回热循环微燃机中换热器计算模型与仿真研究

研究了一维逆流表面式换热器整体集总参数计算模型在稳态计算时的不足以及在动态计算时出现的畸点错误,对产生畸点错误的机理进行分析,在论证分段计算时各段换热系数求取原则的基础上,采用分段方法消除整体计算换热器动态时出现的畸点错误。将换热器的分段集总参数法计算模型应用于某微燃机总体性能仿真计算程序中,对某微燃机转速从70%加速至100%的动态过程进行仿真计算,计算结果表明分段集总参数法避免了以往换热器整体动态仿真计算过程中由于畸点错误导致仿真精度降低或计算无法进行的难题。     

基于渣层法的改进型shell气化炉动态建模与仿真研究

由于普通集总渣层法模型无法反映气化炉中各参数的分布特性,将水煤浆气化炉仿真中运用的小室建模方法与集总渣层法模型相结合,形成一种新的小室渣层法气化炉模型,并使用该模型对shell气化炉进行仿真．将模型仿真得到的稳态与动态结果与已有文献数据及原有集总渣层法的仿真结果进行了对比和分析．结果表明：小室渣层法的仿真结果与文献数据相吻合,具有良好的可行性,且在参数分布变化仿真方面的性能优于传统的集总渣层法模型．     

某大型舰船主汽轮机的建模与动态仿真

以某大型舰船主汽轮机为研究对象,充分考虑了舰船主汽轮机的结构特性,针对舰船主汽轮机特性建立集总参数动态仿真数学模型,在SimuWorks热力系统平台上,搭建相应仿真模型。对主汽轮机进行稳态工况和加速、减速及倒车过程的全工况动态仿真。仿真结果表明,模型具有较高精度,高速工况下偏差在2%以内,动态趋势合理,能准确反映出部件实际工作状态。该仿真模型可以应用于舰船动力系统的仿真。     

余热锅炉动态数学模型建立及仿真

采用集总参数法建立了余热锅炉动态模型。根据余热锅炉的工作原理和特性,以能量和质量守恒原理为基础,详细论述了其内部蒸发器系统和单相介质换热器的数学模型算法,简化了汽水系统结建模仿真的复杂度。仿真结果表明该模型具有较好的动态响应特性,且模型运行稳定。     

变几何多级轴流压气机动态仿真模型的研究与应用

首先采用基于级平均直径上的一维流动逐级叠加法建立了变几何多级轴流压气机全工况性能预估模型,在此基础上,将压气机的级作为控制体,运用一维非稳态质量、动量和能量平衡微分方程来描述级出口截面处热力学参数动态特性,采用模块化方法建立各级集总参数模块,按照工质流程将各级的仿真模块连接起来即形成压气机通流部分机理性动态仿真模型.仿真试验表明:该仿真模型能够正确反映燃气轮机启动过程中与压气机有关的热力学参数变化过程,模型的动态响应特性与实际压气机热力参数的变化趋势基本一致.     

考虑集电网络的风电场建模研究

为提高风电场模型的精度,文章提出建立一种考虑到集电网络影响的模型方法,该模型采用猴群算法计算等值参数。在此模型的基础上对风电场进一步化简,采用基于扩散距离的谱聚类算法对风电机组进行动态分群,得到两机表征的风电场模型,并进行仿真建模过程。通过对一个12 MW的详细风电场模型的仿真分析,将几种模型分别进行了对比,实验结果表明,文章提出的方法是准确有效的,所得到的两机表征模型能很好的反映出风电场并网的动态特性。     

TICC-500储能阶段的建模和热力特性CSCD

以500 k W-TICC系统为研究对象,采用集中参数法建立了系统储能设备的集总参数数学模型,然后用C语言编写相应的程序算法,对所建算法进行算法入库,在华北电力大学STAR-90仿真支撑系统上搭建系统实时动态仿真模型,对500 k W-TICC储能阶段冷态启动阶段进行仿真。分析了压气机环节、换热器环节、储气罐环节和储热罐环节的动态特性。仿真结果表明,进气流量对系统储能阶段参数的影响较大,储气室内气体的温度变化比较平缓。此仿真结果误差满足实际需要,对系统实际运行的动态特性有很重要的参考和借鉴作用。     

间接内重整固体氧化物燃料电池的建模与仿真

建立了一维基于催化涂层重整器的间接内重整固体氧化物燃料电池的动态数学模型.在组分和能量守恒的基础上,考虑了电化学模型,建立了基于分布集总参数技术和模块化思想的间接内重整固体氧化物燃料电池的仿真模型.该模＃型不仅能反映燃料电池的分布参数特性,还可以满足动态仿真的需求.利用该模型分析了某一工况下固体氧化物燃料电池的稳态性能,并进行了动态过程的仿真,结果证明该模型可以反映间接内重整固体氧化物燃料电池的基本性能.     

