碲化铋温差发电模块输出功率的计算与性能测试

温差发电器可广泛用于汽车发动机尾气废热的回收。为优化温差发电模块构型和优选热电材料以获得高输出功率,发展完善的热电耦合物理模型十分必要。本文针对工作在特定热源和热沉温度下的温差发电模块,建立了包含基本热电效应的温差发电器工作过程一维物理模型。物理模型中考虑了热电元件与热源和热沉之间的热阻的影响,并从基本理论出发,分析了包含汤姆逊热的输出功率表达式。通过建立的测量系统测试了碲化铋基(BiTe-based)温差发电模块的输出功率,利用热像仪检测了热电元件温度分布,并将输出功率计算结果与实验测试结果和ANSYS三维仿真结果做了对比。对比结果验证了物理模型的准确性。     

面向LNG汽车的发动机排气与低温燃料温差发电器研究

为实现液化天然气（LNG）汽车的节能,提出了利用温差发电器（TEG）回收发动机排气（EG）的废热和低温燃料的冷能。指出了基于冷源所在的低温区,以及EG与LNG之间的大温差这两个特点,TEG的热电转换效率会高于常规。基于对小型LNG汽车中典型燃料系统的分析,设计了进行能量回收的两种系统流程,计算了其中各状态点的参数、及各换热器中布置温差发电器后的热电转换效率,得到了系统总的回收功率。结果表明,汽化器系统的回收功率大于自复温系统;在两种系统中,合理选取多种材料相较于仅用单种材料,TEG的回收功率更大。     

柔性热电发电器的关键工艺及其展望

热电发电器是固态能量收集器,以可靠和可再生的方式将热能转换成电能。过去几年的研究表明,人体的热量可以很好地被柔性热电发电器转换为电能并加以利用。与用于可穿戴设备的其他传统发电器相比,柔性热电发电器可利用低品位的热能发电且环境友好。柔性热电发电器将有可能为任何无线传感器节点提供足够的能量(通常功率要求小于毫瓦级)。本文综述了热电发电器的概况,重点介绍了制造柔性热电发电器的关键工艺,讨论了热电发电器的基本原理、效率、应用以及存在的一些问题。     

基于热电模块实验的低温下塞贝克系数的测量

利用热电发电器（TEG）进行温差发电是LNG冷能利用的方式之一,而目前低温下热电材料塞贝克系数（α）研究的缺失给低温TEG的设计带来了障碍。因此,本文提出一种通过TEG模块的实验得到低温下该模块所用热电材料α的测量方法,并测试了热电材料Bi2Te3在90~180 K温度范围内的α。结果表明：Bi2Te3在低温下的α随温度的降低而减小,温度从180 K降至90 K,塞贝克系数从124.6 μV/K降至49.3 μV/K,且与温度成二次函数关系。     

多级热电制冷器的制冷性能及主要影响因素分析

目前对多级热电制冷器的研究较少,且对制冷性能的报导尚不统一。为研究多级热电制冷器的确切性能,本文利用商用热电材料的物性参数,建立了一级至六级热电制冷器的多物理场耦合仿真模型,并通过实验验证了模型的准确性。然后从多级热电制冷器的设计角度出发,研究了外部驱动电路及内部结构参数对其制冷性能的影响。结果表明：在热端为27℃时,六级热电制冷器在电串联、电并联和独立电源驱动电路下可分别获得113.32、71.84和129.78℃的最大制冷温差。进一步探究了不同驱动电路的最佳应用场合,分析了不同驱动电路下多级热电制冷器的制冷性能出现差距的原因。并以六级热电制冷器为例,研究了各层级热电臂的高度的影响,结果表明最高层级的臂高是最主要的影响因素。     

