Eulerian–Lagrangian Simulation and Experimental Validation of Pneumatic Conveying Dryer

This paper explores numerical and experimental studies on the performance of a pneumatic conveying dryer. The four-way coupling Eulerian–Lagrangian approach is utilized in the numerical study and the experimental study is carried out in a pilot-scale vertical pneumatic conveying dryer of diameter 8.1 cm and 4.5 m length. The effects of Reynolds number, particle size, solid mass flow rate, and inlet gas temperature on the dryer performance are investigated. It is found that the present model predictions agree well with the experimental data. Generally, it is concluded that the drying rate increases as the Reynolds number increases, while increasing the particle size or the solid mass flow rate decreases the drying rate.     

Eulerian–Lagrangian simulation of bubble coalescence in bubbly flow using the spring-dashpot model

The Eulerian–Lagrangian simulation of bubbly flow has the advantage of tracking the motion of bubbles in continuous fluid, and hence the position and velocity of each bubble could be accurately acquired. Previous simulation usually used the hard-sphere model for bubble–bubble interactions, assuming that bubbles are rigid spheres and the collisions between bubbles are instantaneous. The bubble contact time during collision processes is not directly taken into account in the collision model. However, the contact time is physically a prerequisite for bubbles to coalesce, and should be long enough for liquid film drainage. In this work we applied the spring-dashpot model to model the bubble collisions and the bubble contact time, and then integrated the spring-dashpot model with the film drainage model for coalescence and a bubble breakage model. The bubble contact time is therefore accurately recorded during the collisions. We investigated the performance of the spring-dashpot model and the effect of the normal stiffness coefficient on bubble coalescence in the simulation.The results indicate that the spring-dashpot model together with the bubble coalescence and breakage model could reasonably reproduce the two-phase flow field, bubble coalescence and bubble size distribution. The influence of normal stiffness coefficient on simulation is also discussed.     

Multi-fluid Eulerian simulation of binary particles mixing and gas–solids contacting in high solids-flux downer reactor equipped with a lateral particle feeding nozzle

The performance of binary particles mixing and gas-solids contacting,which is considered qualitatively to have a significant influence on the heat transfer in internal heated circulating fluidized beds,is carefully investigated by means of a numerical approach in the newly developed high solids-flux downer lignite pyrolyzer(φ0.1 m × 6.5 m).Since binary particles are used in this system,a reasonably validated 3 D,transient,multi-fluid model,in which three heat transfer modes relating to the convection,conduction and radiation are considered,is adopted to simulate the flow behavior,temperature profiles as well as volatile contents.The simulation results showed that the solids stream impinges the left wall surface initially and turns towards the right wall in the further downward direction and then shrinks during this process resulting in that the solids concentrate a little more at the central region.In the further downward section of the downer,the particle flow disperses near the right wall and develops uniformly.Meanwhile,the coal phase is slowly heated in the downer and it is found that most of the heat absorbed by the coal is from the convection heat transfer mode.To explore the heat transfer mechanism more quantitatively,two indexes(mixing index and contacting index) are proposed,and it is found that the mixing index initially increased fast and later remained at a relatively flat state.For the contact index,it shows a trend with a first rising and then falling,finally rising continuously.Also,it is found that the convection heat transfer is closely correlated to the contacting status of gas-coal which indicates that the improving of the gas-coal contacting efficiency should be an effective way to strengthen the coal particle heating process.     

Electroless deposited Ni–Re–P, Ni–W–P and Ni–Re–W–P alloys

Coatings of electroless Ni–W–P, Ni–Re–P and Ni–W–Re–P alloys were plated in alkaline citrate baths containing amino alcohols, but not free ammonia ions. The reference Ni–P alloy was used as an intermediate layer in the sandwich: Ni–Me–P/Ni–P/substrate. An extremely homogeneous thickness distribution of all alloy components was found by applying scanning Auger electron spectroscopy (SAES(. The inclusion of refractory metals at the expense of nickel and without substantial change in phosphorus content was established. A non-oxidized state of the codeposited Re and W in Ni–W–P, Ni–Re–P and Ni–W–Re–P alloys was determined by means of X-ray photoelectron spectroscopy examination, as well as by SAES profiles, revealing the absence of oxygen throughout the coatings. All alloy films are amorphous and paramagnetic.     

