A three-dimensional electrode reactor combined with Fenton's reagent was used for advanced treatment of coking wastewater from secondary biological treatment. Effects of some key factors on TOC removal rate were investigated and kinetics of coking wastewater was also studied under certain the operating parameters of the three-dimensional electrode reactor. The orthogonal test results showed that the optimal operating conditions were as follows: H2O2 dosage 300mg/L, initial pH 3.4, reaction time 90min and FeSO4·7H2O dosage 3.5mmol/L. TOC removal rate could reach 61.7% under the optimal conditions. It was found that coking wastewater degradation followed a pseudo-first-order reaction kinetic model. Coking wastewater were well degraded by this system, which provided a theoretical guidance for advanced treatment of coking wastewater by three-dimensional electrode reactor coupling Fenton's reagent process in engineering application.
The support shaft in the Direct Drive Wind Turbine is an important supporting component of the wind turbine and its performance directly affects the safety of turbine. Through combining characteristics of the Direct Drive Wind Turbine's support shaft with finite element method and engineering method, this paper analyzes the support shaft finite element of static and modal fatigue life. Through the static analysis of the support shaft, the deformation and stress-strain results show that the maximum stress is lower than the allowable stress, and the support shaft meets the static strength safety requirements; through fatigue life analysis, the maximum fatigue stress is lower than the theoretical fatigue limit and meets the fatigue strength requirements of the support shaft. The results provide a theoretical basis of improvement of the design and program finalization.
Titania electrode films of dye sensitized solar cells (DSSC) were prepared by cone-jet mode electrostatic atomization spraying a titanium ethoxide precursor solution onto a silicon substrate. The effects of spraying time, substrate temperature and aging on the surface morphology of the films prepared were studied. Thin films obtained after spraying for 600s were aged at room temperature to form a porous TiO2 network with pores in the size range of 100-500 nm. Thicker films were prepared by spraying for 3000s, but these cracked on drying although it can be concluded that films prepared using a higher substrate temperature were denser. By this method, TiO2 films were also prepared on an ITO conductive glass substrate using titania suspension with different particle size distribution. The result implies the potential of an industrial production of DSSC by electrospraying technique.
For comprehensive utilization of solid waste, coal gangue, slag of CFB and washed fly ash provided by a coal mine were evaluated on their potential as calcined kaolin. Studies on these samples include the determination of chemical composition by ICP, the analysis of mineralogical construction by XRD, orthogonal experiments of iron leaching by acids and decarburization by calcination. Results show that the chemical compositions of three samples are very close to the kaolinite and their mass ratios of SiO2 to Al2O3 are all about 1.4:1. The major crystalline phase presented in the coal gangue is kaolinite, while an obvious band of amorphous materials are found in others since they are combustion products, but none of them is in exception of layer structure observed though SEM. Orthogonal experiments of iron leaching by acids reveal that the maximal iron leaching rate and product-calcined whiteness of the coal gangue are 63.59% and 68.54% respectively. For that of the slag of CFB, they are 39.74% and 40.55%, while for that of the washed fly ash, they are 31.58% and 45.92%. Thus, it can be inferred that this coal gangue can better fulfill the preparation of high-quality calcined kaolin.
[Purpose] In order to reducing the toxicity of general cationic surfactants, biodegradable ester cationic surfactants have been developed as novel kinds of environmental products in the world. [Method] Hyperactive etherifying agent of glycidyltriethyl ammonium chloride is very important intermediate product to synthesis biodegradable ester cationic surfactants. In this paper, a kind of hyperactive etherifying agent of glycidyltriethylammonium chloride was synthesized by traditional method with epichlorohydrin and trimethylamine as raw materials. [Results] During the synthesis, the best reaction conditions have been obtained, that the reaction temperature is 25 o C, the reaction time is 3 h, the reaction solvent is acetone, and the best mol ratio of epichlorohydrin to timethylamine is 3:1. [Conclusions] In addition, the chemical structure of the product has been confirmed by FT-IR, it is conformed with glycidyltriethylammonium chloride completely.
The PT equation of state is used in this paper to calculate the thermodynamic properties of propane and carbon dioxide binary mixture. The properties of the mixture of propane and carbon dioxide with three different composition are also studied using PT equation of state and van der Waals mixing rules. The calculating data are compared with the data obtained using software NIST REFPROP 8.0. Results show that the maximum relative error of properties for both saturated liquid and saturated gas is less than 1.471%. And the minimum average relative error is 0.177%. And the maximum average relative error is 0.799%. The computation is accomplished by the program with Visual interface, which makes the calculation process more convenient. And the results are with high precisions.