可穿戴热电发电器的研究进展

人体的能量大部分以热量的形式释放，其与外界的温差平均约5～30℃,因此体热可以很好地作为热电发电器的热源。与传统发电器相比，可穿戴热电发电器将人体所散发的低品位热量转化为有效电能，有可能为一些功率要求小于毫瓦级的无线传感器节点提供足够的能量，同时还具备无污染、轻便、稳定等特性，因此越来越受到关注。目前柔性可穿戴热电发电器的研究主要聚焦基于块体型热电材料、基于薄膜状型热电材料和基于纺织织物型热电材料的三大类热电发电器。其中，块体型热电发电器的输出功率一般为每平方厘米几十微瓦，热电臂材料主要为室温热电性能较高的碲化铋基合金，研究重点在于提升这类器件的输出性能和柔性。薄膜型热电发电器的输出功率一般在每平方厘米纳瓦和微瓦之间，按结构可分为水平型和垂直型，常见的水平型器件包含串联型、堆积与卷起型和折叠型，通常会产生较大的输出电压；而垂直型器件单位面积的热电臂对数增多，会产生较大的功率密度。纺织织物型热电发电器输出功率较小，但是具有优良的拉伸、弯曲和面内剪切性能，可以适应3D变形，更适合在弯曲的人体皮肤表面收集热量。本文综述了以上三大类主流的柔性可穿戴热电发电器的研究状况，并从设计、结构和性能方面...     

热电制冷的应用与优化综述

热电制冷(TEC)是以温差电现象为基础的制冷方式,是基于帕尔贴效应的固态环保型制冷技术。与其他制冷方式相比,热电制冷具有体积小、结构简单、可靠性高、制冷迅速等优点。本文通过研究国内外的相关文献,主要从热电制冷的应用及性能优化两方面综述了热电制冷近年来的研究进展和成果。对热电制冷在热电冰箱、热电空调和电子器件冷却等方面的应用及相关研究进行了归纳分析,并对热电制冷与太阳能、蒸气压缩以及蒸发冷却等复合系统应用进行了分析阐述。在热电制冷性能优化方面,总结了在材料已定时提升热电制冷的性能优化方法,包括热电制冷器结构、工作参数及热端散热等,并在工作参数优化过程中分析了近年来研究较多的脉冲电流研究进展。     

多级热电制冷器的数值模拟与实验研究

对多级热电制冷器进行了理论分析。在三种不同工况下,运用ANSYS模拟四种不同类型热电制冷器的制冷温度,并搭建实验台进行了实验研究。模拟结果表明,热电制冷器热电对之间的距离对其制冷温度有影响,设计热电制冷器时,应对热电对距离进行优化设计。实验结果表明,实验用热电制冷器最佳工作电压为12V,热电制冷器制冷温度受外界环境影响非常大,选择合适的绝热材料对制冷器制冷温度有重要影响。实验结果还表明,热电制冷器输入电流和功率随热端温度升高而减小,制冷温度和最大制冷温差随热端温度升高而增大。     

温差发电的热力过程研究及材料的塞贝克系数测定

建立了半导体温差发电器件的基本模型；从稳态的热传导方程出发，对发电器件进行了热力学分析，推导出P型和N型半导体内部的温度分布函数及输出功率和发电效率的表达式；测定了一种Bi-Te-Sb-Se半导体热电材料在低温下的塞贝克系数随温度的变化关系，绘制了曲线并进行数值拟合；结果表明，该种半导体热电材料在低温下性能不佳，需改进配方或生产工艺方可使用。     

多级压力源切换系统节能特性仿真研究

在多级压力源切换系统中,存在系统节能机理不明晰以及系统关键参数选取缺乏依据的问题。基于此,本文通过建立多级压力源切换系统和传统负载口独立阀控系统的能耗数学模型,对多级压力源切换系统的节能效果进行理论推导;搭建两系统的仿真模型,将两系统在给定工况下进行对比,对多级压力源切换系统的节能效果进行仿真研究;通过绘制系统位移跟随误差和节能功率的曲面图,分析总结了影响系统能耗和控制特性的主要因素,确定了系统的主要工作参数——阀芯位移比和中间压力等级的取值大小。研究结果为提高多级压力源切换系统的系统性能和优化系统参数提供了分析依据。     

