A model for the heat of absorption of CO₂ using ammonia was established in the Aspen Plus software based on the e-NRTL model.The vapor liquid equilibrium and speciation of the NH₃-CO₂-H₂O system were validated with the experimental data in literature.The heat of CO₂ absorption was predicted and compared with the experimental data,combined with the analysis of liquid composition in the CO₂ loaded aqueous ammonia.The results show that the model built in this paper can accurately calculate the vapor liquid equilibrium,speciation,as well as the heat of CO₂ absorption in the ammonia based CO₂ capture process.The heat of CO₂ absorption is mainly affected by the dissociation of H₂O and NH₃,formation and hydrolysis of NH₂COO^- and dissolution of CO₂ in the aqueous ammonia.The heat of H₂O dissociation has the largest proportion in the overall heat of CO₂ absorption,which is in restraint of the dissociation of NH₃.The reaction related to NH₂COO^- is exothermic first and then endothermic with the increase of CO₂ loading.As the temperature increases,the heat of CO₂ absorption decreases.The average heat of CO₂ absorption is 70.5 kJ·(mol CO₂)^-1,when the CO₂ loading is between 0.2—0.5 mol CO₂·(mol NH₃)^-1 and temperature is 80℃.

With increasing concerns for environmental and pollution problems the world is currently facing,hydrogen is being widely used to reduce our dependence on imported oil and to reduce pollution from vehicles.Hydrogen is the lightest gas and very diffusive.It easily leaks from storage tanks and disperses into the air.Fluent can accurately predict the concentration fields and flammability contours for hydrogen leaks,but building the model and running simulations both take much time.The integral model presented here can very quickly compute the trajectory of the hydrogen jet and the hydrogen concentration decay along the jet trajectory,hence it can be used to deal with emergencies.This study compares the integral and CFD models for low pressure,slow leaks with previous experimental data and then uses these models to predict safety zones around tanks based on the flammability limits of various expected size leaks for both horizontal and vertical leaks.The results show that the hydrogen molar concentration decay rate curve for Fr_den=500 is almost linear,indicating that this is a momentum dominated jet.The decay curve for Fr_den=50 is strongly influenced by the buoyancy induced entrainment so the hydrogen concentration decays much faster with the hydrogen concentration reaching the 4% molar concentration,the flammability limit,by S/D equal to about 130,which would be less than 30 cm.The lengths of the jets in both the horizontal and vertical directions predicted by the integral model are proportional to the orifice diameter. The CFD model is also used to predict the jet profiles for a variety of conditions for both 2D axisymmetric and 3D jets.The jet profiles predicted by the CFD model are compared with the integral model results for a vertical jet with Fr_den=268 and an orifice diameter of 1.905 mm.The 4% flammability limit predicted by the CFD model is slightly larger than that predicted by the integral model.The centerline molar concentration profiles predicted by the 2D and 3D models agree well with the experimental data.The three-dimensional CFD model is then used to predict the jet profiles for horizontal jets.The centerline molar concentration predicted by the 3D model for Fr_den=100 and a 1.9 mm diameter orifice show that the flammability envelope extends less than 0.5 m from the orifice and to a height of less than 0.4 m.The centerline molar concentration for Fr_den=100 and a 1.9 mm diameter orifice show that the flammability envelope extends 0.8 m from the orifice and is almost horizontal since such a large Froude number gives a momentum dominated jet.

The flat and curved interface models for gas-liquid separated flows in pipes are developed mostly from air-water flow experiments in low pressure,small diameter,horizontal or nearly horizontal pipes,which may not be suitable for high pressure,large diameter and undulating natural-gas-condensate pipelines.By use of methods for phase behavior and physical properties and coupled thermo-hydraulic computations,the suitability of these two mechanistic separated flow models to gas-condensate flow in long-distance,high-pressure,large-diameter and undulating pipelines was studied.Different combinations of friction factor correlations for the flat and curved interface models were embedded in thermo-hydraulic computations of an actual high-pressure,large-diameter,undulating natural-gas-condensate long-distance pipeline.The computational results of pressure drops and accumulated liquid contents for the flat gas-liquid interface model in this study agreed better with the field operating data than the curved interface model.

Based on the gas-liquid-solid three-phase model,the concerned equations suitable for the 3D flow field were derived for calculating virtual velocity and motion of fiber,and momentum exchange source term.A 3D model of the filling process for short fiber reinforced polymer melts was developed accordingly.3D dynamic simulation was performed by using the finite volume method on non-staggered grids and the Level Set method of capturing melts interface.On this basis,a new model was presented to calculate the mechanical properties parameters of 3D oriented short fiber reinforced composites according to the simulated oriented angle of fibers.Numerical results showed that 3D technology could be used to simulate effectively the flow process with the fountain effect of melts and fibers in injection molding.The fiber orientation analysis showed quantifiably the skin-core-skin structure,namely,the fibers in the skin region had a tendency to align along the melts flow direction,while the ones in the core region were randomly oriented.The calculated elastic modulus were in good agreement with the experimental values,which further demonstrated that the proposed gas-liquid-solid three-phase model and the relative algorithms could be used as a base for predicting composite properties.

To overcome disadvantages of freeze-drying that is usually lengthy and expensive,a novel idea,freeze-drying of initially unsaturated porous frozen material,was proposed.An experimental investigation was performed to verify the effect of unsaturated frozen materials with a certain initial porosity on freeze-drying of liquid materials.A multifunctional freeze-drying apparatus on the lab scale was designed,made and assembled.Mannitol was selected as the primary solute in the solution.Liquid nitrogen ice-cream making method was used to prepare frozen materials with different initial saturations.Results show that the unsaturated frozen material can enhance the freeze-drying process significantly and the drying time is reduced substantially compared to conventional freeze-drying for the same material quantity and initial moisture content under the same operating conditions.The drying time with the unsaturated material (initial saturation=0.28) was 36.4% shorter than that with the conventional one(initial saturation=1.00).The smaller the initial saturation is,the shorter the drying time is and the lower the moisture content of dried products is.

