两组分混合物的偏摩尔体积及体积分量的精确计算

本文根据吉布斯—杜亥姆方程等混合物和分子物理学理论,推导出描述非理想两组分混合物偏摩尔体积和体积分量的两组方程,经用两组分混合物的折射率等实验数据验证,表明用这些方程可十分方便地得到比较精确的结果。

两组分混合物的偏摩尔体积及体积分量的精确计算

本文根据吉布斯——杜亥姆方程等混合物和分子物理学理论,推导出描述非理想两组分混合物偏摩尔体积和体积分量的两组方程,经用两组分混合物的折射率等实验数据验证,表明用这些方程可十分方便地得到比较精确的结果。

Mass Transfer Enhancement of Gas Absorption by Adding the Dispersed Organic Phases

Mass transfer enhancement of gas absorption by adding a dispersed organic phase has been studied in this work. Various dispersed organic phases （heptanol, octanol, isoamyl alcohol, heptane, octane, and isooctane） were tested respectively in the experiment. According to the theoretical model and experimental data, the overall volumetric mass transfer coefficient and enhancement factor were obtained under different dispersed organic phase volume fraction and stirring speed. The experimental results indicate that gas-liquid mass transfer is enhanced at different level by adding a dispersed organic phase. The best performance of enhancement were achieved with the dispersed organic phase volumetric fraction of 5% and under an intermediate stirring speed of 670 r·min^-1. Among the organic phases tested in the experiment, alcohols show better performance, which gave 20% higher enhance-ment of overall volumetric mass transfer coefficient than adding alkanes.

Computation and measurement for distributions of temperature and soot volume fraction in diffusion flames

A combined computational and experimental investigation to examine temperature and soot volume fraction in coflow ethylene-air diffusion flames was presented.A numerical simulation was conducted by using a relatively detailed gas-phase chemistry and complex thermal and transport properties coupled with a semi-empirical two-equation soot model.Thermal radiation was calculated using the discrete ordinates method.An image processing technique and a decoupled reconstruction method were used to simultaneously measure the distributions of temperature and soot volume fraction.The results show that the maximum error for temperature does not exceed 10% between the prediction and the measurement.And the maximum error is 6.9% for soot volume fraction between prediction and measurement.Additional simulations were performed to explore the effects of global equivalence ratio on diffusion flames and the soot formation.The results display that the soot formation increases with decreasing the coflow air velocity.And the soot formation in each case appears in the annular region,where the temperature ranges from about 1 000 K to 2 000 K and the profile becomes taller and wider when the coflow air is decreased.

Photocatalytic oxidation of nitric oxide from simulated flue gas by wet scrubbing using ultraviolet/TiO_2/H_2O_2 process

Nitric oxide(NO) from flue gas is hard to remove because of low solubility and reactivity. A new technology for photocatalytic oxidation of NO using ultraviolet(UV)/TiO2/H2O2 process is studied in an efficient laboratory-scale reactor. Effects of several key operational parameters on NO removal efficiency are studied, including TiO2 content, H2O2 initial concentration, UV lamp power, NO initial content, oxygen volume fraction and TiO2/H2O2 solution volume. The results illustrate that the NO removal efficiency increases with the increasing of H2O2 initial concentration or UV lamp power. Meanwhile, a lower NO initial content or a higher TiO2/H2O2 solution volume will result in higher NO removal efficiency. In addition, oxygen volume fraction has a little effect.The highest NO removal efficiency is achieved at the TiO2 content of 0.75 g/L, H2O2 initial concentration of 2.5 mol/L, UV lamp power of 36 W, NO initial content of 206×10-6 and TiO2/H2O2 solution volume of 600 m L. It is beneficial for the development and application of NO removal from coal-fired flue gas with UV/TiO2/H2O2 process.

Application of Equilibrium Partitioning Approach to the Derivation of Sediment Quality Guidelines for Metals in Dianchi Lake

For the past 20 years, numerous studies have been carried out on the application of equilibrium partitioning approach （EqPA） for the derivation of sediment quality guidelines （SQGs）. However, for metals, few Equilibrium-partitioning- based numerical SQGs have been developed or are currently available because of the confounding factors mediating the bioavailability of metals. A study was conducted at Dianchi Lake, which is a heavily eutrophicated lake on the Yunnan- Guizhou Plateau, China with the focus on the measurement of partitioning coefficient （Kp） and SQGs derivation and normalization to acid volatile sulfide （AVS）, fine material, and organic carbon. Using new normalization methods, SQGs were formulated for seven metals including copper, zinc, lead, cadmium, chromium, mercury, and arsenic in Dianchi Lake. In Dianchi Lake sediments, the fine material contributed 25.4%-36.0% to the SQG values, with the largest contribution to the SQG value of mercury; AVS contributed 2.9%-75.0% to the SQG values, with the largest contribution to the SQG value of cadmium. This indicated that the fine material and the AVS were the most important controlling factors to the bioavailability of mercury and caximium, respectively. The contribution of total organic carbon （TOC） to the SQG values of copper and leaxi was 3.8% and 7.1%, respectively, indicating that at relatively lower concentrations, the contribution of TOC was not significant. In addition to normalization methods, appropriate procedures for the application of EqPA including sample collection, storage, and analysis are also essential to improve the reliability of SQGs. The normalized Dianchi Lake SQGs were higher than most of the empirically based SQGs developed in North America, but lower than Hong Kong interim SQGs except for cadmium and arsenic. The differences could be attributed to the approaches used for derivation of SQGs and the water quality criteria adopted and the differences in the physical and chemical characteristics of the sediments.