The air-side fluid flow and heat transfer characteristics of wavy fin-and-tube heat exchanger with rectangular winglet pairs and combined rectangular winglet pairs were numerically analyzed. The numerical results show that the increase of the six parameters of combined rectangular winglet pairs can result in the increase of heat transfer and pressure drop. The longitudinal vortex generator has the best heat transfer performance, when the distance from the centerline and the borderline is 0.975mm and 1.8mm respectively in the downhill region and the optimum main attack angle of the combined winglet is 30°.
Thermal stabilization effect of tris(hydroxymethyl)aminomethane (TRIS) in poly(vinyl chloride) (PVC) is studied. Discoloration tests and dehydrocholorination tests show that PVC films containing TRIS as the unique main stabilizer present excellent initial color and long-term stability, compared with all their control samples, PVC films containing pentaerythritol (PER), within the ingredient range of 50 g PVC, 0.2 g stearic acid (HSt), and x (x = 0.1, 0.3, 0.5, 1.0, 1.5, 2.0, 2.5) g TRIS or PER. Nucleophilic substitution reaction between TRIS and unstable chlorine in PVC resin and neutralization reaction between TRIS and HCl generated subsequently during heating is respectively suggested as the mechanism of the initial and long-term stabilization.
The catalysts prepared by modifying SAPO-34 molecular sieve catalyst with Transition metals (Zn, Ni, Co, and Fe) by hydrothermal method were investigated for methanol conversion to light olefins (MTO). And the prepared catalysts were characterized by XRD and SEM. The catalytic properties of the modified molecular sieves were evaluated through a fixed bed reactor. The results showed that the ethylene yield of ZnSAPO-34 was increased by 3.2% and total yield of ethylene and propylene was increased by 5.0%.
According to multi-borders, nonlinear, time-varying characteristics of the thermal system of large coal-fired power units, the relationships between the operating parameters and the energy consumption characteristics are very complex. The key operating parameters which influenced the standard coal consumption rate are obtained based on rigorous theoretical analysis. On this basis, features are extracted from the characteristics to be used as inputs of s-SVR for training and testing. Energy consumption distribution model under full conditions of large coal-fired power units based on aforesaid method has high precision.
This manuscript aims to comprehensively analyze the potential of energy consumption and CO2 emissions reduction by the improvement of energy efficiencies at various nodes of China's energy system. First, based on exergy analysis, we map the energy flows of China from useful energy to passive systems to expand the exergy flow diagram developed in a previous study, which already includes sub-processes from energy sources, intermediate conversion, end-use devices, to useful energy. Based on that, we present an evaluation and comparison of the potential of energy and CO2 emissions reduction by efficiency improvements of power generation technologies, end-use devices, and passive systems. The results indicate a tremendous reduction potential by the improvements of passive systems. Besides, the efficiency improvement of coal power generation and coal burners can also bring considerable reductions. We also present an analysis of the magnification effect of passive systems, which illustrates that household appliances and illumination devices can bring large reductions by slight efficiency improvements.
A theoretical model was presented for quickly identifying multiple indoor constant contaminant sources with known releasing time by considering the sensor thresholds and measurement errors. The model was numerically demonstrated and validated by case studies. The results indicated that the model can potentially be effective with high sensor thresholds and measurement errors. This study will contribute to developing source identification techniques using real sensors.
Experiments were conducted to study pool boiling heat transfer on ultra-light porous metal foam surfaces, with deionized water as working fluid. The metal foams have pore densities from 30 to 60ppi (pores per inch) and thickness from 2.0 to 5.0mm. The effects of heat flux, surface superheat, liquid temperature and characteristic parameters of metal foam on pool boiling heat transfer were investigated. It is found that metal foam surfaces can significantly enhance pool boiling heat transfer and lower the surface superheat at the boiling incipience. Pore density and thickness exists an optimal value to strengthen boiling heat transfer. The boiling heat transfer coefficient on the metal foam surfaces is about 2~3 times of those on the plain surfaces. The significant reasons are due to the distinct nature of high porosity and multi-scale pore sizes of metal foams. The larger pores help to release the created vapor while the smaller pores help to suck the liquid toward the heater surface, decreasing the shear stress at the vapor-liquid interface for the counter-current flow.
In order to control the inner status of blast furnace (BF) and save energy costs, improving operation parameters in time with the help of numerical simulation method is necessary. Based on the computational fluid dynamics (CFD) technology, the instantaneous modeling and simulation of multiphase flow in an iron-making BF with pulverized coal injection (PCI) was developed. Including the gas, solid, liquid and powder, four phases were considered with different materials properties in BF. Through computational visualization, the mathematical model simulated transient results of temperature distribution, which make it easier to estimate the profile and position of cohesive zone. The mathematical model considered the simple chemical reactions and coupled relationships of phases. The calculated results show that the multiphase flow varies clearly with time and position from the time of BF being ignited. The coal injection is one important factor for the formation of cohesive zone. The ore particles would be melting slowly form the cohesive zone. After about 15 hours, the cohesive zone showed a steady shape of with the PCI rate: 129 kg/thm (ton hot metal) in the 1750m3 BF. Then the performance of transient model was verified through simulating the BF process.
