乏燃料棒束的辐射换热分析

乏燃组件衰变热导出对核电厂安全十分重要。核电厂乏燃料组件的传统冷却方式是依靠浸没在水中的流动循环冷却。AP1000非能动核电厂增设了乏燃料喷淋冷却装置。文中针对乏燃料棒束喷淋冷却试验,研究了乏燃料棒束喷淋冷却的辐射换热影响。理论分析结果和试验结果符合较好,表明了乏燃料棒束之间主要通过辐射换热进行相互的温度影响。     

连铸机结晶器不同冷却方式的数值模拟

建立了方坯连铸机结晶器冷却过程的二维非稳态传热的数学模型，对结晶器在喷淋冷却与循环冷却下的冷却过程进行了模拟，对不同冷却方式的数值结果进行了对比，并得最喷淋冷却结晶器上的最佳热流分布。     

闭式循环柴油机排出气体喷淋冷却传热模型及实验关联研究

闭式揭环柴油机(CCD)排出气体处理技术是各种不依赖空气动力装置(AIP)的共性技术，优选喷淋冷却方式并对其内部的气液传热模型化是该技术的核心。为此，分析对比了横流式、并流式、逆流式等喷淋冷却方式，对实际选用的CCDAIP横流式喷淋冷却器进行了气液传热分析。从单个液滴传热模型出发，采用分层计算方法建立了喷淋冷却传热计算模型，并应用Matlab语言编程计算各种工况下冷却效果。喷淋冷却实验结果与模型计算结果对比表明，该模型能够较精确地预测CCD排出气体喷淋冷却效果。     

考虑圆坯周向冷却均匀性的传热模型研究及应用

圆坯周向上冷却的均匀性对铸坯的质量有着重要影响,易引发纵裂纹、椭圆度等质量问题。基于此,特建立圆坯的径向和周向二维凝固传热模型,充分考虑其在圆周向上喷淋冷却的均匀性。利用喷嘴与圆坯间的几何映射关系,结合喷嘴冷态性能测试数据,推导并计算出沿圆坯周向上的水流密度分布。相比于板坯等平面喷淋,圆坯曲面喷淋沿周向上水流密度衰减更为急剧,喷淋的均匀性更不易控制。将模型应用于某大圆坯连铸机的凝固传热计算,考察了铸坯各二冷区末端周向上的冷却均匀性,其中一区最大温度偏差19℃,二区12℃,三区7℃,四区5℃。除此之外,计算了铸机保温罩设计对铸坯温度场的影响,相比于无保温罩,铸坯表面温度在保温罩出口区域提升了61℃,凝固终点向后推移了约1 m。     

不同蒸发冷却装置工作的影响因素及对比

采用CFD模拟了2种蒸发冷却装置,讨论了一次空气入口温度和喷淋水温度对蒸发冷却装置效率的影响。通过模拟一、二次空气出口处的温度分布,水蒸气相分布以及装置内整个通道的温度分布,得到影响2个蒸发冷却装置的传热性能的变化规律。同时,比较2个蒸发冷却装置的传热性能,给出了一种确定蒸发冷却装置性能的方法。对于管式蒸发冷却装置,选择管径为5 mm和10 mm,管间距为5 mm和10 mm的装置进行模拟。对于板式蒸发冷却,取板长度为500 mm和1 000 mm,并且板宽度为6 mm,8 mm和10 mm用于模拟。通过模拟得到装置尺寸对蒸发冷却效率的影响。     

高压变频器在方坯连铸机二次喷淋供水泵上的应用

方坯连铸二次喷淋冷却用水量不稳定、压力波动大,导致设备损坏,改用回流装置调节压力浪费了大量富余水量的输送能耗,为此提出采用高压变频器根据水量需求进行控制,从而做到节能。改造实践证明:结合工艺控制需求,采用完美无谐波高压变频器对二次喷淋供水泵实施调速节能控制,系统稳定,调节及时,且节省了大量的电能,具有较好的经济与社会效益。     

高压变频器在方坯连铸机二次喷淋供水泵上的应用

方坯连铸二次喷淋冷却用水量不稳定,压力波动大,导致设备损坏,改用回流装置调节压力浪费了大量富余水量的输送能耗,为此提出采用高压变频器根据水量需求进行控制,从而做到节能。改造实践证明,结合工艺控制需求,采用完美无谐波高压变频器对二次喷淋供水泵实施调速节能控制,系统稳定,调节及时,且节省了大量的电能,具有较好的经济与社会效益。     

