Computational fluid dynamics is an efficient numerical approach for spray atomization study, but it is challenging to accurately capture the gas-liquid interface. In this work, an accurate conservative level set method is introduced to accurately track the gas-liquid interfaces in liquid atomization. To validate the capability of this method, binary drop collision and drop impacting on liquid film are investigated. The results are in good agreement with experiment observations. In addition, primary atomization (swirling sheet atomization) is studied using this method. To the swirling sheet atomization, it is found that Rayleigh-Taylor instability in the azimuthal direction causes the primary breakup of liquid sheet and complex vortex structures are clustered around the rim of the liquid sheet. The effects of central gas velocity and liquid-gas density ratio on atomization are also investigated. This work lays a solid foundation for further studying the mechanism of spray atomization.

The article presents the influence of winglet vortex generators (WVGs) placed in the core flow area on thermal performance enhancement of a tube heat exchanger. The experiment was carried out in a uniform wall heat-fluxed tube by varying turbulent airflowfor Reynolds number ranging from 5300 to 24000. In the present work, the WVGs with an attack angle of 30° were inserted into the test tube at four different winglet pitch ratios (R_p = P/D) and three winglet-width or blockage ratios (R_B = e/D). The experimental results at various R_p and R_B values were evaluated and compared with those for smooth tube and tubes with twisted tape or wire coil. The measurement reveals that the WVGs enhance considerably the heat transfer and friction loss above the plain tube,wire coil and twisted tape. The Nusselt number and friction factor increase with the increment of R_B and Re butwith the decreasing R_p. The average Nusselt numbers for theWVGswith various R_B are in the range of 2.03-2.34 times above the plain tube. The thermal performance for the WVGs is found to be much higher than that for the wire coil and twisted tape and is in a range of 1.35-1.59. Also, a numerical investigation is conducted to study the flow structure and heat transfer enhancement mechanisms in the winglet-inserted tube.

Vertical distributions of local void fraction and bubble size in air-water dispersion system were measured with a dual conductivity probe in a fully baffled dished base stirred vessel with the diameter T of 0.48 m, holding 0.134m³ liquid. The impeller combination with a six parabolic blade disk turbine below two down-pumping hydrofoil propellers, identified as PDT+2CBY, was used in this study. The effects of the impeller diameter D, ranging from 0.30T to 0.40T (corresponding to D/T from 0.30 to 0.40), on the local void fraction and bubble size were investigated by both experimental and CFD simulation methods. At low superficial gas velocity V_S of 0.0077 m·s^-1, there is no obvious difference in the local void fraction distribution for all systems with different D/T. However, at high superficial gas velocity, the systemwith a D/T of 0.30 leads to higher local void fraction than systems with other D/T. There is no significant variation in the axial distribution of the Sauter mean bubble size for all the systems with different D/T at the same gas superficial velocity. CFD simulation based on the two-fluid model alongwith the population balancemodel (PBM)was used to investigate the effect of the impeller diameter on the gas-liquid flows. The local void fraction predicted by the numerical simulation approach was in reasonable agreement with the experimental data.

Experimental investigationwas carried out in an elliptical based stirred tank with a diameter of 0.48m to explore the power demand and mixing performance of coaxial mixers. Syrup and CMC solution (sodium carboxy methyl cellulose) were used as the Newtonian and non-Newtonian fluids, respectively. Four different coaxial mixers were combined with either CBY or Pfaudler impeller as the inner one, and anchor or helical ribbon (HR) as the outer one. Results show that Pfaudler-HR is the optimized combination among four coaxial mixers in this work, which provides the shortest mixing time given the same power consumption. Compared with the syrup solution, the increase of power input can make the mixing time decreasing more obviously in the CMC solution. The quantitative correlations for both syrup and CMC solutions were established to calculate the power draw and the mixing time of four coaxial mixers.

A computational fluid dynamics (CFD) model is carried out to describe the wire-plate electrostatic precipitator (ESP) in high temperature conditions, aiming to study the effects of high temperature on the electro- hydrodynamic (EHD) characteristics. In the model, the complex interactions at high temperatures between the electric field, fluid dynamics and the particulate flow are taken into account. We apply different numerical methods for different fields, including an electric field model, Euler-Lagrange particle-laden flows model, and particle charging model. The effects of high temperature on ionic wind, EHD characteristics and collection efficiency are investigated. The numerical results show high temperature causes more significant effects of the ionic wind on the gas secondary flow. High viscosity of gas at high temperature makes particles follow the gas flow pattern more closely. High temperature reduces the surface electric strength, so that the mean electric strength weakens the space charging. On the contrary, there is an increase in the diffusion charging at high temperature compared with at low temperature. High temperature increases the ratio of mean drag force over mean electrostatic force acting on the particles which may contribute to a decline of collection efficiency.

