凝汽器动态数学模型的研究

凝汽器是凝汽式汽轮机重要组成部分之一。它的工作性能直接影响整个汽轮机组的热经济性和安全性。随着人们对电站仿真、电站设备放障诊断以及凝汽器真空预测等问题的不断重视,电站凝汽器动态数学模型愈来愈引起人们的关注。本文以最常用的表面式凝汽器为研究对象,经适当的假设,建立了凝汽器动态数学模型,并经试验验证。     

联合循环中底循环系统的动态仿真模型

根据底循环系统工作机理和特性，以能量和质量守恒原理为基础，详细论述了非补燃式三压再热自然循环余热锅炉、汽轮机、凝汽器、离心式水泵的模型算法，并结合其它相关模块算法（如凝结水预热器、流体网络、容积模块算法等），以M701F级联合循环机组为仿真对象，用模块化方法建立了完整的底循环系统动态数学模型。仿真试验表明：所建立的数学模型能够正确反映对象的动态和静态特性，整体模型运算收敛快，可为联合循环机组仿真系统的开发和底循环控制系统的设计与分析提供良好的理论模型。图3表1参12     

直接空冷凝汽器仿真模型的研究

充分考虑凝汽器结构参数和工质物性参数对传热过程的影响,运用工程模块化建模方法,建立了直接空冷凝汽器各单元凝结换热及整体压力计算的动态仿真模型.基于STAR-90仿真支撑平台,开发了相应的模型算法.建立了某200 MW直接空冷机组凝汽器系统的整体仿真模型,对在不同负荷下的静态仿真精度以及各种扰动下的动态特性进行验证,表明该模型能满足工程应用要求.     

电厂热力系统的长期动态特性模型

热力系统的长期动态特性对各种火电机组的仿真或控制系统设计具有十分重要的意义。通过合理的机理分析和简化,从整体高度建立起热力系统的长期动态过程的数学模型,这一整体动态模型能较为合理地反映出长期动态过程中热力系统的蓄热与做功规律,弥补了现有火电机组动态模型的不足,更好地满足了机组长期动态特性分析与负荷控制策略研究的需要。最后以此为工具对某600MW超临界机组的长期动态特性进行了仿真研究,仿真结果合理正确。     

锅炉参数变化时汽轮机系统的仿真算法

采用实时仿真算法对锅炉-汽轮机系统动态特性进行了整体性模拟。首先建立了详尽的汽轮机各部件动态数学模型和热力系统流量网络计算模型，特别是除氧器、表面加热器和凝汽器的通用动态数学模型；然后，将汽轮机系统动态模型与锅炉系统动态模型连接为整体仿真模型，并进行仿真。该文还列出了锅炉某些参数变化时汽轮机系统几个关键基本参数仿真结果。对电站锅炉-汽轮机系统的整体性模拟可以对运行人员进行更加全面的指导，并且为进行单元机组的瞬态性能计算，进而修正稳态性能计算结果奠定了基础。图12参3     

直接空冷凝汽器变工况特性仿真分析

以直接空冷凝汽器凝结换热机理为基础,通过合理的系统分解和简化,建立了动态仿真模型.以某200MW直接空冷机组为例,通过仿真模型计算出不同风速、风温和排汽量下凝汽器冷端系统特性曲线;并且分析了管内污垢热阻对凝汽器压力的影响,画出了影响曲线.结果表明:运用仿真模型分析变工况特性具有较好的精确度和实用性,对现场运行具有一定的参考价值.     

空气源热泵机组动态仿真数学模型

为研究大型活塞式空气源热泵机组启机过程和能量调节过程的动态特性,建立了空气源热泵机组动态仿真数学模型,模型中对换热器采用分区集中参数法,即移动边界法进行建模,将压缩机与膨胀阀考虑成小惯性的稳态环节处理,提出了完善可行的空气源热泵机组动态仿真流程。分析了活塞式压缩机的能量调节策略。利用所建模型对一个实际空气源热泵机组典型动态过程进行了计算机仿真,仿真结果与实测结果平均误差在10%以内,说明所建模型可以对实际运行的大型活塞式空气源热泵机组动态启机和能量调节过程进行准确仿真,仿真结果可用于机组运行调节参数的优化,指导机组的实际运行。     

电厂凝汽器分区运行余热回收技术研究

电厂凝汽器的管束区可以按照冷却水温度分为高温区和低温区,可以单独提取凝汽器高温区的冷却水进行余热回收。利用自行开发的凝汽器数值模拟软件对某电厂一台350MW机组凝汽器在冬季额定抽汽供热工况下的热力性能进行了数值仿真,并对凝汽器进行了分区。凝汽器热力性能数值模拟计算和该机组的实际运行工况表明,在冬季额定抽汽供热工况下,相比常规的凝汽器余热回收方式,采取凝汽器分区运行措施可显著提升余热温度,具有更好的经济和社会效益。     

某F级燃气轮机发电机组冷端优化策略研究

在能源结构调整及“双碳”背景下，电力行业的压力增大，电厂冷端系统具有巨大节能潜力，且由于气 电与煤电机组冷端性能差异明显，需开展专项研究。首先针对某F级燃气轮机发电机组凝汽器进行了清洁 度评估，然后通过电厂热力边界及运行参数建立了仿真模型，基于凝汽器、循环水泵、机力通风塔风机开展了 运行策略研究，分析了循环水流量、循环水温度及辅机功率等因素与凝汽器背压的敏感度关系，提出了机组 不同环境温度和机组负荷下冷端系统最佳运行方案，为燃气机组经济可靠运行提供了技术支持。     