Optical fiber sensor,as a new technique in the field of fiber optics,has received more and more attention in the measurement of local parameters in two-phase flow.The mathematical principle of the local instantaneous bubble velocity vector measurement using four-sensor probe was deduced by assuming a plane of symmetry of bubbles normal to the motion,and a new mathematical model was presented.An investigation was conducted for obtaining bubble velocity vector in two-phase flow by using a self-made four-sensor optical fiber probe.By comparing the superficial gas velocity obtained from the new probe method with that measured by flow meter,it was found that average deviation was about 9%,indicating a relatively high metrical precision of the new probe method.A further study indicated that local void fraction and interfacial area concentration(IAC)showed a wall peak or a core peak distribution in the radial direction under different flow conditions.

Faced with the obvious leakage flow phenomena in the heat exchanger with quarter helical baffles,a novel sextant helical baffled heat exchanger was put forward in this paper.The 3-dimensional physical model of sextant helical baffled heat exchanger was built;numerical simulation was performed with different helical angles(10°,20°,30°,40°)under different working conditions.ANSYS CFX software was used to obtain detailed fluid flow and heat transfer characteristics on the shell-side,and comparison was made between the new and the traditional segmental baffled heat exchangers.Results indicate that the leakage flow is significantly reduced with the sextant helical baffles,and shell-side rotational flow characteristics are also improved.As the helical angle increases,the velocity field and the temperature field become much uniform,so the comprehensive heat transfer performance is improved.

In order to study the influence of gas flow rate on flow structure,interface motion of counter-current gas-liquid flow over structured packing surface,a CFD model based on detached eddy simulation(DES)and volume of fluid(VOF)method was developed.Explicit interpolation scheme was used for the VOF formulations,and the Geo-Reconstruct method was chosen as the volume fraction discretization scheme.Structured curvilinear grids were generated for the whole fluid domain and locally refined to ensure that at least 10 grid points were within the liquid film.When F factor was low(F≤1.354 Pa^0.5),the distribution of free-surface and its velocity component v_y were periodic,and the fluctuation amplitude was almost uniform.Along the free-surface all values of v_y were negative.As F=3.386 Pa^0.5,fluctuation of free-surface appeared to be disturbed,while the distribution of v_y kept periodic,and at the lower edge of liquid waves v_y>0.As F=5.418 Pa^0.5,back mixing of liquid phase appeared,recirculation regions were formed in both phases and evolved with the liquid back mixing process,and the liquid film could wholly move upward in some concaves of solid surface.As F≥6.772 Pa^0.5,dry patch was formed at the lower part of packing region and no liquid could flow out from the bottom outlet.With the increment of F factor,both liquid holdup and effective interfacial area increased first and then decreased.

An average modified coefficient was used to modify Fick's second law and a theoretical equation was established to describe unsteady state gas diffusion in fractal porous media.The experimental system for unsteady state gas diffusion in fractal porous media was based on the plug flow diffusion.Three different porous medium samples were used to verify and modify the theoretical equation.The results indicate that Fick's second law is not applicable to unsteady state diffusion in fractal porous media,and unsteady state diffusion law in porous media is same under different conditions,and diffusion law in porous media with different pore structures is different.

Two novel ice-making systems with evaporative supercooled water are introduced with different dehumidification methods.One is the improved ice-making system with liquid desiccant,in which a subsystem of evaporative precooling water is added and the dehumidified air is cooled by cooling water of system itself.The improved system can not only avoid the blocking problem in the traditional supercooled water method,but also can utilize the low humidity ratio air.The other is an ice-making system with condensation dehumidification,which includes two ice-making subsystems,with evaporative supercooled water and supercooled condensed water of moist air separately,and also solves the blocking problem with the traditional supercooled water method.The system is relatively simple in comparison with the improved ice-making system with liquid desiccant.The analysis on thermodynamic properties shows that in comparison with the traditional supercooled water system,the coefficient of performance of the improved ice-making system of evaporative supercooled water with liquid desiccant can be increased by more than 33.8%,while that with condensation dehumidification is basically the same under a certain working condition.

The gas flow behavior of short-contact cyclone reactor with different vane-guide locations was numerically simulated with the Reynolds stress model(RSM).The gas RTD(residence time distribution)in the reactor was studied by using the species transport equation.The effect of vane-guide location on residence time distribution,gas flow field and short-cut flow was investigated.The gas RTD curves at the catalyst outlet of different vane-guide locations were similar,while those of the mixed reaction zone had some deviation.A larger distance from vane-guide location to the inlet of reactor would cause a smaller gas tangential velocity in the mixed reaction zone and induce a larger tangential velocity and smaller quasi-free vortex in the separated reaction zone.Though a smaller distance from vane-guide location to the exhaust pipe inlet would cause weaker short-cut flow near the exhaust pipe inlet,which made it difficult for catalyst to be carried out from the exhaust pipe,it would amplify gas flow rotation intensity in the exhaust pipe which contributed to energy loss.

The formation of fly ash deposition on heat transfer tubes in a boiler taken as the research background,an experiment of fly ash particle impacting plate at ambient temperature and pressure was carried out to investigate the effects of initial velocity and fly ash particle diameter on normal coefficient of restitution.The experimental results show that when particle diameter remained constant,normal coefficient of restitution e_n first increased,then leveled,and finally decreased as normal incident velocity v_i,n increased,and in the rapid increase region of e_n,the slope of the experimental curve(e_n vs v_i,n)was very large.This was due to the variation of the ratios of different types of energy to the total energy in the different ranges of normal impact velocity.When normal incident velocity remained constant,normal coefficient of restitution increased as particle diameter increased.The critical capture velocity changed with microsphere diameter,the larger the size,the smaller the capture velocity.

To solve the problem of non-uniform fouling removal and scale prevention in the heat exchanger tube with vibrating spiral-insert cleaning technology,a vibrating and reciprocating spiral-insert cleaning mechanism is put forward.It makes use of the hydrodynamic force to change the local flow resistance at the tube outlet periodically to cause velocity fluctuation in the tube,so that the vibratory spiral-insert in the tube scratches the fouling with axial reciprocating movement and the fouling on the inside wall can be removed uniformly.The flow characteristic of the baffle is obtained by experimental study.The computation formula for velocity in the tube with the effect of baffle and the computation method for the baffle opening,which makes the vibration spiral-insert produce an axial reciprocating stroke not less than a pitch,are obtained by theoretical analysis.The test proves that the fouling removal and prevention with the vibrating and reciprocating spiral-insert is more effective.Under the same experimental conditions,the heat transfer coefficient is increased by 60% and 20%,respectively,compared to empty tube and vibration spiral.Moreover,the scaling speed is reduced.

