3.5% NaCl solution were evaluated by the mass loss method and electrochemical method. Scanning electronic microscopy(SEM)was used to examine the surface morphology of corrosion samples.Experimental results showed that these seven organic compounds had different corrosion inhibition effects,in which the heterocyclic compound B had the best corrosion inhibition effect.Through SEM observation of pitting characteristics and electrochemical analysis,the excellent corrosion inhibition effect of heterocyclic compound B was attributed to its anode controlling and surface film-forming mechanism.

The possible biosynthesis pathways of poly(β-malic acid)(PMLA)and the feasible approaches to regulating PMLA production in A. pullulans BS24 were studied.To investigate the effects of the metabolic inhibitors of tricarboxylic acid cycle(TCA)cycle on PMLA fermentation,supplementation of the inhibitors to the medium was implemented.The results demonstrated that trifluoroacetic acid inhibited PMLA production,but malonic acid and maleic acid promoted PMLA production and isocitrate lyase activity.It could be concluded that PMLA synthesis was related to the TCA cycle and glyoxylate pathway in A. pullulans.Based on this result,the method of facilitating the accumulation of PMLA via metabolic intermediates was further designed.The medium containing 3.0 g·L^-1 fumaric acid or 1.5 g·L^-1 L-malic acid was used.Isocitrate lyase activity was increased by 18.39% and 25.30%,respectively.And the two added intermediates also increased the activity of L-malate dehydrogenase and fumarase,while reduced the activity of isocitrate dehydrogenase and α-ketoglutaric acid dehydrogenanse,and the final PMLA yield was increased by 46.58% and 43.70%,respectively.The metabolic intermediates could modify the redistribution of metabolic flux between TCA cycle and glyoxylate pathway,therefore,carbon source could be efficiently used to synthesize PMLA.

Experiments investigating transformation,deposition and corrosion behaviour of ash were carried out in a large-scale wastewater incineration plant.Ash deposited samples were collected from the surfaces of heat transfer tubes after operating period of 15 d and characterized using analytical techniques such as X-ray fluorescence spectrometer(XRF),scanning electron microscope coupled with energy dispersive spectroscopy(SEM-EDS)and X-ray powder fluorescence(XRD),to determine their chemical composition,morphology and mineralogy.The results show that Na which volatilizes during wastewater incineration has an even distribution on whole region flue gas flows,while non-volatile elements,Ni and Fe which are transported by ash particles have strong deposition trends at region of high temperatures.Element S is significantly enriched at region of low temperatures.Release and transformation of numerous Na and S as well as heat transfer process during incineration are the key issues for fouling/slagging and deposits growth in the HRSG.Condensation of Na species on surface of heat transfer tube forms a sticky deposition layer,which increases sticking probability of ash particles.At region of high temperatures,main components in ash deposits are Na₂SO₄,NiO and Fe₂O₃.While at 660-900℃,eutectic mixtures with much lower melting temperatures,such as sodium iron sulfate(Na₃Fe(SO₄)₃),nickelblodite(Na₂Ni(SO₄)₂·4H₂O)are formed.They are temperature-dependent and can enhance formation of sintered deposits.Acidic salt sodium sesquisulfate Na₃H(SO₄)₂ is generated at low temperatures and should be responsible for the initiation of low temperature corrosion.

The experiment for removal of NO_x in flue gas by non-thermal plasma generated in dielectric barrier discharge(DBD)was conducted to study the influence of temperature and gas composition of gas containing-ethylene on the removal.The results show that rate of NO removal is accelerated by increase of temperature.Under lower energy density,addition of electronegative molecule CO₂ into simulation gas leads to efficiency reduction of NO removal because of decrease of radical generated,but the effect will be weakened with increasing energy density.The water addition in simulation gas can result in formation of more free radicals such as OH and HO₂ which can promote oxidation of NO.However,if SO₂ is also added which can react with O radical,on one hand,the reaction rate of O and C₂H₄ in the initial stage can be reduced,which makes NO oxidation decrease.On the other hand,free radicals O₃ and HO₂ with strong oxidation ability can react with NO prior to SO₂.So,addition of SO₂ has no influence on NO removal.

