静止液体中浸没垂直导管口气泡形成实验

利用高速摄像技术研究气流通过浸没垂直导管口在液体中形成气泡的机理及其行为规律,分析导管内径、气体流量、导管口浸没深度和导管外径对气泡脱离直径的影响。结果表明:在导管内径分别为7、10和14 mm,气体流量在0~450 mL/s的条件下,气泡脱离直径随导管内径和气体流量的增加而增大;在浸没深度为0.05~1 m的条件下,导管口浸没深度对气泡脱离直径的影响很小可以忽略;当气体流量在100 mL/s以上,导管内径为10 mm、导管外径为14~26 mm时,随着导管外径的增加,气泡脱离直径减小。     

The effect of bottom reflectivity on the performance of a solar pond

The reflectivity of the bottom of a solar pond increases on account of the accumulation of dirt or the presence of undissolved salt. The effect of the reflection of the solar radiation at the bottom of the pond on the seasonal performance of the pond has been studied using a three zone model. The spectral reflectivity of dirt and common salt were measured in the laboratory and used in the analysis. The results obtained from the analysis show that the presence of dirt at the bottom of the pond does not affect the performance of the pond substantially. On the other hand, the presence of undissolved salt at the bottom of the pond results in substantial deterioration of the pond performance.     

基于Scada数据的风电场改扩建数值模拟研究

风电技术发展速度远高于风电场衰老速度,随着技术的不断进步,多数风电场可以进行有针对性的改扩建,并以此来最大化利用已有风电场内风能资源,增加经济收益。根据已建成风电场运行特性对风电场进行精细化设计是已建成风电场改扩建的关键。针对已建成风电场的Scada数据进行统计分析,了解风电场风能资源特征及运行特性,随后根据风电场风资源特征及运行特性,建立CFD模型,并通过对比风电场模型与风电场各机位点实际测风数据的误差,确认风电场CFD模型的精确程度,最后应用修正为自由流的已建机位点机舱测风数据进行模型修正,达到精准模拟风电场的要求,并以此来确定风电场改扩建排布方案,确保风电场发电量。工程实例的数据与结果分析表明了该方法的可行性。     

UASB处理养猪废水条件下进水浓度对污泥颗粒化的影响

通过进行废水浓度变化对污泥颗粒化影响的试验,发现：颗粒直径随进水浓度的上升而增大,受传质过程所能进入颗粒内部的营养量所控制.应根据COD去除率的情况适时提高进水浓度,及时地随微生物数量的增加补充营养,促进污泥颗粒化;避免了浓度变化太快引起细菌生长过快,污泥结构松散,沉降性能下降及COD去除率和产气率降低.     

Heat Transfer Coefficient from the Sheet-Piped Light-Absorbing Panels of the Flat-Plate Solar Water-Heating Collectors to the Heat Transfer Fluid in Their Heat-Removing Channels

It has been proposed to introduce a new parameter into the practice of the heat calculation and testing of the flat-plate solar water-heating collectors (FSWHCs)—the coefficient of heat transfer from the light-absorbing panel (LAP) to the heat transfer fluid in its internal heat-exchange channels (HECs) reduced to the unit area of the frontal surface of their cases. The mechanism of the formation of this parameter is studied, the design expression is derived, and a practical example of the calculation to define its value is performed. The structures of the flowing LAPs of a sheet-piped thin parallelepiped form are selected as the objects of the investigation. The reliability of the results of the investigations is proved by comparing the values of the specific (relative to the area unit of the frontal surface of the case) heating efficiency of the collector obtained based on the various formulas.     

背压微增条件下汽轮机出力的简化计算

为获得准确的背压微增条件下汽轮机出力特性,分析背压变化时机组热力系统变工况实际运行特性,基于对热力系统的合理假设和相关经验公式的应用,在忽略汽轮机本体结构和内部级组热力参数变化的前提下,提出了汽轮机背压微增出力特性的简化计算方法。以某300 MW湿冷机组和660 MW间冷机组的变背压工况性能试验数据为例进行验证,结果表明,简化计算获得的微增出力特性曲线的斜率和试验结果偏差在3%以内,是一种行之有效的背压微增出力特性高精度计算方法。     

