Oily sludge is one of the main pollutants in petroleum and petrochemical industry, which will not only cause environmental damage, but also cause waste of resources. At present, the traditional methods of treating oily sludge mainly include solid-liquid separation, chemical demulsification, solvent extraction, thermal washing, biological treatment and incineration. To a certain extent these methods can reduce the oil content of oily sludge, however, various problems as relatively high processing costs, sophisticated technology and relatively long process become the obstacles. Smoldering combustion is an international burgeoning technology which can make up for the shortcomings of the above traditional methods. In this paper, the research history, working principle, technology classification, research progress and engineering application of smoldering combustion are systematically explained. The main problems of smoldering combustion are analyzed and the research directions are proposed.

The equilibrium molecular dynamics method was used to simulate the thermal conductivity of methane hydrate, and the thermal conductivity of 30—150 K methane hydrate was given. The studies of thermal transport in hydrate have a lot of significance in hydrate exploitation and gas hydrate storage and transport. In this paper, an equilibrium molecular dynamics simulation for 2×2×2 type I methane hydrate periodic structure is carried out by LAMMPS and the thermal transport process is analyzed. For methane hydrate, CH₄ is modeled as OPLS-UA type while H₂O is treated by TIP4P/2005 model. The intermolecular interactions are described by the Lennard-Jones potential function and a Coulombic pairwise interaction. During the simulation, the methane hydrate is successively placed into NVT and NPT ensembles to relax for 1 ns respectively, so as to equilibrate the whole system. Then, it is transferred into NVE ensemble to run 2 ns for calculating the thermal conductivity. The thermal conductivity which is much closer to experiments results can be obtained by quantum correlation. When the simulation temperature is lower than Debye temperature, the quantum effect has a great influence on the molecular simulation results. The relaxation time of acoustic phonons and optical phonons are calculated by fitting the autocorrelation function of heat flow. The results show that the phonon relaxation time decreases with the increase of temperature and the acoustic phonon contributes most to heat conductivity. With the increase of the interaction strength between carbon and oxygen atoms, the coupling of vibration between carbon and oxygen atoms becomes stronger, and the thermal conductivity of methane hydrate increases.

In this paper, the unscented Kalman filter (UKF) is used for the first time to solve the inverse problem of one-dimensional dielectric thermophysical properties. In addition, this paper also studies the inversion of thermal conductivity in one-dimensional media using extended Kalman filter (EKF). The forward model is introduced firstly. Basic principles of the EKF and UKF technique are also introduced in detail. In order to examine the feasibility of the proposed algorithms, the space-dependent and time-dependent thermal conductivities in media are reconstructed by the UKF and EKF techniques, respectively. All the reconstruction results indicate that thermal conductivities of media can be retrieved effectively by the EKF and UKF techniques. Moreover, the small measurement error covariance R should be selected to decrease the time lag of the reconstructed results.

A 3-mm-diameter vacuum cryoprobe was designed. Low temperature problem in non-working section of probe was solved by resistance heating and vacuum layer. The freezing and rewarming process of the vacuum cryoprobe was realized through liquid nitrogen and resistance heating, and the freezing and rewarming properties of the vacuum cryoprobe were studied in air, distilled water and isolated porcine liver. According to the temperature variation data of the vacuum probe s working section in the isolated pig liver, set the corresponding boundary conditions in the numerical simulation, and use the classical bio-heat transfer equation to calculate the temperature distribution of the vacuum probe during freezing and rewarming process in human tissues, which can better understand the performance of the designed vacuum probe. In air, firstly, the vacuum probe has same temperature that working section is -190℃ and non-working section is -100℃ at 0.2 MPa,0.25 MPa,0.3 MPa, but the cooling rate will increase with increasing pressure. Secondly, the vacuum layer outside the probe s non- working section can prevent heat transfer. Thirdly, the resistance heating method can increase the temperature of the vacuum cryoprobe. Resistance heating can make the temperature of the probe s non-working section within the acceptable range of the human body, and without damaging the human normal tissues. In distilled water, the probe s working section can form ice hockey with an axial length of 3.6 cm and a radial length of 1.8 cm at 600 s, and volume of ice hockey is 6.11 cm³. In vitro porcine liver, the freezing phenomenon can be clearly seen. The freezing temperature reaches -192.9℃ and rewarming temperature reaches -55℃ in working section, and average cooling rate is 128℃/min. At the end of the experiment, the axial frozen diameter and axial thawed diameter are 3.6 cm and 1.2 cm, respectively. In simulation, the influence heat sources on the temperature field of human tissues was analyzed. From the nephogram, the tissues form ice hockey and melt gradually. Without heat source, freezing effective area is ellipse which long axis is 12.4 mm at 600 s, while rewarming effective area is ellipse which long axis is 10.4 mm at 1400 s. If heat source is considered, whole tissue s temperature will increase during the freezing and rewarming process, and it has a great influence on rewarming process. From the overall effect, the probe has good freezing and rewarming properties, which promotes the further development of cold-heat compound therapy.

The complex flow in the feed injection zone of the fluidized catalytic cracking (FCC) riser reactor was theoretically analyzed. By introducing a series of simplifications, the concept of“blocking”was proposed for the first time to convert the continuous feed spray into individual clusters, the mixing/contacting of the catalysts with feed oil was discussed in the mesoscopic scale based on the law of momentum conservation. The occurrence of the secondary flow which was separated from feed spray was interpreted sequentially. Furthermore, on the basis of the Kutta-Joukowski lift theorem in aerodynamics, the extension and the development of the secondary flow were theoretically deduced. Thus the whole evolution process of the secondary flow in the feed injection zone was clearly described. By combining the wall jet and the Kutta-Joukowski lift theories, a model for determining the location of the secondary flow centerline is given. Compared with the experimental results, the model curve has a high degree of agreement with the secondary flow development trend in the experiment, indicating that the model can be used to predict the flow characteristics of the secondary flow in the riser.

Based on the three-parameter wall flow model of the packed tower, a wall flow model applied to the semi-circular filler layer of the dividing wall tower is proposed. Refer to experimental data, the model parameters were estimated. The results agree well with the theoretical value. A set of semicircular cold test system with a diameter of 580 mm and a height of 2800 mm was built, and the effect of gas and liquid rate change on the wall flow was analyzed. The residence time distribution(RTD) curves were obtained by pulse injection stimulus-response technique. It is found that the RTD is affected by the change of gas and liquid rate. The influence of wall flow effect is quantified by the average residence time comparison between wall section and bulk section, the results show that the average residence time of wall section was smaller than that of bulk section at the wall flow full development stage. Such data are essential for design and optimization of dividing wall column distillation processes. Correlation of Pe_d is calculated by liner regression. This experiment has reference significance for the development of new packings, inner parts and the improvement of the design method of DWC to achieve safe, reliable and effective amplification.

The oscillatory extinction mechanism of micro-gravitational dimethyl ether (DME) spherical diffusion flame in hot- and cool-flame conditions was studied by numerical modeling with detailed chemistry and transport model. The results show that a stable self-sustaining cold flame can be established under microgravity conditions, and the cold flame reaction can significantly expand the flammability limit of flameout. Oscillation existed prior to the steady-state extinction turning point of either hot or cool flame. The oscillatory extinction of DME hot flame was governed by a single oscillatory mode, and its frequency (1 Hz or so) was independent of the ambient oxygen mole fraction. By contrast, the cool-flame oscillatory extinction was governed by dual mode of oscillation with distinct frequencies, and the oscillation period of the high-frequency mode significantly increased when approaching the extinction limit. Moreover, the dual oscillatory modes showed strong coupling interaction, so the cool-flame extinction was more complicated than hot flames. The sensitivity analysis indicated that the hot flame extinction was controlled by the competition reactions of high-temperature exothermicity/endothermicity and chain-branching/termination involving small molecules, and the cool flame extinction was controlled by competition of low-temperature branching and termination reactions in the negative temperature coefficient regime.

