With the intensification of the global energy crisis and the introduction of carbon neutrality, resources and energy recovery have become research hotspots in the field of wastewater treatment. Capacitive deionization (CDI) has attracted widespread attention for its energy-saving and pollution-free superiorities as a new type of electrochemical technology. By combining one pair of ion exchange membranes and flow electrode based on the basis of traditional CDI device, the flow electrode capacitive deionization(FCDI) achieves continuous operation for uninterrupted water production. This review provides a comprehensive overview of the research progress and future prospects of FCDI, focuses on the topics of principles, cell design (including cell architecture, electrode materials, separator options, and FCDI configurations), operation modes (ICC, SCC, OC, and SC) as well as applications in the environmental field (including sewage treatment, energy recovery and other emerging applications). In addition, this article also introduces the commonly used performance metrics of FCDI for comparison between different systems and operating conditions. Finally, the feasibility and main challenges of FCDI technology in future applications are introduced.

The core-shell nanomaterials prepared by various coating methods have many properties that are better than those of a single material. Their unique core-shell structure can produce excellent synergistic effect and new characteristics, and have been widely used in catalysis, adsorption, energy storage and conversion, drug delivery and optics. In the process of CO/CO₂ thermocatalytic hydrogenation, shell coating can modify the surface of core particles, such as changing the surface charge, functional groups and reaction characteristics of the core, so as to improve the stability and dispersion of the core. Core-shell catalysts can form a closed internal microenvironment to enrich reactants, improve reaction rate and catalytic activity. Some core-shell catalysts can even realize relay catalysis and improve energy utilization in the system. The common preparation methods of core-shell nanomaterials and the application progress of core-shell catalysts coated with different types of shells in CO/CO₂ thermocatalytic hydrogenation were mainly introduced, and the future development in this field was prospected.

As one of the ideal energy carriers, hydrogen energy has not been developed on a large scale in recent years due to the problems of storage and transportation. However, with the maturity of electrocatalytic technology, the route of hydrogen production through electrocatalytic decomposition of hydrogen-containing media under mild conditions may have the potential for large-scale development of clean energy. Due to the advantages of high hydrogen-storage density (17.6%, mass fraction), convenient transportation, and carbon-free, ammonia (NH₃) has been generally considered as a viable choice for chemical hydrogen storage. Electrocatalytic ammonia decomposition includes hydrogen evolution reaction(HER) and ammonia oxidation reaction(AOR). We focus on the recent progress of AOR and summarize the reaction mechanism and catalyst preparation strategies and methods. Although the theoretical voltage for the electrolysis of ammonia is very low, the actual catalytic process needs to provide additional voltage to overcome the obstacle of kinetics. So, the development of efficient and highly selective catalysts is the key to release hydrogen from the decomposition of ammonia. Pt has been proved to be the best pure metal-catalyst for AOR, while Pt-based binary or ternary alloys have higher catalytic activity and stability. In the past ten years, researchers have attempted to optimize the performance of AOR electrocatalysts from the aspects of nanometerization, alloying, morphology control, electronic control, etc. In addition, we discussed the challenges and applied prospects for AOR, hoping to provide guidance for obtaining more active catalysts and developing the route of “hydrogen-storage with ammonia”.

Nanocellulose (NC) is an emerging nanomaterial which has similar structure and properties to natural cellulose. It has been an interest subject in the field of nano-reinforcement, intelligent response, environmental protection and biomedicine, due to their promising properties such as nanoscale effect, huge surface area, chiral liquid crystalline phase, high crystallinity, high transparency and high surface activity, etc. However, due to the abundant hydroxyl groups on the surface of nanocellulose, the surface chemical properties are single, which requires chemical modification to broaden the application field. Therefore, chemical modification of NC to broaden its application in the field of functional/composite materials is of great significance. Atom transfer radical polymerization (ATRP), a “living”/controllable free radical polymerization technology, is one of the most powerful and versatile process used for the synthesis of high value-added NC grafted copolymers. By ATRP grafting, various functional groups or side chains could be accurately introduced onto the surface of NC imparting with some new physicochemical properties (such as hydrophobicity, antibacterial and intelligent responsive properties, etc.). This review describes the recent advances in NC functionalization by ATRP in the past ten years and includes four parts: (1) Traditional ATRP grafting modification of NC including NC initiator, scarification initiator; (2) Surface charge of NC, size of NC as well as grafted monomer; surface grafting modification of NC via four new ATRP [including SET LRP, ARGET ATRP, ICAR ATRP and (metal free) photocatalysis ATRP]; (3) ATRP of NC via end group grafting modification; (4) The application of nanocellulose grafting copolymers in nano-reinforced composites, smart response materials, environmental protection materials and biomedical materials. Finally, current challenges and future perspectives of ATRP for grafting modification of nanocellulose were discussed.

