The acoustic resonance frequencies were measured for argon from 270 to 333.15 K and pressures up to 1000 kPa using a cylindrical resonator.The perturbations in frequency measurements from thermal and viscous boundary layers,the fill duct and shell motions were corrected.The second acoustic virial coefficients were obtained by fitting the measured acoustic data.The results agree well with the experimental results by using spherical resonators.The second virial coefficients were determined by fitting the second acoustic virial coefficient and the square-well intermolecular model.The deviation of this work from the calculated value using the equation of state developed by Tegeler et al.is lower than 0.4 cm³·mol^-1.The results show that the second virial coefficient can be determined using cylindrical resonators with low uncertainties.

In this work,new ASOG-VISCO group pair parameters of O-CH₂,O-CyCH,O-ArCH,O-OH,O-COO,O-CCl₃,and O-CCl₄ are determined based on the experimental kinematic viscosities of 44 binary mixtures containing ethers reported in literature.The ASOG-VISCO method and the new parameters obtained are applied to predict kinematic viscosities for these binary liquid mixtures,including associative mixtures of linear,branched,cyclic,aromatic hydrocarbons,ethers,alcohols,chloroform,carbon tetrachloride and esters.The absolute average deviation between calculated and experimental values is 3.31%.The ASOG-VISCO model and these interaction parameters are also applied to calculate kinematic viscosities for binary mixtures containing polyethers,and the absolute average deviation between calculated and experimental values is 5.95%.

Based on available formulas for cold exergy and exergy loss,exergy analysis was performed for a laboratory-scale vacuum evaporation system to produce ice slurry.By using EES software,calculations were carried out for the mixing of cold water and icy water in the system,spray and evaporation in the vacuum chamber,vapor condensation in the water trap,and saline coolant production with a chiller.The exergy losses and exergy efficiencies were obtained for the three of them and the whole system.The results show that the spray and evaporation in the vacuum chamber has the highest exergy efficiency and the vapor condensation in the water trap has lower efficiency. The lowest exergy efficiency and largest exergy losses occur in the saline production with a chiller,resulting in lower efficiency of the whole system.In order to improve the exergy efficiency of the system,the saline coolant production with a chiller should be optimized or to be replaced by other means.

Effects of ultrasonic vibration on frozen water droplets on cold plate surface were studied experimentally.The phenomenon of removing frozen water droplets from the cold surface subjected to 20 kHz ultrasonic vibration was visually observed.The instantaneous shedding process of frozen water droplets from the surface was recorded and the variation of internal temperature of cold plate was analyzed.The mechanism of ultrasonic vibration for instantaneous removal of frozen water droplets from the cold surface was discussed.The experimental results indicate that due to the ultrasonic vibration,the frozen water droplet instantaneously falls off accompanying with upspring phenomenon.Meanwhile,the internal temperature jump occurs in the cold plate.The combined action of the shear force from ultrasonic mechanical effect and the impact by cavitation effect may be the main reason for the removal of frozen droplets.The ultrasonic vibration can remove the frozen water droplet instantaneously,which is the base for frosting on cold surface,and thus it is a highly effective defrosting method.

The knowledge on the heat and mass transfer characteristics of filamentous particles in a fixed bed is preliminary.This paper describes a numerical model for microscopic heat and mass transfer mechanisms between particles and between gas and particles at particle scale.The CFD-DEM coupled approach was employed to numerical study on the local flow and transfer information in the fixed bed,which is difficult to obtain from experiment.The critical factors influencing the temperature and moisture content distribution in a fixed bed such as the air inlet temperature and superficial gas velocity were examined.The model was validated by comparing the simulation results with experimental data.It is concluded that the temperature of filamentous particles reduces and the moisture content of particles increases with the increase of bed height.The air inlet temperature plays a dominant role in the average temperature of the bed,and the mass transfer rate of filamentous particles is affected more obviously by the superficial gas velocity.

Dynamic behavior of an impacting water droplet was simulated with the VOF(volume of fluid)method.Droplet diameter was 2.6 mm and impacting velocity was 0.5 m·s^-1.Droplet dynamic behavior on simulated,hydrophilic and hydrophobic surfaces was simulated with an impacting angle of 63?,90?,118癮nd 160?.Simulation results showed reasonably good agreement with the experiment data.Surface wettability seriously affected droplet dynamic behavior.Droplet spread well and then sticked on the hydrophilic surface.On the surface with an impacting angle of 90?,droplet partly rebounded away from the surface.While droplet totally rebounded when impacting on the hydrophobic surface.There was an edge liquid ring for liquid sticking on the droplet edge when contact line draw back.The maximum spreading factor and the time needed to arrive at the maximum spread diameter were reduced with increasing contact angle.

Two-phase thermosyphon loop heat exchangers are widely used in different industrial fields.The heat transfer simulation is important for design of thermosyphon.However,due to the complexity of boiling heat transfer and two-phase flow,empirical heat transfer models based on experimental data limit the scope of application,with some difficulties in model choice.In this paper,a mathematical distributed parameter model of two-phase thermosyphon loop is established; the datasets consist of 424 two-phase thermosyphon loop experimental data for 4 working fluids from 5 papers.These datasets are used to evaluate 7 widely used transfer models for evaporation.The results show that Kandlikar's flow boiling model and Rahmatollah's model are the best in calculation accuracy; Cooper's pool boiling model gives relatively good agreement with experimental data,indicating that nucleate boiling is the dominant mechanism; flow boiling models of Gungor and Winterton,Liu and Winterton show similar calculation accuracy and the error is acceptable; but Imura's pool boiling model is not suitable for the thermosyphon heat transfer simulation.

