基于SWMM和AHP的排涝除险设施径流控制效益研究

以南昌市青山湖排水区为例,运用暴雨洪水模型(SWMM)模拟该区域现状和设置雨水泵站、雨水行泄通道、雨水调蓄池三种排涝除险措施在不同设计降雨重现期下的径流控制效果,采用层次分析法(AHP)评价径流控制效益,定量评估不同措施的效益,设计排涝除险组合方案并模拟效果。结果表明,排涝除险措施具有径流控制效果,采用排涝除险措施后的雨水系统,在降雨重现期为2、5、10、20、50年的溢流节点个数、节点最大溢流时间、节点最大溢流深度、满载管道数目、满载管道时间分别减少了5.36%~26.92%、12.77%~50.00%、2.70%~15.38%、1.92%~26.09%、4.49%~28.57%;雨水行泄通道在溢流节点个数、满载管道数目和时间上有较强的削减效果,而雨水调蓄池在减少节点溢流时间和溢流深度上较优;径流控制效益大小顺序为雨水行泄通道雨水调蓄池雨水泵站。组合方案的节点溢流情况优于单项排涝除险方案。     

基于SWMM模型的住宅区层级式雨水系统构建

为研究层级式雨水系统的排水效果,以江西省南昌市某住宅小区为例,构建了由基本单元入渗系统、庭院逐级削减系统、地块层层滞蓄系统和小区末端调蓄系统组成的层级式雨水系统。利用SWMM模型模拟层级式雨水系统方案与传统方案在不同重现期降雨条件下对径流总量、峰值流量和节点溢流的控制效果,并进行整体性分析。结果表明,采用层级式雨水系统后,降雨重现期为0.5、1、2、3、5、10a时的径流总量削减率分别增加了63.20%、58.02%、52.43%、49.61%、44.46%、39.17%;径流峰值分别削减了56.44%、57.79%、58.65%、59.12%、59.36%、59.72%;径流峰值时刻分别延迟了9、8、6、4、3、1min。层级式雨水系统具有较好的径流控制效果,能减少径流总量,削减峰值流量,延缓峰值时间,改善节点溢流,保证研究区域5年一遇降雨不发生积水,有效缓解城市排水问题。     

初期雨水溢流对河道纳污能力的影响分析

为减小初期雨水对河流的水质污染,进一步改善水体环境,采用SWMM排水模型模拟研究区不同重现期下的雨期管网运行情况,通过调节节点高程和调节管径的方式,优化改造管网模拟运行中出现的不足,进一步分析比较了雨水溢流情况对河道纳污能力的影响规律,并探讨了缓解溢流污染问题的思路。结果表明,COD、NH4-N、TP、TSS的最大溢流浓度均随重现期的增大而增大,平均溢流浓度随重现期的增大而减小;截流倍数为1,重现期为10、20年时,河道污染很轻;截流倍数调整为3后,初期雨水对河道纳污基本无影响。研究成果可为河流纳污能力分析与水环境保护提供技术支持。     

基于SWMM模型的雨水管网改造方案优化研究

基于雨洪模型SWMM模拟某老城区雨水管网现状,分析检查井节点溢流与管网荷载状况,分别提出传统改造方案(改变管径(方案1)、改变下垫面性质(方案2))及与海绵理念相结合方案(改变管径+LID即方案3)。在2年降雨重现期下,基于3种方案对管网节点溢流状态进行定量分析。结果表明,3种改造方案均能不同程度地改善区域内涝,其中海绵理念方案缓解节点溢流效果最优。进一步模拟高降雨重现期下(P=5、10年)管网优化效果,发现改变管径+LID方案(方案3)持续有效,较为理想。     

基于Infoworks CS的雨水利用措施对城市雨洪影响的模拟研究

以广州市新河浦社区为研究区域,构建了基于Infoworks CS的城市雨洪模型,对研究区年均可收集雨量和需水量进行分析计算,并设计了雨水利用方案。采用Infoworks CS模型模拟了设置蓄水池、下凹式绿地和透水砖3种雨水利用措施在不同重现期时排水管道出口断面洪峰流量和淹没情况。结果表明,蓄水池、下凹式绿地和透水砖皆可有效地削减洪峰、推迟峰现时刻、减少径流量及被淹没节点数,三者组合可更好地发挥控制流量的作用,增加雨洪资源利用量,且重现期越小,雨水利用措施效果越好。     