Void fraction and pressure drop of gas-liquid two-phase flow in microchannel have remarkable influence on performance of mass and heat transfer,and also are important design parameters of microreactor.A high speed camera and a pressure measuring system were used to investigate void fraction and pressure drop of CO₂ chemical absorption by monoethanolamine(MEA)aqueous solution.The effects of gas/liquid flow rate and chemical reaction rate were studied under Taylor flow.Experimental results showed that,for a given liquid phase flow rate,both void fraction and pressure drop increased with increasing gas phase flow rate,and void fraction decreased while the pressure drop increased with increasing chemical reaction rate.For a given gas flow rate,void fraction decreased while pressure drop increased with increasing liquid phase flow rate and chemical reaction rate.Two semi-theoretical models were proposed for predicting void fraction and pressure drop of gas-liquid two-phase flow accompanied with chemical absorption in microchannel,respectively.The average deviations of the models were 15.79% and 11.12% respectively for void fraction and pressure drop,showing good prediction.

Water-sparged aerocyclone(WSA)is a new type of air stripping equipment with high efficiency for ammonia removal.In order to improve its mass transfer performance and establish design principles,spray hole distribution of WSA was optimized by means of theoretical analysis and experimental method.A new concept,critical distance of spray holes,l_c,and its calculation formula were put forward.The results show that the WSA with square arrangement of spray holes exhibits higher mass transfer efficiency than that with triangle arrangement of spray holes in air stripping of ammonia.The distance between adjacent spray holes of the WSA has obvious effect on volumetric mass transfer coefficient.The optimal distance is about 1.28l_c and the perforation area is about 78% of the central tube height in the WSA.These results could be used as a guide for the design of WSA with good mass transfer performance.

The condenser performance deteriorates sharply with the reduction of gravity.An order of magnitude increase in tube length is required to achieve complete condensation in a tube under microgravity as compared with a tube under normal gravity.The phase distribution and heat transfer are not coordinated under microgravity so that the heat transfer is deteriorated.The new phase separation condenser tube proposed using the passive phase separation concept to modulate flow patterns and enhance heat transfer is suitable for different gravities.This paper focuses on the numerical simulation of the air-water flow pattern modulation process in the vertical phase separation condenser tube under normal gravity,low gravity and microgravity.Three conclusions could be drawn.(1)The phase distributions of “gas near the tube wall and liquid in the tube core” are obtained under the three gravitational conditions.Under microgravity,the annular region is completely occupied by the gas and almost all liquid flows in the core region.(2)Smaller gravity makes the liquid film thickness much less by the flow pattern modulation.Under microgravity,the thickness is decreased to 1/32.(3)Smaller gravity enhances the condensation heat transfer dominated by the thin liquid film more greatly by the flow pattern modulation.Under microgravity,the condensation heat transfer is enhanced 57.4 times.In general,the flow pattern modulation is more helpful to enhance the condensation heat transfer at smaller gravity.

To examine the heat transfer performance of compound enhancement with helical fins and vortex generators for the shell of double-pipe heat exchangers at different curvatures,helical fins and delta-winglet-pair vortex generators are installed on the shell side with different middle diameters at the same pitch.Heat transfer and pressure drop characteristics on the shell side are investigated experimentally and numerically at Re=680—16000 with air as working fluid.The comprehensive performance on the shell side is enhanced and the enhancement mechanism is analyzed.The results show that larger curvature of the shell leads higher heat transfer coefficient and friction factor.For curvatures of 0.131,0.321 and 0.440,heat transfer coefficient is increased by 31.52%,20.83% and 18.33%,respectively,with vortex generators. Vortex generators can change the fluid flow structure and improve the synergy of velocity field and temperature field,so the heat transfer on the shell side is improved.

Different forces at gas-liquid interface with turbulent air flow sweeping over liquid surface were analyzed.With the flow characteristics and the effect of capillary and porosity of ice considered,a model is presented for the mass transfer in evaporation-refrigeration process driven by humidity difference under the critical condition of 0℃.The mass transfer between gas and liquid in different state,such as liquid,solid or their coexisting state,was studied.The results show that the mass transfer coefficient on liquid surface decreases gradually as the liquid changes to a solid.Hence the icing of liquid should be controlled in order to improve the mass transfer and freezing of liquid.The research would be in favor of engineering applications of evaporation-refrigeration.

In view of the hydrodynamic characteristics of water-wall in ultra-supercritical pressure boiler,a hydrodynamic model was established for complicated series-parallel circuit system.The hydrodynamic calculation procedure was developed based on the POWERSTATION4.0 platform.According to the principle of equal exit temperature of working fluid,the throttle orifice plate compensating pressure drop was numerically calculated.The verifying calculation for mass flow distribution and pressure drop characteristics was carried out at a given heat load and designed throttle orifice plate.The hydrodynamic characteristic curve was drawn by Chebyshev polynomial fitting method.The vertical water-wall hydrodynamic characteristics of 1000 MW ultra-supercritical pressure boilers were also investigated numerically.The results show that U-type bifurcate tubes are good for the throttle orifice adjustment of vertical water-wall.The lower furnace of boiler has strong positive flow characteristics at low load rate but weak negative flow characteristics in supercritical load.The upper furnace of boiler has negative flow characteristics at different load rates.The curve of water-wall hydrodynamic characteristics increases monotonically,which means that the pressure drop of water-wall only depends on the mass flow.These results provide reliable theoretical basis for engineering design and operational monitoring of ultra-supercritical pressure concurrent boiler vertical water-walls.

Several low-vanadium SCR catalysts with alkaline-earth metal and transition metal sulfate(V-M_x(SO₄)_y-W/Ti)or oxide(V-M_xO_y-W/Ti)additives were prepared by the impregnation method and evaluated to investigate the effects of the additives on the denitration performance of the catalysts.The results showed that whatever additive it was,the SCR denitration activity of the catalysts doped with metal sulfates was much higher than that doped with metal oxides.Cobalt additive had higher SCR denitration activity in a wide temperature range and showed also good resistance to the poisoning of SO₂ and H₂O.Characterized by XRD,NH₃-TPD,H₂-TPR,TG and BET,the catalysts with higher catalytic activity for denitration at a low temperature,such as V-CoSO₄-W/Ti,showed always higher surface acidity and better low-temperature reduction ability.