柔性直流阀冷喷淋水反渗透处理优化研究

  [目的]  文章旨在解决换流站阀冷喷淋水水质破坏导致系统故障问题。  [方法]  分析了水质破坏机理及常规直流换流阀冷却喷淋水对管路破坏的过程,研究提炼出水处理内容。  [结果]  研究成果为柔性直流换流阀冷却喷淋水提出一种优化反渗透处理技术方案,可高效去除喷淋水中破坏管路的各个因素。  [结论]  该处理工艺出水基本杜绝喷淋水在冷却塔盘管外壁结垢及其他水质破坏的问题,确保整个阀冷系统可靠的冷却效能和稳定的运行。     

大型脱硫塔喷淋段气液两相流动与传热的数值仿真及验证

对大型湿法脱硫塔喷淋段内部的气液两相流动和传热过程进行模拟,并将模拟结果同现场运行数据进行对比.结果表明:良好的喷淋层和喷嘴布置可对塔内烟气流动起到很好的整流作用;在烟气入口对面的浆液池上方存在一气相的最高压区;原烟气的高速冲入对浆液滴的运动轨迹产生明显的影响,使得烟气入口处形成了一个斜向下呈带状的液滴浓度高值区;喷淋塔内温度梯度变化较大的区域在靠近吸收塔入口的位置,且此区域随烟气量的增大而扩大——简单忽略塔内气相温度场的不均匀性势必将给计算带来误差;喷淋塔内的气相温度场和水蒸气浓度场分布有明显的一致性规律,证明了塔内的降温过程主要为蒸发冷却.     

600MW直接空冷机组加装尖峰冷却装置改造及性能分析

为解决空冷发电厂夏季高背压运行影响汽轮机安全问题,保证机组的出力,直接空冷机组都采用了尖峰冷却装置,以提高直接空冷机组渡夏能力.介绍大唐彬长电厂机组空冷尖峰喷淋装置的改造,并针对夏季高温时段,不同负荷、不同环境温度下,投运尖峰冷却装置后机组真空的变化进行了对比分析;结果表明,机组在600MW、550MW、500MW负荷运行且环境温度26℃～31℃时,机组的背压分别下降4.9kPa、5.1kPa、3.3kPa.机组在550MW～ 600MW运行时,投运尖峰冷却装置效率最高,负荷越低,背压越低时,投运尖峰冷却装置效率越低;最后对机组在满负荷运行情况下所取得的经济效益进行了评估.     

600MW直接空冷机组背压偏高因素分析及防范措施

分析了山西漳山发电有限责任公司2×600 MW直接空冷机组背压调整控制过程,并通过实验数据论证了600MW直接空冷机组背压升高的原因,同时对引起背压升高的因素环境温度、风速以及热风再循环等分别进行试验、数据采集,得出热风再循环产生必要条件,并通过试验证明增加空冷喷雾装置可有效可降低机组背压、提高机组效率。     

基于冷却塔气流流场特征分析的增容改造应用

在冷却塔内气流流场特性试验分析的基础上,针对淮北国安电力有限公司2号机冷却塔存在的增容后循环水冷却不够、冷却塔内水流不均的问题,实施了增容改造方案,重新布置了配水系统和淋水装置。淋水区填料采取不等高布置,且不同区域采用不同出水口径达到不同的淋水密度,使配水、配风更趋合理均匀。改造后的应用效果表明,冷却塔的冷却效率大为提高,满足了机组增容改造要求且节能降耗明显。     

Computational and Experimental Study of Cooling Process in Coke Dry Quenching Experimental Shaft

Owing to its merits in energy savings, environmental protection and coke quality improvement, the Coke Dry Quenching (CDQ) technology is favorite in coke making industry today. In order to validate the mathematical model developed for the cooling process of real CDQ shaft, the one-seventh scale experimental setup was established. With the air as the working fluid and the coke as the packed bed, the coke and gas temperatures and the pressure drop in the cooling shaft were measured. A mathematical model based on the non-Darcian and non-thermal equilibrium model for the cooling process of the CDQ experimental shaft was presented. The computational results were compared to the experimental data. It was found that most numerical predictions were supported by the measured values.     