The COSMO-SAC model was used to study the vapor-liquid equilibrium of the ammonia solution in the presence of different ionic liquids (ILs). The effects of the hydrophilicity, acidity, alkalinity, anion and cation types, and functional group modification of the ionic liquids on the relative volatility of ammonia to water were analyzed and discussed. It was found that the vapor-liquid equilibrium of the ammonia-water solution can be strongly affected by ILs due to their diverse properties. The ability to escape of ammonia from the aqueous solution could be generally improved when the interaction energy of water and ILs is higher than that of ammonia and water. The stronger the anion’s hydrophilicity and the ability of forming hydrogen bond is, or the stronger the interaction energy between water and anion is, or the weaker the interaction energy between ammonia and cation is, the better the ability to improve the separation of ammonia and water is. Meanwhile, the greater the difference between the interaction energy of water and ILs and that of ammonia and water, the higher the value of relative volatility of ammonia to water is. In addition, the improvement was observed at low concentration of ammonia when the interaction energy of water and ILs is lower than that of ammonia and water. In general, the anions affect the relative volatility of ammonia to water more than the cations. Among the investigated anions, chloride ([Cl]^-) and acetate ([Ac]^-) are the best for the separation of ammonia and water. For methyl imidazole cations ([C _n mim]⁺, n=2, 4, 6, 8), the longer the alkyl chain is, the more unfavorable the separation of ammonia is, but at the low concentrations of ammonia, the grafting of the amino group (—NH₂) on the [C₂mim]⁺ will improve the separation effect of ammonia.

Calculation of the effective charge of refrigerants in a refrigeration system depends on the separation characteristics of refrigerants in the oil-refrigerant mixture. In the present study, the mass fraction variation with time for the refrigerants in the oil-refrigerant mixture is experimentally measured, and a mathematical model is developed to predict the mass fraction variation. In the experiment investigation, an experiment rig was built based on the principle that the refrigerant will separate from the solution when the external pressure drops, and the real-time variation of the mass fraction of R410A separating from POE68 lubricant is obtained by measuring the refractive index of the solution. It is found that the liquid refrigerant almost simultaneously evaporates to separates from the mixture as the pressure sharply decreases; the mass fraction variation of refrigerants firstly rapidly decreases, then slowly decreases, and finally stabilizes; with the increase of pressure drop, the maximum separation rate of refrigerant is increased by up to 16.4% per second, and the stabilization time of the mass fraction for the refrigerants is maximally decreased to 4 s. In the model developing, a refrigerant separation model is developed to predict the mass fraction changes of refrigerant with time based on the one-dimensional mass diffusion principle. The results show that the average absolute error between the experimental data and predicted data is less than 5% and the average relative error is less than 25%.

In this work, the vapor-liquid equilibrium data of two binary mixtures R32+R1234yf and R1234yf+R1234ze(E), and ternary mixture R32+R1234yf+R1234ze(E) were experimentally studied by using a liquid-recirculating analytical apparatus at temperatures from 263.15 K to 323.15 K. A set of temperature independent parameters was correlated for three binary mixtures with the PRSV+WS+NRTL model. The average absolute relative deviation(AARD) of pressure between experimental data and calculated results for R32+R1234yf and R1234yf+R1234ze(E) were 0.71% and 0.20%, respectively. The average absolute deviation(AAD) of vapor-phase mole fractions were both around 0.0016. This model was also employed to predict the ternary VLE properties. The AARD of pressure for R32+R1234yf+R1234ze(E) was 0.82%. The AAD of vapor-phase mole fractions of the system components R32 and R1234yf were both about 0.007.

In the supercritical carbon dioxide(S-CO₂) Brayton cycle coal-fired power generation system, the deterioration of S-CO₂ heat transfer in the water wall tube in the furnace is of great significance to the design, construction and safe operation of the system. Numerical simulation study of heat transfer for S-CO₂ flowing in vertical tubes is carried out in the present paper. The effect of operating parameters including pressure, mass flow, heat flux and tube diameter, as well as buoyancy and flow acceleration caused by changes in physical properties of S-CO₂ on the wall temperature and convective heat transfer coefficient is analyzed. It is shown that increasing the pressure and mass flow rate can reduce the degree of heat transfer deterioration, while increasing the heat flux density and pipe diameter will aggravate the degree of heat transfer deterioration. In addition, there is an obvious buoyancy effect which will cause heat transfer deterioration, while the influence of flow acceleration on heat transfer can be ignored under the working conditions studied in this paper. A new critical heat flux correlation is proposed using a deep neural network (DNN) method under wide working conditions of the diameter 4—10 mm, pressure 11.07—22.14 MPa, mass flux 0—1200 kg/(m²·s) and heat flux 0—200 kW/m², of which the prediction accuracy can be improved to 94.96%.

The adsorption characteristics of PAM-LiCl hydrogel composite adsorbent is studied. Based on the D-A equation, a three-dimensional mathematical model of the honeycomb gel adsorption bed is established. The adsorption/desorption dynamic phase of the adsorption bed under dry/wet conditions air simulated by COMSOL software. Combined with the experiment, the verification of the mathematical model is completed, and finally the optimization of the adsorption bed structure is realized. The results show that the honeycomb structure dramatically improves the adsorption/desorption performance of the adsorption bed. The water uptake rate is positively correlated with the porosity of the honeycomb mass transfer channel. The total water absorption first increases and then decreases. When the porosity is 20%, the total water absorption is the largest. The water uptake of the adsorption bed decreases with the increase of the thickness of the adsorption bed. When the air velocity is lower than 3.6 m/s, increasing the air velocity can significantly enhance the adsorption performance of the adsorption bed. The honeycomb adsorbent bed has good desorption performance and realizes complete desorption in hot air at 60℃.

