温差发电器中热电材料物性的影响分析

考虑温差材料的塞贝克效应及电流的珀耳帖效应,与传热方程相结合,建立了温差发电器的一维计算模型,数值模拟了温差发电器的热电耦合工作过程。主要分析了温差材料的导热系数、电阻率和塞贝克系数的变化及其变物性计算对温差发电器工作性能的影响。计算表明,材料的导热系数、电阻率及塞贝克系数对发电器转换效率的影响规律均为非线性的,其中导热系数的影响作用最明显;当发电器的温差电元件物性参数差别较大时,其内部有不同的温度分布,采用平均值计算会有明显的误差;温差材料物性参数随温度变化后,发电器工作性能有较大的变化。     

采用热电半导体的小型海上太阳能集热发电系统

海洋中蕴含着多种形式的能源,且储量巨大,为了充分利用这些能源,提出了一种基于热电半导体发电技术的小型海上太阳能发电系统。这种系统利用太阳能产生热量来加热传热工质,利用海洋的波浪能实现传热工质的循环,利用热电半导体实现温差发电,从而实现将海洋太阳能和波浪能同时利用。介绍了该系统的结构组成和工作原理,通过对热电半导体的理论分析和仿真验证,发现热电半导体理论上可以实现10%的能量转化效率。由于该系统结构简单、无机械零部件、集成度高,因此具有可靠性高,维护成本低等优点,有一定的应用前景。     

TLM representation of the hyperbolic heat conduction equation

Many heat transfer situations are adequately described by the parabolic thermal diffusion equation. However, in situations in which very rapid heating occurs or in slower heating regimes for particular materials, the hyperbolic heat conduction equation is a better representation. Here, a parameterized nodal structure for transmission line modelling (TLM) representation of hyperbolic heat conduction processes is devised. A TLM model based on the nodal structure is implemented and temperature field predicted by the model are compared with analytical results for the same physical situation. Copyright © 2002 John Wiley & Sons, Ltd.     

永磁往复发式发电机的温度场计算

研究了1.1kW永磁往复发电机稳态运行时电机内部的发热机理和温度场分布情况。基于有限元法计算了电机稳态运行时电机内的发热源和各部位表面散热系数,计算出定子与线圈的温升分布,找出电机内的最高发热部位,并将计算值与实验值进行比较,验证了求解的正确性。     

Electrical power generation from a knitted wire panel using the thermoelectric effect

Thermoelectric devices have been investigated widely in order to transform a low temperature heat source to the electrical power. In this report, we proposed a knitted wire panel as a thermoelectric power generator. A thermocouple on the knitted wire panel was formed by knitting an alumel wire and a chromel wire (? 0.3 mm). The knitted wire panel was set at a measurement system using a peltier cooling device, and electrical characteristics were measured. Additionally, we discuss here the characteristics of electrical power generation from the panel using an equivalent circuit model. As a result, electrical power from the panel increased linearly with increasing a number of thermocouple formed by wire knitting process on the panel. It ia considered that thermocouples can be formed easily by wires knitting process. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 140(1): 16–21, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10028     

一种温差电器件的发电性能分析研究

BiTe合金是低温热电发电材料的一种典型材料。为获得其在室温范围内的发电方面的热电性能,采用一种BiTe合金材料,制备了多种规格的温差电器件,通过实验研究了该器件在不同温度下的电阻、电压、赛贝克系数等热电性能,给出了其随温度变化的线性近似方程,求得相关的经验参数。在此基础上,推导出最大输出功率的近似数学表达式,并进行了试验验证,实验结果表明近似方程与实际测量结果相吻合。     

商用温差电致冷组件用于发电的研究

由于环境保护和军事应用的需要,近年来温差电材料和器件的研究重新激发起人们极大的兴趣。研究了商用温差电致冷组件用于发电的可行性,实验得出各种条件下三种标准温差电致冷组件在发电模式下的输出性能,并讨论了用于低温发电的经济性。发现以目前的价位为基础分析,温差电致冷组件用于低温热源发电的成本已经低于工业用电的价格。利用商用温差电致冷组件发电技术大规模开发工业余热、汽车废热、垃圾燃烧热的时代已经到来。     

西门子V94．3A燃气轮机配套余热锅炉设计

华能上海石洞口燃机电厂燃气—蒸汽联合循环工程选用西门子V94.3A型燃气轮机,余热锅炉是国内设计生产的第一台配该型号燃机的余热锅炉。由于机组整体性能由西门子保证,故余热锅炉的系统设计必须考虑满足西门子提出的相关要求。介绍了余热锅炉主要设备的结构特点,详细介绍了配V94.3A型燃机的余热锅炉设计技术数据,可为国内大型联合循环机组余热锅炉的设计提供参考。     