不同尺度海绵措施下雨洪控制效果研究

为对比不同尺度海绵措施对雨洪控制效果的差异性,以江西省某市滨江新区为研究区域,根据不同尺度海绵措施的特性和滨江城市防洪排涝需求设计"小海绵"、"大海绵"、"综合海绵"三种改造方案,构建SWMM模型模拟三种方案在不同重现期降雨条件下的雨洪控制效果。结果表明,"综合海绵"方案在遭遇高低重现期降水时均能保持雨洪控制效果最优且效果衰退缓慢。研究成果可为海绵城市建设提供指导。     

基于SWMM的住宅区多LID措施雨水系统径流控制

为分析不同的LID措施对雨水径流的控制效果,以江西省南昌市某住宅小区为例,利用SWMM模型模拟了多LID措施串联的不同方案在不同重现期降雨条件下的削峰减排效果。结果表明,采用下凹式绿地、渗透铺装、植被浅沟的小区雨水系统,在降雨重现期为1、2、5、10、20年时总径流量、洪峰流量分别减少13.9%~25.1%、31.6%~47.9%;在此基础上分别串联屋面雨水桶、绿色屋顶、绿色屋顶+雨水桶的设计方案均能得到更好的径流控制效果;雨水桶相比绿色屋顶对总径流量有更强的削减作用,而绿色屋顶比雨水桶有更好的洪峰控制效果,尤其是在高强度降雨条件下单用雨水桶不能发挥削峰效果;绿色屋顶与雨水桶串联相比单独使用能发挥更强的削峰减排效能,且在高降雨强度下串联优势更明显。研究成果可为住宅区雨水系统的径流控制提供参考。     

基于社会总投入最低的长沙市雨水系统设计重现期研究

设计重现期不仅是暴雨强度公式的重要组成部分,也是雨水排水系统规划与设计的重要参数,重现期选用的合理与否直接关系到城市防洪排涝的安全。为此,以长沙市新开铺污水厂纳污区的青山路、杉木冲路、湘府路三条支系为例,基于社会总投入最低的雨水系统设计重现期分析方法,合理地确定长沙市雨水系统设计重现期。结果表明,长沙市雨水系统规划设计重现期对于一般地区重现期推荐取值3年,重要地区重现期推荐取值5年,为减少城市发生道路积水与内涝提供了参考。     

SWMM模型中的低影响开发模块在排水防涝系统中的应用

针对近年来福建省龙岩市主城区内涝严重的问题,基于SWMM模型中的低影响开发模块(LID),模拟分析了现状条件及渗透路面、植被浅沟单独布设和两种LID措施组合布设场景在不同暴雨重现期时地面淹水状况,评估了不同LID措施对城市洪涝的缓解作用。结果表明,渗透路面、植被浅沟均可有效降低径流系数、推迟峰现时刻、减少溢流检查井个数和最大淹水深度,且对内涝的缓解作用在低重现期时更为显著,尤以组合LID措施对内涝的控制效果最佳。     

前池雨水花园系统径流水量控制性能试验研究

针对现有城市工业区建筑物屋面雨水径流的特点,在原有雨水花园基础上增设蓄存功能,提出了一种前池雨水花园系统,并模拟了降雨量下(降雨条件为重现期0.5、1、2年,降雨历时为30、60、120 min)的径流水量控制试验.结果表明,前池雨水花园系统对径流的削减可达到1/2以上,甚至可全部削减,且蓄水高度、各部分水量分配及流量...     