The effects of Tween20, Span20 and their composite surfactants on the subcooled pool boiling heat transfer characteristics of pure water are studied. Based on the experimental results and the analysis of basic physical properties such as surface tension, contact angle and critical micelle concentration, it is found that the effect of an identical surfactant on boiling heat transfer is determined by its addition type, concentration and heat flux. On one hand, different from saturated boiling, Tween20 added in water can effectively reduce the temperature of onset of nucleate boiling and wall superheat under subcooling condition, but this boiling heat transfer strengthening effect is weakened at high heat flux conditions. On the other hand, Span20 in water only shows the boiling strengthening effect when its concentration is low, and the increase of Span20 concentration will lead to a large increase of wall superheat. Moreover, although both Tween20 and Span20 have the potential to enhance boiling heat transfer, the composite of Tween20 and Span20 surfactants deteriorates heat transfer in the concentration range tested in present experiment. The above research results can provide a basic basis for the analysis of the subcooled pool boiling heat transfer characteristics of the heat transfer-enhanced composite working fluid and provide guidance for its preparation.

The metal porous mesh screen has many advantages such as large specific surface area and good physical stability, and is widely used in the fields of propellant on-orbit gas-liquid separation and phase change heat transfer. Bubble point pressure is the most important parameter governing the separation performance, which is determined by the effective bubble point diameter of the porous material. The effective pore diameter can be estimated through experimental measurements, whereas experimental methods require measurements of several working fluids for each specification of porous mesh. Owing to the experimental limitations, scanning electron microscopy (SEM) analysis is proposed to estimate the pore diameter from SEM images. However, it is proven to be unreliable since the 2D images cannot account for the complex pore structures of the wire mesh. The prediction of bubble point pressure remains a challenge. Herein, this paper presents an analytical model of bubble point pressure for metal wire mesh considering the effect of pore structures. Variation of the effective flow area during the bubble breakthrough is detailed analyzed based on the 3D model of the porous wire mesh. The effective pore diameter is quantified by analogy to a capillary tube, which is expressed as a function of mesh parameters, including the intervals, diameters, relative angle and turn angle of the mesh wires. Each parameter is determined solely from the pore-scale morphology, and hence, the accurate expression for each mesh is derived without introducing any fitting constants. In addition, bubble point pressure measurements are conducted. The predicted effective pore diameters from the proposed model are corroborated by 7 specifications of porous mesh from existing literature and current experiments with a mean absolute relative error of 8%. Moreover, more than 250 data points of bubble point pressure are collected from open literature, focusing on both room-temperature and cryogenic fluids. The applicability of the present analytical model on different mesh specifications and various fluids are validated with the relative error smaller than 10%. The results further verify the validity of the bubble point model based on Young-Laplace equation, which considered the porous media to be analogous to a bundle of capillary tubes. This work deepens the understanding on the periodical porous structures of the wire mesh and proposed an analytical model to predict the bubble point pressure, which breaks free from the experimental limitations.

Experimental methods are used to analyze the flow characteristics of droplets of immiscible liquid-liquid two-phase fluid in sinusoidal microchannels with different inlet structures, including straight channel sine, wave crest sine, and the middle of the wave. Silicone oil is used as the dispersed phase, and distilled water containing 0.5% SDS is used as the continuous phase. Slug, droplet and jet flow are observed in the experiments. Effects of two-phase flow parameters and different microchannel inlet structures on the flow pattern and droplet length are analyzed. The flow pattern is greatly affected by the microchannel inlet structure, and the wave crest sinusoidal microchannel can generate the largest range of stable flow patterns than the other two channels. The droplet length increases with the increase of the volume flow rate of the dispersed phase and the ratio of the volume flow rate of the dispersed phase to that of the continuous phase, and decreases with the increase of the volume flow rate of the continuous phase and the capillary number. The inlet structure of the microchannel has influence on the length of the droplet. The length of the droplet in the sinusoidal microchannel with a straight channel inlet is the shortest, which is more conducive to the formation of droplets. Among the droplets generated by the three channels, the largest droplet size is 1.15-1.39 times larger than the smallest droplet size. The sinusoidal structure of the microchannel has almost no effect on the droplet velocity compared with the straight channel.

The determination of interaction force between droplet and solid surface is of fundamental importance for understanding wetting mechanism and controlling multiphase flow behavior in confine space. In this study, the interaction force between droplet and solid surface is determined by using droplet profile as a probe. The interaction force is calculated by capturing and analyzing the droplet deformation during the interaction. The results are in good agreement with those obtained by the precise commercial weighing sensor. Compared with the atomic force microscope (AFM) and surface force meter (SFA) measurement methods reported in the literatures in recent years, this method does not require external precision mechanical probes, and has the advantages of simple operation, process visualization, and low cost. It is not limited by the light transmittance of the research object. Therefore, it has the advantage of simple, visible, low cost, and not limited to transparent objects. Finally, the dynamic interaction force between the tetradecane droplet and solid surface in various aqueous solutions is determined by the new method. The influence of the component of aqueous solutions is investigated. It is found that the total repulsive force only depends on the droplet deformability.

Three kinds of porous structures, uniform porous layer, composite 16-core and composite 32-core were prepared by solid-phase sintering technology, and a pool boiling heat transfer test system was established to study the boiling heat transfer performance of the porous structure with different number of cores, particle size and structure height impact. The experimental results show that the porous composite 32-core structure with a composite layer height of 1 mm has strong heat transfer performance within the test range, with a maximum critical heat flux of 386 W/cm² and a heat transfer coefficient of up to 9.5 W/(cm²·K). At the same time, high-speed photography is used to observe bubble behavior to study the mechanism of enhancing boiling heat transfer. Visual data shows that compared with light surfaces, the bubble cycle on the porous composite surface is shorter and the separation is faster under high heat flux. The leaving of the bubbles brings more liquid replenishment, which in turn continuously improves the heat transfer performance and achieves higher critical heat flux.