对单相换热器集总参数模型动态初始负偏移的机理分析

以单相换热器的传热方程和能量平衡方程为基础,对不同类型集总参数模型的动态响应的差异,尤其是出口温度在动态过程中的初始负偏移进行了机理分析。指出采用进、出口加权平衡的集总参数模型在全工况范围内很有可能会使出口温度出现负偏移;而在用出口参数作为集总参数时,可以保证不会出现负偏移,但应采用合理的分段建模,使模型有足够的传热温差。     

缸盖冷却水的单相流沸腾模型

针对缸盖水腔内的冷却水流动沸腾传热计算,本文介绍了两种单相流沸腾模型。模型认为流动沸腾总传热量等于泡核沸腾和单相对流传热之和,其中泡核沸腾传热计算采用修正后的容积沸腾传热计算公式。BDL模型在Chen模型的基础上作了改进,考虑了冷却水局部流动参数及饱和状态的影响,适用于局部流动传热计算。     

有限宽轴承-转子系统非线性动力学行为的若干问题研究

利用对非定常短轴承的油膜压力分布公式进行了变分修正所得出的具有足够精度，适合轴径大扰动情况下的有限宽圆轴承非定常油膜力的解析公式，采用数值模拟，对有限宽轴承-刚性Jeffeott转子的非线性动力学行为进行了研究，得出了与已有文献结论相近似的分岔与混沌特性。     

Lumped parameter simulation for charge–discharge cycle of cryo-adsorptive hydrogen storage system

As a renewable energy source, the hydrogen energy receives widespread concerns. Many efforts have been devoted to the commercial application of hydrogen energy. However, the hydrogen storage technology remains one of the primary bottlenecks. A lumped parameter model is developed for the cryo-adsorptive hydrogen storage system. The variational isosteric heat of adsorption based on Dubinin–Astakhov isotherm of adsorption is successfully used for cryo-adsorption model. Lumped parameter simulation is made for charge–discharge cycle of adsorptive hydrogen storage system at cryogenic temperature by Matlab/Simulink. The change of liquid–gaseous interface of nitrogen is considered in the lumped parameter model to improve the simulation accuracy. The lumped parameter model is applied for modeling different processes and well validated by cryo-adsorption experiments. The lumped pressure and the lumped temperature during charge–discharge cycle predicted by Simulink are compared with the two dimensional simulation results by Comsol. Furthermore, the effect of the charge flow rate on the performance of the hydrogen storage system is systematically analyzed. This model provides a feasible approach for the optimization of the cryo-adsorptive hydrogen storage system.     

安萨尔多F级燃气-蒸汽联合循环机组高精度全范围仿真系统的开发

针对上海电气&安萨尔多公司联合制造的F级AE94.3A型燃气轮机,结合四会燃机电厂实际机组,采用虚拟DCS技术及模块化的建模思路,开发基于APROS的高精度全范围燃气-蒸汽联合循环的仿真系统.对该仿真系统动静态特性进行验证分析,仿真试验表明:该仿真系统具有很高的动静态精度,满足实时仿真的需要.可利用该仿真系统对运行人员...     

2002 Summer Meeting Pictorial Review

This letter conducts load flow analysis of a five bus test system and repeats it for various sets of transmission line lengths, each with "lumped" and "distributed" models to compare the convergence, total transmission loss, and slack generation. From this comparison, we conclude that more transmission and generation capacity can be committed if a "distributed parameter" model replaces its "lumped" counterpart in such an analysis. The findings are expected to encourage the operators to take decisions through "distributed model"-based analyses so that more consumer demand can be satisfied as well as the utility's revenue substantially increased.     

Improved lumped models for asymmetric cooling of a long slab by heat convection

Unsteady cooling of a long slab by asymmetric heat convection is analyzed within the framework of lumped parameter model. As the application of classical lumped model is limited to values of Biot numbers less than 0.1075, we propose improved lumped models that can be applied in transient heat conduction with larger values of Biot numbers. The proposed lumped models are obtained through two point Hermite approximations for integrals. Closed form analytical solutions are given for the lumped models. It is shown by comparison with a reference finite difference solution of the original distributed parameter model that the proposed higher order lumped model (H_1,1/H_0,0 approximation) yields significant improvement of average temperature prediction over the classical lumped model.     

Magnetic Equivalent Circuit Modeling of Induction Motors

Finite element models are invaluable for determining expected machine performance. However, finite element analysis can be computationally intense; particularly if a large numbers of studies or high bandwidth studies are required. One method to avoid this difficulty is to extract machine parameters from the finite element model and use the parameters in lumped parameter models. While often useful, such an approach does not represent space harmonics or asymmetries in the motor. A methodology for constructing a state-variable model, based on a magnetic equivalent circuit of the motor is described herein. In addition, the parameters for this model are based solely on geometrical data. This approach is an excellent compromise between the speed of lumped parameter models and the ability of finite element methods to capture spatial effects. Experimental validation of the model is provided.     

Modeling of Flow System Dynamics

This paper presents non-linear and linear models of flow system of laboratory stand (semi-industrial scale) with pressurized fluidized bed boiler. The non-linear model belongs to the class of lumped parameter models. The linear model was obtained experimentally using a novel method for design of control systems in industrial plants - MIKOZ. This study has connection with comparison of various methods of mathematical modeling of flow systems frequently encountered in power equipment.     

Improvement of heat transfer model for adsorptive hydrogen storage system

Hydrogen adsorption on high surface area activated carbon is an effective solution of hydrogen storage. Improvement is necessary for the heat transfer model of adsorptive hydrogen storage system. Distributed and lumped parameter models are implemented by the Comsol software and Matlab/Simulink software respectively. The evolution of pressure and temperature during charge and discharge processes is investigated. We adopted following measures for a further improvement on the model: (1) Wall temperature is improved by varying heat transfer coefficient; (2) A more realistic geometry with insert tube improves near inlet temperature; (3) Lumped parameter model is improved by considering thermal conductivity; (4) Distributed and lumped parameter models are well validated by experiments; (5) Heat transfer is modeled under conditions of air cooling and water cooling. The water cooling condition is better than air cooling condition in decreasing the temperature of the storage tank and improving the storage capacity.