基于单层MNCl(M=Zr,Hf)的温差发电模型仿真分析

在研究单层ZrNCl和HfNCl材料热电性能的基础上,搭建温差发电模型,研究不同规格温差发电模块的输出性能,然后与其他学者研究的温差发电模型及热电材料的热电转换效率进行对比分析.结果表明:在低温区和中温区,单层ZrNCl的热电转换效率更高.温差发电模块的输出功率随温差发电模块横截面积和热电单元对数的增大而增大.单层Zr...     

计及电热耦合的多级温差发电建模和试验研究

为准确描述多级温差发电器实际工作时各级节点温度分布与通过热功率及其热电输出特性之间的关系,文章建立了计及电热耦合的多级温差发电数值分析模型。运用贪心算法(Greedy Algorithm)编程求解,以常见的Bi2Te3,PbTe和SiGe 3种半导体材料的发电片为例,通过试验验证了模型的正确性,并进一步研究了电热耦合效应对多级温差发电器的Seebeck电压、发电功率和热电转换效率的影响。模型的数值求解和实测结果对比表明:由于电热耦合效应的存在,多级温差发电器在实际工作时各级节点的温度上升,但冷、热端的温差值减小;电热耦合效应会使Seebeck电压、发电功率和热电转换效率明显降低,下降幅度随多级温差发电器热端温度的升高而增大,随发电器级数的增加而减小。     

非均质温差发电器的性能分析

建立非均质温差发电器(TEG)理论模型,考虑热电材料的非均质导热系数以及温差发电器与热源间的传热热阻的影响,分析非均质温差发电器的一般性能.讨论热电元件对数、热导率、高温热源温度对非均质温差发电器性能特性的影响.结果表明,相较于均质温差发电器,导热系数不均匀强度越大,非均质温差发电器的最大输出功率和最大效率越高;热电元...     

ZT值温度依存性对温差发电器热电性能的影响

为了评估热电材料ZT值温度依存性对热电发电器性能的影响,基于HZ-20商用热电材料的热物性参数,分别采用定物性与变物性的计算方法,对温差发电器在具有不同热源温度下的工作性能进行理论研究。研究结果表明,当采用定物性方法计算时(即不考虑ZT值温度依存性),输出功率及相应转换效率的计算值都较采用变物性计算时存在一定的偏差。当半导体热端温度低于定物性计算时采用的定性温度值时,偏差很小,但随着半导体热端温度的继续增加,偏差则越来越大,高热端温度下计算得到的计算偏差达30%左右。因此,热电材料ZT值温度依存性对温差发电器热电性能的影响不容忽视。     

基于相变蓄热和热电转换的低品位热能热/电联合回收实验研究

针对低品位热能回收,提出一种采用相变蓄热及热电转换技术以实现热能/电能联合回收利用的新方法,回收的热能用于加热连续供给的冷媒水并同时发电。搭建实验系统对其热/电回收性能进行实验研究,结果表明:综合相变材料(PCM)温度及温差变化曲线可较好地反映出系统的相变蓄热规律,冷媒水温升及热电转换量明显且存在由PCM相变效应引起的平稳变化段,占PCM主要相变阶段的16.7%。增加冷媒水流量及热电转换单元(TEM)数量会降低冷媒水温升、提高热电转换量。冷媒水流量、热源输入功率和TEM数量为影响热/电回收性能及蓄、放热时间比的主要因素。间歇性蓄、放热循环实验中冷媒水温升和热电回收功率分别稳定在6~13℃和0.020~0.085W,显示该文提出的热回收方法对间歇性热能回收具有较好的稳定性。     

船舶柴油机尾气热电装置热分析及结构设计

船舶柴油机具有能耗高,热效率低的特点,对尾气余热回收装置进行热分析和结构优化设计能有效提高余热回收效率.对基于温差发电的船舶柴油机余热回收装置进行热分析,提出余热回收装置的优化规律.选取工程中热电模块材质、船舶柴油机常见工况作为仿真物性,用热电模块冷热端温度差作为热电转换效率的指标.在船舶柴油机常见的温度和速度工况范围...     

温差发电模型的热电性能数值计算和分析

为研究半导体温差发电器的热电性能,利用有限元分析方法分别对由4对、12对和126对p/n结构成的3种温差发电模型进行热电耦合仿真模拟。分析负载电阻、温差、p-n结对数不同时,温差发电模型内阻、开路电压、路端电压、回路电流、功率及效率的变化规律。结果表明:温差发电模型内阻仅随p-n结对数的增大而线性增大,不受其他条件影响;开路电压、路端电压和回路电流均随p-n结对数和温差的增加而增大;功率和效率均随温差的增加而增大,当负载电阻与内阻相等时,温差发电模型的功率和效率最大。当温差由128℃增至218℃时,3种模型的最大功率分别由0.15、0.46和5.7 W增至0.44、1.33和16.5 W,126对模型的最大效率由2.4%增至4%。     