Sol-gel,hydrothermal and photoassisted platinum deposition methods were used to prepare Pt(0.5%)-TiO₂/nanotube catalysts.The results show that catalysts are of ideal tubular morphology and large specific surface area.The highest efficiency of hydrogen production appears when the co-adsorption of methanol and water on the catalyst is at the same order of magnitude after 9 h.The results obtained by ¹H NMR reveal that methanol molecules are cracked on the catalyst surface,and the transitional products can not be desorbed because of the shackles of hydrogen bonds until CO₂ formation.The length of carbon chain,number of branched chains,number of —OH and benzene ring groups on alcohol molecules are of different effects on hydrogen production.The strong or weak adsorption of alcohols on catalysts,and easy or difficult hydroxyl implantation into alcohol molecules can be used to explain these differences.

The Ab initio calculation of quantum chemistry was used to study the reactivity of mercury and bromine compounds.The thermodynamic parameters of HgBr obtained at different temperature were compared with the NIST data to show the calculation reliability.The geometric configurations of reactants,intermediates,transition state and products were optimized.The transition state theory was employed for the calculation of the pre-exponential factors and activation energies in the range of temperature 298—1800 K,and the change tendency with temperature was analyzed for each reaction.The results show that the temperature variation has a minimal impact on the reaction of Br₂ with Hg,and the reaction rate stays at higher level than that of other two reactions in whole temperature range.So,these results obtained are very important for Hg control technology by spraying Br-containing compounds into the flue gas to promote the formation of Br₂.

Reynolds stress model was used to simulate zero axial velocity surface of gas phase flow field in cylindrical cyclone separator.The effects of rotational flow instability,inlet velocity and structural parameters such as inlet area and vortex finder diameter on the distribution of zero axial velocity surfaces were studied.The results show that zero axial velocity boundaries exhibit contorted state in the whole separated space due to the inherent existence of rotational flow instability.In the velocity range studied,the flow field is in mould area and the separator is in kinematic similarity,so the inlet velocity has little effect on zero axial velocity boundaries.Vortex finder diameter and inlet area have significant effects on zero axial velocity boundary around the vortex finder entrance.With the decrease of vortex finder diameter and increase of inlet area,zero axial velocity boundary shrinks gradually.Far away from the vortex finder entrance,the effect of vortex finder diameter and inlet area abates and the width of zero axial velocity boundary increases gradually and trends are similar.The separator with specific vortex finder diameter and inlet area that make the flow field stable can make zero axial velocity boundary of cross section keep preferable circular degree.Simulation results can provide reference on separation mechanism research and structure optimization of separator.

The effectiveness of electrochemical regeneration of activated carbon fiber(ACF)saturated with oily organic wastewater was assessed by adsorption capacity of regenerated ACF achieved in the re-adsorption experiment.The effects of current density,regeneration time,pH value,electrolyte,and structure of ACF were investigated.The regeneration efficiency can reach 90% under such optimum conditions as current density 30 mA·cm^-2,pH 4,15 g·L^-1 NaCl,and 120 min of regeneration time,and ACFs keep high adsorption capacity after five cycles for continuous adsorption and regeneration.The micropore size distribution of the regenerated ACF is in the range from 0.5 to 1.0 nm.It is not found significant damage on the surface of the regenerated ACF or obvious decrease of its BET surface area.The UV spectra show that the electrochemical regeneration process is mainly due to the desorption and decomposition of organics generated by electrochemical oxidation.

Cephalosporin C(CPC)fermentation broth is a typical material with high solid content and high viscosity.Under the condition of constant yield of CPC in filtrate,how to minimize the process time of membrane filtration is an interesting area in industrial applications.Based on the stagnant film theory and mass balance,the estimate equation is founded and the conditions to reach the minimum process time t_min are put forward.The results show that the time consumed is 30%—40% of the total process time when the yield of CPC is from 85% to 95%.Under the experiment conditions(pre-concentration ratio 0.5—0.8,post-concentration ratio 1),the total filtration time is nearly the same.Based on the theoretical and experimental results,the production requirements as CPC yield,the volume of filtrate or retentate and the process effectiveness can be optimized and controlled properly.

The modeling for fermentation process is an important issue in studying microbial fermentation. A precise mathematics model lays the foundation for the subsequent soft measurement and optimization work.The least squares support vector machine(LSSVM)with mixtures of kernels was used for its good performance in the modeling for fermentation process.Global modeling treats entire fermentation process as a study object.It is difficult to guarantee the prediction accuracy.Moreover,it brings about high computing complexity.To solve these problems,a staged modeling method based on LSSVM with optimal mixtures of kernels was proposed.Firstly,secondary variables which presented the characteristics of each stage were selected and modeling samples were classified according to the disparate stages by FCM clustering algorithm.Secondly,local models of stages were built using LSSVM while each local model used the optimal mixtures of kernels.Lastly,the integral process model was constituted with these local models.This method was applied to modeling the penicillin fermentation process based on Pensim and the recombinant E.coli fermentation process in the interleukin-2 production.Simulation results showed that local models of stages were superior to global model both in prediction accuracy and time complexity.The effectiveness of the proposed approach was validated.

Reliability is an important index to evaluate the properties of chemical process measurement data.In practical application and theoretical analysis the method of taking average or weighted average of observed data as the measurement value of unknown parameter is the special case of least square unbiased estimation.The reliability of measurement data arising from unbiased measurement is corresponding to variance.Based on the Gauss-Markov theorem,the variance of unbiased measurement has a lower bound,so the reliability of unbiased measurement cannot be guaranteed.A method used to improve measurement reliability by biased estimation was proposed.Firstly,the equivalence between classical measurement process and LS was discussed.Secondly,a quantitative description method was proposed to evaluate the reliability of biased measurement data.Finally,the effect of biased parameter on reliability was studied.Numerical solution of optimal value of biased parameter was also given.Simulation results showed that the proposed method was always superior to unbiased measurement process in terms of reliability given the reasonable numerical range of biased parameters.