Di(2-ethylhexyl)phosphoric acid was used as extractant of bismuth ions from nitrate medium by emulsion liquid membrane, with Triton X-100 as the biodegradable surfactant in n-pentanol bulk membrane. The novelties and innovative points of this work are the application of emulsion liquid membrane for selective and efficient extraction of bismuth ions as well as the relevant optimization procedures. The extraction of bismuth ions was evaluated by the yield of extraction. The experimental parameters were evaluated and optimized, including the ratio of di(2-ethylhexyl)phosphoric acidmass concentration to Triton X-100 (1.0%:0.5%), nature of diluent (n-pentanol), nature and concentration of stripping solution (sulfuric acid, 0.5 mol·L^-1), stirring speed (1800 r·min^-1) and equilibrium time of extraction (20 min), initial feed solution of bismuth (350 mg·L^-1) and the volume ratio of internal stripping phase to membrane phase (14). The experimental parameters of kinetic extraction reveal that the bismuth ions can be extracted by 100%.

Removal of zinc fromcyanide barren solution is obligatory for its reuse in leach process. Batch experiments were carried out to evaluate the adsorption capacity of resins under different experimental conditions, including concentration, resin amount, initial pH, contact time and temperature. More than 99% of adsorption was achieved under the optimal condition. High adsorption rates on the resin were observed at the beginning and plateau values were obtained in 60 min. The thermodynamic parameters (free energy change ΔG, enthalpy change ΔS and entropy change ΔH) for the adsorption were evaluated. The adsorption kinetic mechanism was studied with four models. The experimental results show that the adsorption follows the Langmuir isotherm and the kinetics follows the pseudo-second-order model.

The effect of varying pore structures on the kinetics of SO₂-CaO reactions is not fully understood in the previous studies. Combining fractal pore model, gas molecular movement model and two-stage reaction model, a new desulfurization model is established in this paper. Fractal pore model is used to simulate CaO particle and gas molecular movement model is used to simulate gas diffusion in pores. Fractal dimension is used to characterize complexity of pore structure instead of tortuosity factor. It is found that the reaction is significantly affected by pore structures. A modulus ø is introduced to characterize the relationship between varying pore structures and apparent reaction parameters. And this relationship is verified by thermo-gravimetric analysis (TGA) data. Comparing to the previous models, the effect of varying pore structure on the kinetics of the reaction is described more accurately by the desulfurization model.

In this paper kinetics of xylose dehydration into furfural using acetic acid as catalystwas studied comprehensively and systematically. The reaction order of both furfural and xylose dehydration was determined and the reaction activation energy was obtained by nonlinear regression. The effect of acetic acid concentration was also investigated. Reaction rate constants were gained. Reaction rate constant of xylose dehydration is k₁= 4.189×10¹⁰ [A]^0.1676 exp (-(108.6×1000)/(RT)), reaction rate constant of furfural degradation is k₂=1.271×10⁴ [A]^0.1375 exp (-(63.413×1000)/(RT)) and reaction rate constant of condensation reaction is k₃=3.4051×10¹⁰ [A]^0.1676 exp(-(104.99×1000)/(RT)) . Based on this, the kinetics equation of xylose dehydration into furfural in acetic acid was set up according to theory of Dunlop and Furfural generating rate equation is [d[F]]/[dt]= k₁[X]₀e^-k₁t-k₂[F]-k₃[X]₀e^-k₁t[F].

Based on a previous investigation, a simulationmodelwas used for optimization of coproduction of ethyl acetate and n-butyl acetate by reactive distillation. An experimental setupwas established to verify the simulated results. The effects of various operating variables, such as ethanol feed location, acetic acid feed location, feed stage of reaction mixture of acetic acid and n-butanol, reflux ratio of ethyl acetate reactive distillation column, and distillate to feed ratio of n-butyl acetate column, on the ethanol/n-butanol conversions, ethyl acetate/n-butyl acetate purity, and energy consumption were investigated. The optimal results in the simulation study are as follows: ethanol feed location, 15th stage; acetic acid feed location, eighth stage; feed location of reactionmixture of acetic acid and n-butanol, eighth stage; reflux ratio of ethyl acetate reactive distillation column, 2.0; and distillate to feed ratio of n-butyl acetate, 0.6.