Performance Comparison of Scramjet‐Driven Experimental DCW‐MHD Generators with Different Cross‐Sections

The purpose of this study is to examine the influence of the shape of the cross‐section of a scramjet engine‐driven experimental diagonal conducting wall (DCW)‐MHD generator on generator performance by three‐dimensional numerical analyses. We have designed MHD generators with symmetric square and circular cross‐sections, based on an experimental MHD generator with an asymmetric square cross‐section. Under the optimum load conditions, the electric power output reaches 26.6 kW for the asymmetric square cross‐section, 24.6 kW for the symmetric square cross‐section, and 22.4 kW for the circular cross‐section. The highest output is obtained for the experimental generator with the asymmetric square cross‐section. The difference in the electric power output is induced by the difference of flow velocity and boundary layer thickness. For the generator with the asymmetric square cross‐section, the average flow velocity is highest and the boundary layer is thinnest. The compression wave is generated with dependence on the channel shape. The difference in the flow velocity and boundary layer thickness is induced by the superposition of the compression wave. © 2014 Wiley Periodicals, Inc. Electr Eng Jpn, 187(2): 9–16, 2014; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.22403     

异步风力发电机流动与传热分析及优化设计

为了研究兆瓦级风力发电机内部流体流动与传热特性,以1台异步风力发电机为研究对象,基于计算流体力学(CFD)与数值传热学(NHT)基本原理,采用有限体积法对发电机进行整机建模,对流场与温度场进行数值计算。通过与试验数据的对比分析,验证了计算方法的正确性与准确性。对发电机内部流场温度场进行了分析,获得兆瓦级风力发电机冷却介质流动特性。最后,对发电机通风道布置方案下进行了优化,有效降低了发电机热点温升。     

3MW双馈风力发电机传热特性数值研究

随着风力发电机容量的增加,电磁负荷不断提高,电机的发热问题成为影响机组性能和经济指标的主要因素之一。为了解决该难题,以一台3MW双馈风力发电机为例,根据流体力学以及传热学理论,结合发电机通风性能以及结构特点,建立了发电机三维流动与传热耦合求解的数学模型与物理模型;并给出基本假设与相应的边界条件,采用有限体积法对三维流体场和温度场控制方程进行耦合计算。最后,对发电机内部的流体流动性能、传热特性以及发电机定转子铁心、定转子绕组以及绝缘的温升分布进行了分析,得到端部气体流动不规律以及二次冷却热能力较强等,为更大容量风力发电机综合物理场的准确计算提供了理论依据。     

基于集总参数法的IGBT模块温度预测模型

从IGBT模块的内部结构和故障机理分析,得到影响IGBT模块可靠性的主要因素是温度的结论,而IGBT模块各层的温度是很难用实验的方法测取的。为了解决这一问题,在分析IGBT模块内部导热机理的基础上,利用瞬时非稳态导热的集总参数法建立热网络模型,并给出热损耗值、等效热阻、等效热容的提取方法。通过与制造商提供的IGBT模块结温实验数据、实测的底板温度和有限元模型相比较,热网络模型温度预测误差小于5%。     

Numerical performance simulation of frozen helium plasma disk MHD generator

MHD electrical power generation with frozen helium plasma (FHP) is examined numerically. The FHP can be initiated by preionized helium without the alkali metal seed at the generator inlet. Since the three‐body recombination coefficient of helium ions is low at electron temperatures above 5000 K, the ionization degree can be kept almost constant in the entire region of the generator channel. The r?θ two‐dimensional numerical results show that the performance of the FHP MHD generator is comparable to that of the seeded plasma MHD generator, if the additional power consumed to preionization is ignored. In the FHP MHD generator, the ionization degree at the inlet should be controlled precisely, as well as the seed fraction in the seeded plasma MHD generator. Under an adequate inlet ionization degree for sustaining the FHP plasma, the plasma maintains the uniform structure. On the other hand, a slightly excess ionization degree causes a strong Lorentz force in the upstream region of the generator, deteriorating the generator performance. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 140(3): 26–33, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10030     

地埋式变压器温升及地埋系统热传递过程

地下式和地埋式变压器长期埋放于地下,热问题十分突出,变压器温升及地坑环境温度对其安全运行起着重要作用。为此,对地坑方式直接埋入配电变压器DGSR11-H-315/10进行试验研究,采用热电偶测量温度,并建立地埋式变压器-地坑流场-土壤介质即地埋系统的热传递模型对该地埋系统的温度场分布进行数值研究。计算与试验结果的对比说明了模型的可行性,为进一步推广和发展地下式和地埋式变压器的应用奠定理论基础。     

