本文選題：溫差發(fā)電器 + 內(nèi)燃機(jī)排氣　； 參考：《天津大學(xué)》2014年博士論文

【摘要】：將內(nèi)燃機(jī)的余熱能回收再利用是提高總能效率、降低油耗和CO2排放的一個(gè)有效途徑。溫差發(fā)電器(Thermoelectric generator,TEG)利用了半導(dǎo)體熱電材料將熱能直接轉(zhuǎn)化為電能的特性,具有無機(jī)械運(yùn)動(dòng)、運(yùn)行安靜、小型輕便和對(duì)環(huán)境無污染等優(yōu)點(diǎn),在內(nèi)燃機(jī)排氣的余熱能回收利用領(lǐng)域具有重要的應(yīng)用價(jià)值和前景。本文采用了模型研究和實(shí)驗(yàn)研究的方法,進(jìn)行了溫差發(fā)電器的特性分析,及其基于發(fā)動(dòng)機(jī)排氣余熱能回收利用的研究。從單電偶臂對(duì)的分析,擴(kuò)展到多個(gè)電偶臂對(duì)串聯(lián)成的溫差發(fā)電器,從穩(wěn)態(tài)模型遞進(jìn)至瞬態(tài)模型,然后將模型進(jìn)行橫向擴(kuò)展,與整車行駛工況相耦合,分析瞬態(tài)工況以及一些典型的車輛行駛工況下發(fā)電器的性能,并進(jìn)行了基于發(fā)動(dòng)機(jī)排氣余熱能利用的溫差發(fā)電器的臺(tái)架實(shí)驗(yàn)。論文主要工作如下:(1)利用CFD(Computational Fluid Dynamics)工具,基于不同的守恒方程表述和邊界條件劃分,對(duì)同一電偶臂對(duì)(即相同的計(jì)算域)建立了兩種三維數(shù)值模型,并指出了前人文獻(xiàn)中相關(guān)模型的不完善之處,對(duì)溫差發(fā)電的深層現(xiàn)象進(jìn)行研究,以理解熱電轉(zhuǎn)換過程。并對(duì)電偶臂的形狀進(jìn)行優(yōu)化設(shè)計(jì),采用新結(jié)構(gòu)的電偶臂對(duì),可以更好的將熱電材料匹配工作溫度區(qū)間,以提高材料的功率密度。CFD模型可以直觀的展示不同工況下電偶臂對(duì)內(nèi)部的溫度分布和電勢(shì)分布云圖。(2)對(duì)于由多個(gè)電偶臂對(duì)組成的溫差發(fā)電器,通過實(shí)驗(yàn)的方法,研究了冷卻方式、冷熱源溫度、裝配壓力、組合方式和負(fù)載電阻等因素對(duì)發(fā)電性能的影響,為CFD模擬和仿真計(jì)算提供數(shù)據(jù)支撐和驗(yàn)證。重點(diǎn)研究了溫差發(fā)電的瞬態(tài)行為,在溫差發(fā)電器的啟動(dòng)過程中發(fā)現(xiàn)了過沖現(xiàn)象,該現(xiàn)象是由于冷、熱端與環(huán)境的溫度變化速率不一致造成的,定義過沖度這一概念對(duì)其進(jìn)行表述。(3)將單電偶臂對(duì)的模型,擴(kuò)展到多個(gè)電偶臂對(duì)串聯(lián)成的溫差發(fā)電器模型,建立了基于發(fā)動(dòng)機(jī)排氣余熱能利用的溫差發(fā)電器的瞬態(tài)模型,并對(duì)求解過程中模型的時(shí)間步長(zhǎng)和空間步長(zhǎng)中的變化給出了介紹。對(duì)于其內(nèi)部不同區(qū)域的守恒方程和邊界條件作了細(xì)致的分析,根據(jù)溫度守恒和熱流密度守恒,建立了四個(gè)界面的熱學(xué)邊界條件;給出了五種啟動(dòng)模式的電學(xué)邊界條件,分別是恒流模式、恒壓模式、最大功率模式、恒功率大電流和恒功率小電流啟動(dòng)模式,分別比較了這五種模式下發(fā)電器的穩(wěn)態(tài)性能和瞬態(tài)行為,分析了啟動(dòng)過程中,電偶臂內(nèi)部的溫度、電勢(shì)和熱流變化,對(duì)發(fā)電性能達(dá)到額定功率的時(shí)間進(jìn)行了研究。同時(shí),考慮了車速和環(huán)境溫度等外部因素對(duì)發(fā)電性能的影響。(4)將發(fā)電器的瞬態(tài)模型進(jìn)行擴(kuò)展,與整車的行駛工況模型相耦合,分析了加、減速工況、階梯車速工況和往復(fù)車速工況中發(fā)電器的性能變化情況。選取了三種典型的車輛行駛工況進(jìn)行分析,分別是10-15、NEDC(New European Driving Cycle)和UDDS(Urban Driving Dynamometer Schedule)工況,代表了日本、歐洲和美國(guó)的典型工況,比較了溫差發(fā)電器在具體行駛工況中,對(duì)于車輛輸出功率的提升。(5)進(jìn)行了溫差發(fā)電器的發(fā)動(dòng)機(jī)臺(tái)架實(shí)驗(yàn)。以某1.5 L汽油機(jī)的排氣為熱源,以恒溫水箱供給的循環(huán)水為冷源,觀察了不同工況下,發(fā)電器的穩(wěn)態(tài)性能以及變工況階段的瞬態(tài)行為。對(duì)變工況下,發(fā)電性能變化的時(shí)間量綱進(jìn)行確定,為基于發(fā)動(dòng)機(jī)排氣余熱能的溫差發(fā)電器的瞬態(tài)模型的變工況數(shù)據(jù)提供了實(shí)驗(yàn)基礎(chǔ)。
[Abstract]:The recovery and reuse of the afterheat energy of the internal combustion engine is an effective way to improve the total energy efficiency and reduce the fuel consumption and CO2 emission. The thermoelectric generator (Thermoelectric generator, TEG) uses the semiconductor thermoelectric materials to convert the heat energy into the electric energy directly, and has the advantages of no mechanical motion, quiet operation, small light and no pollution to the environment. It has important application value and prospect in the field of waste heat recovery and utilization in the exhaust gas of internal combustion engine. This paper adopts the method of model research and experiment research, and carries out the characteristics analysis of the thermoelectric generator and the research based on the recovery and utilization of the exhaust heat energy of the engine. From the analysis of the single couple arm pair, it extends to the series of couple arms to the series. The thermoelectric generator is passed from the steady state model to the transient model, then the model is extended horizontally and coupled with the driving condition of the whole vehicle. The transient condition and the performance of some typical electric appliances under the typical vehicle driving condition are analyzed. The paper has carried out the bench test of the thermoelectric generator based on the exhaust energy of the engine. The following work is as follows: (1) using the CFD (Computational Fluid Dynamics) tool, based on the different conservation equation expression and boundary condition division, two three dimensional numerical models are established for the same electric couple arm pair (i.e. the same computing