加热器内部泄漏故障的实验研究

高压加热器内部泄漏故障是火电厂回热系统主要故障之一,针对加热器的泄漏故障进行实验研究,设计并搭建高加泄漏模拟实验台.通过实验研究和数据处理,找出不同工况下泄漏声发射信号的最大能量值、最大频率值以及平均频率3个参数在发生泄漏故障时的变化规律.以期准确提供泄漏相关参数的特征,这将有利于故障的早期诊断和排除.     

老化30Cr2MoV汽轮机转子钢FATT预测模型的建立

实验选用化学腐蚀法预测老化30Cr2MoV汽轮机转子钢的热脆化程度,用苦味酸添加十二烷基苯磺酸钠(SDBS)作为蚀刻液进行化学腐蚀实验.通过正交实验确定较理想实验条件,并在此实验条件下,对12个具有不同韧脆转变温度的试样进行不同温度下的腐蚀实验,找出各温度下晶界宽度参数与FATT50之间的对应关系,确定回归参数,用统计分析软件SPSS对所得数据进行多元线性回归分析,得出老化汽轮机转子钢FATT50的预测模型,经验证明该模型预测精度在±200C之内,精度较高.     

基于数据分析的钝化层钝化效果分析

太阳电池的钝化层直接影响太阳电池的性能,钝化层界面上固定电荷密度和缺陷密度是分析其钝化效果的关键参数。本文通过建立MOS模型来模拟钝化层的电容-电压(C-V)特性曲线,并使用函数表达模拟曲线,建立基于函数的数据库,将实验获取的C-V曲线与数据库进行比对找出实验数据对应函数,提取出钝化参数N_f和D_(it),并以此分析钝化层的钝化效果。     

链条炉排锅炉炉拱对燃料着火的影响

采用Fluent软件对链条炉排锅炉炉膛的烟气流场进行模拟,分析前拱深度和高度变化与烟气射程的关系。对国内燃煤链条炉排锅炉炉拱参数进行统计,通过炉拱参数的离散度分析,找出对链条炉排锅炉燃料燃烧起决定性作用的参数,并且通过对燃料和烟气、灰粒子的特性分析,找出燃料着火的关键因素。     

电控喷油器的仿真研究

自行开发了一种基于Servojet系统的共轨蓄压式燃油喷射系统，为了找出系统各参数对喷射特性的影响，了解系统内部的燃油流动变化情况，利用一种全新的流体仿真软件FLOWMASTER2对开发系统的电控喷油器进行了仿真分析，结果表明仿真结果和实验结果基本相符，为设计参数的优化提供了依据。     

回采工作面风场FLUENT模拟分析研究

通过FLUENT软件对煤矿U型通风工作面风场进行数值模拟,得出工作面风速分布图、雷诺数分布图等。通过不同的通风参数模拟找出工作面瓦斯集聚情况,可以合理地确定工作面通风参数,达到合理通风。     

由示功图数据计算NO_X浓度中有关计算精度若干问题的探讨

汽车有害排放浓度数值计算,影响因素众多,有设计参数、运行参数、燃烧参数、测试参数、程序的调整参数等,要提高计算精度,就要抓住影响计算精度的主要因素,找出其变化规律。这样,可以缩短计算时间,提高计算精度。     

降膜蒸发过程的传热性能研究

对圆管和平壁的降膜蒸发过程的传热机理及影响因素进行了分析,并对已有的实验结果进行了比较;已有的实验研究主要是围绕圆管或平壁来进行,不利于找出最佳加热元件;提出在平壁表面加圆管型肋的复合加热元件,对其进行研究有利于找出最佳加热元件,对提高降膜蒸发传热效率极具实用价值。     

用水力模型确定盐炉电极尺寸计算公式的研究

本文针对工厂中常用的七种埋入式电极盐炉,首先用量纲分析法,分别找出用来计算电极间熔盐电阻的准则方程的形式。尔后根据相似理论,进行水力模型实验,用一元线性回归分析法,编制程序用电子计算机对实验数据进行处理后,找出了常用的七种埋入式电极的数学实验模型(准则方程),由此分别导出上述电极的尺寸计算公式。     

平板V型小翼各参数对风力机功率系数的影响

为提高风力机的功率系数Cp,对平板V型小翼的参数进行了优化试验.采用正交试验法选取5个基本参数,分析了各个参数对风力机功率的影响,找出了对其影响明显的参数以及小翼尺寸与叶片尺寸的相对关系.     

A building integrated solar collector: Performances characterization and first stage of numerical calculation

A new concept of building integrated solar water collector and the experimentation are described, then experimental results are shown. Numerical calculations are performed in Matlab environment using a finite difference model and an electrical analogy.     

Modeling of a pressure modulated desalination system using bond graph methodology

A desalination system is a complex multi energy domain system comprising power/energy flow across several domains such as electrical, thermal, and hydraulic. The dynamic modeling of a desalination system that comprehensively addresses all these multi energy domains is not adequately addressed in the literature. This paper proposes to address the issue of modeling the various energy domains for the case of a single stage flash evaporation desalination system. This paper presents a detailed bond graph modeling of a desalination unit with seamless integration of the power flow across electrical, thermal, and hydraulic domains. The paper further proposes a performance index function that leads to the tracking of the optimal chamber pressure giving the optimal flow rate for a given unit of energy expended. The model has been validated in steady state conditions by simulation and experimentation.     