Transition strategy of the transportation energy and powertrain in China

The problems of the transportation energy and environment are the major challenges faced globally in the 21st century and are especially serious for China. The future 20 years is the strategic opportunity period of the transition of the transportation energy and powertrain system for China. The greatest characteristics of hydrogen economy lie in its diversity of the primary energy source, the unification of energy carrier and the greening of energy transformation. Development of hydrogen energy transportation powertrain system is suitable for China from the views of the situation of Chinese resources and energy sources, the urban and rural layouts, the superiority of later development and the successful practices of clean cars and electric vehicle development projects. The transition of the transportation energy powertrain system includes three parts: the transition of the energy structure, the transition of the powertrain system and the transition of the fuel infrastructure. The technical pathways of energy powertrain system transition includes expending the use of gaseous fuel to prompt the multiform of the transportation energy and to prepare for the transition of the infrastructure simultaneously, developing and promoting the hybrid technology to solve the current energy and environment problems and to prepare for the transition of powertrain system, and focusing on the research and development and demonstration of fuel cell vehicles and the hydrogen energy technology to prompt the earlier formation of the market of fuel cell vehicles. The goal in the near and medium term of transition is to reduce the fuel consumption by 100 million ton in 2020 by substituting and saving, and the long-term goal is to setup the infrastructure of hydrogen and fuel cell vehicle as the main one replacing the petroleum internal combustion engine vehicle. In order to realize the strategic goals of the transition, the four-phases strategic periods and research and development activities are discussed and proposed.     

抽水蓄能电站甩负荷球阀动水关闭过程流固耦合研究

抽水蓄能电站甩负荷过渡过程中,内部流场与外部结构双向作用,对球阀安全运行造成不良影响。为探讨抽水蓄能电站甩负荷工况球阀动态关闭过程中流场演变对球阀关键部件的影响,基于流固耦合理论,建立球阀系统离散角度有限元仿真模型,以多角度结构分析近似模拟球阀在动水关闭过程中的结构瞬态过程,反映球阀流道的分布特点及薄弱环节的数据特征。为此,先对某抽水蓄能电站进行数值模拟,提取甩负荷过渡过程关键参数,根据仿真结果确定球阀流场边界条件;然后计算球阀流道内流场压力与速度分布;最后基于流场仿真结果建立球阀结构流固耦合模型,求解球阀瞬态过程结构强度相关参数分布。结果表明,甩负荷过渡过程中,在水流三维瞬变流动的影响下,球阀结构的应力分布具有明显规律性,工作密封与检修密封的过流面积突变,导致应力极大值出现在基座与枢轴部位。流场作用于球阀壁面的变形量叠加,球阀总变形量呈现由上游至下游逐渐递增的趋势。     

The influence of ibuprofen ((RS)-2-[4-(2-methylpropyl)phenyl]propanoic acid) additive on the structure ordering of coals of different rank during the process of co-pyrolysis

The mechanism of influence of the addition of 2 wt% of the expired pharmaceuticals (EPs) containing 80% of ibuprofen ((RS)-2-[4-(2-methylpropyl)phenyl]propanoic acid) on the transformation of the ordered structure of the three coals of different ranks was studied. The co-pyrolysates of coals with EP additive were studied with the method of X-ray diffraction (ХRD) and scanning electron microscopy (SEM). It was stated that the addition of 2 wt% of EP to all coals under study increases the intra-crystalline ordering. Under the influence of the addition of 2 wt% of EP at the stage of swollen grains of the co-pyrolysates of all coals, the amount of carbon ordered in crystallites decreases. In the co-pyrolysates of lower-rank coals (LRC) and higher-rank coals (HRC) under the influence of this additive at the stage of coke, the amount of the ordered phase decreases compared to the pyrolysates. In the co-pyrolysate of a medium-rank coal (MRC), the degree of ordering of coke does not change compared to the coke from single coal.     

Analysis of the influence of the current-voltage characteristics of the voltage rectifiers on the static characteristics of hydrogen electrolyzer load

Traditionally, the determination of static load characteristics is one of the main stages in the preparation of a design model of an electric power system. It is especially important to correctly take into account energy-intensive industries, which make a huge contribution to the formation of these characteristics. In particular, the increased interest in hydrogen technologies observed in the world as one of the most promising high-tech areas of energy development, and an increase in the share of the installed capacity of generation units based on renewable energy sources determine the prospects for the development of hydrogen production by water electrolysis. Accordingly, a significant increase in the scale of application of hydrogen technologies, in particular, in accordance with the “Hydrogen Strategy for Climatically Neutral Europe”, the European Commission for the production of “green” hydrogen, determines the task of forming correct mathematical models of these devices in terms planning of modes, analyzing their impact on the parameters of electric power systems. Determination of static load characteristics on the basis of a physical experiment will not allow obtaining a characteristic with a significant increase or decrease in voltage in the node of the electric power system, which occur only in emergency modes of operation of the power system. Therefore, it seems relevant to analyze and determine the electrical characteristics of consumers by mathematical modeling of the power circuit. This article presents the results of correcting the static load characteristic of a high-power electrolyzer used in the production of hydrogen. The analysis of these results obtained with the MATLAB software is carried out using least squares regression to procure polynomial functions of the static load characteristics. According to this analysis, the static characteristics of the considered electrolyzer, being close to linear within the control range, outside the control range acquire parabolic dependences of active and reactive power on voltage. The static load characteristics of the installation are determined by the parameters of the power circuit and the current-voltage characteristic of the rectifiers displacing the vertices of the parabolas from the origin, which should be taken into account to increase the reliability of the design scheme.     