The flow and heat transfer characteristics of falling water film outside horizontal tubes in falling film evaporators in seawater desalination were investigated with two-dimensional numerical simulation. Two types of tubes,including a smooth circular tube and six oval-shaped tubes were employed in the simulation.The physical model and mathematical equations for the circular tube and oval-shaped tubes are represented separately.Volume of fluid method is employed to investigate the influence of sectional shape of tube on distribution of film thickness and heat transfer performance.The numerical results indicate that the flow velocity of falling film on the oval-shaped tubes is larger and the film around the oval-shaped tube is more uniform and thinner than that around the circular tube.The film thickness grows with increasing semi-axis ratio,ε,and decreases gradually at first and then increases rapidly along the circumference.The minimum value of the film thickness appears approximately at the circumferential dimensionless position of 0.69 and 0.70-0.84 for the smooth circular tube and oval-shaped tubes,respectively.Compared with the circular tube,the oval-shaped tubes have lower dimensionless temperature and thinner thermal boundary layer,so that heat transfer performance is better.The oval-shaped tube with ε of 2.4 presents the best heat transfer performance with Nu of 0.32,which is 12.68% higher than that of the circular tube.The numerical results correlate well with the experimental and predicted data in literature.

Three dimensional numerical simulation and field synergy principle analysis were conducted with simplified periodic models for shell and tube heat exchangers with helical baffles at three helix angles(30?,40癮nd 50?),and commercial codes of GAMBIT 2.3 and FLUENT 6.3 were adopted in the simulation.It is found that Nusselt number from the model with 40? angle is the largest and the predicted average field synergy intersection angle is the smallest,which is consistent with the field synergy principle.The distribution characteristics of field synergy angles reveal that the distribution is quite uniform through whole shell side of the exchangers.The investigation on local heat transfer characteristics in different regions on the shell side shows that the heat transfer rate in the central region of the heat exchanger increases with the increase of Reynolds number.

The flow structure induced by plane and cylindrical shell delta winglet,trapezoidal winglet and rectangular winglet vortex generators(VGs)is investigated with the particle image velocimetry(PIV)to obtain the velocity and vorticity fields.A small rectangular wind tunnel is built to carry out experiments at Reynolds number Re=700 and attack angle α=60°.The results show that the vortex structure of plane and cylindrical shell delta winglets is mainly distributed in the central area of the inclination edge and the corner area of the trailing edge of the VG. For trapezoidal and rectangular winglets,vortices mainly distribute in the wing tip region of the leading edge area and the trailing edge area.Besides,the cylindrical shell trapezoidal winglet induces a central area vortex structure,which has the largest influential area among all types of VGs.The vortex structure induced by the leading edge of trapezoidal and rectangular winglets is generally stronger than that by trailing edge area.As the flow goes on,the strength of vortex structures degrades.Only one main vortex can be maintained along the flow direction in the case of a delta winglet,while one main vortex and one trailing edge corner vortex can be identified in a trapezoidal and rectangular winglet.The vortex structure induced by plane shell winglet tends to get away from the bottom wall,while the vortex structure induced by a cylindrical shell winglet tends to maintain close to the bottom wall.

The temperature increase of polyformaldehyde(POM)and polystyrene(PS)melts at the outlet of circular and rectangular micro-channels with the same aspect ratio and diameter/equivalent diameter of 350 and 500 μm was measured at different shear rates using two-cylinder capillary rheometer and self-developed viscous dissipation measurement device.The viscous dissipation and its effect on flow behavior of polymer melt in micro-channels were investigated.The results show that the viscous dissipation is enhanced obviously with the increase of shear rate and diameters/equivalent diameter value in the micro-channels.The viscous dissipation in the rectangular channel is much stronger than that in the circular one.Under the same experimental conditions,the temperature increase at the outlet of crystalline POM melt is larger than that of amorphous PS melt due to viscous dissipation.

The domain coverage method(DCM)was proposed to couple orthogonal structured DEM mesh with irregular Fluent mesh.DCM increased calculation efficiency by decreasing particle searching capacity for each Fluent cell.Particles were positioned in irregular Fluent cells with the vector method.The CFD-DEM platform was built based on DCM.And then solids behavior was studied in a fluidized bed 250 mm in bed width and 800mm in bed height with multi-immersed tubes.Simulation results showed that the proposed CFD-DEM model based on DCM could simulate gas-solids flow behavior in a fluidized bed with complex geometries.Particles moving upward collides with windward side of the fluidized bed and the other side formed a region with low solids fraction. Particles moving downward had an opposite effect on solids behavior comparing with particles moving upward.Solids behavior could be expressed into four regions:solids flow moving upward,solids flow moving downward,solids flow moving circularly and no solids region.

There are both a chaotic mixing region and an isolated mixing region for the high-viscosity laminar flow mixing system.Increasing chaotic mixing is the effective method to enhance mixing performance.To obtain good mixing performance in the high viscosity fluid mixing system,flexible impeller together with floating particles were used in the glycerol mixing system.The largest Lyapunov exponent(LE_max)was obtained to study the relationship between chaotic mixing degree and power consumption(P_v).It indicated that only adding the floating particles had no effect on LE_max,but the flexible impeller could contribute to enlarging LE_max.When P_v was 2000 W·m^-3,the LE_max of the primary system could be enlarged by 10.29% while using flexible impeller,and when floating particles and flexible impeller worked together,LE_max could be enlarged by 30.86%.At a low P_v(P_v≤2000 W·m^-3),the chaotic mixing of high-viscosity fluid using floating particles synergistically with flexible impeller was much better than the system using the traditional turbine impeller.

The influence of activated carbon dispersed particles on the variation of bubble diameter and volumetric mass transfer coefficient of the system of CO₂-water absorption in ultrasonic field of a single frequency and multi-frequency was investigated in real time in a bubble column with a bubble feature measuring system called duplex conductivity probe.The results showed that multi-frequency ultrasonic field was superior to single-frequency ultrasonic field in enhancing volumetric mass transfer coefficient without dispersed activated carbon particles.Volumetric mass transfer coefficient increased by 40%-64% in the ultrasonic field of multi-frequency of 20-50-100 kHz and input power of 100 W.As activated carbon particles of 38 μm were added to the system,volumetric mass transfer coefficient firstly increased and then gradually decreased. However,the trend of variation in bubble diameter was on the contrary. Enhancement of mass transfer was most significant when solids content was 1.0 kg·m^-3.When solids concentration was at a specific value,volumetric mass transfer coefficient decreased with the increase in activated carbon particle diameter.Compared with the system without activated carbon particles,when solids content was 1.0 kg·m^-3,volumetric mass transfer coefficient was enhanced about by 1.58 times,and volumetric mass transfer coefficient further increased by 2.02 times under combined action of particles and reverberating ultrasonic field of multi-frequency of 20-50-100 kHz and input power 100 W,which suggested that multi-frequency ultrasonic field and dispersed particles had a significant synergistic effect on enhancement of mass transfer in CO₂-water absorption system.

