本文選題：溫差發(fā)電器 + 數(shù)值模型　； 參考：《天津大學》2016年碩士論文

【摘要】：能源與環(huán)境是人類面臨的重大課題,開發(fā)新能源和充分利用低品位能源、廢熱能源具有重大意義。內燃機所產生的能量中,大約有30%的能量以廢熱形式由尾氣排出,溫差發(fā)電技術可以利用半導體熱電轉換材料直接將熱能轉換為電能,容易在汽車發(fā)動機上進行布置且環(huán)境友好,可以有效回收內燃機排氣中的余熱。鑒于國內、外在溫差發(fā)電器建模方面存在的缺陷,本文基于熱力學定律和FLUENT UDF基本理論,建立多參數(shù)三維溫差發(fā)電器數(shù)值模型。論文主要工作如下:首先建立多參數(shù)三維溫差發(fā)電單偶數(shù)值模型,此模型所考慮參數(shù)包括變物性參數(shù)、幾何參數(shù)、維度、陶瓷片、外部溫度和流動參數(shù)、可逆參數(shù)和不可逆參數(shù)。其中,可逆參數(shù)主要包括塞貝克效應和帕爾貼效應,不可逆參數(shù)包括傅立葉效應、焦耳效應、湯姆遜效應、空氣間隙熱損失、接觸熱阻和接觸電阻。其次,驗證了本文所建數(shù)值模型正確性。分析不同熱端溫度和不同對流換熱系數(shù)條件下,溫差發(fā)電單偶性能隨電流的變化趨勢;重點分析變物性參數(shù)、湯姆遜效應、空氣間隙熱損失對模型的影響。結果顯示:輸出功率和轉化效率的變化趨勢與之前的數(shù)學模型模擬結果相一致,但是,最大效率電阻并不符合之前的數(shù)學模型所得出最大效率電阻與內阻相等的結論,而是有一定的漂移;物性參數(shù)對數(shù)值模型的影響最大,不可忽略;考慮湯姆遜效應可以提高模型的精度;空氣間隙熱損失僅影響溫差發(fā)電器的轉化效率,而對輸出功率的影響可以忽略。然后,基于所建模型,從溫差發(fā)電單元的長度、截面面積影響兩個方面,對溫差發(fā)電單偶結構做出優(yōu)化設計。結果顯示:存在最優(yōu)長度使得輸出功率和轉化效率均得到最優(yōu)值;最大輸出功率隨橫截面積的增大而增大,但轉化效率隨橫截面積的增大而減小。最后,將溫差發(fā)電單偶數(shù)值模型擴展到溫差發(fā)電模塊層面,利用該數(shù)值模型對溫差發(fā)電模塊與熱交換器進行了模擬分析和優(yōu)化設計,為溫差發(fā)電技術回收發(fā)動機排氣余熱提供依據(jù)。結果顯示:根據(jù)換熱器表面溫度合理的布置不同材料的溫差發(fā)電模塊,可以提高輸出功率。
[Abstract]:Energy and environment are important tasks for human being. It is of great significance to develop new energy sources and make full use of low grade energy and waste heat energy. About 30% of the energy generated by internal combustion engines is discharged by exhaust gas in the form of waste heat. Thermoelectric power generation technology can directly convert heat energy into electric energy by using semiconductor thermoelectric conversion materials. Easy to arrange on the automobile engine and environment friendly, can effectively recover the waste heat in the exhaust gas of the internal combustion engine. In view of the defects in the modeling of the external thermoelectric generator in China, based on the laws of thermodynamics and the basic theory of fluent UDF, the numerical model of the multi-parameter three-dimensional thermoelectric generator is established in this paper. The main work of this paper is as follows: firstly, a multi-parameter three-dimensional thermoelectric single-couple numerical model is established. The parameters of the model include variable physical parameters, geometric parameters, dimensions, ceramic chips, external temperature and flow parameters. Reversible and irreversible parameters. Among them, reversible parameters mainly include Sebek effect and Partier effect, irreversible parameters include Fourier effect, Joule effect, Thomson effect, air gap heat loss, contact thermal resistance and contact resistance. Secondly, the correctness of the numerical model is verified. The variation trend of single couple performance with current under different hot end temperature and different convection heat transfer coefficient is analyzed, and the effects of variable physical parameters, Thomson effect and air gap heat loss on the model are analyzed. The results show that the variation trend of output power and conversion efficiency is consistent with the simulation results of previous mathematical models, but the maximum efficiency resistance does not accord with the conclusion that the maximum efficiency resistance and the internal resistance obtained from the previous mathematical model are equal. But there is a certain drift; physical parameters have the greatest influence on the numerical model, can not be ignored; considering the Thomson effect can improve the accuracy of the model; air gap heat loss only affects the conversion efficiency of thermogenerators, The effect on output power can be neglected. Then, based on the model, the structure of thermoelectric unit is optimized from two aspects: the length of thermoelectric unit and the influence of cross-section area. The results show that the maximum output power increases with the increase of cross-sectional area, but the conversion efficiency decreases with the increase of cross-sectional area. Finally, the single and even numerical model of thermoelectricity generation is extended to the thermoelectricity generation module, and the simulation analysis and optimization design of the thermoelectricity generation module and heat exchanger are carried out by using the numerical model. It provides the basis for the recovery of engine exhaust heat by thermoelectric technology. The results show that according to the surface temperature of heat exchanger, the output power can be increased if different materials are reasonably arranged.
【學位授予單位】：天津大學
【學位級別】：碩士
【學位授予年份】：2016
【分類號】：TM913;TK403

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本文編號：2014653