户外光伏组件背板外层材料的老化研究

针对在户外运行了6年的光伏组件背板外层材料进行了老化测试研究.将光伏组件背板外层材料划分为3个不同的分析测试区域,即太阳电池中心区域、太阳电池边缘区域及光伏组件边缘区域,通过外层材料的厚度、反射率、光泽度、耐磨性、表面微观形貌等参数评估户外光伏组件背板外层材料的老化程度.研究表明,不同分析测试区域的光伏组件背板外层材料...     

热网管道保温与热化发电之间的相互关系分析

热网管道的保温设计，尤其是长距离热风管道的保温设计，对热网管道设计成功与否显得十分重要。而热电厂供热参数的高低不仅与经济发电相关，更主要的是跟热网的保温、散热损失有关。一般热能工程设计手册中，仅有经济厚度等计算方法介绍，而没有考虑保温散热损失对热化发电的影响。这对集中供热来说是合理的，但对于热电联产来说，似乎有点欠缺。本文试图通过实例分析计算，来说明保温厚度、散热损失、热化发电的相互关系。以期重视热网管道的保温设计、施工，正确处理经济厚度与热化发电的联系，进一步降低消耗，节约能源。     

State of the art of the virtual utility: the smart distributed generation network

The world of energy has lately experienced a revolution, and new rules are being defined. The climate change produced by the greenhouse gases, the inefficiency of the energy system or the lack of power supply infrastructure in most of the poor countries, the liberalization of the energy market and the development of new technologies in the field of distributed generation (DG) are the key factors of this revolution. It seems clear that the solution at the moment is the DG. The advantage of DG is the energy generation close to the demand point. It means that DG can lower costs, reduce emissions, or expand the energy options of the consumers. DG may add redundancy that increases grid security even while powering emergency lighting or other critical systems and reduces power losses in the electricity distribution. After the development of the different DG and high efficiency technologies, such as co‐generation and tri‐generation, the next step in the DG world is the interconnection of different small distributed generation facilities which act together in a DG network as a large power plant controlled by a centralized energy management system (EMS). The main aim of the EMS is to reach the targets of low emissions and high efficiency. The EMS gives priority to renewable energy sources instead of the use of fossil fuels. This new concept of energy infrastructure is referred to as virtual utility (VU). The VU can be defined as a new model of energy infrastructure which consists of integrating different kind of distributed generation utilities in an energy (electricity and heat) generation network controlled by a central energy management system (EMS). The electricity production in the network is subordinated to the heat necessity of every user. The thermal energy is consumed on site; the electricity is generated and distributed in the entire network. The network is composed of one centralized control with the EMS and different clusters of distributed generation utilities and heat storage tanks. Each of these clusters is controlled by a local management station (LMS). Every LMS has information about the requirements (heat, cold and electricity) of the users connected to its cluster and the state of the utilities and water level of the storage tanks in its cluster. The EMS receives the information from the LMSs and sets the electricity input or output of every cluster in the network. With the information ordered by the EMS, the LMS set the run or stand‐by of the utilities of its cluster. The benefits of the VU are the optimization of the utilization yield of the whole network, the high reliability of the electricity production, the complete control of the network for achieving the main aim of the EMS, the high velocity for assuming quick changes in the demand of the system and high integration of renewable energy sources, plus the advantages of the DG. This paper indicates the state of the art of the VU concept, analyses the projects that are being developed in this field and considers the future of the VU concept. Copyright © 2004 John Wiley & Sons, Ltd.     

管道末端水击压力计算及误区分析

引水系统的管道参数不同会导致管道末端水击压力波动形态差异较大,在工程仿真计算时得到的管道末端压力变化曲线难以校验。为得到管道末端压力波动曲线,首先结合经典的水击分类图,分析了引用传统水击计算方法时存在的误区。其次,从水击经典理论中的阀门端压力升高方程组出发,推导出各相水击压力升高值的通用形式,得到管道末端水压的简化计算公式,公式表明管道末端阀门开度是影响管道末端水压变化形态的重要因素。最后,利用数值仿真验证所提计算方法的可行性。结果表明,提出的管道末端水压简化计算方法与特征线法得到的压力变化曲线相似度较高,且表现出水压波动形态在管道末端阀门不同初始开度下的变化规律,方法简单实用。     

