扰流小通道液冷冷板流动与传热特性的数值研究

为降低常规蛇形小通道液冷冷板的热阻,提高其对流换热能力,在流道内引入了一种强化换热结构,设计了扰流蛇形小通道液冷冷板,并利用数值模拟方法对两者进行了比较分析。相比于常规蛇形小通道液冷冷板,新的流道设计能够显著降低冷板的总热阻和进、出口压降,降幅分别可达9.2%和66.7%。此外,冷板平均努赛尔数(Nusselt, Nu)提高了17.2%。对冷板内部流动和传热情况进行了详尽的数值分析,研究了扰流小通道的强化传热效果及其作用机理。     

蛇纹石-黏土复合颗粒除氟的动态实验研究

为研究蛇纹石-黏土复合颗粒的除氟性能,采用室内动态实验探讨了复合颗粒在不同氟离子浓度、不同吸附柱高度和不同流速下对含氟水除氟效果的影响及其吸附动力学过程.试验结果表明:吸附剂的动态吸附容量与吸附剂高度、原水氟离子浓度呈正相关,而与进水流速呈负相关;吸附剂传质区长度与进水流速、吸附剂高度及原水氟离子浓度均呈正相关.吸附动力学拟合结果显示:蛇纹石-黏土复合颗粒对水中氟的吸附动力学符合Yoon and Nelson方程,平衡吸附容量与吸附剂高度呈正相关,与进水流速呈负相关.随着初始氟离子浓度的增加,到达吸附平衡时间缩短,吸附容量逐渐增大.     

Local transport phenomena and cell performance of PEM fuel cells with various serpentine flow field designs

The flow field design in bipolar plates is very important for improving reactant utilization and liquid water removal in proton exchange membrane fuel cells (PEMFCs). A three-dimensional model was used to analyze the effect of the design parameters in the bipolar plates, including the number of flow channel bends, number of serpentine flow channels and the flow channel width ratio, on the cell performance of miniature PEMFCs with the serpentine flow field. The effect of the liquid water formation on the porosities of the porous layers was also taken into account in the model while the complex two-phase flow was neglected. The predictions show that (1) for the single serpentine flow field, the cell performance improves as the number of flow channel bends increases; (2) the single serpentine flow field has better performance than the double and triple serpentine flow fields; (3) the cell performance only improves slowly as the flow channel width increases. The effects of these design parameters on the cell performance were evaluated based on the local oxygen mass flow rates and liquid water distributions in the cells. Analysis of the pressure drops showed that for these miniature PEMFCs, the energy losses due to the pressure drops can be neglected because they are far less than the cell output power.     

蛇纹石资源综合利用研究进展

蛇纹石作为一种重要的非金属矿物,广泛用于多种工业领域。本文介绍了蛇纹石的基本物化性质并综述了国内外近年来对蛇纹石综合利用的研究进展,提出了开发综合利用蛇纹石的绿色化学新工艺的重要意义及相关研究方向。     

Design concept and mathematical model of a bi-fluid photovoltaic/thermal (PV/T) solar collector

This paper presents an improved design of a photovoltaic/thermal (PV/T) solar collector integrating a PV panel with a serpentine-shaped copper tube as the water heating component and a single pass air channel as the air heating component. In addition to the electricity generated, this type of collector enables the production of both hot air and water, increasing the total efficiency per unit area compared to the conventional PV/T solar collector. The use of both fluids (bi-fluid) also creates a greater range of thermal applications and offers options in which hot and/or cold air and/or water can be utilized depending on the energy needs and applications. In this paper, the design concept of the bi-fluid PV/T solar collector is emphasized with 2D steady state energy balance equations for the bi-fluid configuration are developed, validated and used to predict the performance of the bi-fluid solar collector for a range of mass flow rates of air and water. The performance of the collector is then compared when the fluids are operated independently and simultaneously. The simulations indicate that when both fluids are operated independently the overall thermal and electrical performance of the solar collector is considered as satisfactory and when operated simultaneously the overall performance is higher. The bi-fluid PV/T solar collector discussed in this paper will add insights to the new knowledge of optimizing the utilization of solar energy by a PV/T solar collector and has potential applications in various fields.     