Compared to a conventional reactive distillation(RD)process combining reaction and separation in a single unit,the distillation column coupled with side reactors(SRC)as an advanced integrated reaction and separation technology can be applicable to the reaction system whether the conditions for reaction and separation are harmonious or mismatched.For the typical consecutive reaction system of benzyl chloride production,the mathematic models of RD and SRC were firstly established.On this basis,under the same total column stages and bottom vapor boil-up rate,process simulation was performed for the given RD and SRC processes,in which the pressures for reaction and separation were set to 101.3 kPa.The results showed that there were consistent vapor and liquid flow rates,temperature, and composition profiles in the given RD and SRC flowsheets.Furthermore,for the given RD and SRC processes operated under the same pressure of 101.3 kPa,and the SRC process,in which the pressures for reaction and separation were respectively fixed at 101.3 and 10 kPa,feed flow rate of chlorine and distribution ratio of chlorine as two critical variables deciding production capacity were optimized by minimizing total costs.Optimization results showed that consistent system performance was achieved in the RD and SRC processes operated under 101.3 kPa,while obviously increased production capacity and improved product purity were observed in the SRC process with reaction and separation operated under different pressures.

The differential evolution algorithm was used to solve heat exchanger networks problems characterized by mixed integer non-linear programming.On the basis of Grossmann stage-wise structure,differential evolution was implemented to solve heat exchanger networks synthesis by handling the discrete variables and constraints,especially the ability of global optimization and jumping out of local solutions were studied.The results showed that differential evolution algorithm was effective to obtain better results for solving heat exchanger networks synthesis,which was a mixed integer nonlinear programming problem.

Considering the effects of both surface micro-scale and gas film thermal viscosity,the expansion average Reynolds equation for compressible fluids was modified based on the theories of gas polytrophic process and gas lubrication.The modified Reynolds equation was solved with the finite element method. The effects of micro-scale and thermal viscosity on a spiral groove dry gas seal(S-DGS)performance were investigated with numerical solution of the modified Reynolds equation.When S-DGS was under normal running conditions,the couple effects of gas slip flow and surface roughness were lessened and even disappeared,and only the influence on leakage was at a fixed value with the pressure increased.The influence of surface roughness on sealing performance should be considered when the non-dimensional film thickness H_s<3.5.If the inverse Knudsen number B≥21 or Knudsen number Kn≤0.0476,influence of gas slip flow could be ignored.Sealing dynamic pressure was increased,while leakage decreased due to the effects of surface roughness and thermal viscosity.On the contrary,the influence of gas slip flow increased leakage and reduced loading capacity of gas film.When the S-DGS was operating at low speed and high pressure,the influence of gas sliding flow on sealing performance was less than the influence of surface roughness.When p_o≥2.02 MPa,thermal viscosity effect dominated in affecting sealing performance.

Wormlike micelles(WLMs)were formed in aqueous solutions of cationic trimer surfactant di(2-hydroxyl-dimethylene ether)-α,ω,γ-triple(dimethylcetylammonium chlorine),referred to as 16-4(OH)-16-4(OH)-16 by addition of sodium salicylate(NaSal)and sodium chloride(NaCl).The rheological properties of the micellar solution before and after polymerization were discussed by solubilizing styrene(S_t)into the cores of WLMs.The temperature(T)and shear resistance of systems of 16-4(OH)-16-4(OH)-16/NaSal/NaCl and cetyl trimethyl ammonium bromide(CTAB)/NaSal were compared with the viscosimetry method,and the properties of 16-4(OH)-16-4(OH)-16/NaSal/NaCl solutions before and after polymerization were characterized with the rheology method.The results showed that the optimum solubilization quantity of S_t for the CTAB/NaSal system was 0.05 g,and at 100℃ or after shearing 90 min,the η_a of its polymerization system was 66.9 mPa·s and 15.5 mPa·s,respectively.For the 16-4(OH)-16-4(OH)-16/NaSal/NaCl system,the best solubilization quantity of S_t was 0.10 g;the η_a of its polymerization system was 99.1 mPa·s after shearing 90 min incessantly at 100℃;the plateau modulus(G₀)of the polymerization system was higher than that of the solutions without S_t.Based on the above discussion,the "lock-in" of the microstructure of wormlike micelles formed by 16-4(OH)-16-4(OH)-16 with NaSal and NaCl can be realized by polymerization of S_t in the hydrophobic core of the micelles.

For the spreading of an insoluble surfactant-laden droplet over corrugated topography,the lubrication theory is used to derive the evolution equations of liquid film thickness and interfacial surfactant concentration.The droplet spreading characteristics and the influence of topography structure are numerically simulated with PDECOL code.The results show that Marangoni effect is weakened and the effect of topography feature is enlarged obviously during the mid-late period of droplet spreading,which has a significant effect on the droplet spreading.Compared with spreading on flat substrate,the minimum film thickness over corrugated topography reduces apparently,and at the advancing front of the droplet,the number of wavelet tends to increase notably and the height curve of wavelet crest presents a single hump shape.The increased height and decreased wave number of corrugated topography give rise to the instability of droplet spreading.

A new method of high-purity calcium citrate synthesized by using an on-line cation-resin column was proposed,and it was monitored by an automatic flow-injection electrochemical analysis system which was established on the basis of dynamic electrochemical technology with flow-through mini-type Na⁺ and Ca²⁺ electrodes.Simultaneous monitoring of the operational state of cation resin and the content of calcium citrate in effluent of the cation resin column was achieved by using this system.Through the investigation and optimization of the relevant factors,the total ionic strength adjustment buffer consisted of 80 mmol·L^-1 tris,175 mmol·L^-1 H₃BO₃,1 mmol·L^-1 KCl and 0.025 mmol·L^-1 CaCl₂,sample injection volume was 150 μl,total flow rate was selected at 2.26 ml·min^-1,length of mixing coil was 120 cm(I.D.0.5 mm).The linear determination ranges of the system were 2.0～1000 mmol·L^-1 for Na⁺,0.2～50 mmol·L^-1 for Ca²⁺,respectively,and the relative standard deviation was less than 0.68%(n=11).The detection limits were 1.12 mmol·L^-1 for Na⁺,0.093 mmol·L^-1 for Ca²⁺,respectively.

