CFD Modeling of Thermoelectric Generators in EGR-coolers
CFD Modeling of Thermoelectric Generators in EGR-coolers
复制标题
EGR 冷却器中热电发电机的 CFD 建模
DOI：
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发表时间：
2011
期刊：
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通讯作者：
Ronnie Andersson
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文献类型：
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作者：
Olle Högblom;Ronnie Andersson
柴油机废气中的大量废热通过废气再循环(EGR)冷却器排出。如果利用热电元件将这种能量部分转化为有用的电能，将会产生重大的环境和经济影响[1]。在废气再循环冷却器中引入热电发生器(TEG)需要一个全新的换热器设计，而要实现这一目标，一个好的模型是必不可少的。温度在热电元件内部和热交换器上都不同[1]。由于TE材料具有不同的最佳工作温度，因此材料的组合将提高TEG的性能[2]。在这项工作中，气体流动和换热的暂态CFD模型与内部代码一起用于预测车辆试验周期中的热电性能。CFD模型使用已公布的数据进行了验证[3]，并用于确定新的TEG-EGR系统的设计要求。除了对传热、Seebeck势、Peltier效应、焦耳加热和热电产生的预测外，模拟还详细地了解了TE元件中气相和内部的温度梯度。结果表明，热电元件的最大热阻位于气相，减小气相热阻对热电元件实现较大温差具有重要意义。对于废气再循环应用，保持气体的低压降也是非常重要的，这与高传热的要求相矛盾。因此，在开发新的三甘醇系统时，重要的是也要把重点放在热传递上，而不仅仅是改进材料。这项工作展示了如何使用先进的模拟方法来获得洞察力并根据所有这些设计要求优化设计。参考文献：N·埃斯皮诺萨、M.Lazard、L.Aixala和H.Scherrer，《电子材料杂志》。39(2010)，1446-1455。[2]M.Lazard，2009年，《热电中的热传递：建模、优化和设计》，载于第七届IASME/WSEAS关于热传递、热工程和环境的国际会议，世界科学与工程学院和SOC，雅典。[3]M.Chen，L.A.Rosendahl和T.Condra，《国际热质传递杂志》54(2011)345。
A large amount of the waste heat in the exhaust gases from diesel engines is removed in the exhaust gas recirculation (EGR) cooler. If this energy partially could be converted to useful electric energy using thermoelectric elements it would give a significant environmental and economical impact [1]. Introducing a thermoelectric generator (TEG) in an EGR cooler requires a completely new design of the heat exchanger and to achieve that, a good model is essential for this development. The temperature varies both inside the thermoelectric elements and along the heat exchanger [1]. Since the TE materials has different optimal working temperature a combination of materials would increase the performance of the TEG [2]. In this work, a transient CFD model for gas flow and heat transfer has been used together with an in-house code for predicting the thermoelectric performance during a vehicle test cycle. The CFD model was validated using published data [3] and used to identify design requirements for new TEG-EGR systems. Besides the prediction of heat transfer, Seebeck potential, Peltier effect, Joule heating and thermoelectric power generation, the simulations also gave detailed insight to the temperature gradients in the gas-phase and inside the TE elements. The results show that the greatest heat transfer resistance is located in the gas phase and it is of high importance to reduce this in order to achieve a large temperature difference over the thermoelectric elements. For an EGR application it is also of great importance to maintain a low pressure drop in the gas which contradicts the requirement of high heat transfer. When developing new TEG systems it is therefore important to focus also on the heat transfer and not only on improving the materials. This work shows how advanced simulations method can be used to obtain the insight and optimize the design with respect to all these design requirements. References: [1] N. Espinosa, M. Lazard, L. Aixala and H. Scherrer, Journal of Electronic Materials. 39 (2010), 1446-1455. [2] M. Lazard 2009 "Heat Transfer in Thermoelectricity: Modelling, Optimization and Design", in Proceedings of the 7th Iasme/Wseas International Conference on Heat Transfer, Thermal Engineering and Environment, World Scientific and Engineering Acad and Soc, Athens. [3] M. Chen, L.A. Rosendahl and T. Condra, International Journal of Heat and Mass Transfer 54 (2011) 345.