某市中心地区无负压供水模拟研究

无负压供水技术作为二次供水的新型模式,节能效果显著,但在应用过程中管网压力稳定性的影响尚未明确,可能存在供水水压不稳定、供水不足或爆管的问题.应用EPANET软件模拟某市中心给水管网进行无负压供水,结果发现无负压设备工作时,无保护情况下无负压供水水量、设备接入管径、设备之间的距离都会对管网水压的变化产生一定的影响.当无...     

空气源热泵热水器夏季吸气压力过高的解决方案

随着环境的变化,热泵热水机将出现冬季结霜,夏季出现低压压力过高的现象。文章对风冷热泵热水机组在运行时压力、温度变化情况进行分析,对机组制热量偏离设计要求的原因进行了分析,并给出三种合理的方法,最后得出最佳的方案。结合实验结果证明了经过改进后稳定性得到改善。     

转叶式螺旋流消能装置消能效果试验探究

为解决高压引起的有压管道输水系统损害的问题,提出了有压管道的转叶式螺旋流消能方法,即将消能装置的三片转叶向同一方向按一定角度进行扭转,形成螺旋式孔口,强制通过孔口的水流发生旋转,形成螺旋流,从而使管道中水流压力大幅降低,达到管道消能降压的目的。试验分析表明,该装置结构简单,消能效果较好,可广泛应用于水利工程的长距离输水系统。     

微狭缝中甲烷吸附特性的分子动力学模拟

为了研究甲烷在纳米尺度狭缝中的吸附特性,采用分子动力学模拟的方法研究了温度、压力以及狭缝表面的水滴对甲烷吸附情况的影响。研究表明:降低温度和增大压力均能使吸附相的密度增大、吸附层的层数增加、吸附区扩大;升高压力将使吸附作用减弱,温度较低时,升高温度将使吸附作用增强,温度较高时,升高温度将使吸附强度减弱;狭缝表面存在水滴时,狭缝对甲烷的吸附作用被明显削弱。     

Economic evaluation of reverse osmosis desalination system coupled with tidal energy

A reverse osmosis (RO) desalination system coupled with tidal energy is proposed. The mechanical energy produced by the tidal energy through hydraulic turbine is directly used to drive the RO unit. The system performances and the water cost of the conventional and tidal energy RO systems are compared. It is found that the proposed tidal energy RO system can save water cost in the range of 31.0%-41.7% in comparison with the conventional RO system. There is an optimum feed pressure that leads to the lowest water cost. The tidal RO system can save more costs at a high feed pressure or a high water recovery rate. The optimum feed pressure of the tidal energy RO system is higher than that of the conventional RO system. The longer lifetime of the tidal energy RO system can save even more water cost. When the site development cost rate is lower than 40%, the water cost of the tidal energy RO system will be lower than that of the conventional RO system. The proposed technology will be an effective alternative desalination method in the future.     

三峡库区奉节县新城植物油厂滑坡地下水动力场分析

三峡库区奉节县新城植物油厂滑坡大多处于三峡水库水位以下,库水位变化对边坡(滑坡)稳定性影响较大,尤其在库水位骤降时,坡体内将产生较大的动水压力,不利于边坡稳定.采用数值模拟方法模拟了边坡地下水渗流场.结果表明,库水位由175 m骤降至145 m时,植物油厂滑坡所受动水压力远高于正常蓄水位时所受的动水压力;采取降低地下水位的工程措施后,有效降低了正常蓄水位下边坡内的动水压力,为科学治理滑坡提供借鉴.     

Hydrogen pressure drop characteristics in a fuel cell stack

Research on hydrogen pressure characteristics was performed for a fuel cell stack to supply a rule of hydrogen pressure drop for flooding diagnostic systems. Some experiments on the hydrogen pressure drop in various operating pressure, temperature, flowrate and stack current conditions were carried out, and hydrodynamic calculation was managed to compare with the experiment results. Results show that the hydrogen pressure drop is strongly affected by liquid water content in the flow channel of fuel cells, and it is not in normal relation with flowrate when the stoichiometric ratio is inconstant. The total pressure drop can be calculated by a frictional pressure loss formula accurately, relating with mixture viscosity, stack temperature, operating pressure, stoichiometric ratio and stack current. The pressure drop characteristics will be useful for predicting liquid water flooding in fuel cell stacks before flow channels have been jammed as a diagnostic tool in electric control systems.     