Ash-forming elements in four Scandinavian wood species. Part 1: Summer harvest

Woody biomass in Finland and Sweden comprises mainly four wood species: spruce, pine, birch and aspen. To study the ash, which may cause problems for the combustion device, one tree of each species were cut down and prepared for comparisons with fuel samples. Well-defined samples of wood, bark and foliage were analyzed on 11 ash-forming elements: Si, Al, Fe, Ca, Mg, Mn, Na, K, P, S and Cl. The ash content in the wood tissues (0.2–0.7%) was low compared to the ash content in the bark tissues (1.9–6.4%) and the foliage (2.4–7.7%). The woods’ content of ash-forming elements was consequently low; the highest contents were of Ca (410–1340 ppm) and K (200–1310), followed by Mg (70–290), Mn (15–240) and P (0–350). Present in the wood was also Si (50–190), S (50–200) and Cl (30–110). The bark tissues showed much higher element contents; Ca (4800–19,100 ppm) and K (1600–6400) were the dominating elements, followed by Mg (210–2400), P (210–1200), Mn (110–1100) and S (310–750), but the Cl contents (40–330) were only moderately higher in the bark than in the wood. The young foliage (shoots and deciduous leaves) had the highest K (7100–25,000 ppm), P (1600–5300) and S (1100–2600) contents of all tissues, while the shoots of spruce had the highest Cl contents (820–1360) and its needles the highest Si content (5000–11,300). This paper presented a new approach in fuel characterization: the method excludes the presence of impurities, and focus on different categories of plant tissues. This made it possible to discuss the contents of ash element in a wide spectrum of fuel-types, which are of large importance for the energy production in Finland and Sweden.     

NEXT GENERATION ENGINEERED MATERIALS FOR ULTRA SUPERCRITICAL STEAM TURBINES

正1 ABSTRACT To reduce the effect of global warming on our climate,the levels of CO2emissions should be reduced.One way to do this is to increase the efficiency of electricity production from fossil fuels.This will in turn reduce the amount of CO2emissions for a given power output.Using US practice for efficiency calculations,then a move from a typical US plant running at 37%efficiency to a 760℃/38.5 MPa(1 400/5 580 psi)plant running at 48%efficiency would reduce CO2emissions by 170kg/MW.hr or 25%.     

Contents in Volume 23,2014

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Aerodynamic performance effects of leading-edge geometry in gas-turbine blades

The purpose of this paper is to illustrate the advantages of the direct surface-curvature distribution blade-design method, originally proposed by Korakianitis, for the leading-edge design of turbine blades, and by extension for other types of airfoil shapes. The leading edge shape is critical in the blade design process, and it is quite difficult to completely control with inverse, semi-inverse or other direct-design methods. The blade-design method is briefly reviewed, and then the effort is concentrated on smoothly blending the leading edge shape (circle or ellipse, etc.) with the main part of the blade surface, in a manner that avoids leading-edge flow-disturbance and flow-separation regions. Specifically in the leading edge region we return to the second-order (parabolic) construction line coupled with a revised smoothing equation between the leading-edge shape and the main part of the blade. The Hodson–Dominy blade has been used as an example to show the ability of this blade-design method to remove leading-edge separation bubbles in gas turbine blades and other airfoil shapes that have very sharp changes in curvature near the leading edge. An additional gas turbine blade example has been used to illustrate the ability of this method to design leading edge shapes that avoid leading-edge separation bubbles at off-design conditions. This gas turbine blade example has inlet flow angle 0°, outlet flow angle −64.3°, and tangential lift coefficient 1.045, in a region of parameters where the leading edge shape is critical for the overall blade performance. Computed results at incidences of −10°,   −5°,   +5°,   +10° are used to illustrate the complete removal of leading edge flow-disturbance regions, thus minimizing the possibility of leading-edge separation bubbles, while concurrently minimizing the stagnation pressure drop from inlet to outlet. These results using two difficult example cases of leading edge geometries illustrate the superiority and utility of this blade-design method when compared with other direct or inverse blade-design methods.     

Hydrogen production by steam-gasification of carbonaceous materials using concentrated solar energy – V. Reactor modeling,optimization, and scale-up

A chemical reactor for the steam-gasification of carbonaceous particles (e.g. coal, coke) is considered for using concentrated solar radiation as the energy source of high-temperature process heat. A two-phase reactor model that couples radiative, convective, and conductive heat transfer to the chemical kinetics is applied to optimize the reactor geometrical configuration and operational parameters (feedstock's initial particle size, feeding rates, and solar power input) for maximum reaction extent and solar-to-chemical energy conversion efficiency of a 5 kW prototype reactor and its scale-up to 300 kW. For the 300 kW reactor, complete reaction extent is predicted for an initial feedstock particle size up to 35 μm at residence times of less than 10 s and peak temperatures of 1818 K, yielding high-quality syngas with a calorific content that has been solar-upgraded by 19% over that of the petcoke gasified.     