A method combined non-thermal plasma and blow-off was employed to wipe out of stench from landfill leachate.A new type of high pulse voltage source with Blumlein pulse forming network(BPFN)was adopted,and all experiments were conducted at a fixed pulse frequency of 100 Hz.The influences of important factors,such as gas flow rate,peak voltage and humidity,on removal efficiency of odors were studied.The results showed that the combined method could wipe efficiently out of stench from landfill leachate.Ammonia was taken as the experimental object since it was the main component of odors from landfill leachate.Higher peak voltages could promote removal efficiency of ammonia while larger flow rates reduced it.The removal efficiency of ammonia in plasma reactor could reach 92.5% after continuous operating 10 min at conditions of:ammonia concentration 520 mg穖^-3,peak voltage 37 kV and flow rate 1000 ml穖in^-1.A dynamic model was developed to describe quantitatively the relation between ammonia and energy density and initial concentration.A certain level of humidity in flow gas could enhance oxidation of malodorous gas such as ammonia.In plasma chemistry process,ammonia was removed by direct decomposition by high energy electrons or by reaction with intermediates to form NH₄NO₂ and NH₄NO₃.

To save energy consumption in domestic wastewater treatment,three-stage autotrophic nitrogen removal process including organics removal SBR,partial nitrification SBR and anammox UASB was proposed.At room temperature of (26±1)℃,short-term effect of aeration rate and MLSS on organic removal process was investigated by seeding activity sludge taken from a pilot-plant reactor of partial nitrification.The results show that both concentrations of NO₂^--N and NO₃^--N were lower than 0.1 mg·L^-1 at various aeration rates and sludge concentrations before the end of COD biodegradation stage.After that,the wastewater entered a difficult-degradating stage in reactor where COD concentration remained at nearly constant level and NO₂^--N and NO₃^--N concentrations accumulated rapidly and nitrifying-bacteria activity increased.Obviously,nitrification did not occur during the process removing organics under different aeration conditions.Therefore,under various conditions of aeration and sludge concentration the first organics was removed and then partial nitrification to remove NO₃^--N.However,for three-stage autotrophic nitrogen removal process,NO₄⁺-N concentration could decrease from 11.6 mg·L^-1 to 3.4 mg·L^-1(TN loss)during organics removal process under aeration values of 100 L·h^-1,60 L·h^-1and 20 L·h^-1.The peak point of pH profile and the inflexion of DO curve stayed the same with the end of removing organics throughout,and so they could be used as real-time control signals to indicate the end of organic removal process.

Propionate-oxidizing bacteria community can oxidize propionate to acetic aid and H₂/CO₂ which can be used by methanogens,and they occupy a unique niche in anaerobic digestion systems.An understanding for the shift of propionate-oxidizing bacteria in anaerobic wastewater treatment system is of important significance for regulating and operating the process.Impacts of hydraulic retention time(HRT)on performance of an upflow anaerobic sludge bed reactor(UASB)and shift in propionate-oxidizing bacteria community were investigated at mesophilic condition.The results showed that shortening HRT within certain range of 24 h to 8 h,at an influent COD of 1000 mg稬^-1,would cause shocks to UASB,resulting in a transient accumulation of propionate and acetate,and after maintaining run for a certain period UASB could achieve new steady states again and keep higher removal efficiency of COD,which were 94.9%,93.9%,92.5%,91.8% and 87.9%,at HRT 24,20,16,12 and 8 h,respectively, during these steady states.An obvious change of propionate-oxidizing bacteria community in anaerobic activated sludge was observed when HRT decreased.Syntrophobacter pfennigi was appeared at HRT 24 h and disappeared completely at HRT 8 h,while S. sulfatireducens, Pelotomaculum and Desulfotomaculum were dominant bacteria at HRT 8 h.Smithella propionica maintained a relatively high richness in whole operational process,indicating its existent in a wide niche. The pollutant removal and running stability of the UASB should be improved by the enrichment of propionate-oxidizing bacteria.

