The condensation of steam from steam-water mixture on water jets at high pressure

A physical model for condensation of steam in water flow at high pressure is developed, and analytical dependences for calculating heat transfer are obtained, in particular as applied to the operation of a direct-contact feedwater heater for a new-generation reactor plant with lead coolant.     

Design of high-pressure direct contact heater for promising power supply units: Experimental substantiation

The results of experimental studies of superheated steam condensation on feed water jets in a highpressure, direct-contact heat exchanger are presented. Direct contact feed water heater (DCFWH) can be used in a dual-flow diagram of a steam-power unit with ultrasupercritical steam parameters (35 MPa, 700/720°C). The direct contact feed water heater is included in the flow diagram of the II circuit in a promising power unit; it provides feed water heating to 340°C in all maintenance and emergency operation modes of the unit. The reliability of the high-pressure direct contact heater operation in this flow diagram is of major importance in relation to the danger of lead solidification in the tube space of the steam generator. Technical requirements to the design of the high-pressure direct contact heater for increasing the heat exchange efficiency are formulated based on the results of earlier studies with steam–water mixture as the heating medium. The results of studies of superheated steam condensation on jets presented in this study testify that feed water is additionally heated to the required temperature at the output of the installation. The influence of initial feed water parameters (outflow velocity and temperature) on the jet heating length is elucidated. The numerical approximation of the experimental data for determination of the jet heating length in the nominal and partial power unit loads is obtained. The results of the calculations are used to simplify the design of the water-supplying element for the direct contact feed water heater. The proposed design of direct contact feed water heater is characterized by simplicity and low metal intensity, which provides the installation reliability at the considered pressure level due to the minimum number of structural elements.     

Development of a Monte Carlo based aggregate model for residential electric water heater loads

A model for a residential electric water heater load is developed using an energy flow analysis of the water heater tank. An aggregate model for residential electric water heater loads is then developed using a rejection type Monte Carlo simulation technique. The resultant aggregate model is then used to assess the effectiveness of several demand-side management strategies using the water heater load profile presented in a previous analysis.     

Experimental investigation of heat transfer during condensation of steam from a steam-water mixture on cold water jets at high pressure

Results from experimental investigations of heat transfer during the condensation of steam from a steam-water mixture on cold water jets at high pressure are presented. These data are essential for developing high-pressure direct-contact feedwater heaters, such as those for power units at nuclear power stations equipped with lead-cooled reactors.     

超声波抑垢强化换热实验研究

一定功率和频率下的超声波不仅可以满足防、除垢要求,而且可以起到强化传热的效果。文章论述了超声波在防除垢与强化传热方面的作用。建立了超声波对防除垢和换热系数影响的数学模型,并通过模拟换热器实际的工作状况,获得有超声波和无超声波的相应的实验数据并进行计算,从而得出了超声波的抑垢率和平均换热系数,证明了超声波可应用于电厂换热器的防除垢和强化换热效果。     

Temperature Stability Analysis of CMOS-SAW Devices by Embedded Heater Design

The design, finite element (FE) modeling, and electrical characterization of an embedded heater in complementary metal–oxide–semiconductor (CMOS) are presented. The heater is used to analyze the temperature stability behavior of CMOS-surface acoustic wave (SAW) devices. The heater employs n-well layer of standard CMOS technology to provide high efficiency resistive heating without physically perturbing the SAW architectures and performances. A detailed 3-D model and FE investigation is laid out to characterize the heat, current, temperature, and thermal energy distributions within the substrate and the piezoelectric material of interest ZnO. Electrical characterization based on Wheatstone configuration is presented to analyze the temperature stability of the sputtered ZnO and the CMOS-SAW delay lines. A temperature coefficient of frequency of $-hbox{48.815} hbox{ppm}/^{circ}hbox{C}$ for the fabricated SAW devices with operating frequency of 322.5 MHz is obtained. The experimental results show close agreement with the FE simulations. The results demonstrate that the embedded heater design can be used as a robust analytical tool to investigate temperature stability of CMOS-SAW devices and potentially be utilized as an on-chip element for chemical, biological, and temperature sensor applications.      