Toluene and ultrapure water were used as the research object of the multiphase system. The high-speed camera test was used to analyze the oscillation behavior of binary droplets after free collision and coalescence. The experimental results show that the oscillation process of toluene droplets after coalescence has obvious periodicity and damping attenuation mechanism, and the Reynolds number, Weber number of droplets are the key dimensionless parameters affecting the process. There is a positive correlation between the inertial force and the oscillation period, while the viscous force dominates the damping attenuation mechanism of the oscillation process. It indicates that the damping coefficient increases with the increasing viscous force. At the same time, the collisional coalescence of droplets is relatively independent of its subsequent oscillation process, which means the collisional coalescence process has no obvious effect on the oscillation behavior of the droplet. In addition, the experimental and theoretical comparison show that the experimental results of the oscillation period are slightly higher than the theoretical values. In general, the standard deviations of the relative errors between experiment and calculation are 44.9% and 14.9% for the damping coefficient and oscillation period, respectively.

Micro-encapsulated phase change material slurry is a new type of heat transfer media which consists of microencapsulated phase change particles and a single-phase heat fluid. Due to the advantages of high coefficient of heat transfer, integration of heat transfer and energy storage, the new media has great development potential. In this paper, we used discrete phase model to numerically analyze the heat transfer characteristics of micro-encapsulated slurry in horizontal circular tube under constant heat flux. The model is verified by comparing with the experimental results. The effects of particle size, mass fraction, phase change latent heat, especially particle distribution on heat transfer were quantitatively analyzed. The results show that as the mass fraction of microcapsules increases, particle size decreases, latent heat of phase change increases, the heat transfer at wall is better. Moreover, the effect of latent heat on wall temperature control and heat transfer is greater than that of particle mass fraction and particle size. The calculation results of the discrete phase model and the commonly used single-phase flow model are compared. It is found that the higher the mass fraction, the higher the degree of particle aggregation, and the greater the deviation of the single-phase flow model.

In this work, the sinusoidal wavy (SW) copper microchannel with triangular cross section is manufactured with the ultrafast laser micromachining approach, which is a promising technique for the fabrication of metallic microchannels due to its high accuracy and high processing efficiency. The experimental setup is established to study flow boiling heat transfer process in SW microchannel and the deionized water was utilized as the working fluid. The flow boiling phenomena in SW microchannel are experimentally investigated under different mass and heat fluxes. Based on obtained experimental results (temperature/pressure data and flow pattern images), it is found that the local heat transfer coefficient experiences a sharp increase and then decreases to a stable value with the increase of outlet vapor quality. The SW microchannel achieves a 127.7% increase of heat transfer coefficient and a 14.4% increase of pressure drop compared to the straight one. The wavy channel structure can significantly inhibit the instability in flow boiling. The dominant heat transfer mechanism gradually changes from nucleate boiling to thin film evaporation.

The interFoam solver in the open source CFD software OpenFOAM was used to numerically simulate the formation of micro-droplets in a flow-focused microchannel. Predictions using the volume-of-fluid(VOF) model and the power-law non-Newtonian model were first validated against measurements in the literature. Then, the formation of Newtonian droplets in power-law shear-thinning fluids was modeled in three different flow regimes. The results illustrate the effects of the power-law index（n） and the consistency coefficient（K） of the power-law fluid on the droplet generation. The results show that the minimum width of the stretching thread has a power-law relationship with using the remaining time in the droplet release cycles in the squeezing and dripping regimes. The thread length increases slowly during the collapse stage and then grows rapidly during the pinch-off stage. The final droplet length decreases with increasing n or K. However, the generation frequency increases as n or K increase. The results also show that n has a greater effect than K on the droplet formation.

The experiment investigated the influence of non-uniform air distribution configuration on the residence time distribution(RTD) of large particles in a fluidized bed with an inclined air distribution plate. The results indicate that, an increase in the discharging velocity makes the E(t) curve more flat and fluctuating, with the mean residence time (MRT) growing exponentially. With an increasing air velocity in the high-gas-flow-rate-zone (HGFRZ), the segregation of tracers is initially dominant and gives way to the mixing process at the late stage. There is an optimal range of the HGFRZ gas velocity for separation. A high air velocity in the low-gas-flow-rate-zone (LGFRZ) induces an intensive mixing and a longer MRT. Additionally, the effects of tracers property are studied, as well. Regarding the particle shape, a spherical and smooth surface is good for the separating and results in a short MRT. As far as the size concerned, its impact couples with that of the density. For the dense particles, a large size causes a short MRT. However, for the light ones, a large size brings about a long MRT. Many characteristics of RTD curves from current works, such as the shape, fluctuation, peak time and value, properly reveal the particle flow and mixing behaviors in fluidized beds. These achievements are supposed to provide tangible references to the mechanism exploring of the internally circulating stream, and the engineering applications of fluidized beds with multiple components.

On the basis of the traditional kinetic theory of granular flow (KTGF), the tangential restitution coefficient β, which characterizes the surface friction and tangential inelasticity of rough particles, and the total granular temperature e₀, which synthetically reflects the fluctuating intensity of the translational and rotational motion of particles, are introduced. Combining with the transport theory, the conservation equations of particle phase mass, momentum and total granular temperature considering particle rotation are established. Under the condition of solving the parameters of energy dissipation and particle phase stress with both translational and rotational motions, the constitutive relations of solids pressure, shear viscosity and energy dissipation, as well as the boundary conditions, are proposed. Finally, the kinetic theory of rough spheres (KTRS) is obtained. By changing the fluid rheological properties, the effects of flow index n and consistency coefficient K_l in the power-law rheology model on the hydrodynamic characteristics in a fluidized bed are studied respectively. The simulation results show that with the increase of the flow index and the consistency coefficient, the energy dissipation rate of the liquid phase turbulence gradually increases, while the particle phase pressure gradually decreases, and the particle rotation increases first and then decreases.

In microfluidic technology, the optimal design of the microchannel structure is an effective method to passively achieve precise control of droplets. To investigate the influence of the local geometries including the dispersed phase inlet, the downstream orifice and their coexistence mode on the droplet formation, this paper adopts the interface capture method coupling the VOF/CSF and level set method to numerically simulate the droplet formation in flow-focusing devices. The results show that when the orifice as a single variable, the droplet generation cycle and diameter increase linearly with the orifice width. The shrinkage rate of the neck width decreases with the increasing orifice width. The narrowing neck is helpful to strengthen the Y-direction squeezing and the X-direction shear stress. When the orifice width is relatively small, the generation cycle and diameter are not sensitive to the included angle of the vertical edge and the horizontal edge on the whole. In this case, the droplet generation is mainly affected by the orifice s focusing effect. When the orifice and the included angle θ₂ vary simultaneously, they two can cooperatively affect the droplet formation. The increasing orifice width gradually weakens the orifice s focusing effect, and thus leads to an increase of the proportion of the extrusion-rupture time in a single formation cycle. In addition, when the orifice width is relatively large, the droplet generation period and diameter increase with the increase of θ₂, and the droplet flow pattern can transform from a dripping regime to a jetting regime, indicating that the included angle θ₂ at the horizontal edge begins to significantly affect the droplet generation.

