风冷热电空调器的研制

建立了风冷热电空调器数值模拟模型 ,对空调器进行了模拟计算 .在对风冷热电空调器研制的基础上 ,进行了最佳隔热层厚度、不同结构形式、变工况、变风量和复现性实验 ,验证了仿真程序的可靠性 ,并应用模拟程序对热电材料的优值系数和空调器冷、热端的传热系数进行了分析     

风冷压缩单元式空调器节能探讨

从分析风冷压缩单元式空调器的制冷原理入手,提出了两种空气源热泵热水模块＋空气源压缩制冷模块机,为提高能源综合利用效率、节约建筑能耗提供了一定的实践思路。     

室温工作的全固态Tm：YAP激光器

研究了室温工作的Tm：YAP 2μm激光器,采用795 nm激光二极管泵浦Tm：YAP激光晶体,晶体采用热电制冷及风冷的致冷方式,实现1.99μm激光输出,最大输出功率为13.5 W,光转换效率28.2%,斜效率高达36%.并对影响激光输出的腔型、晶体工作温度等进行实验分析.     

微型热电能量采集器的研究进展

热电能量采集器是一种基于塞贝克效应,利用温差将热能直接转化成电能的温差发电装置.由于其体积小、重量轻、寿命长、无机械运动部件、绿色环保等优点,微型热电能量采集器(MTEG)已经引起了国内外的广泛关注.综述了微型热电能量采集器在国内外的研究进展,介绍了温差发电的工作原理,从热电材料和器件结构两方面重点探讨了微型热电能量采集器的研究现状.对微型热电能量采集器未来的发展方向进行了分析和预测,认为积极寻找具有高优值系数的热电材料制备易于加工和集成的高性能的微型热电能量采集器是未来研究工作的目标.微型热电能量采集器有广阔的应用前景.     

电子设备散热技术研究

随着微电子技术的发展,使得电子器件的热流密度不断增加,这样势必对电子器件有更高的散热要求,因此有效地解决散热问题已成为电子设备必须解决的关键技术.针对现代电子设备所面临的散热问题,就自然对流散、强制风冷散热、液体冷却、热管、微槽道冷却、集成热路、热电致冷等常用的电子设备散热技术及某些前沿的研究现状、发展趋势及存在问题分别予以阐述,希望对同行能有所帮助.     

军用强迫风冷加固计算机噪声影响因素研究

以某强迫风冷军用加固计算机为研究对象,对加固计算机的噪声源、噪声特性及影响噪声的主要因素进行了实验研究.研究结果表明:影响强迫风冷军用加固计算机声学噪声特性的因素主要包括风机、机箱风道,同时也排除了风机罩对计算机声学噪声特性的影响,并提出各主要影响因素对整机声学噪声贡献的占比,为将来进一步控制强迫风冷军用加固计算机声学噪声指明了方向.     

浙江抽查空调器市场

浙江省技术监督局对全省8个城市销售的39家企业生产的35个品牌共66个型号的空调器、17家企业生产的17个品牌共3O多个型号的电冰箱进行了质量抽查,抽查结果表明各种空调器和电冰箱的安全性能和质量普遍较好,空调器的安全性能指标全部合格,电冰箱除1个进口产品接地电阻超标外,其余产品的安全性能均符合国家强制性标准规定.部分国产空调器和电冰箱的质量指标已达到或超过进口名牌产品的技术指标.     

空调抽检98%合格

近日,国家质量技术监督局对全国房间空调器进行了全面抽检,主要测定了制冷量、噪音、能效比三项指标.有23家企业的24种产品合格,产品抽样合格率为98%,大部分空调器产品质量已经达到国家标准要求.     

分布式能源系统中燃气轮机热电联产运行方式优化方法

为了对热电联产之中电负荷与热负荷变化进行协调,需对热电供需的不均衡问题进行处理,优化分布式能源的系统之中燃气轮机的热电联产运行方式.同时在传统以热定电与以电定热运行基础上,添加辅助的设备方式,对热电联产运行方式进行补充.本文主要分析了燃气轮机的热电联产两类运行方式,深入研究优化分布式能源的系统之中燃气轮机的热电联产运行方式,为相关研究提供参考.     

