AP1000机组蒸汽发生器二次侧经济性研究

蒸汽发生器作为核电站一、二回路的换热枢纽,对于核电站的安全高效运行至关重要。为此,以某AP1000机组蒸汽发生器二次侧为研究对象,根据(火用)成本理论和经济学理论,建立了AP1000机组蒸汽发生器二次侧热经济学成本数学函数模型,对其热经济性进行计算分析。结果表明:负荷降低会加速热经济学成本增加;改善压强条件对二次侧热经济学成本影响不大,但会增加泵功耗,影响整体经济性;改善二次侧换热条件,更容易降低热经济学成本。     

热工水力系统程序RELAP 5的CCFL模型适用性分析

冷却剂丧失事故（LOCA）是重要的核电厂设计基准事故之一。它是指冷管段和热管段的大破口事故,都可能导致相向流动限制（CCFL）现象的发生,在再灌水阶段中,反应堆内的下降段中蒸汽较大的向上流动导致安注系统的水不能向下及时注入堆芯,发生CCFL现象。常用的热工水力系统程序（如RELAP 5）中采用专门的模型描述这一现象,但针对不同的几何结构,程序需要用户选择不同的模型及其参数。针对该现象中的相间作用机理展开模型研究,对以直管段为结构特征的Dukler实验台和以棒束通道为测试段的Karei实验台进行建模,通过与实验数据的对比分析,研究了不同CCFL模型的适用性。     

直接空冷系统冬季防冻问题研究

冬季直接空冷系统面临的一个最为严重的问题是凝汽器管束发生冻结,在环境温度低于0℃时,直接空冷凝汽器翅片管内饱和蒸汽热负荷与翅片管冷却能力不平衡是导致直接空冷凝汽器的管束发生冻结的主要因素,而不凝气体的聚集则加剧冻结。控制蒸汽流量与冷却空气流量、避免不凝气体的聚集能够避免凝汽器冻结的发生。     

船用核蒸汽发生装置稳态运行特性研究

对于船用压水堆核动力装置,在保持一回路冷却剂平均温度恒定的基础上,使蒸汽发生器一次侧冷却剂流量随传负荷变化,有可能实现蒸汽发生器运行压力恒定。本文探讨了冷却剂流量变化对蒸汽发生器传热特性的影响,讨论了实现双恒定运行方式所存在的几个问题。     

蒸汽通道宽度对凝汽器优化布管的影响

以某凝汽器为研究对象,数值模拟其壳侧蒸汽的流动情况,研究了凝汽器留有的蒸汽通道宽度对凝汽器壳侧蒸汽流动以及凝汽器压力的影响.凝汽器蒸汽通道宽度的设置应以使得其内的蒸汽流速适中为宜,流速过大会导致蒸汽流动的不均匀性,增大汽阻;过小会使得蒸汽在管束区内的流动偏低,降低换热效果.     

平行微细通道热沉流体均匀性及传热特性研究

通过数值模拟手段研究平行微细通道热沉内部速度场和温度场的均匀性,探究内部空间结构及流量等因素对微细通道热沉流动及传热特性的影响。结果表明,斜对角单进单出方式的微细通道热沉中间通道流量较小,两侧流量较大,随流量增大非均匀性现象愈加明显;在热沉进、出口联箱处增设导流构件可改善各通道流量分配的均匀性,但随流量增加改善效果不明显;各通道依次错位排列可使导流型热沉流量分配不均匀度最小。综合考虑压降和加热面平均温度,通过通道错位排列导流的热沉具有较低的压降及较低的热面平均温度,表现出良好的综合性能。     

船用压水堆核动力装置双恒定运行方案下的冷却剂流量调节方案

船用压水堆核动力装置采用双恒定运行方案，蒸汽发生器一次侧冷却剂流量必须随着装置负荷按照一定规律而变化。本文对冷却剂流量调节的几种方案进行分析和比较，指出最为理想的调节方式是采用主泵变频调速。     

自然循环蒸汽发生器稳态运行特性实验研究

双恒定运行方案是船用核动力装置的理想运行方案,有利于提高核力装置的总体运行性能,理论分析表明,船用压水堆核动力装置实现双恒定运行方案的热工水工条件,是自然循环蒸汽发发器一次侧冷却剂流量必须与装置负荷保持一定函数关系,通过调节冷却剂流量可改变蒸汽发生器的传热特性,从而在冷剂平均温度不变的关提下保持蒸汽压力恒定,为了证理论分析结果,与核动力运行研究结合作运行了真实运行参数条件下的蒸汽发生器传热实验,实验结果证实了理论计算方法与结果的合理与可信。     