The paper introduces the design principle and experimental prototype structure of an external cooling solution dehumidifier based on evaporative cooling. By using the LiCl and CaCl₂ solution as liquid desiccant and taking the dehumidification rate and corresponding dehumidification air outlet temperature as evaluation indexes, the dehumidification performance difference of LiCl and CaCl₂ solutions under externally evaporative cooling conditions are analyzed and compared through a series of experiments. The results show that the dehumidification performance of LiCl solution with 0.35 mass ratio is similar to that of CaCl₂ solution with 0.45 mass ratio, whose dehumidification rate and corresponding air outlet temperature are both higher than CaCl₂ solution with 0.35 mass ratio. Moreover, the dehumidification rate of LiCl solution with 0.35 mass ratio is about 73% higher than that of CaCl₂ solution with 0.35 mass ratio, and the larger air flow rate leads to a greater dehumidification rate difference. In addition, the increase of evaporative cooling air flow rate can not only increase the dehumidification rate, but also reduce the corresponding air outlet temperature by about 1.4℃. The effect of the spray water temperature on the dehumidification performance of CaCl₂ solution is more obvious than that of LiCl solution. The research results provide a reference for the practical application of this kind of externally cooled dehumidifier.

The feasibility analysis of the use of spiral twisted tubes in gas turbine temperature control heat exchangers was carried out, and the simulation of the actual operating conditions of gas turbine intake heaters was carried out to conduct a comprehensive heat transfer performance experiment. The relationship between heat transfer and flow resistance criteria was obtained. By introducing the concept of comprehensive evaluation factor(η) and comparing the spiral twisted tube heat exchanger with the traditional steel aluminum finned tube heat exchanger, it is found that the value of η of the spiral twisted tube heat exchanger is 1.31—1.52 times of the steel aluminum finned tube heat exchanger. Taking the E-class PG9171E type unit used in a construction project as an example, comparing two kinds of intake air temperature regulating heat exchangers using a spiral twisted tube and a steel aluminum finned tube: when using a spiral twisted tube heat exchanger, under the same heat exchange capacity, the wind side resistance of the heat exchanger increased by 14.7%; under the same mass, the heat exchange capacity of the heat exchanger increased by about 9.9%.

In order to compare the performance of zeotropic mixtures and pure fluids in organic Rankine cycle (ORC), a numerical simulation model is established for basic ORC and ORC with internal heat exchanger (IHE) under the closed heat source with given heat supply and inlet and outlet temperatures. Mixtures R600a/R601a at different mass fractions are employed, and a certain range of mass flow rate of cooling water is considered as the condition of heat sink. In the simulation, the cycle evaporation and condensation temperatures are simultaneously optimized to obtain the maximum net output power, and the performance parameters of mixtures and pure fluids are obtained. Based on the performance comparison, it can be concluded that zeotropic mixtures are not certain to have higher cycle performance than pure fluids. Under the given condition of closed heat source, mixtures generally have better temperature matches in the evaporator and condenser, so that exergy losses of these heat exchangers are reduced. Regarding the ORC with IHE, IHE will affect the temperature distribution of the working medium in the phase change heat exchanger, but it has a small effect on the plutonium loss in the phase change heat exchanger.

In this paper, a casing type phase change heat storage experiment system is set up, which is filled with composite phase change materials made of expanded graphite and n-pentadecane with different mass fractions, and the system is charged and discharged repeatedly . The heat transfer enhancement of the sleeve tube thermal storage system was characterized by effective heat storage ratio E_st and energy storage efficiency ε. The results show that the discharging process was completed by 1770 s (Condition A, k_p =0.14 W·m^-1·K^-1). The completed time for Condition B (k_p =7.10 W·m^-1·K^-1) and Condition C (k_p =11.60 W·m^-1·K^-1) were shortened by 77.3% and 78.9% under the same Reynolds number. E_st and ε of the system increase significantly with the increasing thermal conductivity. As the thermal conductivity increases from 0.14 W·m^-1·K^-1 to 11.60 W·m^-1·K^-1, E_st increased by 33.3%, 350.0% and 129.6% in the laminar region, transition region and turbulent region, and ε increased by 26.8%, 52.9% and 14.6% respectively. However, E_st and ε decrease as Re increases in Condition B and Condition C. E_st in Condition C shows a peak of 1.62 at Re = 4298.

An experimental investigation on the boiling heat transfer of a new mixture R245fa/R141 in a 10 mm horizontal smooth tube was conducted. The boiling heat transfer performances of R245fa, R141b and their mixture were investigated, and the prediction accuracy of four commonly used correlations was compared. The results show that the boiling heat transfer coefficients of pure and mixture increase with the increase of mass flow rate and heat flux, and decrease with the increase of saturation pressure. Besides, the boiling heat transfer coefficient of working fluids increases first and then decreases with the increase of vapor quality, which indicates that there is transitional vapor quality. What s more, the value of transitional vapor quality of R245fa/R141b is greater than that of R245fa and R141b. When the vapor quality is less than 0.55, the heat transfer coefficient of the mixture is lower than that of the pure working fluid. On the contrary, when the vapor quality is greater than 0.55, R245fa/R141b can achieve a higher heat transfer coefficient. The boiling heat transfer coefficient of R245fa/R141b increases with the increase of R245fa mass fraction. Among several selected correlations, the Gungor-Winterton correlation can predict the boiling heat transfer coefficient more accurately, and the average absolute error is 16.67%.

The micro-particle imaging velocimetry(Micro-PIV) system was used to investigate the characteristics of the flow around a microcylinder with D=0.4 mm in the microchannel in the range of 6<Re<300. The velocity field, vorticity field, turbulence intensity field and the vortex structures in flow layers with different heights under different Reynolds numbers were obtained and analyzed. The research results show that the first critical Re of the vortex around the micro-cylinder is around 10, and with the increase of Re, the length and width of the vortex in the wake region increase, the wake region increases, and the center of the vortex moves backward. As the increase of Reynolds number, the length and width of the vortices increased, and the center of the vortices moved downstream. The wake regions in flow layers with different heights had the same length, but the vortex center of the wake region moved downstream for flow in a layer away from the wall. The high vorticity area and the high turbulence intensity area were distributed on both sides of the microcylinder, indicating that the fluid mixing at this position was more severe. With the increase of Re, the vorticity increased, and the high vorticity area became narrower and longer, as well as the turbulence intensity. Besides, the high turbulence intensity area expanded with increase of Re. and the turbulence intensity difference among different flow layers was small at Re>200.

To improve the selectivity of HZSM-5 to catalyze the hydrolysis reaction of cyclohexyl acetate to cyclohexanol, an ionic liquid [BMIm]Br auxiliary was screened. It was found that [BMIm]Br could inhibit the side-reaction, thermal decomposition of cyclohexyl acetate, and increase the selectivity to cyclohexanol greatly. Moreover, the ion exchange between [BMIm]Br and HZSM-5 could promote the generation of H⁺, which could accelerate the hydrolyzation of cyclohexyl acetate. Under the optimized reaction conditions, cyclohexyl acetate conversion was 87.5% with 97.3% cyclohexanol selectivity over HZSM-5 assisted by [BMIm]Br. The reusability of [BMIm]Br and HZSM-5 was investigated respectively, and the former exhibited good stability. However, the catalytic activity of HZSM-5 decreased gradually with the recycling times. It was due to the decreasing of framework Al content of HZSM-5 during the reaction, which led to the reduction of Br?nsted acid sites and therefore resulted in the decreased activity.

Using ammonium tungstate, cerium nitrate hexahydrate, and urea as raw materials, CeO₂-WO₃ / g-C₃N₄ catalyst was prepared by the melt method, and the samples were characterized by XRD, UV-Vis, TEM, PL, and XPS. XRD characterization results show that the introduction of CeO₂ can improve the dispersion of active component WO₃ on g-C₃N₄, and XPS characterization indicates the good oxygen storage and release capacity of Ce⁴⁺/Ce³⁺ is conducive to the formation of oxygen vacancy and reactive oxygen species. The PL characterization also indicates that the introduction of CeO₂ can capture electrons and thus inhibits photogenic electron hole pair recombination. The introduction of the CeO₂ for the catalytic activity of compound photocatalysis was investigated by oxidation and desulfurization experiment, the high-pressure sodium lamp was used to simulate visible light source, using the mixture of n-heptane and dibenzothiophene (DBT) as a simulation oil. Experimental results show that in 80℃, O/S molar ratio 5.0, 5% (mass fraction) CeO₂ payload, 180 min of reaction conditions, the introduction of CeO₂ catalyst on the oxidation of DBT in n-heptane conversion rate was 86.4%, higher than WO₃/g-C₃N₄ on the oxidation of DBT conversion rate 72.9%. The characterization results and oxidation desulfurization experiments showed that the introduction of CeO₂ could interact well with WO₃/g-C₃N₄, thus improving the activity of the composite photocatalyst.