Multijunction thermal converter with improved frequency characteristics between 10 Hz and 1 MHz

A new multijunction thermal converter (MJTC) for precision AC–DC transfer standard has been developed. A U‐shaped heater pattern was sputter‐deposited onto an AlN plate in order to reduce thermoelectric effect, which causes the frequency‐independent AC–DC transfer difference. Both low‐frequency and high‐frequency characteristics improved as a result of the new configuration, and the AC–DC transfer difference of the MJTC was evaluated to be <1 µV/V between 10 Hz and 100 kHz and <10 µV/V up to 1 MHz. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

A hybrid input charge‐pump using micropower thermoelectric generators

For industrial wireless transmitters, a hybrid input charge‐pump utilizing thermoelectric energy from waste heat is proposed in this paper. Unlike conventional converters, the proposed capacitor‐based converter supplies energy to a wireless transmitter by using a thermoelectric power source in combination with a rechargeable battery source. By combining the battery voltage and the thermoelectric generator (TEG) voltage, the proposed converter achieves a wider input range than conventional converters. Consequently, the proposed converter will enable the development of not only an industrial wireless transmitter but also various clean energy applications. Through theoretical analyses, simulations, and experiments, the following results are shown: 1. Even if the voltage of the TEG is small, the proposed converter can provide the sufficient voltage by compensating the insufficient voltage of the TEG with the battery voltage. 2. The formulas obtained by the theoretical analyses are useful for designing the proposed converter because the theoretical results correspond well with the simulation results. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

3 MW空-空冷双馈风力发电机内部流动与传热特性的数值模拟与试验研究

为更好地指导电机设计,以一台3 MW空-空冷双馈风力发电机为研究对象,基于流体力学及数值传热学理论,结合空-空冷却器和发电机模型,搭建了三维流动与传热耦合求解的物理模型和数学模型。依据基本假设和边界条件,采用Fluent软件对电机在额定工况下的稳态三维流场和温度场进行数值求解。通过电阻法和埋置检温计(ETD)法测得电机在额定工况下绕组的平均温升和最高温升。通过对比数值结果和试验数据发现误差在5 K之内,验证了数值方法的正确性。最后,对电机流场和温度场分布进行数值模拟,对电机18档通风道内流量进行数值计算,为新产品电机设计和优化提供支撑。     

裂缝对太阳能储热混凝土温度分布的影响

对存在不同裂缝的储热混凝土模块放热特性进行了数值模拟,主要包括裂缝的方向、位置、长度及宽度对放热过程的影响,给出了放热结束时的瞬时温度分布。结果表明:周向和轴向裂缝极大地增加了导热热阻,应及时更换储热混凝土模块;径向裂缝在储热混凝土模块内部生长时,对放热的影响不大,但贯穿到混凝土模块表面时,增加了换热面积和湍流度,同时也使得储热混凝土内部温差增大,从而增加温度应力,可能会导致裂缝进一步生长。     

Experiments of the improvement in the performance of a disk CCMHD generator

The present experiment has aimed at the improvement in the performance of a shock‐tube‐driven disk CCMHD generator. For that purpose, an experimental setup was arranged as follows: (1) An inlet swirl was introduced. (2) The area ratio of the disk generator was small. (3) A cesium‐seeded helium gas was used as a working medium. Not only these factors but also the production of a homogeneous plasma contributed to outstanding performance characterized by an isentropic efficiency of 63% and an enthalpy extraction ratio of 30.8% at a stagnation temperature of 2250 K and stagnation pressure of 0.14 MPa. Furthermore, a maximum electrical power output of 1.23 MW and a maximum power density of 297 MW/m³ were obtained. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 157(2): 24–31, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20024     

An energy-harvesting system using thermoelectric power generation for automotive application

An energy-harvesting system which extracts heat from an automotive exhaust pipe and turns the heat into electricity by using thermoelectric power generators (TEGs) has been constructed. Two test benches have been developed to analyze the thermoelectric module (TM) performance and TEG system characteristics. The experiments are carried out to examine the influences of the main operating conditions, the hot and cold side temperatures, flow rates and the load resistance, on the power output and voltage. As the performance of a TM is most influenced by the applied pressure and the temperature difference, a thermostatic heater, thermostatic water tank, and clamping devices are used in our experimental apparatus, the three operation parameters such as the applied pressure, cold-side flow rate and cold-side temperature are found to significantly affect the maximum power output. Based on the single TM measurement, the whole TEG system has also been designed and tested on the bench test. Through these experiments, maximum power output of the system is characterized. The results establish the fundamental development of automotive exhaust thermoelectric generator system that enhances the TEG efficiency for vehicles.