Graphene oxide(GO) has high thermal conductivity and strong hydrophilicity, which can significantly improve the heat transfer performance of fluids. In this study, effects of GO nanofluids on the start-up and heat transfer were investigated in a pulsating heat pipe(PHP) through experiment. The PHP consists of a thin copper tube, which was bent into a closed loop with 3 turns in the evaporator and condenser respectively. It was operated in a vertical bottom heating mode, i.e., the evaporation section was in the bottom with an electrical heating power in the range of 10—105 W, while the condenser section was in the top with the air forced cooling. The nanofluid was prepared by dissolving GO nanoparticles into the deionized water, with different mass fraction range of 0.02%—0.11%, and the filling ratio was kept constant about 50%. Results showed that adding appropriate GO nanoparticles could effectively improve the start-up performance, when compared with the pure water PHP. For the concentrations of 0.05% and 0.08%, the PHP could start up more easily and smoothly, in specifically, the start-up temperature reduced about 28.6℃ (33.9%) and 26.2℃ (31.1%) respectively, meanwhile the start-up time shortened about 320 s (19.5%) and 304 s (18.5%) respectively. As for the heat transfer enhancement effect, it was related to the concentration of GO nanoparticles and heating power of the PHP. There existed an appropriate concentration and heating power range (i.e., w=0.02%—0.08%, Q=20—105 W), which could reduce the thermal resistance of GO/water PHP by 18.6%—57.1% when compared with that of pure water. For the concentration range of 0.02%—0.08%, the improvement of thermal performance first increased and then gradually decreased with the increase of heating power. At the case of 30 W, the thermal performance could be improved by 46.1%—57.1%. When the concentration was relatively higher (e.g., w=0.11%), addition of GO nanoparticles could not improve the start-up and heat transfer performance of PHP, and might even worsen the performance. Finally, an empirical correlation was obtained to predict the thermal performance of the GO/water PHP based on the dimensionless combination of Ku, Bo, Mo, Pr, Ja^*.

On the basis of obtaining the optimal mass transfer coefficient in the Lee phase change mass transfer equation, the influence of the groove structure parameters such as helix angle, groove diameter ratio, groove weir ratio and groove depth on the vaporization characteristics of liquid film mechanical seals (characterization of average vapor phase volume fraction) is studied. And based on the uniform experimental design method and the response surface method, the interaction between the groove structure parameters is proved. Finally, the trough structural parameters are used as design variables, the average vapor phase volume fraction is used as the optimization objective, and the constraints are commonly used and empirically selected, and the genetic algorithm is used to obtain the optimal solution range of the structural parameters. Research shows that the average vapor phase volume fraction increases with the increase of helix angle, slot-weir ratio, and slot depth, and first increases and then decreases with the increase of slot-diameter ratio. The interaction between slot-weir ratio and groove depth is extremely significant, and the interaction between helix angle and groove depth is more significant. When the helix angle, groove diameter ratio, groove weir ratio and groove depth are 25.0°—28.0°, 0.10—0.30, 0.10—0.25 and 4.0—6.0 μm, better average vapor phase volume fraction values can be obtained.

With the global energy scarcity, the exploration of process energy conservation method is of great significance. The fire prevention plays an important role in the national economy and social development. If the techniques of drag-reduction by additives being applied into the firefighting system, the jet velocity and range of firefighting water can be increased, consequently, the firefighting efficiency will be improved and the power consumption of fire pumps will be reduced. According to the characteristics of fire water flow, the polymer of polyethylene oxide (PEO) and surfactant of octadearyl dimethyl ammonium chloride (OTAC) are chosen to be mixed as the drag-reduction additives for the firefighting system. The method of mesoscopic molecular dynamics simulation is utilized in the present study to calculate the shear resistance and surface tension of the PEO/OTAC mixed solution. The results show that the PEO/OTAC mixed solution has higher shear resistance capacity than the PEO or the OTAC solution, and higher surface tension than the OTAC solution under the same conditions, i.e., concentration, temperature, and so on. It proves that the PEO/OTAC mixture is suitable for the firefighting system as the drag-reduction additives. Meanwhile, the interaction mechanism of PEO and OTAC molecules is analyzed from the perspective of molecular dynamics deeply, which can provide theory instruction for further research of the suitable drag-reduction additives for the firefighting system.

The fast pyrolysis of cellulose into high-value levoglucosan and levoglucosenone is one of the research hotspots at home and abroad. In this paper, carbon-based solid acids catalysts were prepared and characterized, and the experimental conditions of cellulose catalytic pyrolysis were optimized. At 350℃, Fe₃O₄/C₇₀₀-H₃PO₄ mixed with cellulose at a ratio of 1∶3 could significantly increase the yield of levoglucosan [40.7%(mass)] and levoglucosenone [(13.5%(mass)], which were 2 times and 22 times higher than that of non-catalytic cellulose pyrolysis, respectively. This study was a guide for the directional value-added utilization of cellulose.

