地铁专用间接蒸发冷却器布水方式优化

为了解决常规间接蒸发冷却器由于表面水膜均匀性、完整性差而导致换热效率低的问题,提出了两侧旋转布水间接蒸发冷却器,进行了3种布置方式下的换热性能实验,运用正交实验对影响换热器性能的因素进行研究,研究表明:开孔正对气流方向时换热器换热性能最佳,且旋转布水装置存在最佳转速76r/min,喷水量、空气流速、冷却水流量、冷却水进口温度的增加使换热器的换热量增大,喷水温度、空气温度的升高使换热器的换热量减少,其中冷却水进口温度的改变对换热性能的影响最为显著,温度由35℃上升到39℃时,换热量提高37.62%,单位面积换热量为1.14kW,该换热器可安装于地下车站排风坑道内,可有效地解决地铁站冷却塔安装位置难题。     

家用直接蒸发冷却器性能的实验研究

介绍了直接蒸发冷却以及家用直接蒸发冷却器的工作原理,并采用实验的方法对单台家用直接蒸发冷却器降温和加湿性能进行了测定,得到实际运行工况的性能曲线图,并对实验结果进行分析,确定家用直接蒸发冷却器的使用效果及需要改进的问题,为多台空调扇组合使用的实验奠定了基础。     

大型表冷器在地铁设计中的应用

阐述了在南京地铁二号线采用大型表冷器之前,车站公共区空调系统采用大型表冷器处理送风是一种北京地铁特有的设计方法,提出了一种能够满足通风、空调、事故及火灾工况下的优化方案,从而解决了几种不同运行工况下的技术问题。     

High-Angle annular dark-field imaging on a tem/stem system

The technique of high-angle annular dark-field (HAADF) imaging, which is highly sensitive to atomic-number contrast, can be performed on TEM/STEM systems using the standard annular dark-field detector. For optimum HAADF imaging, the TEM/STEM must have a high maximum diffraction angle, small minimum camera length, and a descanning facility. The sensitivity of the technique is demonstrated to be about 10⁵ to 10⁶ times higher than energy-dispersive X-ray spectroscopy. Examples are shown from semiconductor, catalysis, ceramics, and particle analysis applications.     

Treatment of textile dyehouse wastewater by TiO2 photocatalysis

The oxidative degradation of an actual textile dyehouse wastewater was investigated by means of photocatalysis in the presence of TiO2. The UV-A-induced photocatalytic oxidation over TiO2 suspensions was capable of decolorizing the effluent completely, as well as reducing chemical oxygen demand (COD) sufficiently (COD reduction generally varied between about 40% and 90% depending on the operating conditions) after 4 h of treatment. Two crystalline forms of TiO2, viz. anatase and rutile, were tested for their photocatalytic activity and anatase was found to be more active than rutile. The extent of photocatalytic degradation was found to increase with increasing TiO2 concentration up to 0.5 g/L TiO2, above which degradation remained practically constant, reaching a plateau. Furthermore, textile effluent degradation was enhanced at acidic conditions (i.e. pH = 3) and in the presence of hydrogen peroxide. To assess catalyst activity on repeated use, experiments were performed where the catalyst was recovered and reused; after three successive uses, TiO2 had sufficiently retained its photocatalytic activity. Finally, the luminescent marine bacteria Vibrio fischeri was used to assess the acute ecotoxicity of samples prior to and after the photocatalytic treatment and it was found that ecotoxicity was fully eliminated following photocatalytic oxidation.     

电站设备用A型精密椭圆焊接钢管的研制

介绍了哈尔滨钢管厂在研制A型精密椭圆焊接钢管过程中的材料选择、生产设备、工艺流程、孔型设计、过程质量控制等。所生产的产品经检测,其化学成分、力学性能、实测尺寸及形状公差以及无损检测等结果均满足ASME相关标准的要求,可以替代进口的同类产品。     

立式水冷器冷却水量均布技术试验研究

分析了各传热管冷却水量分布不均匀对立式水冷器运行效率的影响，简要评述了企业常用的分布结构存在的问题及其原因，提出了池式均布筛板理论，并且进行了模拟试验和结构参数的优化研究。试验结果表明，均布技术的关键参数是筛板上的积水池深度达到125mm以上时冷却水分布的整体均匀度可以达到85％以上。可以满意地解决现在普遍存在的不均布问题。这种均布技术结构简单，设计方法也十分简便，可以很方便的推广应用。     

Proton exchange membrane fuel cells

The desire to have compact, high power sources with low environmental impact has focused attention on proton exchange membrane fuel cells (PEMFC). The paper gives a brief overview of processes and technical challenges related to PEMFCs. The main goal is also to give a short overview of the underlying science and to show a feasible approach to implementation of these cells. The potential for use of vacuum-based techniques in PEMFC manufacturing is also discussed.     

Experimental study of the influence of cold heat exchanger geometry on the performance of a co-axial pulse tube cooler

Improving the performance of the pulse tube cooler is one of the important objectives of the current studies. Besides the phase shifters and regenerators, heat exchangers also play an important role in determining the system efficiency and cooling capacity. A series of experiments on a 10 W @ 77 K class co-axial type pulse tube cooler with different cold heat exchanger geometries are presented in this paper. The cold heat exchangers are made from a copper block with radial slots, cut through using electrical discharge machining. Different slot widths varying from 0.12 mm to 0.4 mm and different slot numbers varying from around 20–60 are investigated, while the length of cold heat exchangers are kept the same. The cold heat exchanger geometry is classified into three groups, namely, constant heat transfer area, constant porosity and constant slot width. The study reveals that a large channel width of 0.4 mm (about ten times the thermal penetration depth of helium gas at 77 K, 100 Hz and 3.5 MPa) shows poor performance, the other results show complicated interaction effects between slot width and slot number. These systematic comparison experiments provide a useful reference for selecting a cold heat exchanger geometry in a practical cooler.     

基于流固耦合与多目标拓扑优化的低噪声塑料机油冷却器盖优化设计

机油冷却器盖属于薄壁件,距离振动激励源较近,容易产生较大的振动噪声,且内腔冷却液的存在对机油冷却器盖的振动噪声有着很大的影响。为有效的对塑料机油冷却器盖的振动噪声进行仿真研究及优化,将流体冲击压力作为预应力的同时,结合塑料机油冷却器盖与内腔流体的流固耦合模型,采用流固耦合的方法对塑料机油冷却器盖的振动噪声水平进行了预测评估;根据预测结果,识别出对噪声贡献度较大的耦合模态频率;以降低塑料机油冷却器盖整体噪声为总目标,以提高各贡献度较大的耦合模态频率为子目标,利用加权指数法建立了多目标优化函数,对塑料机油冷却器盖结构进行了多目标拓扑优化。结果表明,优化后降噪效果明显,总声功率级降低了1.79 dB。