An experiment was carried out to study the process of pure water drop and water drop with 4% surfactant AFFF impacting on wood surfaces heated or at room temperature.The temperature of the heated wood surface was 124.7℃,while the height of the drop was varied from 15 cm to 40 cm.The initial diameters of pure water drop and the water drop with 4% AFFF were fixed at (2.4±0.1)mm and (1.8±0.1)mm,respectively.The impacting processes were recorded by using a Photron Fastcam high-speed digital camera with 2000 fps.The experimental results show that the number of splashed droplets and the maximum spread factor increase as the impacting velocity of drop increases.When the pure water drop impacts on the heated charring wood surface,it will splash many daughter drops after 4 ms and produce a big liquid column on the surface.A few milliseconds later,the water drop changes to a small liquid column and stays on the wood surface.However,the well wetting process occurs with the water drop containing 4% AFFF.

A coupling sub-cooler vapor injection air source heat pump system is proposed,which consists of two sub-cooler vapor injection air source heat pumps and two triple tube heat exchangers.The defrost method involves a coupling defrost system based on traditional hot gas bypass defrost,so that the problem of liquid refrigerant evaporation is solved,which is usually encountered in the outdoor heat exchanger with traditional hot gas bypass defrost.The operation reliability of air source heat pump is improved in the environment of low temperature and high humidity.The simulation and optimization for the new system under normal heating conditions give the optimal medium temperatures and corresponding injection ratios in low temperature environment.A binary linear fitting formula for optimal medium temperatures from condensing temperature and evaporating temperature is obtained.

Icing characteristic is important for refrigeration,freezing desalination and chemical engineering. A new freezing method is proposed in this paper,which is driven by humidity difference in 0℃ environment.The evaporation-refrigeration of liquor driven by absolute humidity difference in zero centigrade was studied.Based on heat and mass balance,an unsteady-state thermodynamic model was established with movement characteristic of icing on the surface of liquor,which could simulate icing development under different conditions.The effects of absolute humidity difference,airflow velocity and mass diffusion coefficient on icing development were analyzed.The results indicate that above factors have evident effects on the liquor evaporation-refrigeration.The model and results will provide a theoretical basis and guidance for liquor evaporation-refrigeration driven by absolute humidity difference and its applications.

By comparing the heat transfer characteristics of dropwise condensation of natural refrigerant R290 and conventional refrigerant R22,following conclusions are obtained.The effect of surface subcooling degree on the smallest radius and the critical radius of droplet is much larger than that of the saturation temperature,and larger surface subcooling degree makes the smallest radius and the critical radius of droplet smaller.The smallest radius and the critical radius of R290 show little difference from those of R22.The heat transfer capacity through the single droplet of R290 or R22 increases first and then decreases with the increase of contact angle,suggesting the existence of the maximum heat transfer capacity.The heat transfer capacity through the single droplet increases with the increase of surface subcooling degree and decreases with the increase of the saturation temperature.The heat transfer capacity through the single droplet of R290 is obviously larger than that of R22.The dropwise condensation heat flux of R290 or R22 through the heat transfer surface has maximum value at the optimum contact angle.The dropwise condensation heat flux of R290 is obviously higher than that of R22.

Aiming at the online fouling removal problem in heat transfer tubes,the imbalance spiral-gear inserts are proposed.The self-rotation force moment of such inserts is analyzed theoretically,and the self-rotation performance is examined experimentally.The convective heat transfer characteristics are investigated through experiments in order to evaluate the effect of imbalance on heat transfer enhancement. The result shows that the spiral-gears connected clockwise and counterclockwise alternately have the greatest force moment and can spin more easily.For the heat transfer temperature difference of 7℃,the overall heat transfer coefficient of balanced spiral-gear inserts is 22.2% and 12% higher than that of spiral-wire insert and twisted-tape insert,respectively.For the heat transfer temperature difference of 15℃,the overall heat transfer coefficients of the two kinds of imbalance spiral-gear tubes are 89% and 112% greater than that of straight tubes without any inserts,and are 12% and 25% higher than that with balanced spiral-gear inserts.The flow resistance is increased correspondingly but still in an appropriate range for engineering applications.From the comprehensive performance on heat transfer rate and resistance,the imbalance spiral-gears give the best result.

Polyalcohol is considered as a promising candidate of phase change material for heat storage,but it presents poor heat conduction performance.Fiber-enhanced polyalcohol binary system combines polyalcohol with copper fiber to improve its heat conduction.FLUENT software is used to simulate the temperature field of polyalcohol binary system PE/TRIS in this study,in which molar capacity of polyalcohol binary system PE/TRIS is fitted to polynomial equations.Simulation results present the same trend of temperature distribution in the fiber-enhanced polyalcohol binary system as experimental data.Therefore,the physical model for the simulation is reliable.The simulation shows that fiber planes do contribute to heat conduction.The heat flux first declines sharply with time with or without fiber planes inserted,and then becomes steady.The heat conducted through fiber planes in fiber-enhanced polyalcohol is the main heat flux and is comparable with the heat conducted through five boundary walls.The fiber-enhanced polyalcohol binary system shows quicker response to heat input than the polyalcohol binary system PE/TRIS without fiber.To perfect the temperature field,fiber planes parallel to the bottom copper board should be added to the polyalcohol heat storage system.

