多级蜿蜒磁路式磁流变阻尼器的设计与分析

为了改善磁流变阻尼器的阻尼特性,设计了一种多级蜿蜒磁路式磁流变阻尼器。该磁流变阻尼器通过导磁环和阻磁环的堆叠来引导磁感线的走向,迫使磁感线数次穿过磁流变阻尼器的节流通道,提高了节流通道的利用效率。建立了考虑磁流变液非线性流动特性的数学模型,并通过有限元方法进行了磁路分析,进而对所设计的磁流变阻尼器的特性进行预测。将所设计的磁流变阻尼器的阻尼特性与具有相同体积的传统磁流变阻尼器进行了比较,包括可控阻尼力、等效阻尼和动态范围。结果显示在正弦激励速度为0.125m/s,并通入2.0A电流的情形下,所设计的磁流变阻尼器的最大可控阻尼力为11 000N,约为传统磁流变阻尼器的2.3倍。此外,所设计的磁流变阻尼器并没有使零场情形下的阻尼力增大。所设计的磁流变阻尼器具有优良的阻尼性能,适用于广泛的工程减振应用。     

塔式炉蛇形管受热面工艺研究

本文通过对几种结构形式的蛇形管受热面进行工艺研究,阐述了670MW超临界机组用塔式锅炉蛇形管受热面的关键制造工艺。     

小曲率蛇形微通道弯头处弹状流流动及传质特性的数值研究

采用CLSVOF（coupled level set and volume of fluid）方法,以空气和水为工作流体对小曲率矩形截面蛇形微通道内气液两相流动进行模拟研究。验证模型的合理性后,研究了曲率对弯通道内压降的影响,曲率及气相速度对弹状流气泡及液塞长度的综合影响;同时深入分析了弯管内气液两相流动的传质特性,包括不同曲率下气泡长度的变化,弯管内液侧体积传质系数与液膜体积传质系数的比较,曲率及气相速度对液相体积传质系数的影响。同时,对比了回转弯道与直微通道传质系数的差异,发现弯微通道可以强化传质。     

Evaporation heat transfer and pressure drop characteristics of R-290 (propane), R-600 (butane), and a mixture of R-290/R-600 in the three-lines serpentine small-tube bank

This paper reports an experimental investigation of heat-transfer and pressure-drop behavior of R-290, R-600, and R-290/R-600 in the three-lines serpentine small-diameter (2.46 mm) tube bank. Heat transfer coefficients and pressure drop characteristics are measured for a range of heat flux (5–21 kW/m²), mass flux (250–500 kg/m² s), equilibrium mass quality (0–0.86), and the fixed mixture composition ((R-290/R-600 (55 wt.%/45 wt.%)). The results show that the flow boiling heat transfer coefficients for R-290, R-600, and R-290/R-600 are 1.66–1.96-fold, 1.28–1.38-fold and 1.57–1.88-fold greater as compared with those for R-134a under equal heat and mass fluxes. Also, the two-phase flow frictional pressure drop for R-600, R-290/R-600 and R-290 are 1.41–1.60-fold, 1.32–1.50-fold and 1.22–1.40-fold smaller as compared with that for R-134a. A new heat transfer correlation was presented by using a superposition model to predict the experimental data for both pure refrigerants and refrigerant mixtures. Experimental results were compared with several correlations which predict the evaporative heat transfer, which are in good agreement with experimental data.     

蛇纹石/La复合粉体的制备及其摩擦性能

分别采用水溶液沉淀法和乙醇溶液沉淀法制备了蛇纹石/La复合粉体,并分别在120℃（脱除吸附水）和700℃（蛇纹石脱除羟基）对复合粉体进行了干燥和煅烧热处理。利用X射线衍射法、扫描电子显微镜、能谱分析表征了复合粉体的物相组成、微观形貌。利用MM-10W型多功能摩擦磨损试验机对复合粉体的摩擦性能进行了评价。结果表明：蛇纹石/La复合粉体中,La化合物呈纳米颗粒,并包覆在蛇纹石表面;700℃煅烧将导致蛇纹石/La复合粉体物相变化和摩擦性能变差;120℃干燥处理的蛇纹石/La复合粉体具有良好的减摩-抗磨性能,摩擦因数较未添加者降低22.48%以上。     