热管中冷器的传热与阻力特性

为了研究重力热管在车辆中冷器上的应用可行性,设计用于冷却高温增压空气的热管中冷器.选用水作为工作介质,在风洞实验台架上进行热管中冷器的传热和阻力性能实验.测试热管中冷器在不同冷侧空气流速、冷﹑热侧空气进口温差、热侧空气流量下的散热量和压力降,比较并分析测试结果.结果表明,热管中冷器具有良好的散热性能,在一定范围内可以满足高增压内燃机的散热要求.将实验结果与理论模型计算值进行比较,结果表明,实验值与理论计算值变化趋势吻合较好．     

注蒸汽水平井井筒内参数计算新模型

注入蒸汽在水平井筒内流动时,蒸汽沿着水平段的质量流量越来越小,且加速度压降不等于零,导致蒸汽的物性参数发生变化,而蒸汽物性对井筒内蒸汽的沿程参数分布有较大影响.依据质量守恒和能量守恒,建立了注入蒸汽干度沿水平段的变化方程,利用动量守恒原理,推导了沿水平井筒的蒸汽干度分布和压力分布计算公式,构建了摩擦力做功、湿蒸汽混合物密度、水平段吸汽量和井筒与油层之间的热传递计算模型,模型同时考虑了变质量流与蒸汽PVT参数的变化对计算结果的影响,采用按压力增量迭代的计算方法对模型进行求解.实例的模型计算结果与油藏数值模拟结果对比表明,新模型具有较高的计算精度.     

热管散热器变工况性能实验研究

用实验方法对一台新型热管散热器进行了变工况性能测试研究.人工环境实验室的空气处理机组模拟环境温度（即冷侧进风温度）,用电加热装置调节散热器热侧（热管蒸发段）空气进口温度.冷侧进风温度在5-41.5℃范围调节,热侧进风温度在20-55℃范围调节,得出散热功率与冷热侧进风温差有关而与进出风温度范围无关;对充液率分别为35%和25%热管散热器进行变工况实验研究,得出了热管散热器充液率25%时性能优于充液率35%时性能等结论.     

交混翼对方形棒束通道内超临界流动传热影响的初步研究

以CFD软件FLUENT为工具对超临界水堆的三维带交混翼的方形单通道模型进行了数值模拟.模型考虑了交混翼的仰角对于通道内温度分布及流场的影响,结果表明,交混翼造成流体绕流,使得流道内冷热流体混合,从而使得流道内流体的温度分布均匀,有效改善了燃料棒表面温度分布情况,降低热点温度;交混翼在15°、30°、45°和50°四种仰角情况下,30°仰角情况更有利于温度区域均匀.     

Analysis of temperature,stress,and displacement distributions of staves for a blast furnace

The temperature of gas flow inside a blast furnace(BF) changes significantly when the blast furnace is under unstable operations,and the temperature and stress distributions of cooling staves(CS) for BF work the same pattern.The effect of gas temperature on the temperature,stress,and displacement distributions of the cooling stave were analyzed as the gas temperature inside the blast furnace rose from 1000 to 1600°C in 900 s.The results show that both the temperature and temperature gradient of the hot side...     

Ignition,flame propagation and extinction in the supersonic mixing layer flow

The supersonic mixing layer flow, consisting of a relatively cold, slow diluted hydrogen stream and a hot, faster air stream, is numerically simulated with detailed transport properties and chemical reaction mechanisms. The evolution of the combustion process in the supersonic reacting mixing layer is observed and unsteady phenomena of ignition, flame propagation and extinction are successfully captured. The ignition usually takes place at the air stream side of braid regions between two vortexes due to much higher temperature of premixed gases. After ignition, the flame propagates towards two vortexes respectively located on the upstream and downstream of the ignition position. The apparent flame speed is 1569.97 m/s, which is much higher than the laminar flame speed, resulting from the effects of expansion, turbulence, vortex stretching and consecutive ignition. After the flame arrives at the former vortex, the flame propagates along the outer region of the vortex in two branches. Then the upper flame branch close to fuel streamside distinguishes gradually due to too fuel-riched premixed mixtures in the front of the flame and the strong cooling effect of the adjacent cool fuel flow, while the lower flame branch continues to propagate in the vortex.     