有再循环系统的超音速两相流升压性能的研究

介绍了具有再循环系统的超音速汽液两相流升压装置,并对该装置的各种性能进行了理论计算及实验研究。结果表明,在进口蒸汽参数一定的情况下,升压性能随给水温度的升高而降低,随出口流量的增加而提高;出口水温随出口流量的增加而降低,随给水温度的提高而升高。该装置不仅保留了原有的出口压力自适应特性,而且具有出口流量自适应特性。     

柴油机燃用掺水燃料的燃烧特性及其节油机理分析

通过计算对掺水的综合效果进行了分析,结果表明：1）与纯柴油相比,掺水燃料喷射液体总量增多,存在时间变长,液雾卷吸能力增强,能更加充分地与空气混合使燃烧完全,在上止点附近热量释放集中使柴油机做功能力增强,是提高燃烧效率的主要原因之一;2）燃料中水蒸发做功可以部分弥补由于水分蒸发使温度和压力下降所造成的不利影响而提高功率,这是节油的第2个重要原因;3）掺水后尽管排气带走的水蒸汽潜热会增加,但是同时排气最高温度与平均温度都有所下降,排气损失反而减小,这是节油的第3个重要原因。     

波浪能海水淡化的应用研究

简要介绍了"十五"期间在广东省汕尾市研建的波浪能海水淡化系统的组成和工作原理.为了验证波浪能海水淡化装置运行的实用性和可靠性,在国内外波浪能海水淡化研究的基础上,对汕尾波浪能海水淡化装置进行了不同操作压力情况下的试验研究.研究结果表明,随着高压海水压力的升高,产出淡水量会明显增加,淡水质量提高,装置产出淡水的能耗较低.     

Water and pressure effects on a single PEM fuel cell

A fuel cell is a promising energy conversion system that will eventually become the first-choice for producing power because of its clean or zero-emission nature. A steady-state, two-dimensional mathematical model with pressure and phase change effects for a single PEM fuel cell was developed to illustrate the inlet humidification and pressure effects on proton exchange membrane (PEM) fuel cell performance. This model considers the transport of species along the channel as well as water transfer through the membrane. It can be used to predict trends of the following parameters along the fuel cell channels: mole number of liquid water and water vapor, pressure, temperature, density, viscosity, velocity, saturation pressure, pressure drop, vapor mole fraction, volume flow rate, required pumping power and current density.     

Experimental Investigation of Two-Phase Flow Instabilities in Low-Mass-Flux Water Wall Tubes of Supercritical Circular Fluidized Bed Boilers

For the purpose of disclosing the hydrodynamic flow characteristics, under the low mass velocity conditions of the 600-MW supercritical circular fluidized beds boilers, experimental studies on instability of two-phase flow in parallel vertical internally ribbed tubes were conducted. Two kinds of oscillations, pressure-drop oscillation and density-wave oscillation, have been observed. In the range of test parameters the effects of pressure, mass flux, inlet subcooling, compressible volume, exit throttle, and asymmetric heat flux to the two-phase instability were explored and analyzed. Indications from experiment data are: To increase system pressure, mass flux and inlet subcooling will intensify the stability of water wall tubes. To increase exit throttle will intensify the instability of water wall tubes. The bounding pressure and bounding mass flux of density-wave oscillations and the bounding pressure of pressure-drop oscillation have been obtained. Based on the results of testing and using a homogeneous model, the threshold relational expressions of instability were obtained. The results may be used for the design and safe operation of parallel vertical rifled water wall tubes of supercritical circular fluidized beds boilers.     

Unsteady performance and thermodynamic analysis of aero-engine compressor at different water ingestion conditions

Aero-engine compressor is seriously threatened by the ingestion of liquid water. This article aims to deeply study the influences of different water contents and droplet diameters on the unsteady performance and thermodynamic parameters of compressor through frequency spectrum analysis. The accuracy of numerical calculation for compressor performance is verified by experimental data. Results show that the compression performance will be reduced and the unsteady fluctuations inside compressor will be aggravated after water ingestion. For some important parameters, such as mass flow rate, total pressure and temperature ratio, as well as efficiency, their main frequencies are changed from the original blade passing frequency to the rotor passing frequency (RPF), and their amplitudes are also significantly amplified. The working point of compressor will experience the nonoptimal state with large amplitude and period for a long time, which is not conducive to the stable operation of the compressor. Moreover, within the range of 2% to 8% water contents and 50 to 150 μm droplet diameters, the fluctuation amplitude is correspondingly exacerbated with the increase of water content or droplet size, but its main frequency is maintained at RPF. Particularly, the tip clearance is the most sensitive region affected by water ingestion where the fluctuations of static pressure and temperature are the largest. The point that water content has a greater influence on the performance fluctuation of compressor is also confirmed in this article.     