1–(3–硝基–2–吡啶)–1H–苯并三唑的合成与表征

以苯并三氮唑和2–氯–3–硝基–吡啶为原料,合成出1–(3–硝基–2–吡啶)–1H–苯并三唑。采用元素分析、核磁共振光谱等手段鉴定了目标产物结构,并用DSC测定了产物的熔点。考察了反应溶剂、溶剂用量、缚酸剂种类、缚酸剂用量对该反应收率和产品纯度的影响。确定的最佳工艺条件为:以工业乙醇为反应溶剂,溶剂与反应物的原料比为200 mL∶0.1 mol,Na2CO3为反应缚酸剂,缚酸剂与苯并三氮唑的摩尔比为1∶1,反应时间为12 h。     

Microstructure and mechanical properties of TiC–TiN–Zr–WC–Ni–Co cermets

Cermet cutting tools are widely used for semi-finishing and finishing work on steel and cast iron. However, their brittleness is still an unavoidable limitation for their utilizations. Zirconium was added to improve the fracture toughness of Ti(C, N) based cermets. The microstructure and the fracture surfaces of cermets were studied by using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The experimental results reveal that Zr dissolved and formed solid solutions during the sintering process. The amount of grains with typical core/rim structure decreases and that of coreless grains increases with increasing Zr addition. Moreover, the fracture toughness is improved clearly due to the increased amount of the coreless grains, the spinodal decomposition in cermets, as well as the crack deflection and crack branching mechanisms. Additionally, hardness and relative density were also measured, respectively.     

5–硝基–3–三硝甲基–1H–1,2,4–三唑的合成与性能研究

以氨基胍碳酸氢盐与丙二酸为原料,经缩合–环化反应、重氮化–取代反应和硝化反应合成出5–硝基–3–三硝甲基–1H–1,2,4–三唑。用红外光谱、核磁共振、元素分析对其结构进行了表征。确定了最佳硝化反应体系:5–硝基–1H–1,2,4–三唑–3–乙酸为硝化反应前体,硝硫混酸(V(w为的98%浓硫酸)∶V(发烟硝酸)=1.2∶1)为硝化剂。采用密度泛函理论(DFT)中B3LYP方法在6–31G(d,p)基组水平下对5–硝基–3–三硝甲基–1H–1,2,4–三唑进行了全构型优化,并在优化构型基础上进行了自然键轨道(NBO)分析。差示扫描量热法(DSC)分析结果表明,10℃/min升温速率下,5–硝基–3–三硝甲基–1H–1,2,4–三唑的分解温度为135℃。     

Ablation behavior of (Hf–Ta–Zr–Nb–Ti)C high-entropy carbide and (Hf–Ta–Zr–Nb–Ti)C–xSiC composites

The ablation behavior of (Hf–Ta–Zr–Nb–Ti)C high-entropy carbide (HEC-0) was investigated using a plasma flame in air for different times (60, 90, and 120 s) at about 2100°C. The effect of SiC content on the ablation resistance of HEC–xSiC composites (x = 10 and 20 vol%) was also studied. The linear ablation rate of HEC-0 decreases with increasing ablation time, showing the positive role of the oxide layer with a complex composition. The linear ablation rate of HEC–10 vol% SiC (0.3 µm s⁻¹) is only a 10th of that of HEC-0, showing a significant improvement in ablation resistance, probably due to the formation of a protective oxide layer containing melted SiO₂ and refractory Hf–Zr–Si–O oxides.     