By sweeping binary droplets with N₂ gas,the Marangoni convection driven by desorption of light component into gas phase is observed with the help of laser shadowgraph optical method.The results show that Marangoni convection arises as small-scale vortex and large-scale symmetrical circular flow.The small-scale vortex structure appears in the ethanol-water droplet at the very beginning,and then vortex structure develops and merges to form larger vortex flow.At the interface of acetone-water binary droplet,symmetrical circular flow appears at first,and then vortex flow arises in the circular flow.For the quiescent single binary droplet composed of ethanol-water and acetone-water separately,the mass transfer coefficient is measured to compare with theoretical prediction while N₂ gas purges the gas-liquid interface. Experimental results show that the large-scale symmetrical circular inside the droplet can promote mass transfer process much better than the small-scale vortex near the interface of droplet.

With double volute and double discharge pipe,circumferential unevenness of vertically-installed high-temperature molten-salt pump is expected to be relieved.Standard k-ε turbulent model and implicit multi-grid coupling method were used to simulate the whole-passage three-dimensional inner turbulent flow of the pump.Correspondingly,pump performance of single volute and single discharge pipe molten-salt pump was comparatively studied.Comparisons of pressure and velocity distributions,local turbulent kinetic energy distribution,radial forces at impeller and volute were conducted between two different pumps under different flow rate conditions.Energy performance of the single-volute pump was better than that of the double-volute pump.Good adaptability was shown in the flow field of the double-volute pump at large flow rates.For these two different pumps,the radial forces exerted on the impeller and volute were small at the design flow rate.However,this phenomenon varied under off-design conditions.The radial forces on the impeller and volute of the single volute pump increased rapidly,while the double-volute pump showed superiority over the single volute pump in reducing radial forces at the impeller and volute.The flow field in the double-volute pump was not perfectly symmetric,but under large flow rate conditions,the radial forces exerted on the impeller and volute reached minimum values respectively.

In the process of direct hydrogen production from coal with CaSO₄ as oxygen carrier,CaS and CaSO₄ are used together at a high temperature.There is a dispute in literature whether an eutectic phenomenon occurs between them,although the melting points of them are above 1400℃.TG and DTA measurements of CaS,CaSO₄ mixtures with different molar ratios were performed using a atmospheric thermal analyzer under nitrogen atmosphere.The results showed that within 700℃ to 1300℃,the DTA curves of endothermic peaks within 850-1100℃ were due to the endothermic solid-solid reaction between CaS and CaSO₄.The temperatures when the first endothermic peak appeared and the temperatures when the fastest change of DTG curves happened were compared between different samples.No eutectic point was found,which meant eutectic phenomenon did not exist within 700-1300℃.Similar analyses were performed on CaO,CaS and CaSO₄ mixture samples,and no eutectic evidence was found within 700-1500℃.The conclusions above were also confirmed by the SEM analyses performed on the residue samples.

The influence of alkali metal compound(K₂SO₄)on kinetics of low-temperature SCR of NO by NH₃ over V₂O₅(vanadium pentoxide)/AC(activated carbon)catalyst was investigated.The reaction activity decreased obviously when doping the V₂O₅/AC catalyst with alkali metal compound.The V₂O₅/AC and K_x-V₂/AC(x=0.5,1,2)catalysts were prepared by the pore volume impregnation method.First,the influence of internal and external diffusions on the intrinsic kinetics experiment was eliminated. Then NH₃ SCR experiments with different NO-to-NH₃ ratios at various temperatures were carried out to test the model.Both the mechanical(i.e.Eley-Rideal model,Langmuir-Hinshelwood model,and Mars-van Krevelen model)and empirical(i.e.first-order model and power-rate law model)models were used to correlate the experimental data.The results showed that the Eley-Rideal model could well describe the SCR of NO by NH₃ over V₂O₅/AC catalyst than other models whether alkali metal compound was doped in the V₂O₅/AC catalyst or not.The presence of alkali metal compound increased the reaction activation energy,but not the reaction mechanism.

Pyridine bases were prepared by reactions of aldehydes(formaldehyde,acrolein and/or acetaldehyde)with ammonium acetate,using acetic acid as solvent,in a refluxing tank reactor under atmospheric pressure.Quantum chemical and thermodynamic calculations were conducted to analyze the configurations and charges of acrolein and propylene imine and to investigate the electrostatic interaction,frontier molecular orbital and energy changes during the formations of intermediate dihydropyridine and product 3-methyl pyridine.Based on these results,a reaction mechanism was proposed for the formation of 3-methyl pyridine from acrolein and ammonia,and also,a general rule was summarized for the reaction of aldehyde with ammonia to form pyridine bases.The products distribution predicted theoretically was consistent with that obtained by experiment.

The reaction kinetics of of CO₂(aq),HCO₃^- with monoethanol amine(MEA),2-amino-1-propanol(2-AP),1-amino-2-propanol,iso-butyl amine(IBA),3-amino-1-propanol(3-AP),diethanol amine(DEA),morpholine(MORP),piperidine(PIPD),and 4-piperidine methanol(4-PIPDM)in aqueous solution at 25℃ was investigated by stopped-flow and ¹H NMR spectrometric technologies.One plausible and universal mechanism was proposed.The rate constants for reactions of CO₂(aq),HCO₃^- with the selected amines,the protonation constant of carbamate,and the stability constant of carbamates were obtained by the fitting results.The plot of lgk₇ versus lgK₉ was linear for the primary and secondary amines,respectively.The above relationships indicated that the stability constant of carbamate represented the overall contribution of its electronic,steric and solvation effects.This discovery may provide a theoretical guidance for the design of novel poly-amines in improving CO₂ capture efficiency.

The density functional theory is used to study the adsorption mechanism of volatile organic compounds(VOCs)on MOF-5,including methanol,acetaldehyde and acetone.The results show that these VOC molecules are adsorbed in four adsorption sites of MOF-5 and Zn₄O clusters are the most favorable adsorption sites.Comparison and analysis on the structural properties and adsorption energy of VOC molecules adsorbed on MOF-5 indicate that the functional groups play the key role.The introduction of electron-withdrawing functional groups to the aromatic rings of MOF-5 increases the interaction between organic molecules containing hydroxyl(such as methanol)and MOF-5 frameworks.The introduction of electron-donating functional groups and oxygen containing groups to the organic linkers increases the adsorption capacity of organic molecules containing carbonyl(such as acetaldehyde and acetone)in MOF-5.