Ten MVA superconducting generator development: status at the end of1989

A progress report and some initial results from the experimental program in superconducting generators at the Massachusetts Institute of Technology (MIT) are provided The 10 MVA generator developed at MIT was to demonstrate a number of advanced concepts. These included a fully cold rotor, a cryogenic system with built-in reserves for rapid recooling following serious electrical transients, a two-stage damping and shielding system with a damping resistor tailored to good dynamic performance, a field winding structure which allows for full fault torque without straining the field winding conductors, a limited voltage gradient armature winding, and a monolithic armature structural system that provides both rigid support and good electrical isolation. The generator was completed in 1985, and experimentation has been carried out since then. The basic electrical parameters have been verified through low-level steady-state no-load and synchronous impedance tests, and sudden short-circuit and sudden open-circuit transient tests     

Mathematic models of photovoltaic motor-pump systems

Photovoltaic (PV) pumping offers the possibility of supplying water to remote and desert regions for their daily needs. The sizing of the PV pumping systems is a very significant step in order to optimize the power peak of the PV array and to ensure the best choice of the motor, the pump and the inverter. Two mathematical models were proposed in this article to contribute in the studies of PV pumping sizing. These models link directly the operating electrical power to the water flow rate of the pump versus total head. These models are based essentially on the experimentation of pumps on CDER PV pumping test facility. Two pumping systems are tested: the first uses a centrifugal pump and the second uses a positive displacement pump. The results obtained by the models are very satisfactory. Also, the models enabled us to simulate the electrical and hydraulic performances of two tested pumps. The performances are calculated using the measured meteorological data of different sites located in Sahara and coastline regions of Algeria.     

汽轮机真空严密性试验的一种设想

汽轮机真空是汽轮机经济运行的关键,真空严密性是影响汽轮机真空的主要因素。针对目前真空严密性试验存在的问题,设想了一种新的真空严密性试验系统,为真空严密性试验提供了参考。     

Modelling,simulation and control of a proton exchange membrane fuel cell (PEMFC) power system

Fuel cell power systems are emerging as promising means of electrical power generation on account of the associated clean electricity generation process, as well as their suitability for use in a wide range of applications. During the design stage, the development of a computer model for simulating the behaviour of a system under development can facilitate the experimentation and testing of that system's performance. Since the electrical power output of a fuel cell stack is seldom at a suitable fixed voltage, conditioning circuits and their associated controllers must be incorporated in the design of the fuel cell power system. This paper presents a MATLAB/Simulink model that simulates the behaviour of a Proton Exchange Membrane Fuel Cell (PEMFC), conditioning circuits and their controllers. The computer modelling of the PEMFC was based on adopted mathematical models that describe the fuel cell's operational voltage, while accounting for the irreversibilities associated with the fuel cell stack. The conditioning circuits that are included in the Simulink model are a DC–DC converter and DC–AC inverter circuits. These circuits are the commonly utilized power electronics circuits for regulating and conditioning the output voltage from a fuel cell stack. The modelling of the circuits is based on relationships that govern the output voltage behaviour with respect to their input voltages, switching duty cycle and efficiency. In addition, this paper describes a Fuzzy Logic Controller (FLC) design that is aimed at regulating the conditioning circuits to provide and maintain suitable electrical power for a wide range of applications. The model presented demonstrates the use of the FLC in conjunction with the PEMFC Simulink model and that it is the basis for more in-depth analytical models.     

发动机电喷系统ECU的可靠性研究

本文针对FAI电喷系统中的核心部件即电子控制单元(ECU)进行了可靠性的预测和分析,并从软件、硬件以及封装等角度提出了相应的可靠性解决方案,经过长期老化试验和环境试验,证明ECU的可靠性指标得到了很大提高,满足了相关标准规定。     

污水沉降罐乳化漂浮物成因分析及处理措施

大庆油田第九采油厂龙一联污水处理场沉降罐上部油水界面处出现一层难以去除的乳化漂浮物。通过进行漂浮物成分分析、药剂配伍实验、微生物培养实验、气相色谱分析等研究,发现二矿来水含油高是造成该现象的主要原因。解决方案为加入降凝剂,并在罐上部注入蒸汽。     

Estimation of kinetic and electric parameters of liquid feed passive DMFCs

The study of polarization curves is an important part for evaluating the performance of passive direct methanol fuel cells (DMFCs). This study must be essentially followed by other experiments to gain knowledge of important kinetic and electrical parameters such as exchange current density, charge transfer coefficients, ohmic resistance, etc. This experimentation include in-situ characterization techniques such as electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and current interrupt (CI) technique which are expensive to carry out. Hence, this study develops a semi-analytical model for estimating exchange current density, charge transfer coefficients and ohmic resistance directly from the polarization curves. In addition, a simple “3/4-Point method” is introduced, utilizes the polarization curves for the estimation of kinetic and electric parameters. The triad (proposed model, 3/4-Point method and polarization/EIS experiment) are compared and exhibited similar trends, thereby validating it as a tool for estimation of a large class of parameters. The model is comprehensive as it is valid throughout the polarization curves, thereby avoiding the need for multiple strategies in different regions of the polarization curves to calculate various parameters. The model can serve to know the values of these parameters by-hand before other experimentations which involves high cost and sophisticated experimental conditions.