DX-600中波发射机水冷系统原理及故障处理

美国哈里斯公司生产的大功率中波数字发射机DX600的冷却系统采用水冷和风冷组合方式对发射机产生的热量进行降温,其中风冷系统是在每个功放机柜采用4台风机对功放母版和功率合成器进行降温,水冷系统是发射机主要的冷却部分.本文主要介绍了水冷系统的控制原理及故障处理.     

无量纲优值对热电制冷系统性能影响分析

建立了无量纲稳态系统热力学模型。并用该模型分析了优值系数对系统性能的影响,优值系数是热电制冷器性能的内在制约,散热和温度条件则是热电制冷性能的外在制约,无量纲优值体现了二者对系统的影响。热电制冷系统的特殊优势再度受到人们关注,但在热电材料优值系数受到限制的现实条件下,热电制冷系统在能效上是难以与压缩式制冷空调系统比较的。     

电子元器件热电冷却技术研究进展

在深刻分析热电制冷机理的基础上,结合国内外学者对热电制冷技术用于电子元器件热管理的理论分析,从芯片整体表面散热和局部热点消除两方面,详细介绍了集成电路芯片热电冷却实验的国内外研究进展;对芯片热电冷却技术的数值模拟与热电制冷器(TEC)的选型优化进行了详细报道;指出国内缺乏芯片热电冷却的应用研究,在芯片散热的整体研究水平上与国外仍有差距.芯片热电冷却及其表面的热管理将是今后提高电子元器件散热性能的一个重要研究方向.     

电子器件热电制冷温度条件的优化

基于热电制冷热力学循环分析了热电制冷器正常工作的温度条件,以及两种极限工况性能受工作温度条件的制约关系。优值系数是热电制冷器性能的内在制约,散热和温度条件则是热电制冷性能的外在制约,热电制冷元件工作的温度特性与电子元件工作的理想温度条件是非常适应的。基于热电制冷的主动冷却技术对高热流密度电子集成部件的封装散热具有重大意义。     

Computational Study on Temperature Control Systems for Thermoelectric Refrigerators

Thermoelectric refrigeration has the outstanding advantage of allowing accurate temperature control. However, on the market there are thermoelectric refrigerators which include on/off temperature control systems, because of their simplicity and low cost. The major problem with this system is that, when the thermoelectric modules are switched off, the heat stored in the heat exchanger at the hot end of the modules goes back into the refrigerator, forming a thermal bridge. In this work, we use a computational model, presented and validated in previous papers, to study alternative control systems. A new system is introduced based on idling voltages; that is, once the temperature of the refrigerator reaches the lower limit, the thermoelectric modules are not switched off but supplied with minimum voltage. Computational results prove that this system reduces the electric power consumption of the refrigerator by at least 40% with respect to that obtained with on/off control systems, and the coefficient of performance increases close to the maximum provided by any other control system.     

Can Thermotunneling Improve the Currently Realized Thermoelectric Conversion Efficiency?

In a tunnel junction, electrons can overcome a nanoscale vacuum gap after the application of an electrical voltage. A temperature difference rather than an electrical voltage applied at the junction gives rise to an analogous thermoelectric tunnel effect called thermotunneling. This effect opens the possibility of thermoelectric conversion without phononic thermal backflow, which has encouraged optimism regarding the potential of thermotunneling for power generation and refrigeration. However, thermotunneling implies a photonic thermal backflow caused by radiative heat exchange amplified by photon tunneling of evanescent modes. An investigation based on a free electron model and comprising the combined influence of both electronic and photonic heat transfer through a vacuum tunnel gap is presented. An upper limit M = π ²/12 on the dimensionless thermoelectric figure of merit practically attainable by thermotunneling can be stated. This means that thermo- tunneling cannot outperform the maximum M values achieved by thermoelectric materials research to date.     

