Numerical Study of Heat Transfer and Separated Flow over Rectangular Obstacle in Jet

This paper is about a separated reattaching flow over a hot rectangular obstacle. Two types of incoming flow are examined in order to show the influence of the external zone of the flow on the reattachment process. It comes about due to a wall jet and a boundary layer. The inner region of these two flows is similar, but their external regions are extremely different. The separating and reattaching flow phenomena are of particular interest in engineering fields such as for an aeronautical application. Wall jet flow over an obstacle occurs in many engineering applications such as environmental discharges, heat exchangers, fluid injection systems, cooling of combustion chamber wall in a gas turbine, automobile design, and others. In electronics cooling, the prediction of the Nusselt number distribution along the obstacles is necessary before the design of the apparatus. For a heated obstacle at a constant temperature, T = 350 K and an aspect ratio of 10 (L = 10 H), the problem parameters are: (a) jet exit Reynolds number (Re) ranged from 1000 to 50000, (b) incoming flow configuration (boundary layer and wall jet). The ratio between the thickness of the nozzle (b) to the obstacle height (H) are examined simultaneously. The formulation is based on the SST k–ω turbulence model. The results show that the increasing of nozzle thickness; enhances the heat transfer and considerably modifies the stagnation point location. The highest incoming flow momentum provides the greatest values of average Nusselt number. Such as the boundary layer case in comparison with the wall jet cases. The average Nusselt number is correlated according to problem parameters .     

城市垃圾处理技术分析及对策研究

随着经济的迅速发展,我国城市垃圾量日渐增长,如何合理处理城市垃圾日益引起各界关注。介绍了城市垃圾处理的常规技术和新技术,对各种技术进行了分析,并根据我国国情,对我国城市垃圾处理提出了几点对策。     

240柴油机机体裂损的分析与对策

对DF4型机车240柴油机铸焊机体的裂损部位及规律进行统计分析,并对焊接接头进行取样解剖,认为目前的240柴油机铸焊机体越来越不能满足当今运用要求,提出DF4各型机车采用整铸球墨机体代替铸焊组合机体的必要性和迫切性。     

入世后我国能源面临的挑战与对策

着重阐述了中国入世后，中国能源面临的主要挑战：能源资源相对短缺、能源消耗率高等，在充分利用世界贸易组织规则的基础上，趋利弃弊，提出了能源开发与节约并重，科技创新，以提高国际竞争力为核心的应对对策。     

江苏资源总体态势分析及战略对策

对江苏省资源的总体态势以及未来的严峻形势进行了客观的分析,给出了江苏资源的特点:资源较为匮乏,人均水平低;资源分布不均衡,区域优势明显,与生产力不匹配;矿产资源开发难度大,浪费严重;资源相对衰竭,开发潜力下降。据江苏资源的总体态势,结合工业化过程资源利用的基本特点和可持续发展的战略,考虑世界资源的安全性特性,为了实现“两个率先”的战略目标,必须加强对江苏资源的可持续开发和利用对策研究。     

Aluminum silicate scale formation and inhibition (2): scale solubilities and laboratory and field inhibition tests

The solubilities of pure silica, iron-silicate and aluminum-silicate scales were measured in water from 25–250°C in a laboratory pressure reactor. Iron- and aluminum-silicate scales are significantly less soluble than pure amorphous silica. Aluminum- and iron-rich silica scales at equilibrium conditions are predicted to deposit from near-neutral, low salinity brines at temperatures that are 25 and 75°C above the saturation point for pure amorphous silica, respectively. This laboratory study demonstrates that higher brine injection temperatures are required to mitigate aluminum- and iron-rich silica scaling compared with pure amorphous silica. In a laboratory scale test, pure amorphous silica and aluminum-rich silica deposition rates have been measured at high degrees of supersaturation in the presence of potential inhibitors. Scale deposition was best inhibited by brine pH modification techniques. A commercially available dispersant successfully inhibited amorphous silica scaling, but exacerbated aluminum silicate scaling. Scale inhibition was also achieved in the presence of aluminum complexing\sequestering agents in a patent-pending process. Screening of these potential silica- and aluminum-silicate scale inhibitors in the laboratory will focus the efforts of ongoing field pilot scale testing. The effect of complexing\sequestering agents on scale inhibition was monitored in preliminary field pilot tests. These complexing agents achieved 25% to 80% aluminum silicate scale inhibition.     

超声波防除垢技术的工业应用

分析污垢的危害,阐述各种防、除垢方法的利弊,重点介绍超声波防除垢技术及其实际应用案例。应用实验表明:超声波防除垢技术对空气冷却器、板式换热器、凝汽器以及锅炉的防除垢效果明显,解决了装置多年的结垢问题,同时节能效果显著。     

甜高粱秸秆燃料乙醇产业化问题与对策的探讨

甜高粱具有极高的光合速率,有"高能植物"之称,其单位种植面积的乙醇产量较高.甜高粱特别适合在我国栽培,甜高粱燃料乙醇极具开发价值,它对能源安全和环境保护具有举足轻重的作用.文章简单介绍了新疆甜高粱用于生产低成本燃料乙醇的优势、试验情况以及产业化过程中面临的问题,并提出了解决这些问题应采取的对策.     

浅议跨国水务业抢占中国市场

介绍了中国水务市场面临跨国公司激烈竞争的现状,分析了原因并提出了相应的对策。     

Economies of scale in nuclear power plant

This paper demonstrates that, to first order, the optimum size of nuclear plant depends only on the form of the dependence of capital costs and availability with size and not on absolute levels; it is also independent of nuclear fuel costs. the advantage of this treatment is that the forms of these dependences are less controversial than absolute values and the scope for confusion in determining optimum size is therefore reduced.