The effects of three acidic catalysts HZSM-5, Al-MCM-41, USY and a base catalyst of calcium aluminate (Ca-Al) with different pore structures and acid contents on volatiles conversion were investigated by in-situ filling method in a downer-bed continuous pyrolysis experiment. The results show that Al-MCM-41 catalysts with suitable acidity, large specific surface areas and rich mesoporous structures can reduce the content of heavy components in tar and increase the content of light components, which is superior to HZSM-5 and USY catalysts with stronger acidity in reducing coke and tar loss. Ca-Al promotes the dehydrogenation of hydrocarbons to generate hydrogen-rich small molecules, inhibits the polycondensation of macromolecules, and significantly reduces the yield of carbon deposition. Integrated with the advantages of acid-base catalysts in their respective effects on pyrolytic volatiles, they were combined in different ways to explore the composition and yield changes of pyrolytic volatiles after the combined catalyst. The results show that when the pyrolytic volatiles are first dehydrogenated by Ca-Al and then cracked moderately by Al-MCM-41, the combination catalyst of Ca-Al /Al has a strong ability to regulate the conversion behaviors between components in volatiles and reduce the yield of coke effectively.

Linear alkyl benzene sulfonic acid and its derivatives, straight-chain alkyl benzene sulfonates, are a class of inexpensive surfactants that are widely used in washing and tertiary oil recovery. In this experiment, we propose a continuous synthesis process of linear alkylbenzene sulfonic acid using Linear alkylbenzene produced from industrial mixed olefins in a coal-to-oil enterprise in a microreactor, and investigate the influence of process conditions such as sulfonation temperature, molar ratio of raw materials and concentration of sulfonating agent. It was found that the individual process conditions during the mixed straight-chain alkylbenzene sulfonation process had a significant effect on the product yield. Under the conditions of reaction temperature of 50℃, SO₃∶LAB molar ratio of 1.0∶1 and residence time of 5.09 s, the final product could reach 94.5%(mass) of active species. Meanwhile, a microreactor pilot platform was designed and built to realize the continuous synthesis of mixed alkylbenzene sulfonate,and the yield of sulfonate product was over 90%. The study can provide technical support for the industrial application of the process.

Zeolite adsorbents for the adsorption and removal of volatile organic compounds (VOCs) have attracted considerable attention in recent years. However, the low adsorption capacity, slow adsorption rate, and hydrophilic nature strongly restrict the development of zeolite-type VOCs adsorbents. In this paper, tungsten-substituted MFI zeolites (HWS-1_S and HWS-1_W) with two kinds of hollow structures (fully and multichambered) are prepared by post-treating the siliceous MFI (S-1) and tungsten-substituted MFI (WS-1) through desilication and tungstation, respectively. And the effect of the hollow morphology on VOCs adsorption performance is investigated by using acetone as an adsorbate. The results show that HWS-1_S and HWS-1_W exhibit faster adsorption rates for acetone compared to the parent S-1 and WS-1 benefitted from their highly interconnected hollow structures. HWS-1_S shows a limited adsorption capacity (27.4 mg·g^-1) of acetone than S-1 due to its reduced micropore volume, while HWS-1_W presents an increased adsorption capacity (51.2 mg·g^-1) of acetone compared with WS-1, which could be ascribed to the defect removal by tungstation. Acetone dominatly performs as physical absorption on both HWS-1_S and HWS-1_W based on the fitting results of adsorption kinetics. Moreover, substitution of W atoms within zeolite frameworks can neutralize silanol groups and further enhance the hydrophobicity of zeolite adsorbents, leading an effective resistance of competitive adsorption of water.

The gas-liquid-solid reactive crystallization process of lithium carbonate includes two consecutive steps, which are the carbonization reaction process of lithium carbonate and the thermal decomposition process of lithium bicarbonate solution. First, the factors of the lithium carbonate carbonization reaction rate were investigated. The numerical solution was obtained by solving the established model, which proved that the lithium carbonate carbonization process obeyed the diffusion-controlled mechanism. For the thermal decomposition process, the relationship between the particle size distribution, crystal morphology, and agglomeration of lithium carbonate crystalline products and factors such as the concentration, temperature, stirring, seed crystals, and external field have been studied. Especially, rod-shaped lithium carbonate crystals with complete morphology and no coalescence can be obtained by using ultrasonic sound. Finally, the fouling mechanism of lithium carbonate was revealed by continuous crystallization experiments, which were designed to investigate the fouling phenomenon in industrial-scale production. The smooth surface coupled with the seed addition in metastable zone strategy was proposed to effectively avoid the fouling.

Gas-liquid cylindrical cyclone (GLCC) is a separation device coupling with centrifugal force and gravity, and is often used for deep-sea oil and gas separation. Liquid carry-over (LCO) in the gas phase is a key issue affecting the application of GLCC. Previous studies have pointed out that the percent-LCO is closely related to the liquid film flow pattern in the upper cylinder, so it is reasonable to control the percent-LCO by controlling the liquid film flow pattern. This paper proposes a dual-inlet gas-liquid cyclone separator with an upward-branch inlet, and a valve is added to the upward-branch inlet. The flow ratio between the primary and secondary inlets is controlled to change the liquid film flow pattern of the upper cylinder. Using the high-speed camera, the spatial distribution characteristics of the liquid film are systematically studied by changing the inlet gas-liquid flow-rate and valve opening. And through the numerical simulation, the GLCC liquid film flow pattern, internal streamline and velocity characteristics are analyzed. When the flow area ratio of the secondary path of the inclined pipe is changed from 100% to 0, the flow rate through the primary inlet increases, and the distribution height of the liquid film along the upper cylinder decreases. The liquid film is concentrated near the primary entrance to form swirling flow. Simulation results show that, in the previously described procedure, the center of the swirling vortex core gradually stabilizes, which is beneficial to inhibit the LCO. Adjusting the opening of valve to control the flow pattern of the liquid film is a feasible method to improve the separation performance of GLCC.

