【摘要】：能源是社會發(fā)展的推動力,是人類賴以生存的基礎(chǔ),隨著工業(yè)化的快速發(fā)展,能源的需求量也大大增加。我國是世界上第一大汽車生產(chǎn)和消費國,汽車是生活中非常普及的交通工具,但其燃料燃燒所產(chǎn)生的能量僅有少部分用于驅(qū)動車輛運行,不能被有效利用的能量中更是有一部分以尾氣形式直接排放到大氣中,造成巨大的能源浪費和環(huán)境污染。溫差發(fā)電技術(shù)是利用半導(dǎo)體材料的塞貝克效應(yīng)直接將熱能轉(zhuǎn)換成電能的一種技術(shù),具有經(jīng)濟環(huán)保、壽命長等優(yōu)點,在當前節(jié)能減排的號召下,溫差發(fā)電技術(shù)在低品位能源的回收利用中發(fā)揮著重要的作用。本文就是利用溫差發(fā)電的基本原理,對汽車尾氣中的余熱能進行回收和再利用。由于現(xiàn)有的汽車尾氣溫差電技術(shù)在熱量傳遞過程中熱損失比較大,導(dǎo)致溫差發(fā)電器的輸出功率和熱電轉(zhuǎn)換效率還比較低,根據(jù)傳熱學理論,增加換熱面積可起到強化傳熱的作用,并且考慮到相變換熱導(dǎo)熱穩(wěn)定、熱阻小的特性,可以為發(fā)電器提供穩(wěn)定熱源,優(yōu)化發(fā)電器性能�；谏鲜鲈肀疚脑O(shè)計了一種充有相變工質(zhì)的半導(dǎo)體溫差發(fā)電器結(jié)構(gòu),建立了以汽車尾氣為熱源的發(fā)電器數(shù)學模型,并模擬計算了該結(jié)構(gòu)的輸出性能。結(jié)果表明,在尾氣溫度相同的情況下,增大相變換熱結(jié)構(gòu)的吸放熱端面積比可有效達到強化傳熱的目的,實現(xiàn)整體輸出功率和熱電轉(zhuǎn)換效率的提高。但隨著尾氣溫度的升高,優(yōu)化效果逐漸減弱,所以應(yīng)該針對不同的尾氣溫度范圍選擇相適應(yīng)的相變工質(zhì)對傳熱進行強化。增大尾氣流量同樣可起到強化傳熱的作用,且尾氣流量越大,相變換熱結(jié)構(gòu)對發(fā)電器輸出性能的優(yōu)化作用越不明顯。同樣還計算了發(fā)電器自身幾何參數(shù)對輸出性能的影響,得出輸出功率隨發(fā)電器長度的增加存在一個峰值,而熱電轉(zhuǎn)換效率則不斷減小。增大冷凝段高度會使輸出功率先增加后減小,且峰值點對應(yīng)的冷凝段高度隨發(fā)電器長度的增加而減小,隨蒸發(fā)段管數(shù)的增加而增加。而熱電轉(zhuǎn)換效率隨冷凝段高度增加而降低,隨蒸發(fā)段管數(shù)的增加而升高。本文通過對發(fā)電器工作性能的研究,總結(jié)了輸出功率、熱電轉(zhuǎn)換效率隨尾氣溫度、流量、發(fā)電器幾何參數(shù)的變化規(guī)律,指出了目前研究方面的不足,提出了改進建議,并展望了課題后續(xù)的研究計劃。
[Abstract]:Energy is the driving force of social development and the basis of human survival. With the rapid development of industrialization, the demand for energy has increased greatly. Our country is the largest automobile production and consumption country in the world, the automobile is a very popular means of transportation in daily life, but only a small part of the energy generated by the burning of its fuel is used to drive the vehicle running. Some of the energy which can not be effectively used is discharged directly into the atmosphere in the form of tail gas, which results in huge energy waste and environmental pollution. Thermoelectric power generation technology is a kind of technology which directly converts heat energy into electric energy by using the Seebeck effect of semiconductor materials. It has the advantages of economic and environmental protection, long life, etc., under the current call of energy saving and emission reduction, Thermoelectric technology plays an important role in the recovery and utilization of low-grade energy. In this paper, the waste heat energy in automobile exhaust is recovered and reused by the basic principle of thermoelectric power generation. Due to the large heat loss in the heat transfer process of the existing thermoelectric technology of automobile exhaust gas, the output power and thermoelectric conversion efficiency of the thermoelectric generator are still relatively low, according to the theory of heat transfer, Increasing the heat transfer area can enhance the heat transfer, and considering the characteristics of stable phase change heat transfer and low thermal resistance, it can provide a stable heat source for the generator and optimize the performance of the generator. Based on the above principle, a structure of semiconductor thermoelectric generator filled with phase change working fluid is designed, and the mathematical model of generator with automobile exhaust as heat source is established, and the output performance of the structure is simulated and calculated. The results show that when the tail gas temperature is the same, the heat transfer enhancement can be achieved by increasing the area ratio of the end-to-end of the phase change heat transfer structure, and the overall output power and the efficiency of thermoelectric conversion can be improved. However, with the increase of tail gas temperature, the optimization effect is gradually weakened, so the heat transfer should be strengthened according to different range of exhaust gas temperature. Increasing tail gas flow can also enhance heat transfer, and the larger the tail gas flow, the less the optimization effect of phase change heat transfer structure on the output performance of generator. The effect of generator geometry parameters on output performance is also calculated. It is concluded that there is a peak value of output power with the increase of generator length, while the thermoelectric conversion efficiency decreases continuously. With the increase of condensing section height, the output power will first increase and then decrease, and the condensing section height corresponding to the peak point will decrease with the increase of generator length and increase with the increase of the number of tubes in the evaporation section. However, the efficiency of thermoelectric conversion decreases with the increase of condensation height and increases with the increase of the number of tubes in evaporation section. In this paper, the variation of output power and thermoelectric conversion efficiency with tail gas temperature, flow rate and generator geometry parameters are summarized through the research on the performance of generator, and the shortcomings of current research are pointed out, and some suggestions for improvement are put forward. The future research plan is also prospected.
【學位授予單位】：天津大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TM913

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