活化酸浸蛇纹石提取镁的实验研究

采用球磨和煅烧工艺对蛇纹石进行预处理, 破坏其晶体结构, 改善其物理化学特性, 并用不同无机酸进行浸取。通过实验确定最佳条件是: 在球磨机中球磨1 h后的矿粉, 700 ℃条件下恒温煅烧1 h, 然后用3 mol/L H₂SO₄在常温下搅拌1 h, 固液比为1∶15, MgO的浸出率可达到93%。     

蛇形防护布线设计

高速电路中蛇形线可作为传统防护布线的替代方案，但其提出过程未曾考虑如何进行合理的设计。文中基于蛇形防护布线的外形特征影响耦合参数的原理，通过全波求解器建立蛇形防护布线模型，分析了其端接策略以及特征变化对应的远端串扰变化规律，得出了蛇形防护布线的合理设计方法。结果表明，短路策略作为最佳策略，且在信号边沿变化较快的情况下，应采用线宽小、高度高和长度短的蛇形线作为防护布线。     

Hydrothermal synthesis (200 °C) of Co–kaolinite and Al–Co–serpentine

In the systems CoO–Al₂O₃–SiO₂–H₂O and CoO–Al₂O₃–SiO₂–HCl–H₂O, at initial pH between 5.5 and 8.1 and temperature of 200 °C, kaolinite is unstable and the following phases form through a dissolution-precipitation process: a) kaolinite and Co-bearing kaolinite; b) Al–Co–serpentine; and c) poorly crystalline phases. Identification of the several phases was carried out from a combination of X-ray diffraction and transmission/analytical electron microscopy.Co–kaolinite shows variable morphologies: a) Platy lath-shaped particles with very low Co content; b) Spherical particles, with relatively constant Co contents (in the order of 0.10 apfu); c) Kaolinite stacks with very variable Co contents (up to 0.25 apfu). Analytical data indicate that the presence of Co(OH)₂ in the system favors the dissolution process as well as serpentine formation but it leads to the parallel formation of abundant poorly crystalline phases. The Co-content in kaolinite increased as a function of the Co(OH)₂/CoCl₂ ratio in the initial systems, and it is reflected by a parallel increase of the b-cell parameter of kaolinite. The average composition of the coexisting Al–Co–serpentine is: (Al_1.20Fe_0.11Co_1.27)(Si_1.64Al_0.36)O₅(OH,Cl)₂, with Cl contents in the order of 0.14 apfu.The assemblage Co–kaolinite + Al–Co–serpentine, which appears to be stable at 200 °C, has not been described in natural environments, probably because it requires unusual Al- and Co-rich chemical systems.     

冬瓜山铜矿深部矿石工艺矿物学研究

冬瓜山铜矿属于复杂难选矿石,具有铜磁黄铁矿、层状滑石、蛇纹石类型矿石占比高的特点,该性质对铜的选别过程具有不利影响,影响铜精矿品位和铜回收率。因此,开展该矿石的矿物学特性研究,对指导选矿生产具有重要的现实意义。研究的主要内容包括:矿石化学成分分析、矿物组成及含量、主要矿物的粒度及嵌布特征分析、不同磨矿细度下重要矿物的解离度分析,并对影响选别指标的工艺矿物学因素进行总结。工艺矿物学研究表明,冬瓜山深部矿石中铜矿物绝大部分为黄铜矿,墨铜矿占8.46%,且含有24.26%的滑石、蛇纹石易浮层状脉石矿物;黄铜矿、墨铜矿、磁黄铁矿、磁铁矿和黄铁矿的嵌布粒度不均匀,尤其是20μm以下部分占11.04%,在磨矿细度-0.074 mm粒级含量占75%时,仍有26.06%与脉石连生。以上性质都是铜选矿的重要影响因素,对指导选矿厂生产具有重要的意义。     

石英与蛇纹石异相凝聚及其对黄铁矿浮选的影响

通过单矿物和人工混合矿的浮选试验、Zeta电位测试、吸附量测试,研究了蛇纹石和石英异相凝聚的机理,以及对黄铁矿浮选的影响,以进一步探索多种矿物的体系中,蛇纹石对硫化矿物浮选影响的主要原因。结果表明:通过添加石英,可以恢复黄铁矿对捕收剂的吸附量,减弱蛇纹石的不良影响,不同粒级的石英与蛇纹石的异相凝聚作用强弱不同,粒级越细的石英,与蛇纹石的异相凝聚作用越强。