The higher coke yield in heavy oil fluid catalytic cracking unit(FCCU) will increase the load of the regenerator and reduce the catalyst-to-oil ratio(COR) and light oil yield. In this regard, an external heat extractor is added to the catalytic cracking unit. By adopting the method of combining external heat extraction and external oil slurry rejection, the yield of light oil from the catalytic cracking of heavy oil can be improved. The function of the external cooler is to remove the excess heat of the regenerator part quickly and effectively, so as to achieve the purpose of cooling the regeneration catalyst. The function of the slurry drawoff is to reduce the coke yield and reduce the heat generation of scorching. The reduction of heat can effectively increase the COR and increase the light oil yield. The value of carbon residue in crude oil has a direct impact on product distribution. The higher the residual carbon value of the feedstock, the more coke is produced in the reactor of FCC unit. The carbon mass fraction on the spent catalyst will also increase, and after reaching the regenerator, it will release a large amount of heat. The increase in heat will not only affect the life of the regenerator, but also reduce the COR in FCCU, thereby reduce the light oil yield. In this paper, the control vector parameterization method is used to control and optimize the CO combustion-supporting agent, main air flow rate, heat of external cooler and slurry drawoff on various levels. The results show that the optimization effect of CO combustion-supporting agent and main air flow rate is limited for heavy oil FCCU, but the mutual promotion of heat of external cooler and slurry drawoff can effectively improve the COR and the light oil yield.

In view of the high energy consumption in the pretreatment section of C5 comprehensive utilization, this paper proposes the reactive dividing wall column (RDWC) pretreatment process based on the reactive distillation (RD) pretreatment process. First of all, the chemical simulation software Aspen Plus was used to build the RDWC four tower equivalent rigorous model, and the degree of freedom and univariate analysis were carried out. On this basis, the response surface Box-Behnken Design (BBD) method is used as the model fitting tool to fit the functional relationship between target variables and decision variables, and the fitting results are analyzed by ANOVA. Finally, multi-objective evolutionary algorithm based on decomposition (MOEA/D) is used to optimize the RDWC pretreatment process, and a series of Pareto optimal solutions are obtained. The solution with the smallest TAC is selected and compared with the RD pretreatment process. The results show that compared with RD pretreatment process, RDWC pretreatment process can save TAC 12.8%, save reboiler load 27.8%, and improve selectivity.

The sequential modular method, which is widely used in process simulation, has many difficulties in dealing with stream circulation system, such as the selection of tearing stream and the convergence of iterative equations. Based on the stability theory, this paper solves the process simulation problem of stream circulation system. First, according to the model equation, chemical plants are identified as forward model and backward model, and the variables in stream circulation are defined as iterative variables and convergence variables respectively. Then, the stream circulation is broken at the convergence variables, and the convergence variables are calculated from the iterative variables by the forward model and the backward model respectively; the convergence errors are used for the correction of iterative variables through the gain coefficients, and then the iterative equation is obtained. Finally, the stability theory in control theory is used to determine the gain coefficient of the iterative equation, the iterative equation is linearized, and the Routh criterion is used to determine the stable range of the gain coefficient; when the gain coefficients is within the stable range, the iterative equation must converge. The reaction and regeneration system of FCCU is a typical stream circulation system because of catalyst circulation. The reactor is treated as the forward model and the regenerator is treated as the backward model. The temperature and carbon content of regenerator are treated as iteration variables to build the iterative equation of process simulation for FCCU reaction and regeneration system. The stability range of the gain coefficients is found by using the stability theory to ensure the convergence of the simulation calculation, and the feasibility and effectiveness of this method are verified.

In the industrial process, there is a serious imbalance between the auxiliary variable and the dominant variable. Co-training algorithm is one of the model training methods that uses potential information in unlabeled data to improve learning performance. However, there is a problem of overlapping training characteristics between learners in the current collaborative training using in soft sensor, which will lead to a decline in the prediction performance of dominant variables. To solve this problem, this paper proposes a TSCO-KNN semi-supervised soft sensor model based on two-subspace co-training algorithm. The model combines the two-subspace algorithm with the existing co-training algorithm. By analyzing the correlation between the auxiliary variables and the PCS and the RS, the variables are split into two different learning data sets, and then the KNN regressor is used for collaborative training, which is jointly used to predict the key quality variable. Finally, a simulation study was carried out in the soft measurement of the ethane concentration at the top of the ethylene distillation tower and the product concentration of the TE process to verify the effectiveness of the algorithm proposed in this paper.

In the context of “double carbon”, improving coke quality is one of the key points to ensure the high quality development of the steel industry. The coking industry has the problem of on-line real-time monitoring and the generalization ability of the coke quality prediction model is relatively poor. An adaptive global search algorithm, namely improved whale optimization algorithm (WOA) and long short-term memory (LSTM) recurrent neural network integrated modeling method is proposed to solve this problem. We select the measurable parameters that can reflect the coke quality in the blended coal, and use principal component analysis (PCA) to remove the redundancy factors with small variability to obtain the prediction factors as the external input of LSTM network; add adaptive inertia weight and optimal disturbance update to improve WOA, so as to train the super parameters of LSTM network, and use root mean square error (RMSE) and R-squared to test the algorithm. The improved AGWOA-LSTM model is compared with the LSTM model and WOA-LSTM model to verify the superiority of the method. The results show that the AGWOA-LSTM model has high accuracy and fast operation speed, and has a guiding significance for coke production.