四川蛇纹石猫眼的组成及显微形貌特征

采用傅立叶变换红外吸收光谱、 X射线粉晶衍射和扫描电子显微镜对四川蛇纹石猫眼进行了研究. 结果表明, 四川蛇纹石猫眼的主要组成矿物为纤蛇纹石, 具有斜纤蛇纹石d202, 006=0.244 6 nm(I/I0=29)和d202, 006=0.245 1 nm(I/I0=27)X射线粉晶衍射的特征谱线; 在960～1 100 cm-1间红外图谱分裂成3个明显的谱带, 570 cm-1附近的红外谱带以肩状出现, 在3 600～3 690 cm-1的高频区出现两个谱带. 蛇纹石纤维形态分为两类: 一类是纤维韧性好, 外表光滑干净, 未见明显的溶蚀现象; 另一类纤维平直, 韧性差, 具有较明显的溶蚀现象. 在垂直纤维方向上, 蛇纹石纤维表现出内层为圆柱状、外层为多角形的"内圆外方"的结构模式.     

用蛇纹石制取高纯度活性氧化镁的工艺研究

研究了以蛇纹石为原料制取高纯度活性氧化镁的工艺。以硫酸浸取蛇纹石矿石得到硫酸镁,以精制硫酸镁溶液为原料,氨水、碳酸氢铵为沉淀剂制取碱式碳酸镁前驱体,煅烧碱式碳酸镁前驱体得到高纯度活性氧化镁产品。考察了制取碱式碳酸镁的工艺条件,最佳工艺条件为:预氨pH值为9.6～9.7、镁离子与总铵(NH3+NH4+)摩尔比为0.46、氨与碳酸氢铵摩尔比为1.4。在此条件下,镁的沉淀率达到最大值89%。碱式碳酸镁前驱体最佳煅烧条件为:升温速率10℃/min,煅烧温度650℃,煅烧时间2h。在此条件下得到了碘吸附值为165.1mgI2/gMgO、柠檬酸活性值为3.05s、比表面积为78.03m2/g的高纯活性氧化镁。     

纳米铋/蛇纹石粉复合润滑脂添加剂摩擦学性能及机理初探

 针对纳米复合自修复脂的开发问题,在固定粉体总添加质量分数为3%的条件下,采用四球摩擦磨损试验机研究了纳米铋粉与蛇纹石粉的质量比和载荷对锂基脂摩擦学性能的影响,并通过扫描电子显微镜（SEM）和能谱分析（EDX）探讨了复合粉体在脂中的抗磨减摩机理。结果表明,纳米铋粉与蛇纹石粉复合作为添加剂有利于提高锂基脂的综合摩擦学性能,并且两种粉体的质量比为3∶1时,复合锂基脂在中、低、高载荷下的摩擦学性能最优。该复合粉体提高润滑脂的抗磨减摩机理在于：摩擦副摩擦时,由于纳米铋粉所需要的自修复能量较低,铋粉优先沉积于摩擦副的表面,而粒径较大含量较少的蛇纹石粉体则位于铋粉体之上,两者都起到了自修复的作用,但以铋粉的自修复效果为主。     

镧/蛇纹石复合润滑材料的热力学及摩擦学性能

采用天然岫岩玉和人工合成含镧化合物为原料,通过高能球磨制备粒径小于2μm的镧/蛇纹石复合粉体,分析该复合粉体的热力学及结构稳定性,评价其作为润滑添加剂的摩擦学性能,并探索其减摩抗磨机理.结果表明:镧的加入能降低蛇纹石微粉的热力学及结构稳定性,使蛇纹石的羟基脱除速率更快、反应更彻底.复合微粉较单一的蛇纹石微粉具有更好的减...     

什么是玉德——玉辨之三

在前载“什么是玉——玉辨之一”和“什么是玉石——玉辨之二”这两篇文章的基础上,归结到“什么是玉德”这一命题展开较深入的讨论。就古人对“玉”突出的个性特征(质感、声音、韧性、硬度等方面)的认知和理解,来阐明“玉德”是指‘玉’的个体物理性质和特征,并不是指群体所谓‘玉’(Jade)的物理性质和特征”的观点。并从中国的传统文化观念的传承、有关史料记载及文字含义的逻辑推理上,澄清了在“玉”的命名上的一些谬误,同时,对我国历史上最为著名的似玉之石“珉”作了较详尽的历史考证及对“国石”的评选发表了个人看法。