基于生物质燃料的水冷式温差发电机的实验研究

为解决无电区域和火灾、地震和雪灾等特殊条件下的供电问题,设计了一种可燃用木柴和木炭等生物质燃料的水冷式温差发电机,其特点在于引入了一种辐射型的集热器。温差发电机的总质量为23.3 kg,集成了直流稳压器,可稳定地对外输出电能。测试了温差发电机的启动特性、空载特性和功率负载特性,结果表明：该温差发电机的平均工作温差为68℃,最大空载电压达到116.3 V。当接入负载时,输出功率随外部负载电阻的增大而降低。当外部负载为1.6 Ω时,温差发电机可对外输出最大功率为22.4 W;继续降低负载电阻时,温差发电机将不能维持稳定地输出电能。     

Performance optimization for two-stage thermoelectric refrigerator system driven by two-stage thermoelectric generator

A new configuration of combined thermoelectric device, two-stage thermoelectric refrigerator driven by two-stage thermoelectric generator, is proposed in this paper. The thermodynamic model of the combined device is built by using non-equilibrium thermodynamic theory. The analytical formulae for the stable working electrical current, the cooling load versus the working electrical current, and the coefficient of performance (COP) versus the working electrical current of the combined device are derived. For the fixed total number of thermoelectric elements of the combined device, the allocations of the thermoelectric element pairs among the two thermoelectric generators and the two thermoelectric refrigerators are optimized for maximum cooling load and COP, respectively. The influences of the heat source temperature of the two-stage thermoelectric generator and the heat source (cooling space) temperature of the two-stage thermoelectric refrigerator on the optimal performance of the combined thermoelectric device are analyzed by detailed numerical examples.     

空间百瓦自由活塞斯特林发电机的实验研究

搭建了实验测试系统并对研制的百瓦自由活塞斯特林发电机进行性能优化实验,探究了板簧刚度、运行压力、外负载和冷端温度等因素对发电机输出功率、热电效率、运行频率、热端温度等输出特性的影响.结果 表明:同一工况下,配气、动力活塞板簧刚度均存在最佳值使得发电机的输出功率与热电效率最高,运行频率对前者的变化更为敏感.运行压力和外负...     

A design method of thermoelectric coolerConception d'un refroidisseur thermoélectrique

A system design method of thermoelectric cooler is developed in the present study. The design calculation utilizes the performance curve of the thermoelectric module that is determined experimentally. An automatic test apparatus was designed and built to illustrate the testing. The performance test results of the module are used to determine the physical properties and derive an empirical relation for the performance of thermoelectric module. These results are then used in the system analysis of a thermoelectric cooler using a thermal network model. The thermal resistance of heat sink is chosen as one of the key parameters in the design of a thermoelectric cooler. The system simulation shows that there exists a cheapest heat sink for the design of a thermoelectric cooler. It is also shown that the system simulation coincides with experimental data of a thermoelectric cooler using an air-cooled heat sink with thermal resistance 0.2515°C/W. An optimal design of thermoelectric cooler at the conditions of optimal COP is also studied. The optimal design can be made either on the basis of the maximum value of the optimal cooling capacity, or on the basis of the best heat sink technology available.     

Performance analysis of multi-stage thermoelectric coolers

Multi-stage thermoelectric coolers offer larger temperature differences between heat source and heat sink than single-stage thermoelectric coolers. In this paper, a pyramid-type multi-stage cooler is analyzed, focusing on the importance of maximum attainable target heat flux and overall coefficient of performance, COP. Having considered the COP and the thermal resistance of a heat sink as key parameters in the design of a multi-stage thermoelectric cooler, analytical formulas for COP and heat sink thermal resistance versus working electrical current are derived. For a fixed cooling target heat flux, the ratio of the heat sink thermal resistance to the respective single-stage value and the attainable COP in a cascaded cooler are determined as a function of the number of stages. Numerical simulations clearly indicate that the thermal resistance of the hot side heat sink is the controlling factor in determining the overall performance of a multi-stage thermoelectric cooler.     

