發(fā)布時(shí)間：2018-03-12 08:17

  本文選題：納米流體　切入點(diǎn)：離子液體　出處：《大連理工大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：吸收式熱泵是一種利用余熱來實(shí)現(xiàn)低溫向高溫輸送熱量的節(jié)能環(huán)保設(shè)備。傳統(tǒng)的熱泵工質(zhì)對有氨水和溴化鋰水溶液,但是氨水有毒,溴化鋰水溶液則易結(jié)晶和腐蝕設(shè)備。離子液體是一種新型的綠色有機(jī)溶劑,具有蒸汽壓低,液程寬,熱穩(wěn)定及無腐蝕性等特點(diǎn),而且具有替代傳統(tǒng)熱泵工質(zhì)成為吸收制冷或吸收熱泵冷媒新型吸收劑的可能。納米流體是一種懸浮有納米粒子或納米管而形成的新型冷卻工質(zhì),相比較于傳統(tǒng)的流體,納米流體具有異乎尋常的熱傳遞性能。將離子液體基納米流體作為熱泵新工質(zhì)不僅能強(qiáng)化傳熱,而且具備離子液體獨(dú)特的性能。本文主要利用分子動(dòng)力學(xué)模擬方法,以傳統(tǒng)的水基納米流體為出發(fā)點(diǎn),研究了新型離子液體基納米流體作為熱泵工質(zhì)的傳熱特性。具體工作和成果如下：第一部分：利用分子動(dòng)力學(xué)方法模擬計(jì)算了四種常見水模型的密度、粘度、擴(kuò)散系數(shù)和導(dǎo)熱系數(shù),結(jié)果表明SPC/E水模型的模擬值與實(shí)驗(yàn)值吻合較好。在此基礎(chǔ)上,我們選擇SPC/E水模型作為水基納米流體的基液,計(jì)算了加入納米銅顆粒后的水基納米流體導(dǎo)熱系數(shù),并與實(shí)驗(yàn)值進(jìn)行比較吻合較好。第二部分：利用量化方法對離子液體進(jìn)行幾何構(gòu)型優(yōu)化、頻率分析和能量計(jì)算,選擇出最穩(wěn)定的離子液體構(gòu)型,并得到相應(yīng)的結(jié)構(gòu)參數(shù)和原子電荷,又采用OPLS和Amber混合力場來分別描述離子液體陰陽離子,從而建立起離子液體的力場。為了驗(yàn)證離子液體力場的準(zhǔn)確性,采用分子動(dòng)力學(xué)方法模擬了離子液體在不同溫度下的密度、擴(kuò)散系數(shù)和導(dǎo)熱系數(shù),驗(yàn)證了力場的準(zhǔn)確性。最后,為研究同一納米顆粒不同質(zhì)量分?jǐn)?shù)以及同一質(zhì)量分?jǐn)?shù)不同納米顆粒的離子液體基納米流體導(dǎo)熱系數(shù),建立了各種納米流體模型,結(jié)果表明：各離子液體基納米流體的導(dǎo)熱系數(shù)相比于離子液體均有提高。第三部分：為了工業(yè)應(yīng)用的目的,我們首先模擬計(jì)算了不同摩爾分?jǐn)?shù)下的離子液體二元溶液的密度、擴(kuò)散系數(shù)和導(dǎo)熱系數(shù)。接著模擬計(jì)算了以納米銅顆粒為添加劑的離子液體二元溶液基納米流體的導(dǎo)熱系數(shù),并較其基液二元溶液的導(dǎo)熱系數(shù)有所提高。第四部分：為了探究納米流體導(dǎo)熱系數(shù)增加的原因,我們分析了加入納米顆粒前后各粒子運(yùn)動(dòng)的快慢、微觀結(jié)構(gòu)變化和導(dǎo)熱系數(shù)中各項(xiàng)貢獻(xiàn)大小。結(jié)果表明：維里自相關(guān)項(xiàng)在納米流體導(dǎo)熱系數(shù)的提高當(dāng)中起到了最大的積極作用。
[Abstract]:Absorption heat pump is a kind of energy saving and environmental protection equipment that uses waste heat to transfer heat from low temperature to high temperature. Traditional heat pump working fluid has ammonia water and lithium bromide aqueous solution, but ammonia water is poisonous. Ionic liquids are a new green organic solvent with the characteristics of low vapor pressure, wide liquid range, thermal stability and non-corrosive properties. In addition, it is possible to replace the traditional heat pump refrigerant as a new absorbent for the absorption of refrigeration or heat pump refrigerant. Nano-fluid is a new type of refrigerant formed by suspending nanoparticles or nanotubes, compared with the traditional fluid. Nano-fluids have extraordinary heat transfer properties. Using ionic liquid-based nano-fluids as a new working medium of heat pump can not only enhance heat transfer, but also possess unique properties of ionic liquids. Starting from traditional water-based nanofluids, The heat transfer characteristics of new ionic liquid-based nano-fluids as working fluid of heat pump are studied. The results are as follows: part one: the density and viscosity of four common water models are simulated and calculated by molecular dynamics method. The results of diffusion coefficient and thermal conductivity show that the simulated value of SPC/E water model is in good agreement with the experimental value. On this basis, we choose the SPC/E water model as the base liquid of water-based nano-fluid. The thermal conductivity of water-based nanoscale fluids after adding nano-copper particles is calculated, and it is in good agreement with the experimental data. Part two: the geometric configuration optimization, frequency analysis and energy calculation of ionic liquids are carried out by using quantization method. The most stable configuration of ionic liquids is selected and the corresponding structure parameters and atomic charges are obtained. The mixed force fields of OPLS and Amber are used to describe the anion and anion of ionic liquids, respectively. In order to verify the accuracy of the ionic liquid force field, the density, diffusion coefficient and thermal conductivity of the ionic liquid at different temperatures were simulated by molecular dynamics method, and the accuracy of the force field was verified. In order to study the thermal conductivity of ionic liquid-based nano-fluids with different mass fraction and different mass fraction of the same nanoparticles, a variety of nano-fluid models were established. The results show that the thermal conductivity of each ionic liquid-based nano-fluid is higher than that of ionic liquid. Part three: for the purpose of industrial application, we first simulate and calculate the density of ionic liquid binary solution with different molar fraction. Diffusion coefficient and thermal conductivity. Then the thermal conductivity of ionic liquids based on binary solution with nano-copper particles as additive was simulated. In part 4th, in order to explore the reasons for the increase of thermal conductivity of nano-fluids, we analyzed the speed of the motion of each particle before and after the addition of nano-particles. The results show that the virion autocorrelation term plays the most active role in the increase of thermal conductivity of nanoscale fluids.
【學(xué)位授予單位】：大連理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TQ021.1

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本文編號：1600728