1,1–二甲基–1–烷基胺–2–辛酰亚胺的合成与表征

以偏二甲肼、溴代(十二、十四、十八)烷和辛酰氯为原料,合成了3种脂肪族胺基酰亚胺。分别采用FT–IR和1H–NMR表征了产物的结构,以DSC法分别测试了各产物的熔点和热分解温度,最后探讨了各步反应的最佳条件。结果表明:烷基化最佳反应温度为35~40℃,反应时间为120 min;酰基化最佳反应温度为80~85℃,反应时间为120 min;脱氢反应最佳温度为10~30℃,反应时间为180 min。3种胺基酰亚胺的熔点和热分解温度随胺基碳链的增长而升高。     

2–硝亚胺基–5–硝基–六氢化–1,3,5–三嗪与推进剂常用组分相容性研究

采用差示扫描量热法研究了2–硝亚胺基–5–硝基–六氢化–1, 3, 5–三嗪（NNHT）与固体推进剂和发射药中常用组分硝基胍（NQ）、黑索今（RDX）、奥克托今（HMX）、六硝基六氮杂异伍兹烷（CL–20）、1, 1–二氨基–2, 2–二硝基乙烯（FOX–7）、3, 4–二硝基呋咱基氧化呋咱（DNTF）以及吸收药硝化棉（NC）+硝化甘油（NG）、NC+1, 5–二叠氮基–3–硝基–3–氮杂戊烷（DIANP）、2号中定剂（二甲基二苯脲）的相容性。结果表明,NNHT与HMX、CL–20、FOX–7的相容性好,与RDX轻微敏感,与NQ和DNTF敏感,与吸收药NC+NG敏感,与吸收药NC+DIANP相容,与2号中定剂轻微敏感。     

Electrical transport properties of Co–Zn–Y–Fe–O system

Co–Zn substituted nanoferrites having stoichiometric composition Co_1?xZn_xY_0.15Fe_1.85O₄ (x = 0.0–1.0, step: 0.2) were synthesized by chemical co-precipitation method. Analysis of the XRD patterns confirms the formation of cubic spinel phase as main phase along with few traces of secondary phase. The lattice constant was found to increase from 8.378 Å to 8.438 Å with zinc contents which can be explained on the basis of difference in ionic radii. SEM micrographs indicate nearly uniform distribution of grains. The average crystal size was found to decrease from 38.41 nm to 14.25 nm with the increase of Zn contents. The physical density increases with the increase of Zn contents from 3.95 g/cm³ to 4.42 g/cm³. It was found that the resistivity decreases with the increase of Zn contents from 9.20 × 10⁷ Ω cm to 5.26 × 10⁶ Ω cm which may be attributed to the increase in the number of Fe²⁺/Fe³⁺ ions pairs at B-sites. The transition temperature of the samples with substitution level x = 0.6, 0.8, 1.0 changes at 373, 333 and 313 K, respectively. The transition temperature of the sample with x = 1.0 is close to the room temperature. This may be the Curie temperature. Low Curie temperature material can be used for the preparation of temperature sensitive ferrofluid. Dielectric loss tangent (tan δ) has been observed to increase with the increase of zinc contents. This can be attributed to the decrease in resistivity which in turn increases the dielectric loss tangent.     

碳酸钾分离乙醇–丙酮–丁醇–水体系

测定了乙醇–丙酮–丁醇–水–碳酸钾体系在25℃时的液–液相平衡数据,结果表明, 有机物水溶液可简化为二元系处理, 可用Pitzer理论和Wilson方程对相平衡数据进行关联计算,计算值与实验值符合良好．采用碳酸钾分离乙醇–丙酮–丁醇–水体系,碳酸钾的脱水率高达95.6%．     

丙烯酸–2–((N–甲基–N–氰乙基)胺基)乙酯的合成

以2–甲氨基乙醇和丙烯腈为原料,通过Michael加成反应合成中间体2–((N–甲基–N–氰乙基)胺基)乙醇,进一步与丙烯酸乙酯发生酯交换反应合成目标产物丙烯酸–2–((N–甲基–N–氰乙基)胺基)乙酯,优化了中间体及产品的合成工艺,使其收率分别达到98.5%、85.3%,并采用FT–IR、1H–NMR、元素分析等手段对其结构进行表征。目标化合物具有氧阴离子聚合活性,可用于制备结构易控的新型聚合物键合剂。     

Preparation and properties of Ge–Ga–La–S–AgI chalcogenide glass

Chalcogenide glasses of 65GeS₂–(25–x)Ga₂S₃–10AgI–xLa₂S₃ (x=0, 1, 3, and 5 mol%) were fabricated through the traditional melt-quenching method. The effects of addition of La₂S₃ on physical, thermal and optical properties of the glass system were investigated. The results showed that the fabricated glasses possess considerably high glass transition temperature, exhibit improved mechanical property and excellent infrared transmission. A redshift at the visible absorbing cut-off edge is observed with increasing of La₂S₃ content. The direct and indirect optical band gap values are also calculated. Raman spectra analysis indicated that the band at 265 cm⁻¹ decreased in amplitude and a new peak at 230 cm⁻¹ was detected manifesting the formation of La-S bond in the network. In addition, the mid-infrared emission at 3.74 µm of the glasses doped with Tm³⁺ ions was achieved. The results indicated that the glasses are promising materials for mid-infrared applications such as imaging, remote sensing and lasers.     