基于输电线路垂直档距变化特征的等值覆冰厚度模型研究

针对电网防冰抗冰各业务的具体需求及现有覆冰监测终端受环境的影响使得多个测量值不够准确,从而增加架空线覆冰厚度观测值误差的问题,利用覆冰监测终端历史拉力值、气象因子测量数据,经过对历史拉力值数据合理的质量控制,采用相对值方法并结合实际测量技术手段,建立了考虑线路设计冰厚、垂直档距实时变化特征的更加精确的输电线路等值覆冰厚度计算模型,用于模拟两个冰期内线路等值覆冰厚度,并与实际观测结果进行对比。结果表明,AB相、地线垂直档距随覆冰厚度均呈非线性变化趋势,总体呈现出随覆冰厚度的增加而逐渐减小的变化趋势,且地线变化幅度大于AB相线;线路等值覆冰厚度与监测终端拉力值呈正相关性关系,计算出的线路等值覆冰厚度与同期的气象因子覆冰条件相一致,且模拟结果与实际观测结果误差较小。     

喷油器喷嘴结构参数对空化效应的影响

喷油器喷嘴内部的燃油的流动和空化直接影响燃油的喷射,又可造成喷嘴空蚀。基于不可压缩流体体积函数(VOF)多相流模型,模拟喷油器完整喷射周期内的燃油流动和空化特性,获得喷嘴空化形成及发展的关键区域和影响空化效应的关键结构参数,并分析其对流场及空化特性的影响规律。结果表明：较小针阀升程时,在针阀锥形表面台阶和喷孔下边缘位置处发生明显空化现象,当升程增加,空化集中分布在喷孔位置处,从倒圆处开始诱发,逐渐向下游延伸;针阀台阶夹角增大使得针阀表面台阶处和喷孔下缘的前部的局部空化增强,穴蚀更严重,且燃油流量减小,通过增大针阀座倒圆半径和喷孔直径锥度系数可有效地改善喷孔局部空化程度。     

The effects of the cathode flooding on the transient responses of a PEM fuel cell

This study investigates the effects of the flooding of the gas diffusion layer (GDL), as a result of liquid water accumulation, on the performance of a proton exchange membrane fuel cell (PEMFC). The transient profiles of the current generated by the cell are obtained using the numerical resolution of the transport equation for the oxygen molar concentration in the unsteady state. The dynamics of the system are captured through the reduction of the effective porosity of the GDL by the liquid water which accumulates in the void space of the GDL. The effects of the GDL porosity, GDL thickness and mass transfer at the GDL–gas channel interface on the evolution with time of the averaged current density are reported. The effects of the current collector rib on the evolution of the molar concentration of oxygen are also examined in detail.     

烧失量法测量循环流化床锅炉飞灰碳的系统误差

1前言飞灰的可燃碳含量决定了其在建材方面的应用范围。通常用烧失量(LOI:Loss-On-Ignition)来表征粉煤灰可燃碳含量的大小。例如我国在GBJI46-90,GBI596-91和FGJ28-86等标准中规定,用烧失量表征的可燃碳含量小于飞灰总质量5%的飞灰为I级灰,在5%~8%之间的为II级灰,在8%~15%之间     

分馏与吸收稳定系统的关联性分析及优化

由于原料性质不断"变重",影响了长庆石化公司1.4Mt/a重油催化裂化装置分馏与吸收稳定系统的平稳操作。对分馏与吸收稳定系统主要的关联性操作,即分馏塔顶的富气和粗汽油作为吸收塔进料的单向关联、分馏一中回流与稳定塔底温度的双向关联、轻柴油进再吸收塔与富吸收油返分馏塔的双向关联进行了分析,提出了优化措施建议:应适时调整补充吸收剂的量,使之与粗汽油的量之比保持在0.7～1.3的范围内;在减渣进料加工量为110t/h的工况下,将补充吸收剂流量控制在50t/h;稳定塔底重沸器取热量跟踪温度控制应尽快投用;将热量换算更换为流量换算;对一中和稳定塔底的换热流程进行优化;在处理量变化的情况下,应随着贫气量的变化,适时调节贫吸收剂的流量,保证再吸收塔的吸收效果;贫吸收油可改用分馏塔顶顶循油。     

露顶式弧门液压启闭机上铰点合理位置算法

露顶式弧门广泛应用于水电站表孔及泄水闸等工程部位,其液压启闭机油缸上铰点的位置对启闭机的容量和行程有很大影响.根据典型露顶式弧门液压启闭机的布置型式,建立了上铰点位置的计算模型,并采用几何解析方法得到了确定油缸上铰点合理位置的算法.在工程实践中,运用Mathcad软件编程,将本算法应用于某水电站表孔弧门液压启闭机的设计,既优化了油缸参数,节省了投资,同时又减少了设计工作量.