Firstly, the graphene oxide (GO) was prepared by the modified Hummers method, and modified with 3-aminopropyltrimethoxysilane to obtain NH₂-GO containing amino groups. Then, the single lacunary Dawson type tungstophosphate K₁₀[α-P₂W₁₇O₆₁]·20H₂O (P₂W₁₇) was modified with γ-(2,3-epoxypropoxy) propyltrimethoxysilane (EPO) to prepare EPO-P₂W₁₇ containing epoxy groups. Finally, P₂W₁₇ was covalently bonded onto GO through the reaction of EPO-P₂W₁₇ with NH₂-GO to prepare P₂W₁₇/GO composite catalysts. The structure and composition of the composites were characterized by FT-IR, UV-Vis, TG, XPS, TEM, etc. Tetrahydrothiophene (THT) was used as the object of catalytic evaluation, and the catalytic oxidation activity of P₂W₁₇/GO was initially investigated. The results show that P₂W₁₇ covalent-supported on GO is well dispersed. And the oxidation process of THT catalyzed by P₂W₁₇/GO using H₂O₂ presented the high efficiency and selectivity. The conversion of THT could reach 100% at 75 min with H₂O₂ as oxidant under a small amount of P₂W₁₇/GO (0.02 g), and its catalytic activity is 1.7 times higher than that of EPO-P₂W₁₇. The catalytic oxidation of THT by P₂W₁₇/GO follows the quasi-first order kinetic model. More attractively, P₂W₁₇/GO could be well reused several times, stemming from the strong covalent bonding between P₂W₁₇ and GO surface.

In this study, wood chips and peanut shells were used as raw materials for biomass pyrolysis, and the distribution of organic products was studied. The catalyst was modified by two metal elements, Fe and Zn. The Fe-Zn modified ZSM-5 was analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), infrared, and specific surface area test (BET). Biomass was pyrolyzed using a pyrolysis-mass spectrometer (PY-GC/MS) to investigate changes in product distribution of biomass catalytic pyrolysis. Under the action of the catalyst, the yield of the aromatic hydrocarbon product is greatly improved. In the pyrolysis process of wood chips, the Fe-supported molecular sieve catalyzed the highest yield of phenols, which was 18.30% higher than the catalytic pyrolysis yield of ZSM-5. The single-metal supported catalytic pyrolysis of Fe and Zn yielded the lowest yield of acid products, which was 50.66% lower than that of direct pyrolysis. The metal modified catalyst greatly increases the yield of aromatic products in the pyrolysis of peanut shells. The Zn modified catalyst has the highest yield of aromatic hydrocarbon products, and the Zn modified catalytic pyrolysis is 18.92% lower than that of direct pyrolysis. The lowest ketone yield was obtained by Zn modification, and the ketone yield was reduced by 19.74% compared with direct pyrolysis, showing a strong dehydroxylation effect. In addition, Zn modification catalysis and Fe-Zn bimetallic modification catalyzed the yield of acid products in the pyrolysis of peanut shells, and the acid yield decreased by 30.46% and 36.71% compared with direct pyrolysis. It was found that both Fe or Zn modified ZSM-5 molecular sieves have an inhibitory effect on the acid in the pyrolysis product and reduce the corrosivity of the product. The Fe modified (6%(mass)) ZSM-5 molecular sieve catalyst has a higher yield on the aromatic hydrocarbon product than Zn. The effect of equal mass content of Fe-Zn on the promotion of phenolic products is obvious. In addition, changes in pore volume and pore size distribution occurred on Fe-modified ZSM-5 catalysts, and this change was positively correlated with BTX yield in wood chips pyrolysis. The Fe loading forms a new mesoporous structure on the surface of the molecular sieve, which promotes the formation of aromatic hydrocarbons and phenolic compounds. Compared with the pyrolysis products of peanut shells, the 120—150 molecular weight of the wood chips pyrolysis products is more, which can be used as an intermediate product of cracking, and has a promoting effect on the formation of phenol and BTX. It indicates that different biomass materials, in direct pyrolysis, the molecular weight distribution of the product also affects the catalytic upgrading effect. Under the condition of single metal catalytic pyrolysis, compared with the catalytic effect of Zn-loaded ZSM-5 catalyst, the catalytic effect of Fe-modified catalyst on biomass pyrolysis products is significant.

In order to overcome the limitation to loss of active components of Fenton as well as operation only under pH 2—3, a CuCe oxide catalyst was prepared by a citric acid complex method. A catalytic wet peroxide oxidation (CWPO) reaction system was also established, which aimed at degradation bisphenol A. The effects of calcination temperature, Cu/Ce molar ratio, H₂O₂ dosage, initial concentration of bisphenol A and pH on the structure of the catalyst and the performance of the CWPO were investigated. Possible degradation pathways were also analyzed.The results show that the catalyst has good high temperature stability and pH adaptability, and has high degradation performance for bisphenol A in the range of pH 1.6 to 7.9, and does not need to adjust the pH. The removal rates of BPA and TOC were 91.8% and 84.5%, respectively, with the concentration of Cu²⁺ at 19.3 mg·L^-1 after calcination of 450℃, Cu/Ce molar ratio at 1.0, catalyst dosage at 1 g·L^-1, hydrogen peroxide dosage at 196 mmol·L^-1, BPA concentration at 152 mg·L^-1, pH at 6.6, reaction temperature at 75℃ and reaction for 95 min. The possible degradation pathways of bisphenol A were proposed.

Aiming at the difficulty of recovering the propylene oxide tail gas in the process of producing propylene oxide by the hydrogen peroxide method, a new propylene oxide recovery process using methanol in the reaction unit as the absorbent and extraction distillation column in the refining unit as the desorption tower was proposed. The reactions of both PO hydrolysis and PO and methanol reaction without catalyst were considered and the high-value product of propylene glycol monomethyl ether was additionally obtained through azeotropic distillation technology. The simulation and design optimization for the full process using Aspen Plus package with NRTL thermodynamic model was carried out, and the influence of the main technological parameters, such as solvent ratio, the number of theoretical plates, and the feed temperature of methanol was discussed. The calculations showed that the mass recovery yield of PO was up to 99.99%. The presented process would play an important role in product capacity improvement, energy saving and volatile organic compounds (VOCs) treatment in HPPO plant.

Porous organic polymers (POPs), with high surface areas and well-developed porosities, were always deemed to be ideal candidates as the adsorbents for CO₂ capture. It is popular to introduce amino groups, the CO₂ chemisorptive sites, onto the POPs for improving the CO₂ capture capacities and selectivities of the POPs.In this study, ethylenediamine (EDA) was successfully doped on the POP (code-named nTPB, with 1,3,5-triphenylbenzene as the monomer) by grafting mode and impregnation, respectively. The effects of different doping modes on the textural properties and the CO₂ adsorption performance of nTPB were studied. It was found that both the surface area and pore volume of nTPB decreased after EDA doping. With the same doping amount of EDA, the pore structure of nTPB was more blocked by impregnation than that of grafting mode. The CO₂ adsorption selectivity of nTPB can be significantly improved by the two doping modes, but only grafting mode can promote the CO₂ adsorption capacity (from 4.4 mmol/g to 5.2 mmol/g at 0℃ and 10⁵ Pa) of nTPB, and that of nTPB doped with impregnation was only 3.4 mmol/g at 0℃ and 10⁵ Pa, due to the pores blocked and EDA buried therein. In addition, the ethylene diamine-doped nTPB grafted showed the same good reusability as the nTPB matrix.