domain), and the imperfections of the related models in the previous literature are pointed out, and the deep phenomenon of the thermoelectric power generation is studied. To understand the thermoelectric conversion process, and to optimize the shape of the electric couple arm, with the new structure of the couple arm pair, the thermoelectric material can be better matched to the working temperature range and the power density.CFD model of the material can be used to display the temperature distribution and the potential distribution of the electric couple arm in different working conditions. (2) for the different working conditions, the temperature distribution and the potential distribution of the electric potential can be displayed. (2) The effects of cooling mode, cold and heat source temperature, assembly pressure, combination mode and load resistance on the power generation performance are studied by experiments, and the data support and verification are provided for CFD simulation and simulation calculation. The transient behavior of temperature difference generator is studied. The phenomenon of overshoot is found in the dynamic process, which is caused by the inconsistency of the temperature change rate of the cold, the hot end and the environment. The concept of overshoot is defined. (3) the model of the single couple arm pair is extended to the thermoelectric generator model in series with a number of galvanic arms, based on the use of the exhaust heat energy of the engine exhaust. The transient model of the thermoelectric generator is introduced and the changes in the time step and the spatial step of the model are introduced. The conservation and boundary conditions of the different regions are carefully analyzed. According to the conservation of the temperature and the heat flux, the thermal boundary conditions of the four interfaces are established, and five kinds of start-up are given. The electrical boundary conditions of the model are constant current mode, constant pressure mode, maximum power mode, constant power large current and constant power small current starting mode. The steady-state performance and transient behavior of the five modes are compared respectively. The temperature, potential and heat flux in the electric couple arm are analyzed in the starting process, and the power generation performance is reached. The time of rated power is studied. At the same time, the influence of external factors, such as speed and ambient temperature, on the performance of power generation is considered. (4) the transient model of the generator is expanded to be coupled with the driving condition model of the whole vehicle, and the performance changes of the generator are analyzed in addition, deceleration working conditions, staircase speed conditions and reciprocating speed conditions. Three typical vehicle driving conditions are analyzed, which are 10-15, NEDC (New European Driving Cycle) and UDDS (Urban Driving Dynamometer Schedule), representing the typical working conditions of Japan, Europe and the United States. Compared with the temperature difference generator in the specific driving conditions, the output power of the vehicle is raised. (5) the temperature is heated. The engine bench test of a differential generator, taking the exhaust of a 1.5 L gasoline engine as the heat source, taking the circulating water supplied by the constant temperature water tank as the cold source, observed the steady state performance of the generator and the transient behavior in the variable working condition under the different working conditions. The time interval of the change of the power generation performance under the variable condition was determined, based on the exhaust heat of the engine exhaust. The transient data of the thermoelectric generator can provide experimental basis for the off design data.

【學(xué)位授予單位】：天津大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2014
【分類號(hào)】：TM913

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