In order to consider the influence of the quality variables and dynamic characteristics of the fermentation process on the stage division, a multi-phase fermentation process quality-related fault monitoring method based on the joint canonical variable matrix is?proposed. Firstly, the 3D data were unfolded along the batch direction. Canonical correlation analysis (CCA) was performed on each time slice matrix to obtain the joint canonical variable matrices, which were equipped with process variables and quality variables, and K-mean algorithm was used to realize first partition. Then slow feature analysis (SFA) was used to extract the slow characteristics of the process dynamics, and the K-mean algorithm was used for the second partition. Finally, the production process was divided into different stable phases and transition phases through the comprehensive analysis of the two-step division results. The CCA monitoring model was established in each phase after partition for quality-related fault detection. According to the changes of static and dynamic characteristics, this method can accurately distinguish the strong dynamics and the phase boundaries by a two-step partition, also e?ectively improve the accuracy of quality-related fault monitoring. The feasibility and effectiveness of the proposed algorithm were illustrated by a penicillin simulation platform and an industrial application of E. coli fermentation, respectively.

A microcosmic model of ice-water two-phase was constructed by molecular dynamics simulation method, and the variation of interface structure with temperature and interface structures was studied. The results show that when two phases reach equilibrium, there is a reversible dynamic transition between the disordered water molecules and the ordered ice crystals at interface, which results in the dynamics of the interface structure. The ice-water interface structure is largely dependent on temperature and crystal planes. At the same temperature, the interface thickness of primary prism and secondary prism is slightly thinner than that of the base plane, and the boundary is well-organized and three-dimensional network recombination of intermolecular hydrogen bonds exists. When the degree of supercooling increases, the interface structure tends to the ordered state of six-membered ring arrangement, and the number of disorder water molecules in the interface increases. The residence time of water molecules at the interface layer increases, and the probability of crystal plane growth increases.This article clarified the change law of the interface structure of ice-water system from the molecular scale, which has certain guiding significance for understanding the icing process and the development of ice control technology.

Fretting wear behavior of TC4 alloy was studied under various contact loads at 300℃ and 500℃. Surface wear track morphology, wear volume and wear track profile were characterized by scanning electron microscope and laser confocal microscope to explore the fretting wear mechanism of TC4 alloy under different contact loads in the two temperatures. The results showed that the wear volume and the contact load present a positive correlation, while the friction coefficient and the wear rate present a negative correlation. In the process of lubrication fretting wear at two temperatures, the form of wear is oxidative wear and abrasive wear under the small load and oxidative wear and adhesive wear under the large load. Compared with 300℃, the surface exhibits larger plastic deformation, less friction coefficient, more intensifying oxidative wear and more extending fatigue cracks at 500℃. The fretting wear mechanism of TC4 alloy in high temperature environment involves adhesive wear, abrasive wear, oxidative wear and fatigue wear, in which the dominant function is oxidative wear.

Based on the flame spectrum diagnostic platform, a spectral imaging system composed of a high-resolution CCD camera imaging system and a fiber optic spectrometer is used to study the spectral radiation characteristics of the methane inverse diffusion flame. The OH* and CH* two-dimensional radiation distributions of the IDF with various oxygen-fuel equivalence ratios and CO₂ dilution levels were obtained by the flame spectrum imaging system. The OH* and CH* emission data was deconvoluted by using an inverse Abel transform to analyze flame structure. The results show that the OH* flame gradually became hollow, the flame front was stretched, and the axial height and flame area both increased first and then decreased with the increase of the oxygen-to-fuel equivalence ratio. The position and shape of the CH* flame core reaction zone was unchanged significantly with the change of the equivalence ratio. The OH* flame was stretched and transformed from a completely enveloped shape to a symmetrical envelope shape with the increase of the CO₂ diluent volume fraction in the oxidant. The CH* flame was stretched closer to the central axis. The OH* flame area decreased and the CH* flame area increased due to the influence of CO₂ dilution. Compared with the OH* flame layer, the CH* flame layer was thinner and the peak intensity was low.

Carbon dioxide is not only one of the main greenhouse gases, but also a resource containing carbon and oxygen. Converting relatively inert CO₂ into easy-to-use CO is one of its utilization methods. The effects of reactor parameters (discharge zone length, discharge spacing, and dielectric thickness) and process parameters (input power, discharge frequency and residence time) on the conversion and energy efficiency of CO₂ decomposition into CO were investigated with a dielectric barrier microplasma reactor. The results indicated that the order of affecting CO₂ conversion is: discharge spacing > discharge length > input power ≈ residence time > dielectric thickness > discharge frequency. When the input power was 60.0 W, the discharge frequency was 9.0 kHz and the residence time was 1.5 s, the discharge area length was 60 mm, the discharge spacing was 0.5 m and the dielectric thickness was 1.6 mm, the CO₂ conversion was 10.6% and the energy efficiency was 4.1%.

Low oxygen pyrolysis of microcrystalline cellulose was carried out in a metal mesh reactor (WMR) with minimal secondary reaction. The composition and distribution of water-soluble intermediate active cellulose (WSIAC) and water-soluble primary tar (WSPT) were analyzed by Dionex ICS-6000 ion chromatography (IC) using high-performance anion exchange chromatography (HPAEC-PAD) with pulsed amperometric detection. The formation and transformation of several dehydrated sugars and glycopolymers during cellulose pyrolysis was emphasized. It was found that oxygen predates the decomposition of cellulose by promoting the formation of intermediate cellulose. In oxidizing atmosphere, the higher degree of polymerization, the worse the stability of dehydrated sugar. The presence of oxygen promotes the production of cellobiose and cellotrian. On the other hand, their fragmentation or other decomposition reactions are also affected by oxygen to a certain extent.