The adsorption characteristics of poly-carboxylate dispersant(Tersperse 2700)onto imidacloprid particle surfaces,such as adsorption thermodynamics,kinetics,adsorption force and adsorption conformation,were studied with determining adsorption amounts by remnants of concentration,adsorption layer thickness and Fourier transform infrared spectroscopy.The thermodynamic parameters obtained are as follows:ΔH_ad<0,ΔG_ad<0,ΔS_ad>0,indicating that the adsorption is a spontaneous exothermic process.The adsorption layer thickness decreases as temperature increases.Theoretically,higher temperature is not beneficial to adsorption process.The result of adsorption kinetics shows that the adsorption of dispersant 2700 onto imidacloprid particle surfaces corresponds with Lagergren adsorption rate equation.The adsorption rate increases with temperature and activation energy E_a=12.62 kJ·mol^-1,so the adsorption process is physical adsorption.The result of adsorption force shows that van der Waals force is an important force at different temperatures.The adsorption is monolayer and multi-point.The hypothetical adsorption model shows that the adsorption stability on imidacloprid particle surfaces is maintained by apparent stereo-hindrance effect and electrostatic repulsion produced by dispersant 2700.

High purity capsaicin is in great demand in the fields of medicine and food.The multi-element valued model is used to evaluate four capsaicin extraction technologies including solvent extraction,supercritical fluid extraction,coupled solvent-supercritical extraction and coupled solvent-ion exchange route.The results confirm that coupled solvent-ion exchange route is the optimal technological process,preceding other routes obviously.Experimental study on the coupled solvent-ion exchange route shows that the optimum parameters for capsaicin extraction are:initial concentration 331.4 mg·L^-1,flow rate 18.8 ml·min^-1,pH 5.0,and room temperature.The column purification parameters such as the solution concentration and velocity with its effects are also obtained,and the capsaicin purity of final production reaches 98.42%.

2-Keto-L-gulonic acid (2-KGA),the precursor for vitamin C synthesis,is produced by the mixed culture of Ketogulonicigenium vulgare and Bacillus megaterium.In this paper,the previously established kinetic model for 2-KGA mixed culture was firstly tested with the data of 80 industrial batches.Based on sensitivity analysis,it was found that some insensitive parameters might be assigned fixed values to minimize computing time.Then,the model was used to predict the most important state variables,i.e.,substrate and product concentrations.Moving data window technique and rolling parameter identification approach were used in the prediction process.4 h and 8 h ahead prediction errors for 2-KGA concentration were less than 5%.

Choosing appropriate controlled variables(CVs)is demonstrated to be effective for real-time optimization(RTO)of chemical processes,whereas existing approaches do not allow the CVs to be changed once determined,which leads to limited RTO performances.To this end,this paper presents an approach for on-line modeling CVs.The local modeling method was used to select similar samples to construct estimating models for necessary conditions of optimality(NCO),which were used as CVs to achieve better RTO performance under the functions of feedback controllers.A case study of evaporator demonstrated that the proposed method could increase the economic profit of process operation by accurate modeling for on-line NCO.

Cogeneration of power and fresh water could not only resolve fresh water shortage,but also reduce energy consumption of desalination.A detailed mathematical model of the cogeneration of fresh water and power was established and described as an MINLP problem,which was solved by hybrid-coded genetic algorithm.The result showed that when fresh water demand was the prime target,the optimal pattern of the cogeneration system was integration of power plant,multi-stage flash and reverse osmosis,in which back pressure steam turbine was used in power plant.There was an optimal value of the production ratio for MSF and RO in the integrated system.The water cost of the integrated system and the production ratio for MSF and RO decreased slowly with increase of fresh water demand.

An improved fluid catalytic cracking unit(FCCU)riser-regenerator model combined with carbon-monoxide(CO)combustion was proposed,since multiple steady states of FCCU would change as CO conversion changed with different amounts of CO combustion promoter added.Due to the conservative consumption of CO combustion promoter which contains Pt as the active component in refineries,the amount of the added combustion promoter would significantly affect the economics.Thus,based on the heat balance of the high-efficiency regenerator,heat generation and removal curves were determined and three steady states were found,two of which were thermally stable satisfying the slope condition.From the analysis of the influence of different amounts of CO promoter on the multiple steady states,it was pointed out that the varying distance between the two high steady states resulting from different amounts of CO combustion promoter added would influence the severity of the control system design.

Aiming at problems appearing in model switching of multi-model predictive control,a multi-model switching method based on recognition of operating conditions was presented,and the variations of dynamic characteristics in the process reflected by measurable variables were adopted.Firstly,Gaussian mixture model(GMM)was used to classify historical data into several operating conditions. Then the load vector matrix and the predictive models were built based on the data of different operating conditions. Lastly,the predictive model was chosen according to squared prediction error(SPE)of the principal component analysis(PCA)model.This method was implemented in controlling the coil outlet temperature(COT)in an ethylene pyrolysis furnace.The simulation results showed that the stable and balanced control of multiple COTs were realized by the presented method,and the matched operating condition could be easily found by comparing SPE of different PCA models when the operating condition of the system varied.Meanwhile,the corresponding predictive model was selected,with which the problem of switching lag among predictive models when the dynamic characteristics of the system changed was resolved.