中国煤炭基地水与能源协同发展评估

鉴于中国煤电生产主要集中于黄河中、上游和西北内陆河流域,水资源极为紧缺,扩大火电规模势必加重当地的水资源压力,进而带来严重的生态环境问题。基于全国14大煤炭基地的发展规划和最严格水资源管理制度的用水总量控制指标,分析2020年煤炭基地的火电发展是否超出当地的水资源支撑能力。结果显示,到2020年14大煤炭基地新增燃煤发电的用水量为19.32×108 m3,煤炭基地的新增可供水资源量为45×108 m3,大部分煤炭基地可通过新建水源工程、水源置换等途径满足需求,但神东、晋东、黄陇、河南等四大煤炭基地的新增可供水量不能满足新增煤电用水需求,需要根据当地水资源情况合理控制火电资源开发,该结论为实现水与能源的协同管理提供了依据。     

超临界水葡萄糖制氢中的多元气液相平衡

1引言生物质在超临界水中气化产生氢气成为一种具有发展前景的新能源技术。在超过水的临界点条件下,水的氧化性变强,生物质迅速水解并产生大量的气体产物:CO2、H2、CH4、CO和H2O等[1]。目前许多国家相继展开相关研究,研究葡萄糖或者纤维素在不同反应条件下的气体产物情况[2],确     

我国北方重点煤电基地发展伴生的水资源压力分析

鉴于煤电基地的快速扩张会给区域水资源保障带来极大的压力,运用生命周期评价方法计算了2006～2015年我国北方九大煤电基地煤炭生产和火力发电的水足迹,提出了虚拟水流出伴生的水资源压力指数,评价了煤电虚拟水外送给当地水资源系统造成的压力,分析了未来煤电基地发展的水资源适配性。结果表明,九大煤电基地煤炭生产和火力发电的年均水足迹为13.4×108 m3,占当地淡水资源可用总量的22.8%,煤炭和电力外送伴生的虚拟水流出总量持续增加,增长率为3 031.9×104 m3/a,近10年来,水资源压力指数呈现上升趋势,六个煤电基地达到中度压力等级,造成巨大的水资源压力;2020年,九大煤电基地总水足迹为15.7×108 m3,区域可供给煤电基地的水资源量为11.9×108 m3,只有晋北和准东的水资源满足未来基地扩张需要;晋中、晋东、陕北和鄂尔多斯通过优化调度等增加区域可供水量后可以满足未来生产需要;宁东和哈密发展所需的水资源与供给能力严重不适配,应调整发展战略,保障基地用水安全。     

小浪底工程高压闸门压紧式止水粘弹性力学性能试验研究

高压闸门止水橡皮属子粘弹性材料，在长期荷载作用下其力学性能会发生怎样的变化是设计部门极为关心的问题。本文结合小浪底工程高压闸门止水的实际工况，对其拟采用的止水橡皮进行了长达一年多的蠕变试验观测，分析研究试验成果，导出了蠕变方程及应力松弛方程，探讨了上水橡皮的粘弹性力学特性，为工程设计提供参考。     

萨尔图油田南二区东部基础井网分压注水节能方式探讨

萨尔图油田南二区东部基础井网具有较好的代表性。区块内有萨葡、高台子、过渡带基础等多个层系,其中高台子平均油压最高,过渡带基础平均油压次之,萨葡纯油区平均油压最低,具有分压注水节能潜力。根据理论计算,注水站消除泵管压差、提高泵效及管网消除管井压差的节能潜力每年合计约1732×10^4kW·h,其中井口压差的节能潜力最大,占79.4%。区块内注水压力高于区块平均注水压力10%以上的注水井共计89口,注水压力低于区块平均注水压力10%以上的注水井共计91口。由于注水量较高、注水支线管径较细、管线较长等原因,导致注水支线阻力偏大;还有部分管线由于腐蚀结垢,沿程阻力增大。建议对注水系统的注水井、管网、注水站均进行改造,综合调整,降低井口压差。开发中暂不考虑开发调压措施对注水井节能效果的影响。根据各区块推荐工作压力采取节能措施,南二区东部基础井网节能优化总投资1405万元,预计年节电1268×10^4kW·h,年节约电费695万元。     

进水温度对汽液两相流激波升压特性影响的实验研究

采用实验方法研究了进水温度对汽液两相流激波升压特性的影响。实验采用供热机组的工业抽汽;由蒸汽喷嘴,混合腔及相应的阀门和管道组成汽液两相流激波升压装置,实验发现存在一个临界进水温度,当水温度大于该临界值后,汽液两相流激波升压装置的升压特性将严重下降。     

水工隧洞素混凝土衬砌开裂过程弹性分析

根据弹性力学理论推导了水工有压隧洞素混凝土衬砌开裂时内水压力公式,给出了开裂半径与内水压力关系式,分析了素混凝土衬砌在不同开裂阶段时的结构应力.由计算结果发现,一旦开裂裂缝就会很快贯穿衬砌,裂缝贯穿衬砌前内水压力主要由衬砌承担.