电厂表面式给水加热器瞬态特性模拟与分析

加热器的运行特性决定回热系统的稳定性,进而影响着整个热力系统的性能.为了更好地了解加热器的运行,根据换热工质的不同,采用分段建模的方法,分别建立了加热器单相换热段和汽-液两相换热段的数学模型,进而得到表面式给水加热器的通用瞬态数学模型.对两类换热面分别建模相对于以凝结段模型代替整个加热器分析,精度较好.通过对两类换热模...     

A procedure for calculating the swelling of water level and protective means to prevent it from entering into the turbine flow path with the back flow of steam from direct-contact heaters

A procedure is proposed for calculating the swelling of the level of water on the saturation line when an abrupt drop of pressure occurs. A calculated study of the swelling of water level is carried out for different designs of direct-contact heaters. A comparison between the calculated and experimental data is given. The procedure can be used for calculating the swelling of water level in the apparatuses of turbine units at thermal and nuclear power stations and at boiler houses.     

电缆群直埋敷设散热的试验研究

采用带有内热源的镀铬抛光铜管(发热管)来模拟电缆群,试验采用多点温度测量仪记录发热管在直埋敷设时所加电压和相应的发热管的温度,通过对改变加在发热管上的电压对应的发热管温度进行分析,并与计算结果进行比较,得到其温度随电压增大而升高的规律,温度场实测结果与程序计算结果对比具有较高的一致性。为进一步研究直埋敷设在地下的电缆的温度和电压之间的关系和实际的电缆安全运行提供了数据。     

Design and Performance of a High-Efficiency Commercial

A gas-fired commercial water heater has been developed which achieves a steady-state efficiency of over 95 percent and can obtain overall service efficiencies above 90 percent in many applications. These high levels of efficiency are obtained by operating in the condensing mode over a substantial portion of the duty cycle. The use of a power burner and a coil-type heat exchanger results in a compact configuration which produces both high efficiency and low emissions. The design, operating principles, and performance characteristics of the water heater are described.     

某N200 MW机组高压加热器故障分析

从概率的角度对高压加热器的故障率进行了分析,以某200MW机组高压加热器的故障率为例,分析高压加热器发生故障的时间,指出如何提高高压加热器的投用率。     

A novel domestic electric water heater model for a multi-objective demand side management program

This paper presents a novel domestic hot water heater model to be used in a multi-objective demand side management program. The model incorporates both the thermal losses and the water usage to determine the temperature of the water in the tank. Water heater loads are extracted from household load data and then used to determine the household water usage patterns. The benefits of the model are: (1) the on/off state of the water heater and temperature of the water in the tank can be accurately predicted, and (2) it enables the development of water usage profiles so that users can be classified based on usage behaviour. As a result, the amount of ancillary services and peak shaving that can be achieved are accurately predictable and can be maximized without adversely affecting users.     

A physical model of an induction electric heater for cryogenic control devices

A physical model of an induction electric heater for cryogenic control devices has been proposed. The chosen method of research has been justified. The scheme of the model, the structure of the measuring equipment, and a research technique that determines the energy characteristics of the induction heater have been considered, and recommendations on its design have been made. It is shown that it is advisable to use a three-leg laminated core with the winding located in the middle core as a basic element. Such a structure of the induction heater allows one to carry out research varying the material and shapes of the heated object. A microprocessor measuring complex that allows one to control and record up to six electric signals with an error no higher than 2% has been proposed.     

大型火电机组回转式空气预热器漏风分布

针对某电厂300 MW机组回转式空气预热器,提出了漏风分布的综合模型,求解回转式空气预热器的径向、周向和轴向的漏风分布,得出轴向漏风和径向漏风可以相似化处理的结论。所以在加装径向密封装置时,也应该对轴向密封加以改造,这对回转式空气预热器的状态检修和运行维护具有指导意义。     

基于运行参数的加热器给水端差简易计算模型

传统的加热器给水端差应达值的计算,需具备详细的加热器结构参数和运行参数,在此基础上通过理论计算得出,而在实际计算中,对不同加热器结构参数的搜集比较困难.对于结构参数一定的加热器,通过计算加热器各运行参数对给水端差的影响,建立了一种新的只考虑运行参数的加热器给水端差计算模型.利用660MW和300MW机组卧式加热器运行参...     

