Radio control of air conditioning in Rhode Island

A test is reported in which a VHF-FM radio communication system was used to control the compressors of central air-conditioning systems of 50 residential customers and 35 small commercial customers in Rhode Island between the hours of 12:00 and 5:00 pm during weekdays from June through September of 1988. Topics discussed include recruitment of participants, pre-experiment testing, equipment performance, and analysis of results. The hourly diversified demand reduction attributable to control was 1.0 to 1.6 kW per residence during control hours when the average outside temperature ranges from 88 to 95°F. Commercial units showed a relatively constant demand reduction, on the order of 2.5 kW, at all temperatures in excess of 80°F     

Integrated solar water heaters

The solar water heating installations widely used around the world are briefly reviewed. Special attention is paid to individual storage solar installations.     

热泵热水器与储水式电热水器脉冲压力试验对比研究

本文对比GB/T 23137—2008《家用和类似用途热泵热水器》以及GB/T 20289—2006《储水式电热水器》脉冲压力测试的相关条款要求,分析热泵热水器水箱以及储水式电热水器水箱结构,并提出了标准条款修订的建议。     

"Hands-On" Microprocessor Education at the University of Rhode Island

This paper documents the impact of microprocessor technology on electrical engineering education at the University of Rhode Island. Originally introduced as a method of giving computer experience to a larger number of students, it has become a key element in the undergraduate curriculum. "Microprocessor Laboratory" emphasizes hands-on experience by making computers available for "checkout" use at home. It is introduced as a required course at the sophomore level and the textbooks used are manufacturers' manuals. We employ a series of nine basic exercises and couple these to an end-of-semester project. The course is offered each semester and attracts students from other engineering disciplines and from other colleges within the University. It has been successfully adapted to a five-week summer session and a four-day short course for engineering faculty. The course forms the basis for introducing microprocessors into other, more advanced engineering courses.     

Analysis of thermal stresses in horizontal delivery water heaters

Analysis of thermal stresses in tubes and a compensator, taking into account water heating in each heater bunch and temperature at which its mounting is implemented, and of stresses on pressure is presented. The 3D-model of the horizontal delivery water heater of PSG-4900-0.3-1.14 type is used. The tube plate is represented as the 3D-body with 6863 holes with offset center of the perforated area, the steam space shell is represented as a cylindrical casing, the bottoms of water chambers are considered as elliptical casings, the four-lens compensator is represented in the form of toroidal casings, and the tubes are considered as beams operating in tensile-compression and bending in two planes. Calculations were carried out for different temperatures of superheated steam and a steam space shell, respectively, as well as designs with compensator and without it. Various temperature values of the tubes on the passes were calculated and set. The studies were carried out taking into account nonaxis-symmetrical spacing the tube plate and compensator deformation. The calculation results of tensile-compression stresses in the tubes are presented. Furthermore, the central tubes experience compressive stresses, whose maximal values take place on the border between the tubes of the fourth and of the first passes. For its decrease, it is recommended to increase the distance between the tubes of these passes. The tension stresses in the peripheral tubes are the maximal stresses. To reduce the stresses and, therefore, increase service life of the delivery water heater at using wet or superheated (not more than by 30–50°C) steam in it (the larger value refers to the brass tubes and the water pressure of 1.6–2.5 MPa), it is necessary to recommend the noncompensatory design at using the steam superheated by more than 30–50°C (at Ural Turbine Works, it is the turbines of T-250/300-23.5 and T-113/145-12.4 types with intermediate superheating) and to recommend the installation of the compensator operating only at compression.     

“多模式”电热水器的消费需求分析

"多模式"电热水器的优势迎合了某些市场需求,引来诸多企业纷纷开发这类产品,但各家采取的技术方案各具特色,各有千秋。那么,"多模式"电热水器迎合的是哪些消费需求?是否属于一类新的器具类别?本文试图对上述问题做些分析。     

储水式电热水器性能测试实验室的设计

根据GB 21519-2008储水式电热水器能效限定值的技术要求,设计并建造了一套由空气处理系统、恒温水系统、数据采集系统、电气控制系统组成的6工位储水式电热水器性能实验室.该测试系统可以从额定容积,24小时固有能耗,热水输出率三个指标来对储水式电热水嚣性能做出评价.经过验收审核,该储水式电热水器性能测试实验室测试精度满足作为国家检测机构评定使用,自动化程度高,使用简单.     

用于消纳风电的城区用户电热水器负荷群滑模控制策略研究

居民电热水器是一种典型的热储能负荷,用电产生的热水具有热存储性,可以消纳波动性风电。提出了用于消纳风电的电热水器负荷群滑模控制策略,来实时控制电热水器负荷群。控制率与电热水器群数量、热水使用情况等相关,对于消纳风电具有较强的鲁棒性。采用某城区居民区电热水器负荷群的仿真研究表明,提出的电热水器群滑模控制策略能有效消纳风电,验证了电热水器负荷群滑模控制策略有效性。     

快热储水一体式电热水器因电子线路故障可能导致的安全隐患及改进方法

目前市场上快热储水一体式电热水器成了很多人的选择,本文结合此类电热水器的结构,对部分此类产品中由于电路设计问题而导致的并可能引发安全隐患的一种特殊故障进行分析,提出整改方法及安全可行的改进电路,为家用电器生产厂家及家用电器安全检测部门提供参考.     