The adsorption of interfacial active molecules on oil-water interface will directly affect its interfacial properties,such as interfacial tension,interfacial dilatational rheology,which influences the stability of oil/water emulsions.The interfacial properties could be quantitatively analyzed by introducing a proper adsorption model.In this work,Span 80 was selected as the surface active component and added in a mineral oil-deionized water system.The interfacial tension and dilatational rheology were measured below and above the critical micelle concentration(CMC,0.45 mmol·L^-1 in this work).It was found that the interfacial dilatational modulus increased first and then decreased as the concentration of Span 80 continued to increase.Since the pure diffusion controlled model was insufficient to accurately describe the relaxation behavior,the relaxation model from Lucassen-van den Tempel was combined with dynamic adsorption models,such as Langmuir,Frumkin,reorientation,and rigorous reorientation model.The results showed that a combination with rigorous reorientation model accurately predicted the oil/water interfacial tension and indicated the influence of surfactant,frequency on interfacial dilatational modulus properly. Interfacial tension and dilatational modulus were measured with the spinning drop method.During the measurement,an oil drop of 2.5 μl was injected into the capillary filled with deionized water.The capillary was rotated at 10000 r·min^-1,and the temperature was maintained with an air bath circulation system.The image profile of the droplet was recorded with a video camera at 4 fps.Interfacial tension was calculated from the geometric contour of the drop with the Young-Laplace equation,while interfacial dilatational modulus was determined from the difference of interfacial tension and interfacial area. Interfacial dilatational modulus was determined after equilibrium adsorption of Span 80 molecules.

1,3-Bis(4-hydroxyphenyl)adamantanea(DPAD)was synthesized via Friedel-Crafts alkylation of 1,3-dibromoadamantane and phenol with the catalyst of Lewis acid.Williamson condensation reaction of 1,3-bis(4-hydroxyphenyl)adamantane and halogenated sulfone alkylating reagent and neutralization led to 1,3-bis(4-(2-ethoxyl sodium sulfonate)phenyl)adamantane in alkaline condition.The structures of compounds were characterized by IR,¹H NMR and elemental analysis measurements.The surface tensions of the target compound in different concentrations were tested.The effects of reaction solvent,halogenated sulfone alkylating reagent,reaction temperature and time,and raw material ratio on the yield of the target compound were discussed.The optimal reaction conditions were as follows:DMF as solvent,n(DPAD):n(BrC₂H₄SO₃Na)=1:2.2,then the mixture reacted for 3 h at 60℃.Under the optimized reaction condition,the total-yield of the target compound can reach 72%.

Failure behavior of polyaspartic ester polyurea(PAEP)coating in humidity environment was studied by means of electrochemical impedance spectroscopy(EIS)and scanning electron microscope(SEM).A series of impedance spectra of PAEP coating during humidity experiment were measured,and the protection properties of the coatings were evaluated according to the spectra.Equivalent circuit models were proposed to interpret the electrochemical impedance data for the present coated systems.The protection properties of the coatings were evaluated and analyzed by electrochemical specific parameters of coating(water absorption and porosity).The experimental results indicated that coating failure behavior could be divided into three main stages:firstly,permeability of electrolyte to the coating; secondly,initial transition of base metal corrosion reaction; thirdly,coating failure due to aggravated corrosion of metal matrix.Then water absorption and porosity of polyaspartic ester polyurea coating were used to evaluate the coating aging performance,and the result showed that both changes presented three stages:rapid growth stage,slow growth stage,and stable stage.From the beginning 24 h of humidity experiment to 4752 h,water absorption increased to 0.216% from initial 0.046%,and porosity increased to 2.32×10^-5 from initial 2.31×10^-9.SEM images of coating surface showed that roughness of coating surface increased and defect of fracture appeared after 4572 h of humidity experiment,indicating the failure of coating.

When cells are cryopreserved,the morphology of cryoprotectant at crystallization and recrystallization would influence the survival rate of cells.The cryo-microscope system was used to observe the morphology of crystal and sizes of two cryoprotectants during cooling and rewarming at different speeds.It is found that crystals during cooling are smaller and less at higher speed than at lower speed,and the former is favorable for preservation of cells.When the vitrified cryoprotetant is rewarmed,crystals during recrystallization are smaller and less at higher speed than at lower speed,and the former with narrow danger zone is favorable for the survival of oocytes.Besides,high concentration of cryoprotectant is more favorable for the survivalrate of oocytes than lower concentration.

Sampling system with Dekati Gravimetric Impacter(DGI)was positioned in front of the 2^# boiler ESP of a power plant in Nanchang and used to collect PMs,while the samples of raw coal and bottom ash were also taken.The massive particle size distribution of fly ash,the distribution characteristics of minor and trace elements in bottom ash and fly ash were measured and analyzed.The results indicate that the mass of PM_1.0 and PM_2.5 are 16.0%-17.4% and 46.9%-50.6% respectively.Na,Mg,P and S mainly enrich in submicron particles,and Al,Si,K,Ca,Ti and Fe mainly do in supermicron particles. With the decrease of particle size,the concentration of As,Cd,Cr and Pb increases,and the growth rate is higher for submicron particles than for supermicron particles,the concentration of Mn in different PM is similar.A large amount of As,Cd,Cr and Pb involves in the submicron PM,but Mn has no significant difference for different size PM particles.The volatileness of trace elements is As>Cd>Cr>Pb>Mn,and their emission factors under non-controlled conditions are listed in the paper.For PM_1.0,the order of emission ratio of trace elements is the same as volatility,i.e.,As>Cd>Cr>Pb>Mn.

Spores of Bacillus subtilis(ATCC6633)could be used as a potential model for the resistant microorganisms.The inactivation effect of the spores in drinking water by chlorine was studied,and such factors as chlorine concentration,contact time,pH,temperature,and initial density of spores,which might influence the inactivation were evaluated.The results showed that the inactivation process of spores by chlorine was characterized by a lag phase and a logarithmic phase of inactivation.With chlorine concentration from 2.06 to 10.30 mg·L^-1,reaction time from 0 to 166 min,pH from 6 to 9,temperature from 1 to 30℃,and initial density of spores from 10² to 10¹² cfu·ml^-1,both chlorine concentration and reaction time influenced the inactivation effect of spores,and rate of inactivation would increase at either higher chlorine concentration or longer reaction time.The inactivation ability of chlorine was stronger under acidic condition than that under alkali condition.With increasing temperature,the inactivation ability of chlorine was enhanced,while initial density of spores nearly had no effect.This study indicated that Bacillus subtilis spores were more resistant to chlorine than Bacillus anthracis spores.