The key of production planning of refineries is to determine the production planning of units and blending schemes of blends in each period of the plan horizon, since they affect the effective utilization of components of refineries and hence profits. The optimization is difficult, because of many complicated product production-consumption relationships in production processes,which are closely related to the running modes of the units. Additionally, the blending products, such as gasoline and diesel, may use multiple blending schemes for their production that increase the complexity of the problem. This paper models the production planning problem as a mixed integer nonlinear programming. Computational experiments for a refinery show the effectiveness of the model. The optimal results give the effective utilization of the self-produced components and increase of the profit.

Production of polysilicon by chemical vapor deposition of SiHCl₃ with a fluidized bed reactor is a competitive technology. As equilibrium conversion can be approached in a fluidized bed reactor, a reliable thermodynamic analysis is very important. However, inconsistent thermodynamic analysis results have been reported in the literature. The present work studied the effects of thermodynamic data and species selection, and recommended that JANAF was the best Cp data source and the minimum set of species included the following eight species: H₂, HCl, SiCl₄, SiCl₂, SiHCl₃, SiH₂Cl₂, SiH₃Cl and Si. Then, the influence of operating conditions on the equilibrium was studied. For the SiHCl₃-H₂ system, both the yield of silicon and selectivity to silicon reached their maximum at (up to 1100 ℃), and low pressure and high H₂ feed ratiowere of benefit for silicon production. For the SiHCl₃- SiCl₄-H₂ system, silicon could be produced only at 900-1400 ℃, and reducing pressure and increasing H₂ feed ratio enhanced the yield of silicon.Meanwhile, the operation map for zero net by-production of SiCl₄ by directly recycling the produced SiCl₄ was determined.

Ultrasonic speeds have been measured at 298.15 K and 308.15 K formixtures of formamide+1-propanol or 2-propanol. For an equimolar mixture, excess molar compressibility follows the sequence of 1-propanol > 2-propanol. The ultrasonic speed data are correlated by various correlations such as Nomoto's relation, van Dael's mixing relation and impedance dependence relation, and analyzed in terms of Jacobson's free length theory and Schaaff's collision factor theory. Excess isentropic compressibility is calculated from experimental ultrasonic speed data and previously reported excess volume data. The excess molar ultrasonic speed and isentropic compressibility values are fitted to Redlich-Kister polynomial equation. Other properties such as molecular association, available volume, free volume, and intermolecular free length are also calculated. The excess isentropic compressibility data are also interpreted in terms of graph theoretical approach. The calculated isentropic compressibility values are well consistent with the experimental data. It is found that the interaction between formamide and propanol increases when hydroxyl group attached to a carbon atom has more -CH₃ groups.

Phenazine antibiotics phenazine-1-carboxylic acid (PCA) and 1-hydroxyphenazine (1-OH-PHZ) were purified from culture broth and mycelia of Streptomyces griseoluteus P510. Both PCA and 1-OH-PHZ exhibit strong antifun-gal activity against six plant pathogens, especially Fusarium oxysporium, with minimal inhibition concentrations less than 1 and 2 μg·ml^-1 for PCA and 1-OH-PHZ, respectively. The presence of PCA and 1-OH-PHZ indicates that S. griseoluteus P510 can be used as a potential source of pesticides.

Simulated wastewater of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7- tetrazocine (HMX)was treated under anaerobic conditions with co-substrates such as ammonium chloride, dex-trose, sodium acetic, sodium nitrate and sulfate. The results showed that with nitrogen compounds such as ammonium chloride added as co-substrate, no significant change was observed, indicating that the molar ratio of N/C for RDX and HMX is sufficient for biodegradation.With the addition of dextrose and acetate to the system, biodegradation efficiency was enhanced greatly. For example, with dextrose as the co-substrate, degradation efficiency of 99.1% and 98.5% was achieved for RDX and HMX, respectively, after treatment for 7 days. When sodiumacetic was used as the co-substrate, the enhancement of degradation percentage was similar, but was not as high as that with dextrose, indicating the selectivity of RDX and HMX to co-substrate during anaerobic degradation. With sodium nitrate as the co-substrate, the degradation efficiency of RDX or HMX decreased with the increase of salt concentration. Sodium sulfate has no significant effect on the biodegradation of RDX and HMX. A well-selected co-substrate should be employed in applications for degradation of RDX and HMX wastewaters.