As a kind of metal-capture-agent,food grade tannic-acid(TA)was immobilized on commercial powdered activated carbon(PAC).Adsorption of low concentration Cr(Ⅵ)(0.500 mg·L^-1)on the TA-PAC was investigated at various dosage and pH,and adsorption capacities and adsorption isotherms were measured at 275 K.Compared with HNO₃- and NaOH-modified PAC(N-PAC and OH-PAC),the results obtained from the BET,Boehm’s titration and FTIR indicated that TA-PAC is of larger specific surface area,total pore volume and more abundant acid functional groups.The performance of TA-PAC,expressed by removal efficiency of Cr(Ⅵ)and total chromium,is much more excellent than N-PAC and OH-PAC.Its adsorption capacity for Cr(Ⅵ)was found to be pH-dependent,the removal efficiency both Cr(Ⅵ)and total chromium were notably higher in the acidic medium(pH=3.0-6.0)than in alkaline medium(pH=7.0-10.0).The adsorption data for total chromium were fitted using two-parameter isotherm models and the related parameters were estimated.Freundlich model is the best for data of C_e from 0.010 to 0.404 mg·L^-1,R²=0.9941,indicating a heterogeneous coverage of chromium on TA-PAC.Langmuir(Ⅰ),Langmuir(Ⅱ)and Temkin models didn’t fit the data well,because of occurring piecewise node at 0.149 mg·L^-1,0.151 mg·L^-1 and 0.163 mg·L^-1 respectively.The adsorption mechanism of TA-PAC for Cr(Ⅵ)was assumed to be chemical process,such as surface reduction of Cr(Ⅵ),esterification between chromate and catechol,and ion exchange.

The packed bed bioreactor was designed and set up,active carbon was selected as carrier to immobilize Acidithiobacillus ferrooxidans(A. f).The process parameters of oxidizing ferrous were investigated by simulating ferrous concentration and solution pH value in uranium mine in bioreactor.The results showed that the ferrous oxidation rate could increase 1.4 times from 0.5 g·L^-1·h^-1 to 1.2 g·L^-1·h^-1 with active carbon carrier. Iron in solution was consumed due to formation of NH₄Fe₃(SO₄)₂(OH)₆ during operation.It’s necessary to add ferrous periodically in order to keep certain iron concentration in solution and clean up NH₄Fe₃(SO₄)₂(OH)₆ in bioreactor.The optimum operation condition of bioreactor was ventilation from bottom,ferrous concentration keeping 5 g·L^-1 and solution flux keeping 1.2-1.4 L·h^-1 or ferrous concentration keeping 1 g·L^-1 and solution flux keeping 5.4 L·h^-1.

To study anode effect on electro-Fenton reaction,three kinds of electrode,including SnO₂/Ti electrode with nanocoating(DSA),activated carbon fiber(ACF)and graphite paper(GE)were combined to form three electrode couples,and they were applied to degrade activated brilliant red X3B. The order of decoloration and mineralization rate for these various electrode couples are as follows:a(cathode/ACF,anode/DSA)>b(cathode/ACF,anode/GE)>c(cathode/GE,anode/DSA).Under the optimum conditions,for electrode couple a,X3B was decolored completely in 90 min,mineralization rate and average current efficiency(ACE)in 180 min were 75.3% and 56.7% respectively.XRD and SEM images implied that structure of ACF and DSA were stable for electro-Fenton reaction conditions.The CV curves of electrodes suggested that the direct anodic oxidation was not involved in electro-Fenton system.The flurosence method was used to detect oxidation activity species,the results indicated that result of X3B degradation was in proportional to amount of hydroxyl radical formed.The study demonstrated that DSA can enhance efficiency of electro-Fenton reaction by a pathway activating H₂O₂ to hydroxyl radical.

Oxidation adsorption of NO was investigated on HZSM-5 without and with transition-metal-salt [3.85%(mass) of metal] as adsorbents in a fixed bed.These adsorbents were characterized by SEM,BET,XRD and XRF.The results demonstrated that both HZSM-5 and transition-metal-salt-modified HZSM-5 can efficiently remove NO from CO₂,reducing to a level of less than 0.1?10^-6,but for HZSM-5 exist of CO₂ will significantly affect NO adsorption.Co/HZSM-5(25)is the best adsorbent with the highest NO adsorption capacity,while the results of NO_x-TPD revealed that there is good feasibility of industrial application for Cu/HZSM-5(25),Mn/HZSM-5(25).

