高背压发电用柴油机动态过程建模及仿真

在稳态工况仿真的基础上,建立了船用高背压涡轮增压柴油机动态过程的非线性仿真模型,并开发了仿真软件,对稳态和动态过程进行仿真。通过与试验数据对比,该仿真模型具有较高的精度,可以用于研究高背压发电用柴油机在动态工况下的运行特性。     

Numerical Study of Spray Dispersion in a Premixing Chamber for Low-NOx Engines

IntroductionThe present work is devoted to particle dispersionin confined two-phase turbulent jets, which has become amajor domain of research attracting increasingly interestand with challenging fundamental aspects. Describingthe motion of a dispersed phase is complex and is ofgreat interest in several practical systems. Theapplications that require the solution of this problem areas varied as the dispersion of passive pollutant particlesin the atmosphere to combustion systems with dispersing…     

Calculation of CO2, CH4 and H2S solubilities in aqueous electrolyte solution at high pressure and high temperature

This paper reports an investigation into the characterisation of liquid-vapor electrolyte solutions at high pressure and high temperature,A procedure to enable calculations of methane,carbon dioxide and hydrogen sulphide solubilities in brines(0-6m.) for temperature from 25 to 350℃ and for pressures from 1 to 1800 bar is presented.The model is based on Helgeson,Kirkham and Flowers modified equations of state(HKF)and on the semi-empirical interaction model introduced by Pitzer,HKF modified equations of state are used to calculate the reference fugacity of gas species,and the Pitzer ionic interaction model is used to calculate the activity coefficient of dissolved species(i.e.ionic or neutral).The efficiency of the combination of the two models is confirmed by several comparisons with data in the literature.     

基于纹影法的高压柴油喷雾反射激波特性

使用某型柴油机燃烧室的截面拉伸模型,在其内部进行常温下的高压柴油喷射,通过纹影法研究诱导激波撞壁反射之后本身的运动特性以及对喷雾发展造成的影响,并与无燃烧室模型的试验数据对比.结果表明:诱导激波撞壁反射按照时间发展顺序主要分为3个类别;其中第一类反射激波主要影响喷雾横向扩散,会造成喷雾锥角相较于无激波工况减小,并且其抑制效果与喷射压力及背景压力均呈反比,同时,第一类反射激波两翼的运动不对称性也会造成喷雾明显偏离轴心,其偏轴程度与背景压力呈反比,与喷射压力无关.     

水电厂高压气系统集成监测策略

辅助系统运行可靠性将直接影响水电厂的安全经济运行,有必要对辅助系统的运行状态进行实时在线监测。基于水电厂高压气系统工作原理,总结了水电厂高压气机异常启、停与相应故障对应关系,提出了高压气系统集成监测策略,并利用梯级水电厂群远程集控系统提供的海量数据源,建立了水电厂高压气系统的远程分析与故障诊断平台,成功诊断出水电厂高压气系统漏气故障。     

高含水采油期油气水混输水平管路压降试验研究

随着油田开发的不断深入,大庆油田原油综合含水不断提高,许多区块的水的质量分数已达到90%,有的甚至达到或超过了95%.由于缺乏对特高含水采油期油气水混输水平管路压降的研究,制约了高含水采油期不加热集输规模的扩大.针对大庆采油六厂高含水采油期油气水混输管道,设计了一套试验装置,试验研究高含水采油期油气水混输水平管路压降.对试验测试数据进行了回归处理及分析,得出了百米压降及油气水三相压降与油水两相压降的关系.     

Mathematical modeling of gasification of high‐ash Indian coals in moving bed gasification system

Simulation of gasification of high‐ash Indian coal in an updraft moving bed gasification system is presented in this paper. A steady one‐dimensional numerical model, which takes into account of drying, devolatilization, combustion and gasification processes, is used to solve the mass and energy balances in the gasification system. The results from the model have been validated against the experimental data available in literature for various types of coals. The predicted product gas composition, its calorific value and the exit temperature are in agreement with the reported results. The validated model is used to study the effect of input parameters such as oxygen content in air stream, steam flow rates and the pressure of the gasification system. Results indicate that the value of oxygen mole fraction around 0.42 in the oxidizer stream can provide optimum performance in oxygen‐based gasification systems. There is a range of steam‐to‐coal ratio that is dependent on the oxygen content in oxidizer stream. For air‐based systems, this value is around 0.4 and for oxygen‐based systems it is 1.5. The gasification performance improves with operating pressure significantly. An operating pressure of around 8 bar and higher, based on the application, can be used for achieving the required performance with high‐ash coals. The model is useful for predicting the performance of high‐ash Indian coals in a moving bed gasification system under different operating parameters. Copyright © 2013 John Wiley & Sons, Ltd.     