Composite nanoporous electrodes made of ZnO/SnO2 nanopowders were fabricated and applied to dye-sensitized solar cells. The morphology and structure of the prepared electrodes was investigated by field emission scanning electron microscope (FE-SEM). It is found that the overall conversion efficiency of DSSCs with composite electrodes was enhanced by almost 32% as compared to DSSCs with pure ZnO electrodes. Adding SnO2 nanopowders to ZnO nanoporous electrodes improved the stability and microstructure of the whole nanoporous electrodes during the dye absorption, thus enhanced the photovoltaic efficiency of the DSSCs based on ZnO nanoporous electrodes.
A series of titanium dioxide (TiO2) nanostructures with different microstructures were synthesized through hydrothermal synthesis. By controlling the ratio of hydrochloric acid in the reactants, which in turn varying hydrolyzing tetrabutyl titanate (Ti(OBu)4) rates, the structures with shapes of nanosheets, nanorods, nanoflowers and nanoclusters were obtained, and the feature of these microstructures was depicted in details through scanning electron microscope(SEM). The formation processes and mechanisms for the different nanostructures were analyzed and discussed. The photocatalytic properties were also researched, which showed that different microstructures had disparate photocatalytic properties.
Particle number emissions from a light-duty vehicle diesel engine during transient state operating conditions were studied. Test fuels were petroleum diesel, pure Jatropha biodiesel, B20 and B50 biodiesel blend fuels. The results show the number of nucleation mode particles from the engine increases when using petroleum diesel during the transient operating condition (Increasing torque at constant speeds). The number of accumulation mode particles increases at the initial stage of transient process, and then descends with increasing torque. The total particle number increases continuously with torque during the transient operating condition, and accumulation mode particles play an important role in the beginning, and nucleation mode particles dominate the later part of the transient operating condition. Dynamic characteristics of particle number using lower biodiesel blend during the transient process is similar to that of petroleum diesel, whereas higher biodiesel blends show distinct differences, and the total particle number and nucleation mode particle number using B50 and pure biodiesel fuels are obviously larger than pure diesel from beginning to end, while the accumulation mode particle number keeps smaller. For the pure biodiesel fuel, the nucleation mode particle number rapidly ascends until the end of the transient process, and accumulation mode particle number continuously descends.
LiNi0.305Mn0.33Co0.33M0.025O2 (M=Al, Y, Cr) materials were synthesized via the sol-gel method. The structure and electrochemical properties were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and charge/discharge tests. The materials were maintained the α-NaFeO2 type layered structure and the discharge capacity was also increased by doping. The Y- and Al- doping slightly decrease the initial discharge capacity of LiNi0.33Mn0.33Co0.33O2 while the Cr-doping can increase the initial discharge capacity. The cycling performances are improved after doping. When cycled at 1.0C, about 99%, 98.6% and 97.1% of their initial capacities can be retained after 40 cycles for Y-, Al- and Cr-doped materials, respectively. Their rate capabilities are also better than that of the un-doped one. EIS measurement shows that the Y-doped electrode has the lowest resistance impedance value during cycling.
In order to get high transparent and conductive Al-doped ZnO (AZO) films at room temperature, an off-axis RF magnetron system and i-ZnO buffer layer were introduced to deposit AZO thin films. By varying the deposition time of i-ZnO, we studied the crystal, structural, optical and electrical properties of the the AZO films as a function of the buffer layer's thickness. The samples showed good crystallinity with sharp (002) peak and smooth surface morphologies. The appearance of micropits and the films' thickness versus time revealed the buffer layer not only helped to release the stress but also offered a template for the AZO films to grow. As shown in SEM cross-sectional images, the films can be separated into bottom layer, main body and upper layers, indicating a structure revolution. With the thickness of about 500nm, the AZO films had transmittance above 85% in the visible region and resistivity as low as 1.0·10 -3 Ω·cm.
In order to indicate the droplet evaporating process directly, a new evaporation model for the drying of a single solution droplet into a solid, dense particle is present, taking account of the changing of temperature gradient and concentration gradient. Simulations are made to achieve a more fundamental understanding of the coupled relationship of solvent percentage, droplet specific heat, saturated vapor pressure and solvent diffusion coefficient. According to the moving boundary problem, the numerical method of droplet evaporation is constructed by the mesh-reconstruction technology, and the visualization of the simulation results is realized by Matlab. Taking the evaporation process of water and ammonium nitrate solution for example, the transient variations of drop diameter, inner temperature gradient, inner solute concentration gradient are analyzed under different gas temperature and flow velocity. Model predictions are in good agreement with the experimental data, indicating that the model describes the most important physical phenomena of the evaporating process.