Correspondence of bubble size and frother partitioning in flotation

The size of bubbles created in the flotation process is of great importance to the efficiency of the mineral separation achieved.Meanwhile,it is believed that frother transport between phases is perhaps the most important reason for the interactive nature of the phenomena occurring in the bulk and froth phases in flotation,as frother adsorbed in the surface of rising bubbles is removed from the bulk phase and then released into the froth as a fraction of the bubbles burst.This causes the increased concentration in the froth compared to the bulk concentration,named as frother partitioning.Partitioning reflects the adsorption of frother on bubbles and how to influence bubble size is not known.There currently exists no such a topic aiming to link these two key parameters.To fill this vacancy,the correspondence between bubble size and frother partitioning was examined.Bubble size was measured by sampling-for-imaging(SFI)technique.Using total organic carbon(TOC)analysis to measure the frother partitioning between froth and bulk phases was determined.Measurements have shown,with no exceptions including four different frothers,higher frother concentration is in the bulk than in the froth.The results also show strong partitioning giving an increase in bubble size which implies there is a compelling relationship between these two,represented by CFroth/CBulk and D32.The CFroth/CBulkand D32 curves show similar exponential decay relationships as a function of added frother in the system,strongly suggesting that the frother concentration gradient between the bulk solution and the bubble interface is the driving force contributing to bubble size reduction.

Experimental study on gas explosion suppression based on ferrocene

In order to study the gas explosion suppression performance based on ferrocene, the self-constructed experimental facility was used to accomplish the experiment of gas explosion suppression. By means of thermogravimetric analysis, the thermal characteristics of ferrocene have been gotten and the gas explosion suppression mechanism of ferrocene has been analyzed. The results show that ferrocene had good effects on gas explosion suppression, and the explosion pressure and flame propagation speed declined obviously. When ferrocene concentration is 0.08 g/L and methane volume concentration is 9.5%, the maximum explosion overpressure and maximum flame propagation speed of methane-air respectively decreased by about 59.5% and 19.6%, respectively. TG and DSC curves showed that the mass loss of ferrocene consists of two processes, which are sublimation and lattice fracture. The temperature of mass loss ranged from 128 ℃ to 230 ℃. The results showed profoundly theoretical significance to gas explosion suppression by ferrocene in coal mines.

Using a Membrane Reactor for Sucrose Hydrolysis： The Effect of Reactor＇s Design on Invertase Stability

Invertase hydrolyses sucrose, produces inverted sugar syrup, which is used, mainly, as a food composition in industries. To carry out the hydrolysis properly, the invertase should be stable in the soluble form through a considerable reaction period and recovered afterwards. The chosen reactor was a CSTR-type （continuous stirred tank reactor-type） coupled with an UFM （ultrafiltration-membrane）, the so-called MR （membrane reactor）. The varied parameters were： sucrose concentration （10-300 mM）, temperature （5-65 ℃）, reaction volume （14 mL and 65 mL）, stirring （100-500 rpm）, volumetric feeding rate （2.2-12 mL/h） and UFM MWCO （molecular weight cut off） （10, 20, 30, 50 and 100 kDa）. The invertase kinetic constants （KM = 23.5 mM; Vmax = 2,758 μmolgluJmin-mgprot; Ea = 9.1 kcal/mol） and the temperature deactivation energy （Ead= 20 kcal/mol） were calculated. Moreover, the invertase was unstable as the MR capacity diminished and the agitation increased up to 500 rpm most likely due to the damaging effect of shearing forces （present inside the MR） on the invertase molecule. Finally, both the MWCO and the chemical nature of the UFM affected the invertase stability along the hydrolysis. The enzyme stability increased as the UFM cut-off decreased, the highest value being observed with the 10 kDa-UFM.