The high temperature–high pressure sintering of diamond–Cu–Si–B composite

Such elements like Si, B and Cu have been utilized as components of binder aiming at acquiring high adhesion of the binder with the diamond grains, thermal stability of the composite and, relatively low fusion temperature of the binder. The present work has as its main objective the study of the interaction between components during sintering of polycrystalline diamonds with addition of binders under high pressures, in the range from 5.0 to 6.0 GPa and high temperatures, in the range from 1473 to 1773 K with process time between 15 and 30 s. After sintering the compacts were subjected to investigations concerning the influence of the mixture composition and of the process parameters on the density and wear resistance of the compacts. The method of factorial planning was utilized in order to obtain model which describes influence of sintering parameters on the properties of compacts.     

3–硝基–1,2,4–三唑–5–酮纳米多孔炸药及其制备方法(CN107512994A)

<正>将炸药进行微纳米化,能够大幅度提高能量释放速率,同时纳米特性将使炸药具有低的临界爆轰直径。中国工程物理研究院化工材料研究所于2017年开发了一种3–硝基–1,2,4–三唑–5–酮纳米多孔炸药的制备方法,它包括:将3–硝基–1,2,4–三唑–5–酮炸药溶于去离子水,在超     

Vapor–liquid equilibrium in the sodium carbonate–sodium bicarbonate–water–CO2-system

Vapor–liquid equilibria of the carbon dioxide loaded sodium carbonate–water system were measured in the temperature range 40–80 °C and for sodium carbonate concentrations 8–12 wt%. In addition the vapor pressure of water over 10–30 wt% sodium carbonate solutions for the temperature range 27–100 °C was measured in an ebulliometer. The system was modeled using the electrolyte-NRTL model. Experimental vapor–liquid data from this study as well as data available in the literature from 25 to 195 °C and for sodium carbonate concentrations from 0.5 to 12 wt% were used for parameter fitting. The average deviation of the model predictions compared to all experimental data found is 9.8% for the partial pressure of CO₂. For vapor pressure of water the standard deviation is 0.6% up to 100 °C and 30 wt% sodium carbonate solutions.     

Electrochemistry of molten LiCl–KCl–CrCl3 and LiCl–KCl–CrCl2 mixtures

Chemical reactions during dissolution of CrCl3 or CrCl2 in molten LiCl–KCL eutectic have been demonstrated to occur, but the nature of the reactions is not yet well understood. Reduction of CrCl3 to chromium metal occurs through two well-characterized electrochemical steps, at approximately +0.1 and –0.9 V vs Ag/AgCl. Each step was studied in the 0.025–0.085 molar CrCl3 concentration range, at various temperatures between 375 and 550 °C. The Cr(iii)/Cr(ii) electron transfer step exhibited reversible behaviour under all the experimental conditions studied. In contrast, the Cr(ii)/Cr(0) step could involve Cr(ii) adsorbed species and initial chromium electrocrystallization phenomena, mainly depending on the nature of the substrate.     

3,4–二(4'–氯–3'–硝基苯–1'–基)氧化呋咱的合成及热性能

以4–氯苯腈(CCB)为原料,经肟化、重氮化–氯化、缩合环化、硝化多步反应设计并合成了一种新型氧化呋咱化合物——3,4–二(4'–氯–3'–硝基苯–1'–基)氧化呋咱(DCNBF),采用红外、核磁共振、质谱及元素分析等表征方法鉴定了目标物与中间体的结构,确定了肟化和环化反应的较佳合成条件;采用差示扫描量热、热重等热分析方法研究了目标化合物的热性能。