Dissipative particle dynamics(DPD)simulation was performed to study the microphase separation and self-assembly dynamics of thermo-responsive amphiphilic triblock copolymer PCL₁₆-PNIPAM₆₃-PCL₁₆ in aqueous solution.The effects of temperature and volume fraction of the copolymer on its phase behavior were investigated.The simulation results showed that different self-assembly morphologies,such as sphere,cylinder,laminar etc.,could be obtained by varying the volume fraction of the copolymer.Besides,it was found that temperature had a remarkable effect on the copolymer phase behavior in dilute solution.When temperature was low,a stable spherical core-shell micelle could be obtained with PCL as its core and PNIPAM as its shell.However,with the increase of temperature to a specific value,it was clearly seen that the spherical core-shell micelle formed at a low temperature changed to a multicompartment micelle whose surface was covered by several discontinuous micro-domains formed by PCL.This thermo-responsive phenomenon was captured in DPD simulation for the first time.Moreover,the lower critical solution temperature(LCST)obtained from the simulation was in good agreement with that determined by experiment.A more detailed explanation was given to illustrate this thermo-responsive phenomenon.This work demonstrated that dissipative particle dynamics could be used to study the influence of temperature and to reveal the mechanism and general rule of the phase behavior of thermo-sensitive amphiphilic block copolymers.

Vacuum pyrolysis residue of flame retardant FR-1 phenolic resin laminated board was used to prepare high quality activated carbons(ACs)by CO₂ and KOH activation,respectively.The effects of activation temperature by CO₂ activation and KOH/char ratio by KOH activation on the properties of obtained ACs were investigated.The pore structures were characterized by N₂ adsorption.Methylene blue(MB)and iodine(I₂)adsorption capacities were also measured.The results showed that ACs obtained by KOH activation had a higher I₂ adsorption value(2442.2 mg穏^-1 vs 946.6 mg穏^-1),MB adsorption value(928.3 mg穏^-1 vs 231.5 mg穏^-1),specific surface area(2289 m²穏^-1 vs 1198 m²穏^-1),and larger total pore volume(1.317 cm³穏^-1 vs 0.703 cm³穏^-1).All the products reached the national first class standard.A double benefit may be obtained by this study,for it not only achieves the purpose of utilization of pyrolysis residue of waste printed circuit board,but also finds a novel and cheap material for the preparation of high quality ACs.

Octadecyl methyl dihydroxyethyl ammonium bromide(OMDAB)was used in polypropylene(PP) as antistatic agent.The moisture absorption and thermal stability of OMDAB were investigated.The influence of OMDAB on antistatic property of PP was studied.Crystallization behavior was explored by X-ray diffraction(XRD)and differential scanning calorimetry(DSC).The thermal property of PP was studied by thermogravimetric analysis(TG).The test results showed that the moisture absorption of OMDAB was greater than the commonly used antistatic agent SN because of multi-hydroxyl group. After adding 0.3%(mass) of OMDAB into PP surface resistivity of the blend decreased to 1.05×10¹¹Ω 7 d later.The blend had good antistatic durability and launderability.When humidity increased by every 10% or ambient temperature increased from 10℃ to 30℃,surface resistivity of the blend decreased by one order of magnitude.OMDAB did not change crystal structure of PP but reduced the rate of crystallization. Thermal stability of PP was weakened by OMDAB.

The article reveals the spontaneous ignition characteristic of activated carbon(AC)as well as its key influencing factors in order to avoid or reduce the spontaneous ignition risk of AC in the process of storage and transportation.The AC samples were successfully prepared with cottonwood powder as carbon precursor and zinc chloride as activated agent at temperature from 300℃ to 700℃,and the variation of spontaneous ignition temperature with the activation temperature was also investigated.The microstructure and surface functional groups of AC samples were characterized by X-ray diffraction(XRD)and Fourier transform infrared(FT-IR)spectra and the thermostability was studied by simultaneous thermal analyzer(STA).The results show that activation temperature has a great influence on the spontaneous ignition temperature of AC samples.Spontaneous ignition becomes easier if decreasing the activation temperature,which is attributed to the gradual increase of the quantities or varieties of surface functional groups of AC.It is also confirmed that the DSC and TG curves of the AC samples tend to shift to the high-temperature region with the activation temperature increasing.In other words,a higher activation temperature in the preparation process is beneficial to reduce the spontaneous ignition risk of AC.