Current and future miniature refrigeration cooling technologies for high power microelectronics

Utilizing refrigeration may provide the only means by which future high-performance electronic chips can be maintained below predicted maximum temperature limits. Widespread application of refrigeration in electronic packaging will remain limited, until the refrigerators can be made sufficiently small so that they can be easily incorporated within the packaging. A review of existing microscale and mesoscale refrigeration systems revealed that only thermoelectric coolers (TECs) are now commercially available in small sizes. However, existing TECs are limited by their maximum cooling power and low efficiencies. A simple model was constructed to analyze the performance of both existing and predicted future TECs, in an electronic packaging environment. Comparison with the cooling provided by an existing high-performance fan shows that they are most effective for heat loads less than approximately 100 W, but that for higher heat loads, fan air cooling actually yields a lower junction temperature. Thermal resistance between the refrigerator and the chip is not as critical as the thermal resistance between the refrigerator and the ambient air.     

Modeling of a Thermoelectric Generator for Thermal Energy Regeneration in Automobiles

In the field of passenger transportation a reduction of the consumption of fossil fuels has to be achieved by any measures. Advanced designs of internal combustion engine have the potential to reduce CO₂ emissions, but still suffer from low efficiencies in the range from 33% to 44%. Recuperation of waste heat can be achieved with thermoelectric generators (TEGs) that convert heat directly into electric energy, thus offering a less complicated setup as compared with thermodynamic cycle processes. During a specific driving cycle of a car, the heat currents and temperature levels of the exhaust gas are dynamic quantities. To optimize a thermoelectric recuperation system fully, various parameters have to be tested, for example, the electric and thermal conductivities of the TEG and consequently the heat absorbed and rejected from the system, the generated electrical power, and the system efficiency. A Simulink model consisting of a package for dynamic calculation of energy management in a vehicle, coupled with a model of the thermoelectric generator system placed on the exhaust system, determines the drive-cycle-dependent efficiency of the heat recovery system, thus calculating the efficiency gain of the vehicle. The simulation also shows the temperature drop at the heat exchanger along the direction of the exhaust flow and hence the variation of the voltage drop of consecutively arranged TEG modules. The connection between the temperature distribution and the optimal electrical circuitry of the TEG modules constituting the entire thermoelectric recuperation system can then be examined. The simulation results are compared with data obtained from laboratory experiments. We discuss error bars and the accuracy of the simulation results for practical thermoelectric systems embedded in cars.     

Experimental Study of a Thermoelectric Generation System

A flat wall-like thermoelectric generation system is developed for applications in exhaust heat of kilns. The design of the whole experimental setup is presented. The essential performance of the thermoelectric generation system is tested, including open-circuit voltage, output power, and system conversion efficiency. The results illustrate that, when heat source insulation is not considered, the system conversion is efficient at hot-side temperatures between 120°C and 150°C. In addition, the nonuniformity of heat transfer is found to significantly affect the power-generating ability of the system. System-level simulation is carried out using a quasi-one-dimensional numerical model that enables direct comparison with experimental results. The results of both experiment and simulation will provide a foundation to improve and optimize complex thermoelectric generation systems.     

Modeling a Thermoelectric Generator Applied to Diesel Automotive Heat Recovery

Thermoelectric generators (TEGs) are outstanding devices for automotive waste heat recovery. Their packaging, lack of moving parts, and direct heat to electrical conversion are the main benefits. Usually, TEGs are modeled with a constant hot-source temperature. However, energy in exhaust gases is limited, thus leading to a temperature decrease as heat is recovered. Therefore thermoelectric properties change along the TEG, affecting performance. A thermoelectric generator composed of Mg₂Si/Zn₄Sb₃ for high temperatures followed by Bi₂Te₃ for low temperatures has been modeled using engineering equation solver (EES) software. The model uses the finite-difference method with a strip-fins convective heat transfer coefficient. It has been validated on a commercial module with well-known properties. The thermoelectric connection and the number of thermoelements have been addressed as well as the optimum proportion of high-temperature material for a given thermoelectric heat exchanger. TEG output power has been estimated for a typical commercial vehicle at 90°C coolant temperature.