喷雾冷却在单相区中换热特性的数值模拟研究

喷雾冷却是一种高热流密度的冷却方式,按传热机理的不同可以分为单相区和两相区。针对单相区,建立三维传热模型,利用CFD仿真技术对喷雾冷却过程进行数值模拟,并研究了喷雾的高度、流量密度等参数对喷雾冷却传热性能的影响规律。结果显示:当传热稳定时,传热面温度由圆心沿径向逐渐增高,并且随喷雾流量密度的增大,温度分布的均匀性变差;保持喷雾作用面积不变,增大喷雾流量或减小喷雾高度,喷雾的传热能力显著增强;数值模拟结果与实验数据吻合,验证了该模型的可靠性,可为喷雾冷却系统的设计、优化提供依据。     

Numerical simulation of a closed wet cooling tower with novel design

A closed wet cooling tower with novel design was proposed and numerically investigated. The studied cooling tower consists of two main parts: one heat and mass transfer unit (HMTU) and one heat transfer unit (HTU). In the HMTU, copper tubes are arranged as heat transfer tubes while plastic tubes are collocated to enlarge the mass transfer area between the spray water and the airflow. In the HTU, only copper tubes are adopted as heat transfer tubes. Heat and mass transfer process takes place among the process water, airflow and spray water in the HMTU, while in the HTU only heat transfer between the process water and the spray water is observed. A transient one dimensional distributed-parameter model was adopted to evaluate the cooling tower performance under different operating conditions. Determination of heat and mass transfer coefficients, as well as the influence of Lewis number on the cooling tower performance, was presented.     

Recent Advances in Closed Loop Spray Cooling and its Application in Airborne Systems

In recent years,the problem of heat dissipation in airborne directed energy weapons has attracted considerable research interest.Spray cooling can be applied to cool airborne directed energy weapons,owing to its several advantages such as a large heat transfer coefficient,absence of boiling hysteresis and uniform surface temperature.To examine the potential of an airborne spray cooling system,the typical high heat flux dissipation methods were compared,and the state of the art research on spray cooling was reviewed.This review was focused on studies related to the spray cooling hydrodynamic mechanism,experimental studies of closed loop spray cooling,numerical simulation studies about spray cooling and the identification of the factors influencing spray cooling systems,and investigations related to the multiple nozzle spray cooling technology and heat transfer correlation predictions.Overall,there is a need for further research to investigate the failure phenomenon after the critical state,matching operation of the total system and microscopic characteristics of airborne specific parameters.     

TSD09型摆式动车组冷却装置的研制

介绍了TSD09型摆式动车组冷却装置的任务来源、设计过程、冷却装置结构方案、运用的冷却技术、部件特点以及相关试验。通过对冷却装置进行的地面通风试验和环线牵引热工试验,验证了冷却风扇的性能以及装置设计的合理性,表明冷却装置达到了设计要求,满足动车组的冷却需要。     

车用柴油机燃油喷雾的研究发展

详细描述了柴油机燃油喷雾领域的国内外研究现状,并在此基础上分析了柴油机燃油喷雾领域中面临的几个关键问题——柴油喷雾的可视化测试技术研究、柴油喷雾中的空气卷吸运动分析、CFD喷雾模型的持续完善,这些关键问题的解决也预示着对柴油机燃油啧雾的更深一步的认识,同时比较分析了研究喷雾特性的实验设备,指出设计更加类似柴油机真实工作环境的光学设备是深入理解柴油机缸内过程的关键.     

Performance Evaluation and Design of a New Cooling Tower Spray System for Uniform Water Distribution

ABSTRACT

The performance of wet cooling towers can be improved by installing sprayers that distribute the cooling water uniformly onto the fill while operating at a low pressure head. This paper presents the methodology that was followed to design a new cooling tower spray nozzle. The fluid dynamics of an orifice nozzle, such as the effect of a change in pressure head, spray angle, spray height, orifice diameter, and wall thickness on drop diameter and spray distance, is experimentally investigated, and ultimately a model with which a spray nozzle can be designed is presented. The manufacture and testing of a prototype spray nozzle show that it is possible to enhance the performance of sprayers and thus wet cooling towers by means of the methods presented.