Surfactant was used in the study to help dispersing TiO₂ nanoparticles in deionized water.The effects of different surfactants(sodium dodecyl benzene sulfonate(SDBS),polyvinylpyrrolidone(PVP)and cetyl trimethyl ammonium bromide(CTAB))on the dispersion stability and solid-liquid phase transition of TiO₂-H₂O nanofluids were investigated.Surfactants SDBS and PVP significantly enhanced the dispersion stability of TiO₂-H₂O nanofluid,and reduced its degree of supercooling by about 37.02% and 9.65%,respectively.Whereas,surfactant CTAB showed no effect on improving the dispersion stability of TiO₂-H₂O nanofluid,and even worse,increased the degree of supercooling of nanofluid by about 6.11%.The adsorption structures of SDBS,PVP and CTAB were analyzed by measuring the adsorbent layer thickness on TiO₂ nanoparticles(X-ray photoelectron spectroscopy).The adsorption structures of surfactants SDBS and PVP were hydrophilic while that of surfactant CTAB was micellar,which could explain the above phenomena.In addition,all three surfactants were found to extend the phase transition time of TiO₂-H₂O nanofluid due to the decrease in the thermal conductivity of nanofluid.

According to the relationship between the structure and function of enzyme,it was speculated that the combination of the mutant enzyme D168L and E435T might improve the catalytic ability of indole to generate indigo.The mutant enzyme D168L/E435T was produced by site-directed mutagenesis conducted on the 168th site of the P450 BM-3(A74G/F87V/L188Q/E435T)and it was identified with higher hydroxylation activity toward indole in comparison to its parent enzyme.Concomitantly,its K_m for indole was 1.72 mmol·L^-1 and this value was lower compared to its parent enzyme(2.09 mmol·L^-1).Also with the k_cat=28.15 min^-1,the turnover rate of the mutant enzyme was increasing up to 6.97-fold that of its parent enzyme(4.04 min^-1).The catalytic efficiency(k_catK_m^-1)was correspondingly raised to 8.48 times as much as that of its parent enzyme.Moreover,the proportion of the byproducts indirubin reduced to 1.2%,much lower than that of its parent mutant(7.3%),which indicated that this regioselectivity of mutant enzyme to catalyze indole was more conducive to generating indigo.

This work compared the activation reactivities of different carbonized materials to justify the adsorption properties of the activated carbons prepared under the same steam activation conditions but from different raw materials,including rice husk,sawdust and lignite.The results showed that the activation reactivity of biomass feedstock was higher than lignite,and the activation rate of carbonized material varied in a descending order of ash-removed rice husk,sawdust,rice husk and lignite.Characterizing the carbonized materials by ultimate and proximate analysis,BET,SEM,XRD,FTIR,and XPS was performed to clarify further the reason for such different activation characteristics.It was found that the higher the volatile component and organic oxygen and the lower the ash content in the raw material,the easer it would be to produce high quality activated carbon via a short-time activation.

The main drawback of amine-based CO₂ capture system is high heat requirement for the solvent regeneration.The optimization of the process parameters is an effective way to break this limitation.In this paper,the experiments are carried out to investigate the stripper performance under diverse parameters of regeneration process,including the effects of CO₂ loading and feeding temperature of rich-solutions,reboiler temperature,regeneration pressure and alkanolamine type.The changes of sensible heat and heat of vaporization were analyzed.A rate-based model in Aspen Plus simulator was used to simulate the regeneration process.The results show that the heat requirement for the regeneration can be reduced by using higher CO₂ loading and feeding temperature of rich-solutions,while the heat requirement for regeneration increased with increasing reboiler temperature and regeneration pressure.The regeneration heat of monoethanolamine(MEA)is quite high,and can be reduced by blending methyldiethanolamine(MDEA).The CO₂ desorption rate increased with the CO₂ loading of rich solution and reboiler temperature.

A catalyst of V₂O₅-WO₃-MoO₃/TiO₂ was prepared from industrial pure chemicals in which ammonium metavanadate was the main active component,ammonium tungstate and ammonium molybdate were active and structure coagents,anatase titanium dioxide was catalyst support.The catalyst could be suitable for the application in various diesel engine working conditions and the complicated exhaust compositions.It was tested on a Lister Petter TR1 type fuel injection single cylinder diesel engine to investigate conversion of NO_x and catalytic selectivity.The results show that the NO_x conversion declined with the increase of diesel engine loads.As the diesel engine running at 1800 r·min^-1,the maximum conversion of NO_x was 87.1% at load 25% and at the conditions of SV(space velocity)20000 h^-1,reaction temperature 380℃ and NH₃:NO_x 1.0.For different loads,reaction temperature had greatly effect on NO_x conversion.The temperature window(NO_x conversion>70%)of the catalyst was 340—440℃ at load 25% and changed to 400—440℃ at load 50%,reducing about 60℃.Increase of diesel engine load could improve initial temperature of NH₃/N₂O reaction,while it could lead to increase of N₂O generated at high temperature(>400℃).

In order to enhance nitrogen removal of sewage treatment processes in cold areas or seasons,a cold-adapted ammonia-oxidizing functional flora was obtained by domestication of activated sludge and used to augment the ammonia oxidation function in an anaerobic-anoxic-aerobic(A²/O)process operated at(14±1)℃.The seed sludge was collected from the secondary sedimentation tank of a local urban sewage treatment plant and domesticated in a sequencing batch reactor(SBR)for five operational cycles with selective medium at(14±1)℃.Loading with semi-soft fiber filler,the SBR was operated for another five operational cycles to immobilize the cold-adapted ammonia-oxidizing functional flora.The results showed that the ammonia oxidation capacity of the inoculated activated sludge was enhanced remarkably after domesticating for the five operational cycles with NH₃-N removal of 79.5% when the initial NH₃-N ranged from 205—236 mg·L^-1 in the SBR.After the next 5 operational cycles the cold-adapted ammonia-oxidizing functional flora was immobilized on the filler as biofilm.When the cold-adapted ammonia-oxidizing biofilm was put into the aerobic pool of the A²/O process with a mass ratio of 3.24%,the average ammonia removal in the process increased from 65% to 78%.The COD and total nitrogen removal was significantly improved as well.However,the ammonia removal in the low temperature A²/O process dropped slowly along with running time.Thus,the bioaugmentation effect in the long run should be investigated in the future.