高压共轨柴油机喷射系统参数优化方法研究

提出了基于代理模型的高压共轨柴油机喷射系统参数优化方法。首先通过试验数据对CFD软件中的喷雾燃烧模型进行了校核和验证,然后利用中心复合法进行试验设计,并用CFD软件进行仿真计算试验,由此建立响应面代理模型,最后对此模型进行全局寻优,得出了最优的喷射系统参数。     

共轨管压力波动对喷油率影响的仿真研究

利用仿真软件GT-Suit构建了高压共轨燃油喷射系统的仿真模型,分析了不同长径比下的共轨管内的压力波动规律、平均压力波动规律、喷油压力波动规律,进而分析了对喷油率的影响.通过仿真数据对比,在共轨管长为310 mm、长径比为16时,可使喷油系统的稳定性最优.     

A unified, global model for the pyrolysis of cellulose

Complex interactions occur between the many competing and sequential chemical reactions during the pyrolysis of cellulose, making the prediction of the pyrolysis products relatively difficult. The purpose of this paper is to present cellulose pyrolysis as a comprehensible interaction of time, temperature and pressure. Appropriate kinetic data for seven first-order global reactions for the pyrolysis of cellulose were found in the literature. A mathematical model was developed, in which the seven reactions occurred simultaneously so long as the feedstock for the particular reaction existed. The seven differential equations representing the reaction rates were numerically integrated simultaneously to obtain the products of pyrolysis as a function of time, temperature, heating rate and pressure. This program was used to predict many results and trends observed in both slow and fast pyrolysis: very high yields of condensible vapors (primary oils) were predicted under high heating rates to modest final temperatures; high char yields were predicted for slow heating rates at low temperatures; high gas yields were predicted for fast pyrolysis at high temperatures.     

无电晕式高温高压静电除尘器阴极电发射特性的试验研究

在不同的温度、压力、电压条件下,对所开发的阴极材料进行了电发射特性的试验研究。研究结果表明：温度、压力、电压对发射电流均有不同程度的影响。在高温（〉８００℃）条件下,由阴极材料热发射所获得的电流密度比采用常规电晕方式所得到的电流密度至少高２个数量级。发射极具有良好的稳定性,可在高温高压条件下长期使用。图４参２     

某300MW亚临界机组高中压转子裂纹的故障诊断

针对某300MW亚临界机组高中压转子在运行过程中出现振动值逐渐增大的问题,通过对高中压转子的历史振动数据进行分析,判断高中压转子存在扩展式弯曲故障。现场对高中压转子平衡后,短时间内振动状态恶化,诊断为高中压转子出现裂纹。及时停机揭缸检查,发现高中压转子高压第一压力级前的应力释放槽存在裂纹,避免了断轴毁机的安全事故,具有一定的借鉴意义。     

煤粉高浓度输送阻力特性的试验研究

本文在东南大学磁流体发电ＭＨＤ燃烧室供粉系统上对煤粉高浓度气力输送阻力特性进行了试验研究,运用相似理论对试验数据进行关联,得到了用以计算煤粉高浓度的输送水平阻力系数的准则式,该准则与试验数据吻合良好,同时给出了计算任意管长压降的程序流程图。     

Critical heat flux under conditions of high subcooling and high velocity at atmospheric pressure