Effects of a flexible net barrier on the dynamic behaviours and interception of debris flows in mountainous areas

Flexible net barriers are a new type of effective mitigation measure against debris flows in valleys and can affect the kinematic energy and mass of debris flows. Here, ten flume tests were performed to study the dynamic behaviours of debris flows with differences in volumes, concentrations(solid volume fraction), and travel distances after interception by a uniform flexible net barrier. A high-speed camera was used to monitor the whole test process, and their dynamic behaviours were recorded. A preliminary computational framework on energy conversion is proposed according to the deposition mechanisms and outflow of debris flow under the effects of the flexible net barrier. The experimental results show that the dynamic interaction process between a debris flow and the flexible net barrier can be divided into two stages:(a) the two-phase impact of the leading edge of the debris flow with the net and(b) collision and friction between the body of the debris flow and intercepted debris material. The approach velocity of a debris flow decreases sharply(a maximum of 63%) after the interception by the net barrier, and the mass ratio of the debris material being intercepted and the kinetic energy ratio of the debris material being absorbed by the net barrier are close due to the limited interception efficiency of the flexible net barrier, which is believed to be related to the flexibility. The energy ratio of outflow is relative small despite the large permeability of the flexible net barrier.

Process Optimization and Characterization of Sorghum Based Extruded Product

Expanded snacks made up of corn, wheat and rice is very popular because of their texture. Sorghum is one of the important cereals, which is not so far studied well for extrusion processing. Due to presence of high amount of starch （56%-73%）： sorghum could be the good candidate for manufacturing of expanded snacks. The extruded products obtained using extrusion conditions such as feed moisture content （12%-16%）, die temperature （150-190℃）, screw speed （150-210 rpm） and feed rate （50-70 g min1） are further characterized by analyzing bulk density, expansion ratio, water absorption index （WAI）, water solubility index （WSI）, textural properties, color and sensory evaluation. Increase in feed moisture content resulted in extrudates with gradual increase in density, WAI and hardness and decrease in expansion, WSI, crispness and whiteness. Higher barrel temperature reduced the extrudate expansion, bulk density and hardness and increased the WSI and crispness of the extrudates. The most acceptable product is obtained using response surface methodology （RSM）.

A New Approach to Energy Integral for Investigation of Dust-Ion Acoustic(DIA)Waves in Multi-Component Plasmas with Quantum Effects in Inertia Less Electrons

Dust-ion acoustic waves are investigated in this model of plasma consisting of negatively charged dusts, cold ions and inertia less quantum effected electrons with the help of a typical energy integral. In this case, a new technique is applied formulating a differential equation to establish the energy integral in case of multi-component plasmas which is not possible in general. Dust-ion acoustic （DIA） compressive and rarefactive, supersonic and subsonic solitons of various amplitudes are established. The consideration of smaller order nonlinearity in support of the newly established quantum plasma model is observed to generate small amplitude solitons at the decrease of Mach number. The growths of soliton amplitudes and potential depths are found more sensitive to the density of quantum electrons. The small density ratio r（= 1 - f） with a little quantized electrons supplemented by the dust charges Zu and the in-deterministic new quantum parameter C2 are found responsible to finally support the generation of small amplitude solitons admissible for the model.

A 3D numerical simulation of laser-induced incandescence of soot particles in coal combustion products

Laser-induced incandescence (LII) has received increasing attention as a potentially powerful technique for in-situ measuring of the volume fraction and primary size of soot particles in combustion systems. In this study, a 3D Monte Carlo simulation combined with a Mie equation was developed to analyze the influence of spectral absorption and scattering on the measured LII flux emitted by soot particles. This paper represents a first attempt to analyze soot measurement using the LII technique in coal combustion products. The combustion products of gases (CO2, N2), soot, and fly-ash particles, present between the location of laser-excited soot and the LII flux receiver. The simulation results indicated that an almost Beer-Lambert exponential decrease in LII flux occurred with an increase in the volume fraction of soot particles, while a nearly linear decrease occurred with an increase in the volume fraction of fly-ash particles. The results also showed that scattering effects of both soot and fly-ash particles on the LII flux could be neglected. Compared with the absorption of gases, a decrease of 20% of LII flux was observed with soot particles, and a decrease of 10% with fly-ash particles.

Effects of TiO_2 volume fraction on the microstructure and magnetic properties of CoPt-TiO_2 nanocomposite films

CoPt-TiO2 nanocomposite films were synthesized by rapid thermal annealing of CoPt/TiO2 multilayers.The effects of TiO2 volume fraction on the microstructure and magnetic properties of the nanocomposite films were studied.Results showed that the ordering and texture of the L10-CoPt particles did not change with TiO2 content up to 76 vol.% of TiO2.However,the volume of the L10-CoPt particles in the film decreased with an increase in TiO2 content.Increasing TiO2 content effectively reduced the coalescence of magnetic grains when TiO2 content was larger than 56 vol.%.Both the out-of-plane coercivity and remanence ratio of the film decreased slightly with TiO2 content,but the in-plane coercivity and remanence ratio of the film decreased firstly and then increased after TiO2 content was larger than 56 vol.%.The reduction in the coercivity of the film should be due to the reduction in the size of the L10-CoPt particles.The reduction in remanence ratio might be due to the weakening of the exchange coupling strength between the magnetic grains when TiO2 content was increased,as indicated by the MFM images.