The effect of additive NaCl on microwave-assisted removal of ammonia nitrogen by natural zeolite,including factors influencing adsorption and ion-exchange,was investigated.The results show that microwave-assisted can greatly improve the efficiency of zeolite denitrification.The best conditions are:microwave power 343 W,time 4 min,concentration of NaCl 4%,size of zeolite particles 0.1-0.15 mm,and the best removal efficiency is up to 99.70%.As a comparison,no NaCl addition but microwave auxiliary,the removal rate of ammonia nitrogen by zeolite is 76.46%. If only zeolite was employed the removal rate is 60.70%.So the increase of efficiency is significant,39%,15.76% respectively. The results of zeolite surface morphology and element measurements by SEM,EDS and XRD indicated that sodium chloride could improve microwave heating and ion exchange of zeolite.Its ion exchange capacity for ammonia at microwave condition increases greatly by NaCl.

In this paper,taking acrylic wastewater from the sewage treatment workshop of a chemical fiber company in Jilin as an object,the effect of Fe⁰ on acrylic wastewater treatment in SBBR reactor was studied via parallel comparison test.The test results showed that:(1)It could improve the start-up rate of SBBR reactor by adding Fe⁰.(2)While the reactor was at the stable operation stage,in 2^# reactor with added Fe⁰ and 1^# reactor without adding Fe⁰,the average removal rates of COD_Cr were 70.7% and 60.5% and the average removal rate of NH₃-N were 60.6% and 13.5%,respectively.The average removal rate of COD_Cr and NH₃-N were improved by 10.2% and 47.1% by adding Fe⁰.(3)The mixed liquor suspended solids(MLSS)and mixed liquor volatile suspended solids(MLVSS)in 2^# reactor with added Fe⁰ were 1.60 and 1.35 times than those in 1^# reactor,respectively.Adding Fe⁰ was beneficial to the growth of heterotrophic nitrification bacteria-Alcaligenes sp.,thus significantly improving NH₃-N removal rate.

The formation and degradation mechanism of soluble microbial product(SMP)and the effect of SMP on membrane filterability for membrane bioreactor(MBR)were investigated.The experimental results indicated that utilization associated products(UAP)were major components of SMP when organic substrate was present.Biomass associated product(BAP)from the hydrolysis of loosely bound(LB)extracellular polymeric substances(EPS)dominated SMP when organic substrate was consumed.By Fourier transform infrared spectroscopy(FTIR),the major components of UAP were proteins and polysaccharides,but the major components of the BAP were polysaccharides and humic substances. Compared to UAP,the membrane rejection of BAP had better performance.The effluent of membrane bioreactor(MBR)contained UAP and BAP at optimal hydraulic retention time(HRT).Membrane resistance was directly related to concentration of BAP.

The morphological characteristics of waste polyvinyl chloride(PVC)plastics during its pyrolysis from ambient temperature to 500℃ were investigated with a purpose to obtain the morphological parameters characterizing reaction stages.PVC granules and films were used as typical waste PVC plastics for testing,and influence of impurities was also investigated.During experiments the image changes of PVC were recorded with a high-speed infrared camera,quantitative morphological parameters were explored with the help of a digital image processing software "Image Pro Plus(v6.3)".Two representative morphological signals describing the pyrolysis stages were obtained:pixel area(PA)and bubble ratio(BR).Experimental results showed that plastics pyrolysis involved four stages:melting,two stages of decomposition and a quasi-stable stage in between.For both PVC films and granules,the BR curve could always reflect reaction stages and reaction intensity, while PA could be used as key signal of complete HCl release.The shape of original PVC materials only affected the melting stage.When impurities were involved,the BR curve showed that intense decomposition started earlier at a lower temperature, but overall morphological characteristics remained the same.The morphological signal obtained here could be used as a guide to control dechlorination process of waste PVC and to make a better reactor design.

The development of anaerobic ammonia oxidation (anammox) process, makes it possible to achieve domestic wastewater treatment with low energy consumptions.And the recovery of energy and resources from domestic wastewater can be realized through biological adsorption.The enhanced biological phosphorus removal (EBPR) system was successfully started under sludge retention time (SRT) of 2 d.The SVI of activity sludge was only 50 and the effluent of EBPR system was stable under fluctuant influent.While, the carbon content in EBPR system sludge was only 37%.Stable operation of organic matter removal SBR was achieved by decreasing the aerobic hydraulic residence time (HRT) to 40 min.The carbon content of sludge was then increased to 48%.93.8% of the removed COD was achieved during the anaerobic phase which meant the organic matter was mainly removed by the biological adsorption.Due to the consumption of organic matter by heterotrophic bacteria and the adsorption of phosphorus by PAO occurred simultaneously, when the C/P of domestic wastewater was relatively low, it was difficult to recover both organic matter and phosphorus at the same time.To enhance the recovery of organic matter, HRT of aerobic phase should be decreased and the chemical removal method should be applied to remove part of the phosphorus.The anaerobic mixing time, aeration time and sludge age should be optimized in order to achieve a higher efficient recovery of C and P.

In this paper,pilot test was carried out on a 30 t·d^-1 desalination device with multi-effect and operated at low temperature by evaporation of seawater,which was designed and constructed in the earlier phase of a project.Using the results obtained,the relationships between various key parameters,including motive steam,operating maximum temperature,temperature difference,spray density,extraction method of non-condensing gas,flow of steam ejector,gained output ratio,and product conductivity,were analyzed.Based on these test results,the conclusions drawn are as follows:(1)device stability,productivity of water and GOR are strongly affected by the fluctuation of motive steam pressure;(2)temperature difference by optimal design of heat transfer is about 3℃,and the spray density between 240 L·(m·h)^-1 and 300 L·(m·h)^-1 in desalination;(3)Water productivity increases by 3.64% when vacuum pump is operated from parallel mode changing to series mode;(4)application of thermal vapor compressor(TVC)can increase water productivity and gained output ratio(GOR),at the same time can reduce system energy consumption.If the deviation between real running conditions and design value of the parameters was ≥20%,the injecting ratio will be reduced.The results obtained in this paper can be as a knowledge accumulation and design basis for design of large-scale,low-temperature,multi-effect seawater desalination devices.

