本文選題：無(wú)機(jī)-有機(jī)復(fù)合殼層 + 納米膠囊相變蓄冷流體��； 參考：《華南理工大學(xué)》2015年碩士論文

【摘要】：潛熱型蓄冷流體是一種集蓄冷和強(qiáng)化傳熱為一體的功能流體。傳統(tǒng)的有機(jī)相變微膠囊蓄冷流體存在流動(dòng)阻力大、導(dǎo)熱系數(shù)低等不足�；跓o(wú)機(jī)納米粒子的高導(dǎo)熱性及納米膠囊相變流體的低流動(dòng)阻力,研究新型無(wú)機(jī)-有機(jī)復(fù)合殼層的納米膠囊相變蓄冷流體,具有重要的理論指導(dǎo)意義和實(shí)際應(yīng)用價(jià)值。本文開(kāi)展以聚苯乙烯(PS)和二氧化硅(Si O2)作復(fù)合殼層,正十四烷(Tet)作芯材的新型納米膠囊相變蓄冷流體熱物性及傳熱性能的實(shí)驗(yàn)研究。采用細(xì)乳液原位聚合法合成了新型PS-Si O2@Tet納米膠囊相變材料(Nano-encapsulated phase change material,NEPCM)及其乳液;探討了抗凍劑乙二醇質(zhì)量分?jǐn)?shù)對(duì)新型蓄冷流體冰點(diǎn)及穩(wěn)定性的影響;對(duì)復(fù)合殼層納米膠囊的熱性能進(jìn)行差示掃描量熱(DSC)、熱失重(TG)表征,并測(cè)量其相變蓄冷流體的熱物性,包括粒徑大小及分布、導(dǎo)熱系數(shù)、表觀比熱容、粘度和密度等。測(cè)試結(jié)果表明:制備的新型PS-Si O2@Tet NEPCM的平均粒徑為151.3 nm,相變潛熱達(dá)83.38 k J·kg-1,具有較高的熱穩(wěn)定性;以質(zhì)量分?jǐn)?shù)為15%的乙二醇和OP-10/SDS復(fù)合乳化劑以及水組成的混合液為基液,當(dāng)PS-Si O2@Tet NEPCM的質(zhì)量分?jǐn)?shù)為5%時(shí),新型蓄冷流體的導(dǎo)熱性能(5℃時(shí)導(dǎo)熱系數(shù)為0.4035 W·m-1·K-1)和表觀比熱容(6.79℃時(shí)比熱容峰值達(dá)8.842 J·g-1·℃-1),均高于未用Si O2改性的PS@Tet NEPCM蓄冷流體,且新型蓄冷流體具有較低的粘度(5℃時(shí)粘度為2.76 c P)、較高的機(jī)械穩(wěn)定性,適合作為潛熱型蓄冷功能流體。在自行建立的新型蓄冷流體傳熱性能實(shí)驗(yàn)臺(tái)開(kāi)展了復(fù)合殼層NEPCM蓄冷流體的對(duì)流換熱特性實(shí)驗(yàn)研究;分析影響其釋冷/蓄冷過(guò)程強(qiáng)化換熱的因素。實(shí)驗(yàn)結(jié)果表明:在釋冷過(guò)程中,質(zhì)量分?jǐn)?shù)為5%的復(fù)合殼層NEPCM流體,其對(duì)流換熱系數(shù)較未用Si O2改性的提高了8%,較基液提高了50%;對(duì)應(yīng)地,在蓄冷過(guò)程中,其提高分別為6%和30%。在釋冷/蓄冷過(guò)程中,隨著雷諾數(shù)的增加,復(fù)合殼層NEPCM流體的對(duì)流換熱系數(shù)增大,但是其強(qiáng)化換熱的程度隨之降低;隨著復(fù)合殼層NEPCM質(zhì)量分?jǐn)?shù)的增加及管外換熱介質(zhì)流量的增大,新型蓄冷流體強(qiáng)化換熱的效果均有所增強(qiáng)。
[Abstract]:Latent heat storage fluid is a kind of functional fluid which integrates cold storage and enhanced heat transfer. The traditional organic phase change microencapsulated cold storage fluid has many disadvantages, such as high flow resistance and low thermal conductivity. Based on the high thermal conductivity of inorganic nanoparticles and the low flow resistance of phase change fluids in nano-capsules, it is of great theoretical significance and practical application value to study the novel inorganic / organic composite shell phase change cold storage fluids. In this paper, the thermal properties and heat transfer properties of phase change storage fluid with polystyrene (PS) and silica (SiO2) as composite shell and tetradecane (Tet) as core material were studied. A novel phase change material PS-Si O2@Tet phase change material material NEPCM and its emulsion were synthesized by in-situ polymerization of fine emulsion, and the effects of the mass fraction of ethylene glycol, an antifreeze, on the freezing point and stability of the new cold storage fluid were investigated. The thermal properties of composite shell nanocapsules were characterized by differential scanning calorimetry (DSC) and thermogravimetric analysis (TG). The thermal properties of phase change cold storage fluid, including particle size and distribution, thermal conductivity, apparent specific heat capacity, viscosity and density, were measured. The results show that the average particle size of the new PS-Si O2@Tet NEPCM is 151.3 nm, the latent heat of phase transition is 83.38 kJ / kg -1, and it has high thermal stability, and the mixture of 15% mass fraction of ethylene glycol and OP-10/SDS and water is used as the base solution. When the mass fraction of PS-Si O2@Tet NEPCM is 5, the thermal conductivity of the new cold storage fluid is 0.4035 W m-1 K 1 at 5 鈩，

本文編號(hào)：1782897