半导体温差发电技术在铝电解槽中的应用研究

介绍了铝电解槽的结构与散热特点,通过计算侧部散热量及测试槽壁热流密度与温度,对温差发电技术在铝电解过程中的应用可行性进行研究。根据电解槽结构特点和温差发电的要求,设计加工温差发电装置,并在电解槽上进行现场实验,对发电装置的输出功率、热电转换效率进行测试计算。数据表明,温差发电在铝电解中应用是可行的,为铝电解过程的节能探索一条新途径。     

新型发动机排气温差发电器结构探索

根据汽车发动机排气可利用能量的形式,提出了一种新型的置于排气通道内的热电转换系统,使热电偶与热气流直接进行对流/辐射换热,将强化热流密度和转换电流密度、提高系统的温差。在使用现有热电材料的条件下,提高温差发电器的功率密度。     

温差电池冷端冷却的实验研究(摘要)

温差电池是一种热电直接转换的装置。所谓温差电池实际上是利用多对热电偶组合而成的热电换能器,它不仅可用来将太阳能、地热转换为电能,还可以作为工业余热、废热回收的换能器。这种热电换能器体积小、结构简单、无旋转运动件、寿命长、维护少且没有污染。由于温差电池效率低,多     

Electric power generation by super-adiabatic combustion in thermoelectric porous element

A new system for converting combustion heat into electric power was proposed on the basis of reciprocating-flow super-adiabatic combustion in a catalytic and thermoelectric porous element. Self-sustaining combustion of an extremely low-calorific gas was successfully achieved in the element; because a reciprocating flow in the porous element recirculated energy, effectively regenerating combustion gas enthalpy into an enthalpy increase in the low-calorific gas. In the combustion system, a trapezoidal temperature distribution was established along the flow direction, resulting in a steep temperature gradient in the thermoelectric porous element. Numerical simulation showed that 94% of the combustion heat was transferred through the thermoelectric element by conduction. As a result, the total thermal efficiency, which was defined as the ratio of the electric power generated to the combustion heat, attained a value close to the conversion efficiency of the thermoelectric device itself.     

Segmented thermoelectric generator: exponential area variation in leg

The innovative design of segmented thermoelectric generator with exponential area variation is introduced. Thermal efficiency and power output are assessed for various values of the design parameter (a = (L/x) ln[A_a/A(x)], where A_a is constant, and a is the dimensionless geometric parameter, L is the pin length, and A(x) is the pin cross‐sectional area), external load parameter (R_L/R₀, ratio of external electrical resistance to reference electrical resistance), and temperature parameter (θ = T_low/T_high, ratio of cold junction temperature to high junction temperature). The device efficiency obtained is validated through the previous experimental data for various hot and cold junction temperature differences. The findings reveal that thermal efficiency resulted from the current study agrees well with the experimental data. The innovative design of the segmented thermoelectric generator with exponentially decaying pin configuration enhances the thermal efficiency and output power as compared with the device having a single material pin configuration. Increasing temperature ratio results in the reduction in the thermal efficiency and the output power of thermoelectric generator. In addition, lowering the external load parameter improves the thermal efficiency and the output power of the thermoelectric device. The design parameter that maximizes the thermal efficiency of the thermoelectric generator does not maximize the device output power.     

Transport properties of some bismuth-antimony alloys

The thermal and electrical conductivities, as well as the thermoelectric powers for single crystals of BiSb alloys, in the temperature range 60 to 90 K have been measured. The thermoelectric power behaviour is attributed to a change from extrinsic to intrinsic conduction occurring near 80 K for alloys with between 9 and 32 atomic % Sb. For alloys having less than 24 atomic % Sb, the phonons suffer a large strain field scattering whereas, for higher concentrations, bipolar diffusion probably ensues.     

一种新型汽车尾气多通道热能发电系统

根据温差发电原理,设计了一种新型网格状通气管式的温差发电装置,实现对汽车尾气热能的再利用。通过优化温差发电装置的结构,改变了水箱结构,增加了废热通道数量,能够贴更多的温差发电片,从而提高转换效率。通过UG(计算机辅助设计软件)建立汽车尾气温差发电装置的理论模型,经过计算,当温差等于100℃时该装置的转换效率约等于5.67%。与其他温差发电装置进行比较,热油式温差发电器在260℃温差下最大热能转换效率可达4.389%,而汽车尾气温差发电器输出功率随着烟气温度的升高近似成线性递增,热能转换效率较低[1],通过比较得出,本装置不仅提高了转换效率,且达到相同转换效率时所对应的温差值也相应减少。     

Development of temperature‐change sensor by thermoelectric elements and its response evaluation on dropping into water

A temperature‐change sensor by thermoelectric elements that is directly connected to a p‐type element and an n‐type element was developed. A β‐FeSi₂ thermoelectric semiconductor made by a spark plasma sintering method was used as a prototype sensor. Evaluation of this thermoelectric temperature‐change sensor was carried out by measuring its electromotive force when it was dropped into a thermostated water bath. It was confirmed that there existed a correlation between the temperature difference and the electromotive force of the sensor, i.e., approximately 5 mV of electromotive force was generated at a temperature difference of 30 K. In addition, the dependence of electromotive force on the size and properties of the thermoelectric elements was evaluated by carrying out FEM analysis. © 2009 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20268     