Chemically activated cotton nut shell carbons (CTNSCs) were prepared by different chemicals and they were used for the removal of fluoride from aqueous solution. Effects of adsorption time, adsorbent dose, pH of the solution, initial concentration of fluoride, and temperature of the solution were studied with equilibrium, ther-modynamics and kinetics of the adsorption process by various CTNSC adsorbents. It showed that the chemically activated CTNSCs can effectively remove fluoride from the solution. The adsorption equilibrium data correlate well with the Freundlich isotherm model. The adsorption of fluoride by the chemically activated CTNSC is spontaneous and endothermic in nature. The pseudo first order, pseudo second order and intra particle diffusion kinetic models were applied to test the experimental data. The pseudo second order kinetic model provided a better correlation of the experimental data in comparison with the pseudo-first-order and intra particle diffusion models. A mechanismof fluoride adsorption associating chemisorption and physisorption processes is presented allowing the discussion of the variations in adsorption behavior between these materials in terms of specific surface area and porosity. These data suggest that chemically activated CTNSCs are promising materials for fluoride sorption.

A systematic laboratory study was conducted on current efficiency and corrosion obtained in cryolite-aluminamelts with SnO₂-Sb₂O₃-CuO ceramic inert anodes. The current efficiency (CE) was determined by measuring the total amount of oxygen evolved at the anode andwas found to be ~95%. The influence of operating parameters (inter-electrode distance, temperature and current density) was evaluated. The quantitative interdependencies as well as the ranges of CE optimal values were established (2-3 cm, 940-960 ℃ and 0.7-0.8 A·cm^-2). The corrosion process of these anodes was evaluated by themass lossmethod. The evaluation also took care of the corrosion data, as the problem of the anode corrosion appeared to be themain obstacle for the use of those anodes in the commercial cells. Lowering of the ACD up to 2 cm did not aggravate anode corrosion.

Well-defined Fe₃O₄/MnOOH nanoparticles with 61.1 emu·g^-1 in magnetization intensity and 90.53 m²·g^-1 in surface area have been synthesized by a new-style of high-frequency impinging stream (HFIS) reactor. In this reactor, two streams first collided together to form nano Fe₃O₄ suspension, which subsequently flew through an S-shaped main channel to generate high-frequency reversing high-gravity fields. At the same time, 24 thin liquid sheets impinged into the main channel at the frequencies higher than 100 Hz to create nano Fe₃O₄/ MnOOH colloids. The obtained powders were characterized by transmission electron microscopy/energy dispersive spectrometer (TEM/EDS), X-ray diffraction (XRD), Brunner-Emmet-Teller (BET) and vibrating sample magnetometer (VSM). Experimental results indicated that low coating ratio prolonged the induction period of heterogeneous nucleation. The high-frequency impingements of 24 thin liquid sheets greatly accelerated the macro-mixing and the initial dispersion. The high-frequency reversing high-gravity fields promoted the mesoand micro-mixing. As a result, nano Fe₃O₄ cores were fleetly and uniformly covered by MnOOH precursor. As a continuously operated and static high-gravity reactor, the high-frequency impinging stream (HFIS) reactor is being developed to the large-scaled and low-cost production of various nanocomposites.

Soft magnetic composites (SMCs) were prepared from three different ferromagnetic powder particles: iron powder ASC 100.29, spherical FeSi particles and vitroperm (Fe₇₃Cu₁Nb₃Si₁₆B₇) flakes. Two types of hybrid organic-inorganic phenolic resins modified with either silica nanoparticles or boron were used to design a thin insulating layer perfectly covering the ferromagnetic particles. Fourier transform infrared (FTIR) spectrometry confirmed an incorporation of silica or boron into the polymer matrix, which manifested itself through an improved thermal stability of the hybrid resins verified by thermogravimetric-differential scanning calorimetry (TG-DSC) analysis. The core-shell particles prepared from the ferromagnetic powder particles and themodified hybrid resins were further compacted to the cylindrical and toroidal shapes for the mechanical, electrical and magnetic testing. A uniform distribution of the resin between the ferromagnetic particles was evidenced by scanning electron microscope (SEM) analysis, which was also reflected in a rather high value of the electrical resistivity. A low porosity and extraordinary high values of mechanical hardness and flexural strength were found in SMC consisting of the iron powder and phenolic resinmodified with boron. The coercive fields of the prepared samples were comparable with the commercial SMCs.

Bacillus subtilis produces many chemically-diverse secondary metabolites of interest to chemists and biologists. Based on this, this review gives a detailed overview of the natural components produced by B. subtilis including cyclic lipopeptides, polypeptides, proteins (enzymes), and non-peptide products. Their structures, bioactive activities and the relevant variants as novel lead structures for drug discovery are also described. The challenging effects of fermentation metabolites, isolation and purification, as well as the overproduction of bioactive compounds from B. subtilis by metabolic engineering, were also highlighted. Systematically exploring biosynthetic routes and the functions of secondary metabolites from B. subtilis may not only be beneficial in improving yields of the products, but also in helping themto be used in food industry and publicmedical service on a large-scale.