Assessment methods of material ageing using Sdobyrev''s creep rupture model

The physical aspects of the activation energy, in higher and high temperatures, of the metal creep process were examined. The research results of creep-rupture in a uniaxial stress state and the criterion of creep-rupture in biaxial stress states, at two temperatures, are then presented. For these studies creep-rupture, taking case iron as an example the energy and pseudoenergy activation was determined. For complex stress states the criterion of creep-rupture was taken to be Sdobyrev's, i.e. σ_red = σ₁ β + (1 − β)σ_i, where: σ₁-maximal principal stress, σ_i-stress intensity, β-material constant (at variable temperature β = β(T)). The methods of assessment of the material ageing grade are given in percentages of ageing of new material in the following mechanical properties: 1) creep strength in uniaxial stress state, 2) activation energy in uniaxial stress state, 3) criterion creep strength in complex stress states, 4) activation pseudoenergy in complex stress states. The methods 1) and 3) are the relatively simplest because they result from experimental investigations only at nominal temperature of the structure work, however, for methods 2) and 4) it is necessary to perform the experimental investigations at least at two temperatures.     

Production of hydrogen from sewage biosolids in a continuously fed bioreactor: Effect of hydraulic retention time and sparging

Hydrogen was produced from primary sewage biosolids via mesophilic anaerobic fermentation in a continuously fed bioreactor. Prior to fermentation the sewage biosolids were heated to 70 °C for 1 h to inactivate methanogens and during fermentation a cellulose degrading enzyme was added to improve substrate availability. Hydraulic retention times (HRT) of 18, 24, 36 and 48 h were evaluated for the duration of hydrogen production. Without sparging a hydraulic retention time of 24 h resulted in the longest period of hydrogen production (3 days), during which a hydrogen yield of 21.9 L H₂ kg⁻¹ VS added to the bioreactor was achieved. Methods of preventing the decline of hydrogen production during continuous fermentation were evaluated. Of the techniques evaluated using nitrogen gas to sparge the bioreactor contents proved to be more effective than flushing just the headspace of the bioreactor. Sparging at 0.06 L L min⁻¹ successfully prevented a decline in hydrogen production and resulted in a yield of 27.0  L H₂ kg⁻¹ VS added, over a period of greater than 12 days or 12 HRT. The use of sparging also delayed the build up of acetic acid in the bioreactor, suggesting that it serves to inhibit homoacetogenesis and thus maintain hydrogen production.     

汽轮机数字电液调节系统挂闸异常的技术完善

分析了200MW汽轮机数字电液调节系统在运行中存在的挂闸异常问题,采取了相应的技术处理措施,且运行实践效果良好。     

新型高压共轨ECU升压模块的数字化开发与优化

为了提高喷油器电磁阀的响应速率,提出了一种基于CPLD(复杂可编程逻辑器件)应用于高压共轨ECU的数字升压模块。鉴于该升压电路结构参数多,其升压电压的恢复响应要求高等特征,基于Pspice建立了升压电路的仿真模型,研究了不同电路参数下升压模块的输出特性,全面优化了该升压模块的性能。结果显示,该升压模块的最大转换效率可以达90%以上。在柴油发动机上对ECU的试验表明,升压电压最大波动不超过10%,其恢复时间仅为1.3ms,功率管最大温升仅为41℃,满足整机运行范围内ECU的需求。     

Trace metal chemistry and silicification of microorganisms in geothermal sinter, Taupo Volcanic Zone, New Zealand

As part of a pilot study investigating the role of microorganisms in the immobilisation of As, Sb, B, Tl and Hg, the inorganic geochemistry of seven different active sinter deposits and their contact fluids were characterised. A comprehensive series of sequential extractions for a suite of trace elements was carried out on siliceous sinter and a mixed silica-carbonate sinter. The extractions showed whether metals were loosely exchangeable or bound to carbonate, oxide, organic or crystalline fractions. Hyperthermophilic microbial communities associated with sinters deposited from high temperature (92–94°C) fluids at a variety of geothermal sources were investigated using SEM. The rapidity and style of silicification of the hyperthermophiles can be correlated with the dissolved silica content of the fluid. Although high concentrations of Hg and Tl were found associated with the organic fraction of the sinters, there was no evidence to suggest that any of the heavy metals were associated preferentially with the hyperthermophiles at the high temperature (92–94°C) ends of the terrestrial thermal spring ecosystems studied.