Investigation and development of advanced models of thermoelectric generators for power generation applications
Investigation and development of advanced models of thermoelectric generators for power generation applications
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研究和开发用于发电应用的先进热电发电机模型
DOI：
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
Emil Sandoz
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文献类型：
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作者：
Emil Sandoz
随着热电发电应用的发展以及先进材料对热电器件制造的影响越来越大，对更好地理解模块级行为的需求越来越大。同样地，正在探索新的模块几何形状以获得更高的性能，并且需要复杂的建模方法。除了新的几何设计，传输现象，如汤姆逊加热和接触电阻，加剧了建模热电模块（TEM）的复杂性，从而限制了设计能力。通常情况下，这些影响要么近似（或在某些情况下完全忽略），很少探索与近似相关的基本假设的有效性。因此，标准模型往往是基于无法超越非常有限的操作制度的假设。因此，大多数TEM分析通常利用模块级规模上的建模的简单方法，这引入了必须纠正的不准确性。特别是对于较大的温度梯度，通常可忽略的影响可能开始影响整体系统性能。材料属性温度依赖性，结合泄漏效应，留下很多需要的简单的属性平均为基础的模型。此外，一维（1-D）模型忽略了可以显著影响TEM性能的三维（3-D）模块刻面的贡献。为了解决分析问题，复杂的材料技术正在出现，这将需要强大的模块设计模型。随着在汽车、工业过程和发电厂中利用热电技术进行废热回收的研究日益受到重视，高温TEM的新应用和商业开发迫在眉睫。然而，TEM的建模设计和优化一直是零碎的。因此，必须为TEM开发一个全面的模型，以解决由于过度简化而产生的一些分析问题。这项工作的主要目的是开发和验证一个全面的模型，可以用作TEM设计工具，并量化在简单的1-D分析模型的误差。这项工作的范围是多方面的。首先，几个模型的开发，实施和相互比较的设计工具，是有用的，用于确定材料的性能和优化TEM性能。建立了改进的一维分析模型、唯一的渐近模型和全面的三维有限元模型。这些模型进行比较，以验证和量化分析模型中的误差。其次，基于模块参数的1-D分析模型中的误差量化（称为误差映射）本身可用作设计工具，以识别1-D模型不准确的区域（从而确定何时需要3-D FE建模），或作为1-D模型的校正因子。第三，开发了一个实验测试台，用于器件表征，用于系统级集成或未来的模型验证。最后，汤姆逊效应分析探讨和详细的，其对TEM的整体性能的贡献是量化的。汤姆逊效应在以前的分析模型中的作用是模糊的，但在这篇论文中已经阐明了推导和发展的渐近模型，这是第一个解析解的非线性热电控制方程。最后，本文定义了当前TEM模型的优点和局限性，量化了它们的误差，并提供了几个新的设计工具，可用于材料选择，模块优化和系统级设计。这些新的设计工具将提供新的杠杆，以推动热电技术作为一种强大的发电技术，在这种能力至关重要的时候。
With developing interest in power generation applications of thermoelectrics and the growing influence of advanced materials on thermoelectric device fabrication, there is an increased demand for better understanding of module-level behavior. Likewise, novel module geometries are being explored for higher performance and require sophisticated modeling methods. In addition to new geometrical design, transport phenomena, such as Thomson heating and contact resistances, aggravate the complexity of modeling thermoelectric modules (TEMs) and thus limit design capability. Typically, these effects are either approximated (or in some cases neglected entirely) with little exploration in to the validity of the underlying assumptions associated with the approximation. As such, standard models are often predicated on assumptions that cannot be made beyond very limited operating regimes. Consequently, most TEM analysis generally utilizes simplistic methods of modeling on a module-level scale, which introduce inaccuracies that must be redressed. Particularly with larger temperature gradients, typically negligible effects could begin to impact overall system performance. Material property temperature-dependency, combined with leakage effects, leave much to be desired of the simple property-average-based models. Additionally, one-dimensional (1-D) models neglect the contribution of three-dimensional (3-D) module facets that can significantly impact TEM performance. To compound the analytical issue, complex material technologies are emerging that will require robust models for module design. With burgeoning focus in using thermoelectrics for waste heat recovery in automobiles, industrial processes and power plants, new application and commercial development of high temperature TEMs is imminent. However, modeling design and optimization of TEMs has been piecemeal at best. Hence, it is imperative that a comprehensive model be developed for TEMs that addresses some of the analytical problems stemming from over-simplification. The primary intention of this work is to develop and validate a comprehensive model that can be used as a TEM design tool and to quantify the error in the simple 1-D analytical models. The scope of this work is multifaceted. First, several models are developed, implemented and compared to each other as design tools that are useful for determining material performance and also for optimizing TEM performance. An improved 1-D analytical model, a unique asymptotic model and a comprehensive 3-D finite element (FE) model are created and established. These models are compared to each other for both validation and for quantification of error in the analytical models. Secondly, the quantification of error in 1-D analytical models based on module parameters, called error mapping, can be used as a design tool in and of itself to either identify regimes where a 1-D model is inaccurate (and thus establish when 3-D FE modeling is required), or as a corrective factor to a 1-D model. Thirdly, an experimental test stand is developed for device characterization, to be used either for system-level integration or for future model validation. Finally, the Thomson effect is analytically explored and detailed, and its contribution to the overall performance of a TEM is quantified. The role of the Thomson effect in previous analyitical models is nebulous, but has been elucidated in this thesis both with derivation and the development of the asymptotic model, which is the first analytical solution to the non-linear thermoelectric governing equations. Ultimately, this thesis defines the advantages and limitations of current TEM models, quantifies their error and provides several new design tools that can be used for material selection, module optimization and system-level design. These new design tools will provide new leverage to advance thermoelectrics as a robust power generation technology at a time when such capability is critical.
影响因子：
2.1
作者：
Freunek, Michael;Mueller, Monika;Reindl, Leonhard M.
通讯作者：
Reindl, Leonhard M.