核电站反应堆堆芯温度测量K型热电偶的国产化研制

用于测量核电站反应堆堆芯出口温度的K型热电偶是重要的1E级设备，但该设备一直依赖进口；巴基斯坦恰希玛核电站3、4号机组为我国向巴基斯坦出口的第三、四座核电站，考虑到重要设备国产化对我国核电走出去的积极意义，这两座核电站所用堆芯温度测量K型热电偶由国内相关单位进行研制。通过对运行环境和安装要求的详细研究，在K型热电偶结构上采用了全铠装、分段式及新型热电偶接插件进行连接的创新设计，充分考虑了各部件材料选择对于K型热电偶性能及安全的影响，对传统铠装热电偶的制作工艺进行了优化与改进，最终研制的样件通过了性能试验及1E级鉴定试验，实际产品也顺利安装于巴基斯坦恰希玛核电站3、4号机组，核电站堆芯温度测量K型热电偶的研制取得了阶段性的成功。     

Performance analysis of cascaded thermoelectric converters for advanced radioisotope power systems

Advanced radioisotope power systems (ARPSs) for future planetary missions require higher conversion efficiency than the state-of-the-art (SOA) SiGe thermoelectric converter in order to decrease system mass and reduce mission cost. The performance of three cascaded thermoelectric converters (CTCs) for potential use in ARPSs is investigated at heat rejection temperatures of 375, 475 and 575 K and input thermal powers of 1, 2 and 3 W_th. These CTCs have top SiGe unicouples that are thermally, but not electrically, coupled to bottom unicouples having one of the following compositions: (a) TAGS-85 (p-leg) and 2N–PbTe (n-leg); (b) CeFe_3.5Co_0.5Sb₁₂ (p-leg) and CoSb₃ (n-leg); and (c) segmented p-leg of CeFe_3.5Co_0.5Sb₁₂ and Zn₄Sb₃ and n-leg of CoSb₃. The top and bottom unicouples in the CTCs are of the same length (10 mm), but the optimized cross-sectional areas of the n- and p-legs for maximum efficiency are different. The nominal hot junction temperature of the top SiGe unicouples at their peak efficiencies is 1273 K and that of the cold junction is 780 K when the bottom unicouple is of composition (a) and 980 K for compositions (b) and (c). The hot junction temperatures of the bottom unicouples are taken 20 K lower than the cold junctions of the top unicouples, but the input thermal powers to the former are the same as those rejected by the latter. Assuming zero side heat losses and a contact resistance of 150 μΩ cm² per leg in the top and bottom unicouples, the calculated peak efficiencies of the CTCs vary from 9.43% to 14.35%. These efficiencies are 40–113% higher, respectively, than that of SOA SiGe (∼6.5%) when operating at the cold junction temperature of 566 K and the same hot junction temperature (1273 K) and contact resistance per leg. Decreasing this resistance to a realistic value of 50 μΩ cm² per leg increases the peak efficiencies of the CTCs by 0.5–0.9 percentage points to 9.93–15.25%.     

Configuration of segmented leg for the enhanced performance of segmented thermoelectric generator

Thermal analysis of a segmented thermoelectric generator is performed, and the segmented leg configurations maximizing the efficiency and the output power are formulated. The effect of operating conditions such as external load resistance, the temperatures of hot and cold junctions, on the device performance is studied. The segmented thermoelectric generator has the leg configuration consisting of the combination of modified lead telluride and modified bismuth telluride. The segmented thermoelectric generator performance, such as device efficiency and output power, is compared with those corresponding to a single material leg configuration (modified lead telluride or modified bismuth telluride) for various operating conditions. It is found that a unique value of the segmented leg combination maximizes the efficiency and the output power for each operating condition. The variation in the operating conditions changed the locus points of the maximum efficiency and the maximum output power. The segmented thermoelectric generator gives rise to the higher device efficiency and the output power than those of the single material leg configuration, especially for the low external load resistance. Copyright © 2016 John Wiley & Sons, Ltd.     

Power generation characteristics of a sandwich‐type self‐heating thermoelectric generator with spatially varying embedded heat source

Power generation characteristics of a sandwich‐type thermoelectric generator in which the heat source is embedded into thermoelectric elements are investigated. Our previous work on a similar concept only considered a uniform heat source distribution inside thermoelectric elements. In this work, the effect of the spatial distribution of a heat source is examined. In particular, the effect of the concentration of heat source near the one end, that is, the hot end, is intensively studied as a potential means of improving the efficiency of the device. Although the effects of heat source concentration in impractical cases without heat transfer limitations on the cold side remain ambiguous, it become clear that heat source concentration indeed has positive effects in more realistic cases with finite heat transfer coefficients imposed on the cold side. Because of the relatively low efficiency of typical thermoelectric generation, a significant amount of heat must be dissipated from the cold end of the thermoelectric element. Greater heat source concentration near the hot end leads to more effective utilization of available heat source, reduces the amount of heat rejected at the cold end, and lowers the hot end temperature of the thermoelectric element. Overall, it is suggested that heat source concentration can be used as a method to achieve more efficient operation and better structural integrity of the system. Copyright © 2015 John Wiley & Sons, Ltd.