The surface reaction between zero-valent iron and Cr(Ⅵ)makes the utilization rate of Fe⁰-permeable reactive barrier(PRB)very low.In order to resolve this problem,sodium alginate(SA)was used to coat cast iron(SAC)and copper-iron bimetallic particles(SAB),and they were tested in treating chromium-polluted groundwater.The results show that SAB is the best.Adsorption capacity of SA to Cr(Ⅵ)is small,chemisorptions of copper-iron bimetallic particles in SAB plays main role.As indicated by FEI and XPS,pore structures were created by cross-linking of SA with Ca²⁺,which not only provided a lot of attaching points for bimetallic particles,but also diffusion path for Cr(Ⅵ)to enter interior of copper-iron bimetallic particles.The results of XPS also indicate that variation of copper valence was used for transfer of electrons from reaction of Cr(Ⅵ)by Fe⁰ and the role of copper is as if a catalyst.Under neutral condition,the removal process of Cr(Ⅵ)by SAB follows the pseudo first-order kinetics.The rate constant k increase with increasing copper loading(for SAB)and copper-iron bimetal amount(for SAB₂), and decrease with Cr(Ⅵ)concentration(for SAB₂).The rate constant is higher and removal capacity greater for SAB than for cast iron powder.Using SAB as the PRB is feasible for remediation of chromium contaminated groundwater.

The metal-tolerant bacterium strain BX,was isolated from polluted soils.The result of 16S rDNA sequence analysis indicated that the bacterium was Providencia alcalifaciens.The adaptability of bacterium BX to surroundings was discussed.The effects of the adsorption conditions,such as pH and temperature on the adsorption capacity by the bacterium BX from aqueous solutions were also investigated. Kinetic and isothermal study of BX toward Cu²⁺ was carried out.Immobilization was performed taking porous ceramics as carrier.The results showed that the bacterium BX could tolerant 7 mmol·L^-1 of Cu²⁺ and 7.5% of NaCl,and its growth was observed at conditions of pH4.0—11.0 and 15—50℃.The bacterium BX removed 85.84% of Cu²⁺ after 240 min of incubation in a solution containing 100 mg·L^-1 of Cu²⁺ at pH5.5,and the adsorption capacity of Cu²⁺ reached 128.74 mg·g^-1(dry bacterium).Kinetic study showed that the pseudo-second-order kinetic model fitted well with the experimental data whereas intraparticle diffusion could not be ignored,suggesting a chemical reaction mechanism.This would indicate that the adsorption of Cu²⁺ is a complex mix of surface adsorption occurring in the boundary layer of the bacterial particle and intraparticle diffusion.The isotherm biosorption of BX toward Cu²⁺ was in accordance with the Freundlich model,suggesting that the adsorption process followed a monolayer sorption.After the formation of biofilm on the porous ceramics,the adsorption rate of BX on 50 mg·L^-1 copper ion solution reached 92.53%.The experimental results demonstrated the potential application of the tested bacterium BX in the treatment of heavy metal wastewater for the strong adsorption under a wide range of environmental conditions.

Refractory organics are the main composition of residual COD in the effluent of s petrochemical biological wastewater treatment plant.It is the bottleneck in improving water quality with biological methods.The effect of pre-ozonation on a typical petrochemical biological effluent was studied.Molecular weight distribution(MWD),3-D fluorescence scan,gas chromatography-mass spectrometry(GC-MS)were used to analyze water quality before and after pre-ozonation.The removal rates of COD and UV₂₅₄ were 11.4% and 23.9% respectively with an ozone dosage of 10 mg·L^-1 and a duration of 4 min.Pre-ozonation could remove the refractory organics,such as soluble microbial products(SMP)and humic acids,including some unsaturated bond organics.Pre-ozonation changed the MWD of the wastewater,increasing the percentage of small-molecular-weight organics(<1×10³)from 53% to 67%.And it greatly improved the ability of bio-treatment performance of wastewater.Compared with the original biological effluent,COD removal rate of pre-oxidation wastewater treated by the biological aerated filter(BAF)increased by 14.9%.

The fry-drying method was used to dry oily sludge from Liaohe oilfield,and spent lubricating oil of vehicle(SLOV)was used as frying medium.The permeation process of SLOV in the oily sludge sample during the fry-drying process was studied.The effects of oil temperature,size and initial moisture content of oily sludge sample on the change of its oil and water contents were also investigated.At the initial stage of the fry-drying process,SLOV entered the interface with oily sludge sample,and then permeated into oily sludge sample gradually.During the whole fry-drying process,the oil content change of oily sludge could be divided into three periods,i.e.decreasing period,increasing period and essentially constant period.Most of the oil uptake was sucked by oily sludge sample during the increasing period.The temperature of frying SLOV and size of sample affected the oil content of oily sludge sample during the fry-drying process,but the effect on final oil content of oily sludge sample was not obvious.The final oil content of oily sludge sample was affected greatly by initial moisture content of the sample.Therefore,pre-drying would be a useful method to reduce the amount of oil uptake by oily sludge.

An anodic denitrification MFC(AD-MFC)was constructed by inoculating denitrifying bacteria enrichment culture into anode chamber of a dual-chamber MFC,and its capacity of denitrification and electricity production was investigated with methanol as electron donor and nitrate as acceptor in a batch cultivation mode.When initial nitrate and COD concentration were (100.22±0.62)mg·L^-1 and (500.40±1.67)mg·L^-1,the volumetric nitrogen and COD removal rates reached 0.31 kg N·m^-3·d^-1 and 1.06 kg COD·m^-3·d^-1,respectively,coupled with the maximum voltage of (602.80±5.42)mV and the maximum power density of (908.42±0.07)mW·m^-3.The results demonstrated that power generation in the AD-MFC was due to a coupling of methanol oxidation and nitrate reduction,and voltage changes were closely related to denitrification,indicating the course of denitrification.Voltage curves of the AD-MFC showed three-phase characteristics of descend phase,ascend phase and redescend phase,which could be ascribed to the succession of denitrification,methanol degradation and cell hydrolysate fermentation as dominant reaction in the anolyte.