真空膜蒸馏浓缩枇杷叶提取液的可行性研究

真空膜蒸馏是一种新型膜分离技术,可以实现较低温度条件下的浓缩分离,特别适合于热敏性中药.研究了枇杷叶提取液真空膜蒸馏过程的影响因素,并分析了浓差极化问题.实验结果表明:枇杷叶有效成分通过真空膜蒸馏没有损失,渗透通量随热侧的温度和流量及冷侧的真空度的增加而增加.     

用于供冷的闭式冷却塔换热模型与性能分析

目的分析闭式冷却塔内各参数。即空气焓值、含湿量、冷却水温等的分布情况；探讨空气入口参数、空气质量流量、喷淋水量对闭式冷却塔冷却性能的影响规律．方法通过对闭式冷却塔内部换热机理的分析，建立描述冷却塔内传热传质性能的数学模型，并得到模型的解析解．结果闭式冷却塔结构参数不变时，随着入口空气湿球温度的升高，冷却水出口温度升高；随着空气质量流量和喷淋水量的增加，冷却水出口温度降低，但是变化斜率逐渐减小，即存在着一最佳喷淋水量和空气质量．结论利用闭式冷却塔数学模型的解析解，可以实现分析空气和喷淋水参数对闭式冷却塔供冷性能的影响及各参数沿闭式冷却塔高度的分布情况，为闭式冷却塔的结构设计及性能优化提供帮助．     

High mixing effectiveness lobed nozzles and mixing mechanisms

For a circular lobed nozzle with the exit plane displaced from the center body,adding a central plug at exit or replacing the nozzle with an alternating-lobe nozzle can improve the mixing effectiveness.In this study,numerical investigations of jet mixing in the lobed nozzles with a central plug and alternating-lobe nozzles in pumping operation were conducted.The effects of the central plugs with the wake ranging from attached to separated flow on the mixing were analyzed,along with the mechanism of improving the mixing performance in a"sword"alternating-lobe nozzle.The simulation results reveal that the large-scale mixing rate,which is dominated by streamwise vortices,is related to the intensity of the attainable heat and mass transfer in the streamwise vortices.The effects of the streamwise vortices on the normal vortex ring are virtually a manifestation of the heat and mass transfer/mixing process of the streamwise vortices.The simulation results also show that the central plug with the attached rear-flow performs better in improving the mixing effectiveness and pumping performance;on the contrary,if the rear-flow is separated,more pressure loss will be induced.In particular,a completely separated flow over the rear of the central plug will severely degrade the attainable heat and mass transfer in the streamwise vortices.For the sword alternating-lobe nozzle,wider sword deep troughs help to increase the flux of the secondary stream around the core region and delay the confluence of the primary stream in the region between the deep and shallow troughs.Thus,the mixing is improved in the middle and posterior segments.Compared to the lobed nozzle with a central plug,the improved sword alternating-lobe nozzle can achieve a higher mixing effectiveness with much less pressure loss,which is preferred in situations when the power loss of the engine is restricted.     

Numerical Simulation of Basic Parameters in Plasma Spray

On the basis of energy balance in the plasma gas, a new, simplified but effective mathematical model is developed to predict the temperature, velocity and ionization degrees of different species at the torch exit, which can be directly calculated just by inputting the general spraying parameters, such as current, voltage, flow rates of gases, etc. Based on this method, the effects of plasma current and the flow rate of Ar on the basic parameters at the torch exit are discussed. The results show that the temperature, velocity and ionization degrees of gas species will increase with increasing the plasma current; while increasing Ar flow rate can increase the velocity at the exit but decrease the temperature and ionization degrees of plasma species. The method would be helpful to predict the temperature and velocity fields in a plasma jet in future, and direct the practical plasma spray operations.     

静叶内弧中部热蒸汽喷射的数值研究

为了使汽轮机更安全运行,在除湿级的静叶内弧中部开设宽度和喷射角度不同的缝隙除湿结构.对流体区域进行定常三维雷诺平均N-S方程的两相数值模拟,分析热蒸汽喷射对流场的影响.引入火用参数的方法进行能量转化过程的经济性评估.结果表明:同一喷射流量下,顺主流喷射且缝隙宽度越大,喷入热蒸汽的火用值越小且与主流的掺混强度越弱,其火用有效效率越高,即流动损失越小.在喷射流量比小于6%时,各方案的火用有效效率均比无热蒸汽喷射的原型要高.