The BaFe₂O₄ oxygen carrier and BaFe₂O₄ oxygen carrier modified by Ni, Ce and K were prepared by the sol-gel method, and the best oxygen carrier was selected as 10%(mass) K modified BaFe₂O₄ (10K-BF), and the difference was explored. The effect of reaction conditions on its performance was characterized by H₂-TPR, XRD, SEM, and BET on the oxygen carrier. The experimental results showed that the addition of Ni, Ce and K all increase the syngas yield. The 10K-BF oxygen carrier exhibited the best performance when the mass ratio of steam to biomass (S/B) was equal to 3, peroxygen coefficient α=0.20 and t=800℃. Its syngas yield was 1.864 m³/(kg Biomass), hydrogen production rate was 1.038 m³/(kg Biomass), carbon conversion rate was 90.49% and carbon deposition rate was 1.33%. After 10 cycles, there was still a high syngas yield and carbon conversion rate. H₂-TPR result indicated that the 10K-BF oxygen carrier starts to release oxygen at 300°C and can participate in the reaction at the initial stage of biomass pyrolysis, which is beneficial to the cracking of tar. XRD characterization showed that the 10K-BF oxygen carrier can recover part of the spinel structure after regeneration.

The bio-mixed alcohol production process via biomass gasification and the followed catalytic conversion of syngas has the advantages of simple procedure, high yield and diverse utilization of alcohols as bioenergy or biochemicals. To ascertain its environmental performance such as resource consumption and emissions, the analysis and comparison of the impact was carried out for mixed alcohols from agricultural and forestry residues of corn stalk and wood chips via gasification and catalytic synthesis processes, following life cycle assessment frame (LCA) and midpoint impact method of ReCiPe2016. 9 environmental impact categories were considered such as global warming potential (GWP) and fossil resource scarcity potential (FDP). The main environmental impact for both alcohol systems was derived from agricultural and forestry stages. The potential environmental impact values of alcohols from corn stalk were higher than those from wood chips. And the ratios of ozone depletion potential (ODP), marine and freshwater eutrophication potential (MEP and FEP) and global warming potential (GWP) of the systems between mixed alcohol production from corn stalk and wood chips were above 9. The relatively high carbon content and high alcohol yield will benefit the decrease of resource consumption and environmental impact. Compared with petrochemical gasoline, the global warming and fossil energy consumption potential of the mixed alcohol of straw and wood chips are reduced by more than 40%.

Based on the first law of thermodynamics, a thermodynamic analysis of the recompression Brayton cycle with supercritical CO₂ mixed working medium is carried out. The effects of the gas type and proportion, turbine inlet temperature, turbine inlet pressure, split ratio and main compressor inlet temperature on the thermodynamic performance of the cycle are mainly discussed under the medium and low temperature heat source (200—400℃). The results show that the addition of 0—10% propane, neopentane, isobutane, and n-butane can all increase the cycle efficiency and improve the thermodynamic performance of the cycle system. When the turbine inlet temperature is lower than 260℃, the cyclic thermal efficiency of adding ethane is lower than that of CO₂. With the increase of mixing ratio, turbine inlet temperature and pressure, and shunt ratio, the system circulation efficiency also increases. As the inlet temperature of the main compressor increases, the circulation efficiency decreases.

As an efficient, energy-saving, and pollution-free chemical separation technology, pervaporation(PV) has great application potential for organic wastewater treatment. In this study, the AZLs were synthesized by modifying two-dimensional ZIF-L with 3-aminopropyltriethoxysilane(APTES). The AZLs were incorporated into the poly(ether-block-amide)(PEBA) to prepare AZLs/PEBA mixed matrix membranes for phenol separation from aqueous solution. The membrane microstructures and physicochemical properties were characterized in detail. Effects of the APTES addition amount, AZLs loading, operating temperature, and feed concentration on separation performance of the membranes were investigated. The AZLs were uniformly dispersed within PEBA matrix, indicating their good interfacial compatibility. The addition of AZLs increased the hydrophobicity and reduced the surface free energy of PEBA membrane, thereby enhancing membrane selectivity. The AZLs/PEBA membrane had a total flux of 2046 g/(m²·h) and a separation factor of 25.4 in separating 1000 mg/kg phenol aqueous solution at 80℃. The AZLs/PEBA membrane also displayed a certain stability. The as-prepared AZLs/PEBA mixed matrix membranes were promising candidates in the phenolic wastewater treatment.

Due to the detriment and non-renewable of formaldehyde in phenolic resin, a novel phenolic resin, terephthalaldehyde phenolic thermosets, was synthesized by using a safe and renewable terephthalaldehyde instead of formaldehyde. NMR, IR, GPC and rheometer were utilized to explore the structure and properties of the resin. To further improve the thermal properties of the resin, ferrocenecarboxaldehyde was choosed to modify the resin. The curing mechanism of the modified resin was systematically clarified according to the curing kinetics of resin by Kissinger, isoconversion and autocatalytic kinetic model. Finally, the thermal properties of the cured resin were studied by MDSC and TG. When adding 15% ferrocenecarboxaldehyde, the modified resin presents excellent thermal properties whose glass transition temperature and initial decomposition temperature was 319.3℃ and 397.7℃ respectively, and the weight retention rate was as high as 76.07% under 800℃ nitrogen atmosphere.