Using ionic liquid 1-butyl-3-methylimidazolium dicyandiamide ([BMIM][DCA]) as extractant, the separation of tetrahydrofuran (THF)-ethanol-water ternary azeotrope was studied by process simulation and mechanism analysis. Based on COSMO-RS theory, suitable ionic liquid [BMIM] [DCA] was selected with selectivity as performance index, and the extractive distillation process was established with [BMIM] [DCA] as extractant and suitable operating conditions. The simulation results showed that the mass fraction of THF, ethanol and water was close to 1. Through the analysis of σ-profiles of [BMIM] [DCA] and three solutes, it is found that [BMIM] [DCA] can form stronger hydrogen bonds with three solutes respectively, thus breaking the inherent hydrogen bonds between the three solutes and eliminating their azeotropy.

Magnesium-loaded biochar adsorbent was prepared from waste cassava stalks. The effects of modification of different magnesium salts, MgCl₂ concentration, carbonization temperature, solid-liquid ratio and carbonization time on the adsorption of ammonia-nitrogen and phosphorus were studied using the controlled variable method. Samples of magnesium-loaded cassava stalk-based biochar (Mg-BC) using the process with the best adsorption performance were prepared and batch adsorption experiments for ammonia-nitrogen and phosphorus were carried out. The adsorption characteristics were studied using isothermal models (Langmuir and Freundlich model) and kinetic models (quasi-first-order kinetics, quasi-second-order kinetics and intra-particle diffusion model). The adsorption mechanism was also studied using FTIR, XRD, SEM-EDS and XPS. The results show that the adsorption process of ammonia-nitrogen and phosphorus by Mg-BC conforms to the Freundlich model and quasi-second-order kinetic model, and is multilayer chemisorption. The theoretical saturated adsorption capacities were 43.48 mg·g^-1 and 96.00 mg·g^-1 for ammonia-nitrogen and phosphorus respectively. Combined with the characterization results, it is speculated that magnesium-titanium-based biochar (Mg-BC) adsorbs ammonia nitrogen and phosphorus mainly through functional groups, complex precipitation and ion exchange and other processes.

The complicated topological structure of dividing-wall columns(DWC) with double columns and multiple separating sections allows many possibilities to use vapor recompressed heat pumps (VRHP), including single VRHP, multiple VRHPs, multi-stage VRHPs, and their various potential combinations, and this adds great complexities and tediousness to the synthesis and design of the vapor recompressed dividing-wall columns(DWC-VRHP).To address the issue, we derive the optimum topological configuration of the DWC-VRHP in the current work for the separations of light-component dominated and wide boiling-point ternary mixtures, based on which the structural searches involved in process synthesis and design can be avoided and the burden of process modeling and search computation can be reduced. The light-component dominance and wide boiling-points of the mixtures separated make the top condenser and the stripping section of the pre-fractionator the primary heat source and heat sink, respectively, and determine essentially the optimum topological configuration of the DWC-VRHP, i.e., a DWC plus a two-stage VRHP. The first-stage VRHP is employed to pre-heat the feed, not only taking the advantages of the small temperature elevation available but also favoring the intensification of mass transfer between the vapor and liquid phases through feed splitting. The second-stage VRHP is employed to heat the stripping section of the pre-fractionator(or the common stripping section), being capable of reducing the irreversibility to its fullest extent. With the separations of two ternary mixtures of benzene/toluene/o-xylene and n-pentane/n-hexane/n-heptane as examples, the derived optimum topological configuration of the DWC-VRHP is analyzed and validated through detailed comparison with the DWC and other potential configurations of the DWC-VRHP. The systematic comparison with DWC and other potential structures of DWC-VRHP shows the superiority of the proposed system structure in terms of steady-state performance.

During the operation of upstream pumping mechanical seal, the dynamic pressure groove blockage often occurs due to the deposition of solid particles. To study the solid particle deposition characteristics of the micro-gap lubricant film, a three-dimensional geometric model of the seal lubricant film and a gas-liquid-solid multi-phase flow calculation model were established. The Mixture model and DPM model were applied to study the different particle diameter, rotational speed, medium pressure, particle import volume fraction and the lubrication film thickness on the influence of solid particle deposition characteristics. The results show that the deposition rate and deposition area of solid particles from the inner diameter side of the lubrication film are related to the particle diameter, particle import volume fraction, sealing condition and lubrication film thickness. Smaller particle size, larger rotating speed, larger medium pressure and smaller film thickness are beneficial to lower particle deposition rate. The low-pressure area of spiral groove is the main part of particle deposition. With the increase of particle diameter, particle import volume fraction, rotating speed and film thickness, medium pressure decreases and the deposition area obviously extends outward to the root of the groove, which is the reason why the spiral groove is prone to blockage and failure. Particle deposition is easy to occur in dam area and particles in the non-slot area are circumferentially distributed at low rotating speed.

The geometrical shape of dimples has significant influence on the leakage rate of mechanical seal with dimples. Based on the wedge effect theory, the relationship between the geometrical shape of dimples and the leakage rate is studied. Firstly, the analytical method of equilateral triangular dimples multi-wedge phenomenon is extended to the elliptical, diamond, rectangular and isosceles triangular dimples. The wedge feature of elliptical, diamond, rectangular dimples is two centrosymmetric wedges, and the wedge feature of isosceles triangular dimples is two non-centrosymmetric wedges. Secondly, the effect of multi-wedge phenomenon on the outlet suction flow rate, reversed flow rate and leakage rate is analyzed. The low pressure zone induced by the divergent wedges is the main influencing factor of the outlet suction flow rate. The high pressure zone induced by the convergent wedges is the main influencing factor of the reversed flow rate. The leakage rate is affected by the combination of the former two factors. Finally, based on the understanding of the multi-wedge phenomenon, two wedge-shaped structures with the strongest suction ability and the strongest return ability were selected and combined to design a new type of dimple. Compared with the original four oriented dimples, its leakage rate is the smallest.

Taking hydrostatic dry gas seal (DGS) with single-row and multi-row orifices in the radial direction as the research object, the influence of orifice position and film thickness on steady-state performance, including opening force, film stiffness and leakage rate,of hydrostatic DGS with single-row orifice were analyzed utilizing large eddy simulation (LES) method, together with the influence of different exhaust modesand circumferential position of orifice on steady-state performance of hydrostatic DGS with multi-row orifices. The optimized exhaust modes for large opening force and low leakage rate were obtained at different film thickness, and a new type of hydrostatic DGS with adjustable exhaust mode was proposed on this basis. The results show that compared to typical hydrostatic DGS with single-row orifice, opening force and film stiffness of hydrostatic DGS with up-down stream orifices and with up-mid-down stream orifices enhanced remarkably at when film thickness smaller than 10 μm and larger than 10 μm, respectively. The maximum increment ratio of opening force and film stiffness of hydrostatic DGS with multi-row orifices are 15% and 25% larger than those of hydrostatic DGS with single-row orifice, respectively. By selecting a reasonable orifice outlet mode, it can meet the performance requirements of static gas dry gas seal high gas film carrying capacity, low leakage rate and low gas consumption under different conditions.

