發(fā)布時(shí)間：2018-01-26 00:01

  本文關(guān)鍵詞： 熱電發(fā)電器 湯姆遜效應(yīng) 附加熱阻 鋸齒錯(cuò)列肋片 凈輸出功率 泡沫金屬　出處：《天津大學(xué)》2014年碩士論文　論文類型：學(xué)位論文

【摘要】：隨著經(jīng)濟(jì)的快速發(fā)展,中國(guó)的汽車數(shù)量平均以每年超過(guò)1100萬(wàn)輛的速度快速增加。然而,當(dāng)前的汽車燃料燃燒所釋放出的熱量中只有25%左右能被有效利用,超過(guò)30%的熱量均以廢熱的形式隨汽車尾氣直接排放到環(huán)境中。因此,若能回收和再利用這一部分能量,將對(duì)提高汽車發(fā)動(dòng)機(jī)效率,減少環(huán)境污染具有非常重要的意義。熱電發(fā)電是一種可以將熱能直接轉(zhuǎn)化為電能進(jìn)行發(fā)電的全固態(tài)綠色環(huán)保的能量轉(zhuǎn)換方式,具有性能穩(wěn)定、無(wú)噪聲、使用壽命長(zhǎng)等優(yōu)點(diǎn),在汽車尾氣余熱回收利用方面具有其獨(dú)特的優(yōu)勢(shì)和良好的應(yīng)用前景。針對(duì)湯姆遜效應(yīng)及陶瓷板、金屬導(dǎo)流片、接觸表面產(chǎn)生的附加熱阻等影響熱電模塊性能的因素,本文通過(guò)數(shù)值模擬計(jì)算的方法,對(duì)比研究了考慮與不考慮湯姆遜效應(yīng)及附加熱阻時(shí)熱電模塊的性能。結(jié)果表明:相比不考慮湯姆遜效應(yīng)和附加熱阻,當(dāng)熱電模塊的工作電流比較大時(shí),考慮湯姆遜效應(yīng)和附加熱阻,熱電模塊的輸出功率、熱電轉(zhuǎn)化效率及?效率均顯著減小。且隨著熱端溫度的增加,考慮和不考慮湯姆遜效應(yīng)及附加熱阻兩者的最大輸出功率差不斷增大;最大熱電轉(zhuǎn)化效率差先增大后減小;最大?效率差不斷減小。此外,強(qiáng)化熱端換熱是提高熱電發(fā)電器性能的主要手段之一。針對(duì)強(qiáng)化熱端換熱帶來(lái)汽車尾氣壓降增加這一問(wèn)題,本文提出了采用熱電發(fā)電器的總輸出功率減去為維持尾氣壓降不增加所需的泵功后的凈輸出功率為優(yōu)化標(biāo)準(zhǔn),通過(guò)數(shù)值模擬的方法,分別研究了保持熱端換熱器外部尺寸不變的情況下,熱端采用鋸齒錯(cuò)列肋片及泡沫金屬?gòu)?qiáng)化換熱時(shí),熱電發(fā)電器的性能變化。結(jié)果表明:采用鋸齒錯(cuò)列肋片增強(qiáng)熱端換熱效果時(shí),存在最佳的肋片間距和肋片厚度使得熱電發(fā)電器的凈輸出功率達(dá)到最大值。采用泡沫金屬增強(qiáng)熱端換熱時(shí),同一種泡沫金屬材料,孔隙率越低,孔密度越小,熱電發(fā)電器的凈輸出功率越大。相比于鋸齒錯(cuò)列肋片,采用多孔介質(zhì)材料增強(qiáng)熱端換熱時(shí),熱電發(fā)電器雖可獲得更大的總輸出功率和熱電轉(zhuǎn)化效率,但由于汽車尾氣流過(guò)熱端換熱器時(shí)的壓降過(guò)大,凈輸出功率甚至為負(fù)值。為此,作為后續(xù)工作,本文提出具有熱電發(fā)電和催化轉(zhuǎn)化兩個(gè)功能的新型熱電發(fā)電器,以期避免汽車尾氣流過(guò)整個(gè)排氣系統(tǒng)時(shí)產(chǎn)生過(guò)大壓降。
[Abstract]:With the rapid development of the economy, the number of cars in China is increasing rapidly at an average rate of more than 11 million vehicles a year. At present, only about 25% of the heat released from automotive fuel combustion can be effectively utilized, and more than 30% of the heat is discharged directly into the environment with the automobile exhaust gas in the form of waste heat. If this part of energy can be recovered and reused, it will improve the efficiency of automobile engine. It is very important to reduce environmental pollution. Thermoelectric power generation is a kind of all-solid-state green energy conversion mode which can directly convert heat energy into electric energy for power generation. It has stable performance and no noise. With the advantages of long service life and so on, it has its unique advantages and good application prospects in the recovery and utilization of automobile exhaust waste heat, aiming at Thomson effect, ceramic plate and metal diversion sheet. The additional thermal resistance produced by the contact surface affects the performance of the thermoelectric module. In this paper, the method of numerical simulation is used to calculate the performance of the thermoelectric module. The performance of the thermoelectric module considering and without Thomson effect and additional thermal resistance is studied. The results show that compared with not considering the Thomson effect and the additional thermal resistance, when the working current ratio of the thermoelectric module is larger. Considering Thomson effect and additional thermal resistance, thermoelectric module output power, thermoelectric conversion efficiency and? With the increase of the temperature at the hot end, the maximum output power difference between considering and not considering the Thomson effect and the additional thermal resistance increases, the difference of the maximum thermoelectric conversion efficiency increases first and then decreases, and the maximum power difference decreases with the increase of the temperature at the hot end. In addition, the enhancement of heat transfer at the hot end is one of the main means to improve the performance of the thermoelectric generator. In this paper, the optimization standard of the total output power of the thermoelectric generator minus the pump power needed to maintain the pressure drop of the tail gas is proposed as the optimization standard, and the method of numerical simulation is used. Under the condition of keeping the external dimension of the hot end heat exchanger unchanged, the heat transfer strengthened by the saw teeth staggered rib and foam metal was studied respectively at the hot end. The performance of thermoelectric generator is changed. The results show that the effect of heat transfer at the hot end is enhanced by using the jagged staggered ribbed blade. The optimum rib spacing and thickness make the net output power of the thermoelectric generator reach the maximum. The lower the porosity, the smaller the pore density of the same metal foam material when the hot end heat transfer is enhanced by foam metal. The larger the net output power of the thermoelectric generator is, the greater the total output power and the efficiency of thermoelectric conversion can be obtained when the heat transfer at the hot end is enhanced by using porous dielectric material, compared with the jagged staggered fin. However, the pressure drop of the heat exchanger at the overheated end of the automobile exhaust flow is too large, and the net output power is even negative. Therefore, as a follow-up work, a new type of thermoelectric generator with the functions of thermoelectric power generation and catalytic conversion is proposed in this paper. In order to avoid excessive pressure drop when the exhaust gas flows through the whole exhaust system.
【學(xué)位授予單位】：天津大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：U463.6;TM617

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本文編號(hào)：1464070