The contact time of glass melt and mold is very short in glass blow forming process in which there is a rapid and intensive heat exchange,and the temperature of contact surface changes significantly.Glass viscosity governing glass flow during the forming process is strongly dependent on temperature.A small temperature variation in glass melt may produce a great change in its viscosity,which further affects the distribution of final product thickness.Therefore a coupling simulation of melt and mold heat transfer is crucial.An interface element was developed to deal with heat transfer between glass melt and mold in the glass forming process.The governing equations of melt flow and heat transfer based on the principles of conservation of mass,momentum and energy were expressed in the Lagrangian method.The finite element formulations to solve velocity,pressure and temperature were derived by means of the Galerkin method,and the corresponding program with VC++ was developed.Temperature distributions were calculated from both coupling and iteration methods.The coupling method could give very good result,but the iteration method could not meet the accuracy requirement.The temperature in most parts of the mold kept stable during continuous production except for the area close to contact surface where temperature had high periodic changes.The simulation result was compared with the real industry product.The prediction of thickness distribution was consistent with the real part.The accuracy was more than 88%.

A novel curing agent 1,4-bis(4-diaminobenzene-1-oxygen) n-butane(DDBE)was synthesized and its molecular structure was characterized by FTIR,¹H NMR and DSC.It was used to cure N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenyl methane(TGDDM).The non-isothermal reaction kinetics of TGDDM/DDBE system was investigated by dynamic DSC according to the model-fitting Málek method.The results showed that the apparent activation energy of the curing reaction was 58.5 kJ·mol^-1 according to the Kissinger method,and the Šesták-Berggren model could satisfactorily describe the non-isothermal reaction of this epoxy resin system.The glass transition temperature of the cured TGDDM/DDBE was 195℃ according to DSC.

The starch based ionic and nonionic composite superabsorbent(SCSA)used for agriculture was synthesized from mechanically activated cassava starch(60 min ball milling),partially neutralized acrylic acid by KOH and acrylamide.The functional groups and granular morphology of the samples were characterized by FT-IR and SEM,respectively.The SCSA was swollen in urea solution(5.0 mol·L^-1)until equilibrium swelling and then the hydrogel(SCH)was obtained.The SCH was used as the release material for urea in aqueous solution.The effects of synthesis conditions and release environment on the release process were investigated.It was found that the release of urea from SCH was controlled by Fickian diffusion mechanism,and the release rate decreased with increasing swelling ratio and increased with increasing temperature.The activation energy for releasing urea from the SCH prepared under the conditions of m_AA:m_AM=3:3 and dosage of N,N'-methylenebisacrylamide solution 1.0 ml(0.02 mol·L^-1)was 17.28 kJ·mol^-1.

Spherical chitosan hydrogel crosslinked with L-cystine(L-CYS)was synthesized by the dropping method.Chemical structure characterization of the product was performed with FTIR,¹³C NMR and SEM.The results showed that chitosan was amidated and esterified with L-cystine,resulting in internal porous structure.The disulfide bond on L-CYS contributed to Cu²⁺ adsorption.The adsorption capacity for Cu²⁺ reached 72.96 mg·g^-1,which was close to that of the uncrosslinked chitosan hydrogel. But the anti-swelling property was better than the latter.

In order to study the effect of CaCl₂ on macromolecular conformation and form of poly(3,3'-diphenylsulfone terephthalamide)(mt-PSA)in DMF,rheological behavior of concentrated solutions was studied with rheometer.Solution viscosity and coil dimension of diluted solutions were analyzed by viscosity and light scattering measurements.Addition of CaCl₂increased specific viscosity(η_sp)of concentrated solutions,and increased intrinsic viscosity([η])and hydrodynamic radius(R_h)of dilute solutions due to the interaction between macromolecule and solvent.The mt-PSA chain extended with the addition of CaCl₂.However,the weight-average molecular weight(M_w)of mt-PSA had no significant change by addition of CaCl₂.This would indicate that the conformation of macromolecule did not collapse or aggregate.

A novel high safe trimethylsilyl substituted propylene carbonate(TMSPC)was designed and synthesized as electrolyte for lithium-ion batteries.Its physicochemical properties,such as thermal property,ionic conductivity,electrochemical window,and flammability were investigated in detail.With adding 30%(vol) TMSPC into the electrolyte of 1 mol·L^-1 LiPF₆/EC:DEC(1:1,vol.ratio),the propagation rate could be reduced significantly.LiFeO₄/Li half cell test showed that the cycling performance could be improved with 30%(vol) TMSPC additions in the electrolyte of 1 mol·L^-1 LiPF₆/EC:DEC(1:1,vol.ratio),exhibiting a specific capacity of 109 mA·h·g^-1 and a capacity retention of 87% as compared with 106 mA·h·g^-1 and 81% for the base electrolyte at 0.2 C rate after 110 cycles.

In view of thermodynamic instability of inverse suspension polymerization,and the difficulty to clean dispersant adsorbed on the microsphere surface,the double dispersion inverse suspension polymerization method,in which mechanical stirring was used first and then natural sedimentation facilitated second dispersion,was established,and a preparation equipment was designed based on the theory of measuring viscosity coefficient by a falling sphere.The sphere diameter was determined from stirring speed and ratio of water phase volume and oil phase volume.Microspheres would polymerize when settling by gravity,and microsphere adhesion agglomeration could be avoided without adding dispersant. The preparation equipment with simple structure,easy processing could realize continuous production.The reactor height should be more than 2 m to provide microsphere sedimentation with a sufficient distance and ensure reaction time.The reactor was made of non-polar material to prevent microsphere from adsorbing on the inner wall.Polyacrylamide microspheres experiments showed that this preparation method with simple operation,absence of microsphere adhesion,repeated use of dispersion medium,low production cost,harmlessness and non pollution was convenient for industrial production.

A series of simultaneously interpenetrating polymer networks of polyurethane and poly(methyl methacrylate)were synthesized.Dynamic mechanical analysis was carried out to determine the system damping performance.The effects of composition ratio,crosslinking density,nano-SiO₂ content,content of octadecyl methacrylate with long and soft pendant group,and content of internetwork grafting agent,hydroxyethyl methylacrylate on the system damping performance were investigated.The morphology of the interpenetrating polymer networks system was studied with transmission electron microscope.The damping performance of interpenetrating polymer networks system could not be improved by changing the system crosslinking density,but could be improved in the range between the two glass transition phases by adding a moderate amount of nano-SiO₂.With the addition of octadecyl methacrylate,the glass transition of poly(methyl methacrylate)phase shifted to a lower temperature to obtain a continuous and widened damping range.Hydroxyethyl methylacrylate was an efficient internetwork grafting agent.The system would be optically transparent and only one glass transition could be found,when 3% hydroxyethyl methylacrylate was added.