The mechanical seal ring is supported on the shaft or in the seal cavity by an auxiliary O-ring. Different structural designs will change the seal ring support boundary. Aiming at the three structural models of mechanical seals, this paper simulates the deformation of the end facies of friction pair of mechanical seals by using ANSYS finite element analysis software, and discusses the deformation law of the surfaces of mechanical seals under different stress boundary conditions of rubber O-ring. When SiC is used in both rotating ring and static ring, it is found that divergent clearance is formed on the end faces of the friction pairs of the three kinds of support structures in static state (structural analysis), and the deformation of the end faces is greatly affected by the contact stress of the support boundary. And the thermal structure coupling analysis shows that the three end facies of the rotating ring and the static ring are convergent. When graphite is used in the rotating ring and SiC is used in the static ring, it is found that the end gap may be convergent or divergent, which is related to the support boundary. Therefore, the different supporting boundary conditions of the O-ring will affect the end deformation of the rotating ring during operation. So different support boundary conditions of O-ring of rotating ring will affect the deformation of seal ring s end face. At the same time, the elastic modulus of the material of the dynamic and static rings has a great influence on the deformation of the end face, thus affecting the sealing performance. The research has guiding significance for mechanical seal design.

Equilibrium surface tension and adsorption dynamic characteristics of perfluoroalkyl quaternary ammonium iodide (Le-134), perfluoroalkyl phosphate (Le-107) and perfluoroalkyl polyether (Le-180) were investigated. The relationship between the critical micelle concentration is Le-180 (15×10^-6) <Le-134 (40×10^-6) <Le-107 (150×10^-6); the saturation adsorption amount Γ_max is Le- 107 <Le-134 <Le-180. The effect of three kinds surfactants on reducing surface tension is similar, and the surface tension of surfactant aqueous solution can be reduced below 20 mN/m. Equilibrium surfaces tension characteristics were analyzed from the hydrophilic and hydrophobic groups and counterions. The dynamic surface tension (DST) of Le-134 drops fastest while Le-180 in second and Le-107 is the slowest. When the concentration of surfactant is relatively small, the adsorption is controlled by diffusion. Whereas the adsorption mechanism changes from diffusion controlled to barrier controlled at high concentrations. The variation of apparent diffusion coefficients (D_a) and adsorption barriers (E_a) of three aqueous surfactant solutions at different concentrations were investigated. It can be indicated that the variation of adsorption dynamics is mainly due to the difference in molecular structure and the influence of micelles on adsorption process.

Na₂S₂O₃ is the main byproduct salt in the waste liquid discharged from the wet desulfurization process. Reducing the amount of Na₂S₂O₃ is important for green production. Firstly, the key factors affecting the production of Na₂S₂O₃ were screened out by Plackett-Burman test, i.e. pH, sulfur concentration and temperature. On this basis, the response surface methodology is used to optimize the design of three factors and three levels with the production of Na₂S₂O₃ as the objective function. The results show that pH has the greatest influence on Na₂S₂O₃, followed by temperature and sulfur concentration. And the interaction between factors is small. The optimal operating conditions are pH 8.25, sulfur concentration 0.47 g/L, temperature 31.80℃, PDS concentration 90 mg/L, oxygen-sulfur ratio 1.2 mmol/mmol, and Na₂S₂O₃ production is 1.838 mmol/L. The influence of various factors is explained by the reaction kinetics from Na₂S₂O₃ and the equilibrium reaction of polysulfide ions. Finally, the actual production process was analyzed and it was found that the pH obtained by the experiment was too low, which was not conducive to the stability of the absorption process. The existing elemental sulfur melt separation method is not conducive to reducing the content of elemental sulfur in the desulfurization solution, and accelerates the formation of byproduct salts. Some suggestions for improvement are put forward and remarkable results are obtained.

To effectively improve the denitrification efficiency and reduce the operating cost of microbial fuel cells, a new multi-channel and baffled membraneless microbial fuel cell (MLMB-MFC) was designed. The system coupled biological cathode simultaneous nitrification and denitrification (SND) to realize the synchronous denitrification and carbon removal while generating electricity. The startup and stable running of the system had been investigated. Moreover, the influence of different cathode dissolved oxygen (DO) and different carbon and nitrogen ratio (C/N) of the inflow on the electricity production and SND performance of MLMB-MFC were studied. The average power density was 42.65 mW·m^-3 after starting operation for 5 days. The maximum power density (P_M) was 94.22 mW·m^-3, the organic matter removal efficiency was 96.6% after stable operation. When the DO in the cathode was between 4.90—5.23 mg·L^-1 and the C/N ratio of inflow was 4, the total nitrogen (TN) removal efficiency was 27.9% and the SND rate was 48.7%, which can indicate that the system can integrate nitrification, heterotrophic denitrification and autotrophic denitrification into biological cathodes to achieve nitrogen removal.

The effects of initial free chlorine concentration, activated carbon particle size and dosage on free chlorine removal by activated carbon were studied. The activated carbon before and after the reaction was analyzed by means of Boehm titration, Fourier transform infrared spectrometer, specific surface area analyzer, scanning electron microscope, and photoelectron spectroscopy. It is found that the failure of the activated carbon was mainly due to the consumption of reductive functional groups on the surface and the oxidative destruction of the surface structure, causing the loss of pore structure and specific surface. The thermal regeneration of the spent activated carbon under different atmospheres (nitrogen, hydrogen and ammonia) can recover the removal ability on free chlorine; and the ammonia gas regeneration is the best, which is mainly due to the improvement of pore structure and the regeneration of the reductive functional groups. The performance of regenerated activated carbon in continuous flow column test was evaluated, and it was confirmed that the regenerated one can achieve an effective and long-time operation.

Aiming at the problems of high chroma, complex composition, and difficult degradation of printing and dyeing wastewater, the iron-carbon micro-electrolysis process is used to treat the wastewater to improve its biodegradability and treatment efficiency. The effect of initial pH, iron dosage, iron/carbon mass ratio and reaction time on the treatment efficiency of dyeing wastewater was investigated. Scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS) and X-ray diffractometry (XRD) were used to analyze the changes in the compositions of iron and carbon before and after the treatment of dyeing wastewater. Zeta potential and UV-Vis spectra were used to compare the changes of organic matter before and after wastewater treatment, and the degradation mechanism of dyeing wastewater was explored. Under the initial pH 4, the iron dosage of 80 g/L, the iron-carbon molar ratio of 0.8 and the reaction time of 90 min, the removal efficiencies of COD, turbidity, chroma, ammonia nitrogen and TOC were 75.48%, 87.88%, 75.34%, 92.01% and 81.09%, respectively. Before the treatment of dyeing wastewater, the composition of the iron-carbon reactor was mainly composed of iron and carbon, and the pore structure of the activated carbon was developed. After the reaction, the surface of the iron carbon adhered to other metal substances such as Al, K and the hydroxide flocs of iron. The iron-carbon micro-electrolysis process can degrade esters, alcohols and organic substances, decompose macromolecular substances and improve the biodegradability of wastewater.

The macromolecular structure model of organic matter in Majiliang vitrain was constructed by means of proximate analysis, ultimate analysis, ¹³C nuclear magnetic resonance spectroscopy(¹³C NMR), Fourier transform infrared spectroscopy(FTIR) and X-ray photoelectron spectroscopy(XPS). In this structural model, the ratio of aromatic ring bridge carbon to peripheral carbon is 0.24, the aromatic compounds mainly exist in the form of anthracene and naphthalene; the aliphatic structure mainly exists in the form of methyl, methylene, methyne and quaternary carbon, the content of oxygen-bound aliphatic carbon is the least; each macromolecule contains an average of 22 oxygen atoms, the oxygen atoms exist in the form of phenolic hydroxyl group, carbonyl group, carboxyl group and ether oxygen with the numbers of 9, 4, 3 and 3, respectively; nitrogen atoms exist in the form of a pyridine and a pyrrole. The average molecular formula of the macromolecule is {\mathrm{C}}_{\mathrm{222}}{\mathrm{H}}_{\mathrm{168}}{\mathrm{O}}_{\mathrm{22}}{\mathrm{N}}_{\mathrm{22}}, and the molecular weight is 3212. The molecular model of the built molecular model was simulated by ¹³C NMR, infrared and density, and compared with the test results. The results show that the model can reflect the macromolecular structure of the organic matter of the Majiliang vitrain.