大型电站多压凝汽器的仿真建模

针对新型培训仿真机开发，以质量和能量守恒定律为基础，应用传热学的有关理论，在MATLAB／Simulink平台基础上依据图形组态的方法，建立了大型电站凝汽器的动态数学模型，同时采用模块化的建模方法，建立了单压、双压、三压凝汽器的动态仿真模型，并利用经验数据进行了正常工况扰动和故障设置的数值实验。通过比较不同背压凝汽器的调试结果，表明建立的多压凝汽器模型具有较高的精度和通用性，适合于各种工况下的仿真运行。     

管壳式水冷冷凝器的模拟方法研究

初步建立了管壳式水冷冷凝器的换热模型，考虑了在冷凝器中上层管子上产生的制冷剂凝结液对下层管子的换热性能的影响。基于该模型编制了管壳式冷凝器的仿真程序，并对冷凝器的性能进行模拟，对仿真结果进行了分析。     

侧向进汽凝汽器汽相流动与传热的物理模型及数值模拟方法

根据侧向进汽凝汽器壳侧的蒸汽一凝结液两相流流动特点,利用现有实验数据建立了考虑液相重力及汽流方向对溢流影响的阻力系数与汽侧换热系数的关联式,并将其用于侧向进汽凝汽器汽相流动与传热的数值模拟方法与程序。采用所发展的程序预测了一台实验凝汽器的工作特性。计算结果与现有实验结果较一致,证实了所用物理模型与计算方法的适用性,同时也揭示了侧向进汽凝汽器流动与传热的一般特性。     

基于冷却水温求解的凝汽器全三维数值模拟

文章通过求解与凝汽器壳侧传热相耦合的冷却水温的微分方程,实现了基于冷却水温求解的凝汽器全三维计算,计算模型更接近真实的物理模型。对某600MW机组凝汽器的计算表明,计算结果可以展现出凝汽器壳侧蒸汽流动换热以及冷却水温分布的三维性,计算结果更为合理。     

凝汽器喉部蒸汽流动的三维数值模拟

应用具有超粒子模型的直接模拟蒙特卡罗方法,对汽轮机凝汽器喉部进行区域分解和数学建模,及对具有典型结构的凝汽器喉部蒸汽流动进行了三维数值模拟,重点分析了凝汽器喉部流场的流动分布情况,揭示了喉部流场不均匀性流动特点及其产生原因。     

Performance analysis of an air-source heat pump using an immersed water condenser

A distributed model of an air-source heat pump (ASHP) system and its experimental setup using an immersed water condenser were presented. Dynamic performance of the ASHP was then evaluated by both simulation and experiment. The results indicated that the system coefficient of performance (COP) decreased as the condenser temperature increased, ranging from 4.41 to 2.32 with the average COP equaling 3.29 during the experiment. Comparisons between simulation results and experimental measurements demonstrated that the model was able to yield satisfactory predictions. Furthermore, temperature profiles of the refrigerant in the evaporator and condenser were also given. This paper provides the theoretical and experimental background for ASHP system optimization and a valuable reference for a solar air-source heat pump water heater when the solar irradiation energy is insufficient on cloudy or rainy days.     

Performance analysis of an air-source heat pump using an immersed water condenser

A distributed model of an air-source heat pump (ASHP) system and its experimental setup using an immersed water condenser were presented. Dynamic performance of the ASHP was then evaluated by both simulation and experiment. The results indicated that the system coefficient of performance (COP) decreased as the condenser temperature increased, ranging from 4.41 to 2.32 with the average COP equaling 3.29 during the experiment. Comparisons between simulation results and experimental measurements demonstrated that the model was able to yield satisfactory predictions. Furthermore, temperature profiles of the refrigerant in the evaporator and condenser were also given. This paper provides the theoretical and experimental background for ASHP system optimization and a valuable reference for a solar air-source heat pump water heater when the solar irradiation energy is insufficient on cloudy or rainy days.     

大型电站凝汽器动态数学模型的研究

在对凝汽器工作过程中工质物性合理简化的基础上,详细论述了建立凝汽器动态数学模型的机理;讨论了蒸汽凝结量的两种计算方法,并将计算结果与现场设备调试曲线进行对比。通过在电站仿真工程中的应用,证明本文所建立的动态数学模型在仿真领域具有较高的实用价值。     

Modelling of a condenser-fan control for an air-cooled centrifugal chiller

There is a lack of detailed experimental and simulation studies on air-cooled centrifugal chillers. This paper investigates how to optimize the control of condenser fans within the chillers to maximize their coefficients of performance (COPs). A thermodynamic model for the chillers was developed and used to analyse the steady-state COP under various load and ambient conditions. An algorithm is introduced to compute the number of staged condenser fans based on settings of the condensing pressure and outdoor temperature. The model was validated using the experimental data and performance data of an existing chiller running under various operating conditions. It is found that the best strategy for switching condenser fans is to vary their rotating speed by the use of a set point of the condensing temperature, which is adjusted in response to the chiller load and condenser air-inlet temperature. The results of this paper provide an important insight into how to increase the COPs of air-cooled chillers.     

Numerical simulation and experimental validation of a helical double-pipe vertical condenser

A predictive model is developed to describe heat transfer and fluid dynamic behavior of a helical double-pipe vertical condenser used in an absorption heat transformer integrated to a water purification process. The condenser uses water as working fluid connected in countercurrent. Heat transfer by conduction in the internal tube wall is considered; in addition the change of phase is carried out into the internal tube. The dynamic model considers equations of continuity, momentum and energy in each flow. The discretized governing equations are coupled using an implicit step by step method. Comparison of the numerical simulation over range of experimental data presented in the heat device is applied to validate the model developed. The model is also evaluated of form dynamic to determine the principal operation variables that affect the condenser with the main objective to optimize and control the system. A variation of mass flow rate in the internal pipe induces important changes on the heat flux that the pressure and temperature.