Effect of gas sparging on the rate of mass transfer at fixed beds of horizontally stacked screens

Rates of mass transfer at air sparged fixed beds of stacked screens were measured by an electrochemical technique. Variables studied were air superficial velocity, physical properties of the solution and bed thickness. The liquid mass transfer coefficient was found to increase with air superficial velocity up to a certain point and then remain almost constant with further increase in velocity. The increase in the mass transfer coefficient as a result of air sparging ranged from 2.8 to 10 times the natural convection value depending on the operating conditions. Increasing bed thickness was found to decrease the mass transfer coefficient at a given air superficial velocity. Mass transfer data at fixed beds were correlated by the equation: j = 0.268 (Re · Fr)^?0.25 (L/d)^?0.35. For a single horizontal screen the data were correlated by the equation: j = 0.275 (Re · Fr)^?0.21.     

风力机优化设计的DSFD方法

简述了进行风力机叶片外形优化设计的转轴直接搜索可行方向法ＤＳＦＤ。根据该方法并参考南澳２００ｋＷ定桨距风力机整体设计参数进行优化设计，给出了一组设计结果，获得了令人满意的叶片外形和气动性能。     

Short‐term extreme response analysis of a jacket supporting an offshore wind turbine

Wind turbines must be designed in such a way that they can survive in extreme environmental conditions. Therefore, it is important to accurately estimate the extreme design loads. This paper deals with a recently proposed method for obtaining short‐term extreme values for the dynamic responses of offshore fixed wind turbines. The 5 MW NREL wind turbine is mounted on a jacket structure (92 m high) at a water depth of 70 m at a northern offshore site in the North Sea. The hub height is 67 m above tower base or top of the jacket, i.e. 89 m above mean water level. The turbine response is numerically obtained by using the aerodynamic software HAWC2 and the hydrodynamic software USFOS . Two critical responses are discussed, the base shear force and the bending moment at the bottom of the jacket. The extreme structural responses are considered for wave‐induced and wind‐induced loads for a 100 year return‐period harsh metocean condition with a 14.0 m significant wave height, a 16 s peak spectral period, a 50 m s ^{? 1} (10 min average) wind speed (at the hub) and a turbulence intensity of 0.1 for a parked wind turbine. After performing the 10 min nonlinear dynamic simulations, a recently proposed extrapolation method is used for obtaining the extreme values of those responses over a period of 3 h. The sensitivity of the extremes to sample size is also studied. The extreme value statistics are estimated from the empirical mean upcrossing rates. This method together with other frequently used methods (i.e. the Weibull tail method and the global maxima method) is compared with the 3 h extreme values obtained directly from the time‐domain simulations. Copyright © 2012 John Wiley & Sons, Ltd.     

固定式光伏支架可承受荷载有限元分析

针对固定式光伏支架,使用实测的材料属性和三维线性开口梁单元进行有限元模拟分析。基于实测方法,通过简易横梁验证有限元模拟的准确性。根据有限元模拟结果,确定支架在正常使用极限状态下可承受的荷载。然后分别探究横梁间距、立柱数量、前后立柱间距对可承受荷载的影响,结果表明立柱数量的影响最显著,随着立柱数量增多,荷载更加均匀地分布到整个支架上,可承受荷载增加,平均每增加一对立柱,提升约1953 N;随着横梁间距的增加,中间两根横梁受到立柱的支撑效果减小,受载时局部挠曲变形增加,可承受荷载下降;前后立柱间距的变化主要影响支架受载均匀性,在间距为斜梁水平投影长度的50%时,挠曲变形较均匀地分布于4根横梁上,支架可承受荷载最大。     

固定床电极处理含氰废水的研究

本文采用一种新型的电极——固定床电极,处理含氰废水。建立了固定床内超电位沿床层厚度方向的一维分布方程。通过实验证明:采用固定床电极处理含氰废水,无论是电流效率、电能消耗,还是单位体积电解池的处理能力,均优于目前使用的平板电极。     

固定资产投资项目节能评估和审查工作的探讨与实践

固定资产投资项目在社会建设和经济发展过程中占据重要地位,北京市在开展固定资产投资项目节能评估和审查工作方面率先进行了探索与实践。本文对北京市固定资产投资项目节能评估和审查体系、特点、已开展工作及成效进行了总结,并对该项工作今后的发展提出了一些建议。     

Control of collection efficiency for axial flow cyclone dust collectors with fixed guide vanes and with funnel shaped exit pipes

The experimental result of the collection efficiency of the axial flow cyclone with the fixed guide vanes is lowerthan that with the tangential inlet pipe to the cyclone body due to the weak angular momentum transfer given byflowing through the guide vanes.However,one of the interesting points is the control of the collection efficiencydepended on the funnel shaped exit pipes.The collection efficiencies for these funnel shaped exit pipes aredepended on the Froude number.Then,in this paper,the experimental results of the pressure drop and also thecollection efficiency using the fly-ash particles and also the comparison of the calculated results of the collectionefficiency with the experimental results are described in detail.     

IGCC蒸汽侧合理的运行方式

通过对两种ＩＧＣＣ系统的变工况分析,比较了蒸汽侧滑压运行与定压运行时的性能,指出以选用滑压运行为佳,这时不仅ＩＧＣＣ的效率高些,且汽轮机的排汽干度较高,有利于汽轮机的安全运行。     

渐近伪压缩半群公共不动点的强收敛结果

在实Banach空间中研究渐近伪压缩半群公共不动点的强收敛性问题,提出黏制迭代算法,并且证明了该公共不动点是一个变分不等式的唯一解.所得结果将文献[8]中的结果从Halpern迭代算法推广到了粘制迭代算法,将文献[9]中的结果从非扩张半群推广到了渐近伪压缩半群.     

新型台式变频履带牵引机的设计

介绍了新型台式变频履带牵引机的结构设计、工作负载转矩计算及拖动系统设计。该牵引机具有结构简单、台式安装、低速机械特性较硬、牵引力大等显著特点。实验证明:设计计算合理、工作平稳可靠,是理想的缓凝预应力筋包覆设备的牵引装置,在一定范围内适用其它管(线)材的牵引,具有推广价值。