In the light of the problems existing in the application of air source heat pump in cold regions, a new single-fluid cascade air-source heat pump (SC-ASHP) has been developed, combining with cascade cycle and compressor DC speed regulation technology. The new-type heat pump can operate not only in a single-stage heating cycle (SHC) mode, but also in a cascade heating cycle (CHC) mode. Under different operating conditions, simulation calculations and experimental studies were performed on the compression ratio, exhaust temperature, heating capacity, and coefficient of performance (COP) of the SC-ASHP system in two different heating modes. The results show that, in low temperature environment, the compressor discharge temperature and the compression ratio of the CHC mode are much lower than the SHC mode; when the condensing temperature of 46℃ and an evaporating temperature of -35℃, COP of the CHC mode is higher than 1.8, the compressor discharge temperature is lower than 120℃, and the compression ratio is not more than 5.0, the system can operate stably and reliably; in addition, the heating capacity is rising steadily by increasing the speed of the low temperature compressor in low temperature environment, meeting the heating supply. New heat pump system expanded the application range of air source heat pump system.

The non-equilibrium molecular dynamics method was used to simulate the normal thermal conductivity of the three-dimensional graphene-carbon nanotube composite structure. The structure is based on multi-layer graphene, and the graphene layers are connected with each other through nanotubes. In this way, it is expected to have both low contact thermal resistance and high normal thermal conductivity. In this paper, the out-of-plane thermal conductivity of 3D GCHs is simulated by non-equilibrium molecular dynamics method. The results show that the out-of-plane thermal conductivity increases by one order of magnitude compared with that of multi-layer graphene, and the interface resistance decreases by one order of magnitude in comparison with thermal contact resistance of CNTs. However, the interface between graphene and CNT hinders the heat transfer of GCHs enhancing further. The heat transfer and phonon localization of the GCHs are further investigated through its phonon vibrational density of states and overlap energy. The results show that the addition of carbon nanotubes stimulates more medium and high frequency phonons to participate in heat transfer, but the low frequency phonons still dominate. It is verified that the deformation at the interface is the main factor to prevent the out-of-plane thermal conductivity from further increasing. This paper provides some directional guidance for the improvement and development of high thermal conductivity materials: in the three-dimensional structure of the same element, the fewer types of structural atoms, the better the coordination of inter-atomic vibration, the fewer phonon scattering, the lower the degree of energy localization, and the higher the thermal conductivity

A polyvinyl alcohol/carboxymethyl cellulose porous hydrogel (D-PC) was prepared by yeast foaming. The chemical structure was characterized by FTIR and combined with Zeta potential analysis to prove the interaction between yeast and materials. The three-dimensional network structure was observed by SEM and BET, and the specific surface area and pore size were measured. The effects of D-PC on the removal of the basic dye methylene blue (MB) at different conditions were studied, and the removal mechanism was explored. Degradability of D-PC was tested by cellulose degrading enzyme experiment. The results showed that yeast was encapsulated in D-PC by electrostatic action. As the amount of yeast increases, the specific surface area of D-PC increased and the average pore size decreased. The removal efficiency of MB by D-PC increased with the increase of yeast, and increased first and then decreased with the increase of pH and temperature. The removal mechanism was dominated by chemical adsorption. The kinetic data were fitted to the pseudo-second-order kinetic model reasonably well. Under certain conditions, the yeast could degrade the polyvinyl alcohol in the hydrogel, so the hydrogel had double degradation versatility.

In this work, a facile one-step electrodeposition method is developed to prepare 3D Ni₃S₂ interconnected nanosheet arrays on Ni foam as electrodes for suprecapacitors, resulting in excellent pseudocapacitance performance. The composition, microstructure and morphology of the prepared Ni₃S₂ materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The electrochemical capacitance properties were tested by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) measurements in a three-electrode system. Taking advantage of the highly conductive 3D architectures, the Ni₃S₂/NF-10 electrode exhibits a superior specific capacitance of 2850 F/g at current density of 1 A/g. Remarkably, a specific capacitance of 1972 F/g could be still achieved at a high current density of 10 A/g, indicating its excellent rate capability. With the increase of the electrodeposition time, the 3D architectures of Ni₃S₂ begin to disappear, resulting in a reduced specific capacitance. The appropriate electrodeposition conditions is the key of preparation of high performance electrode materials. Test results show that the prepared Ni₃S₂ material is expected to be used in the field of electrochemical energy storage.

Nanoparticle assembled 3D Co₃O₄ micro-flower anode materials were prepared by soft template method (surfactant cetyltrimethylammonium bromide,CTAB) combined with subsequent air atmosphere heat treatment. The synthesized sample was characterized and analyzed by employing X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), cyclic voltammetry (CV), galvanostatic charge/discharge test and electrochemical impedance spectroscopy (EIS). The unique micro-flowers structure endows the prepared Co₃O₄ anode with excellent lithium storage properties. The reversible specific capacity of about 920 mA·h·g^-1 can be achieved at the current density of 100 mA·g^-1. The synthesized electrode displays almost no capacity decay over 200 cycles with the specific capacity of 757 mA·h·g^-1 at the current density of 500 mA·g^-1. The high current cycling performance test gives the specific capacity of 476 mA·h·g^-1 even at 2 A·g^-1. The simple, effective, and low-cost preparation process of high-performance micro-flower structure transition metal oxide anode materials in this paper will greatly accelerate the practical application of conversion-type electrode materials.

A kidney anemia drug roxadustat is a new drug to be hatched in China and to be approved in China. Roxadustat has a poor solubility with 1.71 mg/L in water. In order to improve the solubility of roxadustat, we carried out co-crystal investigation of roxadustat. Hundreds of experiments were carried out using a serial of CCF. Four roxadustat co-crystals, synthesized with cinnamamide, niacinamide, benzamide and proline, were prepared by solution crystallization. Their structures were characterized by X-ray powder diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier transform infrared spectra (FTIR) and ¹H nuclear magnetic resonance (¹H NMR) respectively. These results show that the new crystalline phase of roxadustat was formed and there was no electronic transfer between roxadustat and CCF indicating the formation of roxadustat co-crystals. Intrinsic dissolution rate, solubility and stability of roxadustat co-crystals were investigated. The results show that the intrinsic dissolution rate of the four roxadustat co-crystals are faster than that of roxadustat form A in pH 4.5 buffer and roxadustat-cinnamamide is the fastest, nearly 10 times as large as that of roxadustat form A．The equilibrium solubility of the four roxadustat co-crystals are higher than that of roxadustat form A in water at 37℃ and the solubility of roxadustat-proline co-crystal is the highest, nearly 5.3 times as large as that of roxadustat form A．The stability results show that roxadustat-cinnamamide co-crystal and roxadustat-niacinamide co-crystal had good light-stability and thermostability. Therefore, these rosalastam co-crystals can provide options for new formulation design and circumvention of patents for rosalastam generics.

Non-covalent hydrophobic modification of magnetic nanoparticles Fe₃O₄@SiO₂ with a redox-active molecule acetylferrocene azine (Fc⁺A), and the modified particles were used as emulsifiers to prepare Pickering emulsions. The modified particles were used as emulsifiers to prepare Pickering emulsion. The structure and properties of nanoparticles and Pickering emulsion were characterized by TEM, SEM, FTIR, XRD, contact angle measurement and optical microscopy. The experimental results showed that the mono-dispersed nanoparticles with particle size 150 nm were synthesized and Fc⁺A was successfully introduced onto the surface of nanoparticles. With the increase of Fc⁺A concentration, the contact angel of nanoparticles increased. The Pickering emulsion obtained could be stabilized when the concentration of Fc⁺A was 12.5 mmol/L, the emulsifier concentration was 0.3%(mass), oil-water ratio was 4∶6 and rotation speed was 10000 r/min. Finally, the stability of emulsion was reversibly regulated by redox and magnetic field.