A quantitative analysis of critical heat flux (CHF) under high mass flux with high subcooling at atmospheric pressure was successfully carried out by applying a new transition region model for a macro-water sublayer on heated walls to the existing model of a vapor blanket over the macro-water sublayer. The CHF correlation proposed in this study could predict well the experimental data obtained for water mass flux of 940 to 20,300 kg/m²s using circulate tubes 2 to 4 mm in diameter and 30 to 100 mm in length with inlet subcooling of 30 to 90 °C and rectangular channels heated from one side with gaps of 3 to 20 mm, length of 50 to 305 mm, and inlet subcooling of 30 to 77 °C and revealed a unique feature of CHF, namely, that the effects of wall friction of subcooled boiling flow and the velocity of the steam blanket above the macro-water sublayer at atmospheric pressure become the dominant factors while they were not dominant at higher pressures. © 1997 Scripta Technica, Inc Heat Trans Jpn Res, 26 (1): 16–29, 1997     

光谱消光法测量高压湿蒸汽的研究

在前人工作的基础上发展了光谱消光法在线测量技术,并将其应用于高压湿蒸汽两相流湿度和水滴尺寸分布的测量.在数据处理上,提出了改进的 optimized regularization 反演算法,该算法比以往的 Phillip-Twomey-NNLS 算法有更大的抗噪性、准确性和稳定性.还进行了标准颗粒测量实验和高压湿蒸汽在线测量实验.结果表明:通过增大测量区与接收光纤间距和减小接收光纤面积,可大大降低颗粒前向散射光(包括低浓度时的不相关单散射光和高浓度时的复散射光)对消光光谱的影响,从而保证了在高浓度情况下湿蒸汽测量的准确性.湿蒸汽实验结果表明:在高压状态下湿蒸汽中的水滴尺寸比低压汽轮机内湿蒸汽中的水滴小,并且分布也较窄,这也是核电高压汽轮机水蚀较少的原因之一.     

Dynamic pressure measurements of a hot gas filter as a diagnostic tool to assess the time dependent performance

Dynamic pressure measurements are introduced as powerful tool to detect filter failures at early stage. Data of single recleaning pulses or a time series of recleaning pulses can be used to detect filter failures and changes in filter candle conditions during commissioning and operation. High frequency sensors were used to record recleaning back pressure pulses enabling the detection of filter failures such as leakages or blockages. Changes in filter wall resistance due to patchy cleaning or depth filtration can be detected much faster with dynamic pressure measurements than with conventional differential pressure measurements. Parameters derived from dynamic pressure data were monitored over time and compared with reference data. The method complements standard pressure difference measurements. Dynamic pressure measurements were conducted at a hot gas filter applying a coupled pressure pulse (CPP) recleaning system.     

亚临界600MW汽轮机高压隔板套热应力分析

应用有限元分析程序对亚临界600MW汽轮机高压隔板套进行三维有限元应力分析,提出采用截面应力与最大应力比值作为判断结构设计是否合理的标准,并与原二维有限差分法计算结果比较,提出采用带有一半圆槽的新型高压隔板套设计方案,可有效降低高压隔板套应力。     

汽轮机高背压出力试验实例

进行汽轮机高背压出力试验,可以明确机组在高背压条件下的出力。简要阐述了汽轮机高背压出力试验过程,包括条件准备、参数调整方法和数据调整依据,并提供了2个试验实例,介绍了试验简化实施方案和估算方法。     

高原环境对柴油机性能的影响及解决措施

柴油机在高原地区运行时,由于受到特殊的地理环境和气候条件的影响,其动力性、经济性、可靠性和废气排放性等指标都大幅下降。为了满足高原地区柴油机的使用要求,分析了高原温度、气压和空气密度等条件与海拔高度的对应关系及其各自对柴油机造成的影响,提出了一系列的改进措施。     

服役工况下汽轮机平衡盘区域强度及间隙变化

以某超超临界机组的高压模块的平衡盘作为研究对象,利用ABAQUS软件建立高压模块的轴对称模型,并根据电厂实际运行工况的蒸汽温度压力数据计算加载边界条件,分析了实际启动和满负荷运行工况下高压平衡盘及前后密封区域的温度、应力和位移的变化及密封处径向间隙变化规律。研究表明:运行过程中服役工况下温度和应力产生了波动,在启动阶段最为剧烈,稳态运行时波动幅度较小;启动阶段径向间隙会明显减小。