Engineering solutions for polymer composites solar water heaters production

Analysis of engineering solutions aimed at a considerable decrease of solar water heaters cost via the use of polymer composites in heaters construction and solar collector and heat storage integration into a single device representing an integrated unit results are considered. Possibilities of creating solar water heaters of only three components and changing welding, soldering, mechanical treatment, and assembly of a complicate construction for large components molding of polymer composites and their gluing are demonstrated. Materials of unit components and engineering solutions for their manufacturing are analyzed with consideration for construction requirements of solar water heaters. Optimal materials are fiber glass and carbon-filled plastics based on hot-cure thermosets, and an optimal molding technology is hot molding. It is necessary to manufacture the absorbing panel as corrugated and to use a special paint as its selective coating. Parameters of the unit have been optimized by calculation. Developed two-dimensional numerical model of the unit demonstrates good agreement with the experiment. Optimal ratio of daily load to receiving surface area of a solar water heater operating on a clear summer day in the midland of Russia is 130?150 L/m². Storage tank volume and load schedule have a slight effect on solar water heater output. A thermal insulation layer of 35?40 mm is sufficient to provide an efficient thermal insulation of the back and side walls. An experimental model layout representing a solar water heater prototype of a prime cost of $70?90/(m² receiving surface) has been developed for a manufacturing volume of no less than 5000 pieces per year.     

Characteristics of high frequency radio wave propagated in heated ionospheric regions

A two-dimensional Ohm heating theoretic model in the magnetizing ionosphere and a ray-tracing model in a discrete ionosphere background are used to analyze quantitatively the characteristics (mainly the Doppler shift and the phase shift) of the over-the-horizon radar (OTHR) wave, which propagates through the ionospheric region heated by high frequency radio wave. The simulation results about the Doppler and the phase shift are obtained within two minutes after the heater is on. Preliminary conclusions are given by comparing the numerical results with experimental data. __________ Translated from Chinese Journal of Radio Science, 2008, 23(3): 466–470 [译自: 电波科学学报]     

基于无量纲的电站加热器变工况建模和研究

回热系统是发电机组热力系统重要组成部分,加热器是其主要的辅助设备。传统回热系统加热器变工况运行的数学模型非常复杂,建模过程中涉及流体相变问题。本文基于电站加热器在实际运行中的数据,采用无量纲方法建立加热器运行模型,无需考虑加热器内部复杂的传热过程。将模型用于某660 MW超超临界汽轮机组的低压加热器上,结果表明:利用该模型计算的加热器出口水温和实际测量数据偏差很小;在满足精度要求的情况下,该模型简单方便,工程上可用于回热系统加热器的经济运行指导和故障诊断。     

燃气采暖热水炉单风压管测风压的可行性研究

本文通过研究及实验验证,验证燃气采暖热水炉单风压管测风压的可行性,实验结果表明在风机上选取适当的取压点及设置适当的风压开关,能使风压开关稳定闭合,燃气采暖热水炉可实现单风压管测风压,为燃气采暖热水炉单风压管测风压提供了依据,对于优化产品具有现实意义。     

含大规模风电及光热电站的电力系统优化调度方法

含储热和电加热的光热电站的出力具有良好的灵活性和可调度性,能够有效提升电力系统调节水平和新能源消纳能力。首先,基于光热电站运行机理,建立含储热及电加热的光热电站运行模型,描述光热电站的能量转换特性及运行约束。进而,以系统运行成本最优为目标,计及系统各项运行约束,建立含大规模风电及光热电站的电力系统优化调度模型,并利用优化软件CPLEX求解模型。该模型综合考虑光热电站提供备用容量能力、系统运行稳定性及整体经济性,从而确定最优日前调度策略。最后,通过IEEE 39节点系统算例仿真验证了该方法的可行性和有效性。