Flame retardant hexa (4-anilino-methylenephenoxy-diethyl phosphite) cyclotriphosphazene (HADPPCP) was synthesized with hexachlorocyclotriphosphazene, p-hydroxybenzaldehyde, aniline, diethyl phosphite. Then it was used to prepare flame-retardant polyurethane foam. HADPPCP has good thermal stability and char formation. The initial decomposition temperature in a nitrogen atmosphere is 191.9℃, and the residual carbon content at 700℃ is as high as 46.8%(mass) in nitrogen. The addition of HADPPCP improved the fire safety of polyurethane rigid foams. When adding 25%(mass) HADPPCP, the limiting oxygen index of rigid polyurethane foam increased from 18% to 25%. The peak heat release rate and total heat release of polyurethane foam decreased from 230 kW/m² and 20.1 MJ/m² to 213 kW/m² and 16.6 MJ/m², respectively. Moreover, the total smoke production decreased from 10.5 m² to 5.3 m². It suggested that HADPPCP was an efficient flame retardant for RPUF, which can not only decrease heat release rate, but also suppress the smoke release rate of RPUF during the combustion.

A polyvinylidene fluoride/graphene oxide composite material (PVDF/GO) was prepared by a solution blending method, and GO was reduced by hot pressing to obtain a polyvinylidene fluoride/reduced graphene oxide composite material (PVDF/rGO). The effects of filler types and contents on the electrical properties, thermal stability and mechanical properties of composites were studied. The results showed that both the addition of GO and rGO can improve the dielectric constant (ε _r), thermal stability of PVDF at low content, and the dielectric loss (tan δ) of the composites change little, but PVDF/rGO composites always had higher properties than PVDF/GO composites. The ε _r of PVDF/rGO composites increased from 3.60 to 38.30 at 100 Hz with the filler content from 0 to 8%(mass), the decomposition temperature of 5% mass loss in PVDF/rGO [4%( mass)] composites was 6.44℃ higher than that of pure PVDF. The rigidity of PVDF enhanced by rGO, the tensile strength of PVDF/rGO composites increased firstly and then decreased, and the Young modulus of the composites increased gradually. When the content of rGO was 4%(mass), the tensile strength of PVDF/rGO reached the maximum value, tensile strength and Young modulus increased by 35.30% and 22.58% respectively compared with pure PVDF. However, the breakdown strength of the composites decreased with the addition of GO and rGO.

The use of electromagnetic wave absorbing materials to reduce the interference of electromagnetic waves on equipment and harm to the human body is one of the currently used electromagnetic wave protection methods. As a one-dimensional dielectric material, silicon carbide whiskers with specific structure have better absorption performance than ordinary whiskers, bulk materials and particle materials. It has become a hot topic in this area. In this study, bamboo-like silicon carbide whiskers were prepared from bamboo powder, silicon powder and silica by carbothermal reduction at different temperatures, then the structure and absorbing properties of bamboo-like whiskers were tested and analyzed. The sintered bamboo-shaped whiskers at 1400℃ have a minimum reflection loss of -14.4 dB and an effective absorption bandwidth of 1.8 GHz at a thickness of 3 mm and a frequency of 9.1 GHz. Its absorbing performance is the best and has further research value.

A three-dimensional CFD numerical model for the leakage of underwater gas pipelines is established. The variation of bubble plume velocity, plume radius and fountain height at different leakage rates and water depths are studied. The results show that the bubble plume has experienced the initial stage, the full development stage and the surface flow stage, accompanied by the phenomenon of entrainment and turbulent boiling. The plume radial velocity is approximately Gaussian distribution and decreases with the radial distance. The axial velocity of plume decreases with the increase of water depth, and the velocity of plume decreases rapidly at the position near the leakage hole. With the development of bubble plume turbulence, plume radius gradually develops to both sides and increases linearly with water depth. Compared with the integral model, although the CFD model is more complicated in calculation, but the predicted results are roughly consistent with the experiment, it is necessary to carry out experiments with high leakage flow rate under deep water conditions to determine the accurate empirical coefficient to further improve the calculation accuracy of the integral model.

To study the influence of the shape of flat obstacle channel on the characteristics of gasoline-air explosion, a comparison experiment was performed under three initial gasoline vapor concentration conditions of 1.3% (low), 1.7% (medium), and 2.1% (high). The results show that: the shape of obstacle channel has little effect on the evolution of overpressure time series curve of gasoline-air explosion. The effect of obstacle channel shape on the peak value of maximum overpressure, the maximum rate of pressure rise and the average rate of pressure rise is increased in the order of“trapezium—circular—triangle—square—rectangle”,“trapezium—circular—triangle—square—rectangle”and“trapezium—circular—square—triangle—rectangle”, respectively. The shape of the obstacle channel has little effect on the upstream flame shape of the obstacle, but the rectangular channel has the most significant effect on the turbulence characteristics of the downstream flame of the obstacle, followed by the square, trapezoid, triangle and circle, respectively. The effect degree of obstacle channel shape on the maximum flame propagation distance and average flame propagation velocity under the initial gasoline vapor concentration of 1.7%, which is close to the equivalence ratio, is smaller than that of low concentration (1.3%) and high concentration condition (2.1%), and the influence degree of circular channel plate obstacle is the smallest, while that of rectangular and square channel is relatively larger.

To investigate explosion limits parameters of propylene with inert gas dilution, the explosion limits, critical oxygen concentration and minimum oxygen concentration of propylene, with the dilution effect of N₂ and CO₂, were determined by using a standard equipment on basis of GB/T 12474—2008. Furthermore, the explosion triangle diagram of C₃H₆-N₂/CO₂-Air was proposed, and in this way the inertial effect of N₂ and CO₂ on propylene explosion was obtained and analyzed. The results show that the addition of N₂ and CO₂ will reduce the explosion limit of propylene and reduce the risk of explosion. More specifically, the addition of N₂ in 49% would merge the upper and lower explosion limits of propylene which the critical oxygen concentration was 9.79%. While for that of CO₂, the corresponding added volume fraction and the critical oxygen concentration are 34% and 12.94%, respectively. For each propylene at a specific volume fraction, the value minimum oxygen concentration inerted by CO₂ was higher than that of inerted by N₂. Moreover, the explosion triangle diagram shows that the explosive area diluted by CO₂ is much smaller than that diluted by N₂. It takes more less CO₂ in volume to completely inert propylene explosion, compared with N₂.The obtained data can provide fundamental parameters for the prevention of propylene explosion in related industries.

In order to study the influence of alumina on the explosion of aluminum powder, the explosion experiment was carried out in a self-built vertical duct. The flame structural evolution, flame front propagation and explosion overpressure waveform were analyzed. The results show that with the increase in the inerting ratio, alumina showed an obvious inhibitory effect on the flame at the aluminum explosion, and the alumina powder with small particle size had better inhibitory effect. Moreover, alumina exerted obvious inhibitory effect on flame front propagation in later stage, the flame propagation speed decreased, and the time required for the front to reach the duct exit was longer. For 4 μm alumina, the second peak overpressure disappeared at the inerting ratio of φ =30%, while the suppression efficiency was as high as 88.9% at the inerting ratio of φ =70%. However, the alumina explosion-proof effect with a particle size of 89 μm has obvious limit values. Exceeding the limit value, the explosion-proof effect is no longer improved.