Effect of heat transfer on the performance of thermoelectric generator-driven thermoelectric refrigerator system

A model of thermoelectric generator-driven thermoelectric refrigerator with external heat transfer is proposed. The performance of the combined thermoelectric refrigerator device obeying Newton’s heat transfer law is analyzed using the combination of finite time thermodynamics and non-equilibrium thermodynamics. Two analytical formulae for cooling load vs. working electrical current, and the coefficient of performance (COP) vs. working electrical current, are derived. For a fixed total heat transfer surface area of four heat exchangers, the allocations of the heat transfer surface area among the four heat exchangers are optimized for maximizing the cooling load and the coefficient of performance (COP) of the combined thermoelectric refrigerator device. For a fixed total number of thermoelectric elements, the ratio of number of thermoelectric elements of the generator to the total number of thermoelectric elements is also optimized for maximizing both the cooling load and the COP of the combined thermoelectric refrigerator device. The influences of thermoelectric element allocation and heat transfer area allocation are analyzed by detailed numerical examples. Optimum working electrical current for maximum cooling load and COP at different total number of thermoelectric elements and different total heat transfer area are obtained, respectively.     

Integration of dye-sensitized solar cells, thermoelectric modules and electrical storage loop system to constitute a novel photothermoelectric generator

This study self-develops a novel type of photothermoelectric power generation modules. Dye-sensitized solar cells (DSSCs) serve as the photoelectric conversion system and a copper (Cu) heat-transfer nanofilm coating on both sides of the thermoelectric generator (TEG) acts as a thermoelectric conversion system. Thus module assembly absorbs light and generates electricity by DSSCs, and also recycles waste heat and generates power by the TEG. In addition, a set of pulsating heat pipes (PHP) filled with Cu nanofluid is placed on the cooling side to increase cooling effects and enhance the power generation efficiency. Results show that when the heat source of thermoelectric modules reaches 90 degrees C, TEG power output is increased by 85.7%. Besides, after thermoelectric modules are heated by additional heat source at 80 degrees C, the electrical energy generated by them can let a NiMH cell (1.25 V) be sufficiently charged in about 30 minutes. When photothermoelectric modules is illumined by simulated light, the temperature difference of two sides of TEG can reach 7 degrees C and the thermoelectric conversion efficiency is 2.17%. Furthermore, the power output of the thermoelectric modules is 11.48 mW/cm2, enhancing 1.4 % compared to merely using DSSCs module.     

Analysis of optimum configuration of two-stage thermoelectric modules

In this paper, the theoretical analysis and stimulating calculation were conducted for a basic two-stage thermoelectric module, which contains one thermocouple in the second stage and several thermocouples in the first stage. The study focused on the configuration of the two-stage thermoelectric module, especially investigating the influences of some parameters, such as the allocation of the junction temperature difference in the module, the length of thermocouples and the number of thermocouples, on the cooling performance of the module. The obtained analysis results indicate that changing the junction temperature difference in the second stage, the length of thermocouples and the number of thermocouples in the first stage can improve the cooling performance of the module. These results can be used to optimize the configuration of the two-stage thermoelectric module, and provide guides for the design and application of thermoelectric cooler.     

半导体温差发电器的工作性能优化

应用有限时间热力学理论分析了半导体温差发电器的工作性能.推导了在内外均不可逆情况下发电器的输出功率和效率的表达式,并在此基础上重点讨论了发电器在外部条件变化时的性能,获得了一些有意义的结果.     

Enhancing the maximum coefficient of performance of thermoelectric cooling modules using internally cascaded thermoelectric couples

This paper presents an approach of fabricating thermoelectric cooling (TEC) module for enhancing the maximum coefficient of performance (COP) of TEC module. A significant novelty is that each stage thermoelectric couples have different leg lengths which decrease stage by stage from cold side to hot side of TEC module so that the lower stage can completely pump the heat dissipated by the upper stage. In the design configuration of the TEC module, the lower and upper stages are connected electrically in parallel and thermally in series only through intermediate copper metal strips and copper conducting wires, and thus the interstage thermal resistances and the heat leakage can be reduced compared with that of a conventional pyramid-styled configuration. A mathematical model is also developed to simulate the performances of the TEC module. The simulation results show that the enhancement in maximum COP of the TEC module can be obtained by using internally cascaded multistage thermoelectric couples.