Bromate is a potential carcinogen and formed in treatment of bromide-containing water using ozone-based technologies.So,the study on bromate formation during removal of organic pollutions is necessary for applying UV/O₃ process.The effects of water background,initial MTBE concentration,ozone dosage and dosing method on removal of methyl tert-butyl ether(MTBE)and formation of bromate were studied.Besides,the mechanism of action for ozone dosing method was explored.The results showed that MTBE removal rates obtained by UV/O₃ process in ultrapure water and tap water were 93.5% and 88.67%,and bromate concentration were 18.01 μg·L^-1 and 12.13 μg·L^-1,respectively,which were higher than the standard value of 10 μg·L^-1.The promotion of initial MTBE concentration inhibited bromate formation,but longer reaction time were compulsory since MTBE concentration was required to be lower than proposed concentration of 5 μg·L^-1.In this case,bromate formation was eventually enhanced.Increase of ozone dosage was favorable for MTBE removal,but caused decline of the utilization rate of ozone and the promotion of bromate formation.Comparing three ozone dosing methods in which the same ozone dosage of 5 mg·min·L^-1 was applied,the highest hydroxyl radical(·OH)exposure and minimum ozone exposure were obtained in the method at ozone concentration of 0.75 mg·L^-1 and reaction time of 120 min.Therefore,the concentrations of MTBE and bromate in water both met the standard values after treatment.

In this paper,the effect of modes introducing Mg(OH)₂ on hydrogen peroxide(H₂O₂)bleaching processes was investigated for the eucalyptus kraft pulps.There are three ways to introduce Mg(OH)₂ into the bleaching system,i.e.,the direct-addition,or fresh-formed Mg(OH)₂ by adding magnesium sulfate into a pulp slurry pre-mixed with sodium hydroxide,or vice verse.The results showed that the particle size distributions of Mg(OH)₂ were quite different for the three cases.The average particle sizes are much smaller for fresh-formed Mg(OH)₂ than for direct-addition.As a consequence,the processes with fresh-formed Mg(OH)₂ were proved more effective for the pulp bleaching,and there were more hydrogen peroxide found in the bleaching effluents and the favorable pulp qualities.The time-dependent pH profiles of the process effluents also indicated that the decomposition of H₂O₂ for direct-addition or for no addition of Mg(OH)₂ was very significant,especially during the early stage of the bleaching processes.

Filling behavior of micro-array structure product of iPP was investigated by numerical analysis and injection molding experiments.An injection mold was designed to produce products with micro-cylinder structure 500 μm in diameter.The filling process of flow front of micro-cylinders of numerical simulation and injection molding experiment was relatively consistent in the general trend.However,formation of flow front and varying patterns of the height of micro-cylinder in the filling process in the numerical simulation deviated from the experiment.Injection molding experiment showed that micro-cylinder mold wall,melt flow rate,and melt flow inertia played an important role in the formation of flow front.Early filling contributed little to the micro-cylinder molding.Turbulence appeared on the melt flow directly below the micro-cylinder.The flow front was like the shape of acentric ellipsoid crown and gradually developed into the shape of spherical crown.

Zinc oxide was prepared by the combustion method.ZnO/CeO₂ composite oxides were synthesized by the precipitation method with zinc oxide as the coated object.The samples were characterized by XRD,SEM,IR,TG-DTA,UV-Vis and TEM.ZnO was coated by CeO₂ and composite oxides were formed.The composite oxides were modified with modifier reagent,and modification effect was evaluated by the degree of oil-affinity.The type of modifier,mass ratio of modifier,reaction temperature and pH value of solution were studied.The optimal reaction conditions were as follows:modifier stearate,temperature 60℃,mass ratio of modifier 4% of composite oxides,pH value of solution 7.Particle size became smaller,dispersion of samples was better and the degree of oil-affinity of sample was improved after the samples were modified.

Eosin Y(EY)dye sensitized nanocomposite of TiO₂ with graphene(T-G-EY)was prepared by hydrothermal process starting from EY,TiO₂(P25)and graphene oxide(GO).X-ray photoelectron spectroscopy(XPS)measurement showed dramatically decrease in the content of oxygen-containing functional groups due to the reduction of GO in the hydrothermal process.Transmission electron microscopy(TEM)observation illustrated that the graphene in T-G-EY nanocomposite was relatively uniformly covered and anchored by P25.The nanocomposite had a band gap of 2.75 eV,which was narrower than that of P25(3.25 eV)and light absorption was extended to the visible light region.Photoluminescent quenching was also observed in the T-G-EY nanocomposite,illustrating the interactions between components.The photocatalytic activity of T-G-EY for hydrogen evolution from water under a 500 W xenon lamp irradiation was greatly enhanced than that of P25.

A new type of inorganic polymer coagulant,poly-aluminum ferric silicate sulfate(PAFSS),was prepared by alkali leaching,acidic leaching,oxidation,and polymerization.Fly ash,crap iron and waste sulfuric acid were utilized as raw materials.The structure,morphology and coagulation property of the sample were characterized by XRD,TEM,microelectrophoresis,ultrafiltration and coagulation experiments.The results showed that the multi-core PAFSS sample,which possessed larger amounts of Al-O-Si and Fe-O-Si,was synthesized from the interaction between Fe³⁺,Al³⁺,their hydrating polymers,SO₄^2- and poly-silicic acid.The polymer displayed branch-like structure with higher polymerization degree,and larger molecular weight.The coagulation property of samples was excellent when the Si/(Fe+Al)ratio was equal to 0.06-0.10.pH adaptability was much better than that of commercial polymerized ferric sulfate(PFS),polymerized aluminum chloride(PAC)and poly-aluminum ferric sulfate(PAFS).