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.     

裸露元件式快热电热水器安全性实验研究

本文结合国家标准、国家认证认可监督管理委员会TC04专家组决议、用电环境接地可靠性、水源电阻率等因素开展裸露元件式快热电热水器产品安全性的实验研究,探讨其安全要求.     

变频调速技术在低压加热器疏水系统中的应用

介绍了现有低压加热器疏水系统水位控制存的问题,以及变频调速技术应用在低压加热器疏水系统中的调节原理,运行状态及优点,该项技术不仅降低了设备故障率,减少了维护工作者,而且具有良好的节能效果,值得在条件合适的厂家推广使用。     

Making the tube system of horizontal delivery water heaters more reliable

The influence of tensile-compression stresses on the natural frequencies of tubes is investigated. A continuous spectrum of frequencies is obtained. Methods for detuning from resonance are proposed. The effect of a compensator on the stresses in tubes is studied.     

Movement and evaporation of water droplets under conditions typical for heat-exchange chambers of contact water heaters

The macroscopic regularities and integrated characteristics of the motion and evaporation of sprayed water droplets in the field of high-temperature (1100 K) combustion products under the conditions typical for water heaters of contact type (economizers) were studied using a cross-correlation complex working on the basis of panoramic optical methods (particle image velocimetry, particle tracking velocimetry, shadow photography) and high-speed (10⁵ fps) Phantom video cameras. High-speed video recording devices with specialized software were used for continuously monitoring the motion and evaporation of droplets. Titanium dioxide nanopowder tracer particles were introduced to determine the rate of high-temperature gases. The characteristic distances covered by water droplets before their full retardation in the counter-flow of high-temperature combustion products were determined. The integrated dependences were obtained, and the main characteristics of evaporation were determined, which allow one to predict the intensity of the phase transformations of droplets (with sizes of 0.05–0.5 mm) and the distances covered by them before they completely turn in the opposite direction under the conditions corresponding to the heat-exchange chambers of contact water heaters: the vapor-droplet rate 1–5 m/s, gas flow rate 0.5–2 m/s, and gas temperature ~1100 K. Approximating expressions were derived to predict the characteristics of the processes. The performance of the economizers under study can be significantly increased by using the obtained experimental dependences, the corresponding approximating expressions, and the resulting conclusions. Conditions were determined under which the influence of phase transformations on retardation exceeds the contribution of the counter-motion and active retardation and evaporation of water droplets occur in the heat-exchange chambers of contact water heaters of typical sizes.     

家用和类似用途热泵热水器国家标准与行业标准分析

摘要：本文主要以热泵热水器标准和技术发展情况为基础,介绍了目前已经发布或完成制定的国家标准和行业标准的主要技术内容和特点．同时针对家用电器标准体系逐渐完善的发展趋势,对于下一步热泵热水器标准的制定范围和方向进行了分析和预测。     

国产300MW机组低压加热器疏水系统连接方式的改进

解决国产300MW机组给水低压加热器疏水系统存在的问题，交原设计为疏水逐级自流与疏水泵相结合的连接方式，以疏水逐级自流与外置式疏水冷却器相结合的方式来取代，不仅计算热经济性相当，而且因取消了转动设备疏水泵，提高了系统实际运行的经济性和安全性。     

电感应热水机组的谐振变换器研制

结合大型电感应热水机组的应用背景,设计了利用大型电感应热水机组的感应线圈及漏电感、补偿电容组成的超音频IGBT-FB-ZVS-PWM谐振变换器,通过工作过程分析和样机运行表明,装置具有功率调节简便、器件损耗小、性能可靠、运行噪音低等优点.使得大型电感应热水机组能够广泛地用于居民生活和工业生产等需要加热水的场所.     

低压加热器疏水方式节能讨论

对热力发电厂中低压加热器疏水系统所采用的不同疏水方式进行分析,通过对不同疏水方式的比较和计算,表明300 MW机组的低加回热系统采用疏水冷却器比采用低加疏水泵更经济、安全.     

混合负载下基于虚拟振荡器控制的离网逆变器控制策略研究

虚拟振荡器控制(virtual oscillator control, VOC)策略是一种新型分布式控制方法,在离网和并网逆变器中具有巨大的应用潜力。然而,当负载变化及非线性不平衡负载接入系统时,基于VOC的离网逆变器系统会存在频率偏差和谐波问题。针对上述不足,通过分析混合负载对电力系统造成的影响,提出一种改进的VOC策略,并引入电压、电流正负序分离技术,设计了二次频率补偿器。同时改进了电压电流双闭环控制结构,进一步提高了系统抑制谐波的能力。在Matlab/Simulink平台中搭建了离网逆变器系统仿真模型。通过与传统VOC进行对比,验证了所提控制策略在解决频率偏差和抑制谐波问题中的有效性。     

液体加热器产品抽查质量分析

本文针对2011年第1季度上海市液体加热器产品抽查结果进行质量分析。针对抽查中暴露出来的产品问题进行全面而深入的分析,以帮助企业更好的改进产品。