本文選題：相變材料 + 硅藻土��； 參考：《中國地質(zhì)大學(xué)(北京)》2017年博士論文

【摘要】：建筑能耗約占社會總能耗的30%左右,把相變材料摻入到傳統(tǒng)建筑材料中制成相變儲能建筑材料,將太陽能以相變潛熱的形式存儲與釋放,對降低建筑物能耗有重要的意義。本論文針對相變材料在實際應(yīng)用中存在的兩大致命問題:相變過程中因穩(wěn)定性差造成的滲漏問題和相變材料導(dǎo)熱率低的問題,提出利用我國豐富的硅藻土資源加工成高效定形復(fù)合相變儲能材料,并在高導(dǎo)熱速率等方面的應(yīng)用上開展研究工作,實現(xiàn)建筑行業(yè)的節(jié)能降耗,為硅藻土的高附加值利用開辟新途徑,具有明顯的經(jīng)濟和社會效益。采用真空浸漬法,制備聚乙二醇(PEG)/硅藻土定形復(fù)合相變儲能材料,首先對硅藻土進行堿處理,將硅藻土規(guī)則的孔雕飾成海綿狀的孔。PEG均勻地浸漬到硅藻土的孔結(jié)構(gòu)中,吸附量為70%,提高了46%,該數(shù)值為目前文獻中的最高數(shù)值,且經(jīng)過200次加熱-冷卻熱循環(huán),PEG不發(fā)生滲漏,具有優(yōu)異的形態(tài)穩(wěn)定性。PEG/硅藻土復(fù)合相變材料具有優(yōu)異的儲能密度,熱穩(wěn)定性和循環(huán)穩(wěn)定性,活化能為1031.85 kJ/mol,高于純PEG的活化能。采用水熱還原法和溶液共混法分別在硅藻土的表面修飾納米Ag顆粒和碳納米管(SWCN),硅藻土的孔結(jié)構(gòu)及比表面積均未發(fā)生明顯變化,再浸滲液態(tài)PEG,獲得高穩(wěn)定性和高導(dǎo)熱率的硅藻土基定形復(fù)合相變儲能材料。當修飾粒徑為3~10 nm的納米Ag(7.2 wt%)顆粒時,復(fù)合相變材料的導(dǎo)熱率為0.82 W/mK,較PEG本身提高了240%;當修飾SWCN(2 wt%)時,復(fù)合相變材料的導(dǎo)熱率為0.87 W/mK,較PEG本身提高了260%。隨著導(dǎo)熱率的提高,PEG的熔化和凝固時間大大縮短了,過冷度降低,儲熱密度不發(fā)生變化。采用熔融共混法,制備LiNO_3/硅藻土和Na2SO_4/硅藻土中溫和高溫定形復(fù)合相變材料,LiNO_3和Na2SO_4均勻地浸漬到硅藻土的孔結(jié)構(gòu)中,經(jīng)過200次加熱-冷卻熱循環(huán),不發(fā)生液相滲漏,具有優(yōu)異的形態(tài)穩(wěn)定性。LiNO_3/硅藻土和Na2SO_4/硅藻土的工作溫度分別為240~255℃和887.61~877.61℃,具有優(yōu)異的儲能密度,熱穩(wěn)定性和循環(huán)穩(wěn)定性。分別以油頁巖灰渣和正硅酸乙酯為原料,采用溶膠-凝膠法制備PEG/SiO_2低溫和Na2SO_4/SiO_2高溫定形復(fù)合相變材料。經(jīng)過200次加熱-冷卻熱循環(huán),相變材料的化學(xué)性質(zhì)與熱物性能不發(fā)生變化,具有優(yōu)異的熱循環(huán)穩(wěn)定性。這兩種復(fù)合相變材料具有優(yōu)異的儲能密度,傳熱效率,熱穩(wěn)定性和形態(tài)穩(wěn)定性。
[Abstract]:The building energy consumption accounts for about 30% of the total energy consumption of the society. It is of great significance to reduce the building energy consumption by adding the phase change material into the traditional building material to make the phase change energy storage building material and store and release the solar energy in the form of phase change latent heat. In this paper, there are two fatal problems in the practical application of phase change materials: the leakage caused by poor stability and the low thermal conductivity of phase change materials. It is put forward that using the rich diatomite resources in our country to produce high efficiency amorphous composite phase change energy storage materials, and to carry out research work on the application of high thermal conductivity rate, so as to realize energy saving and consumption reduction in the construction industry. It opens up a new way for the utilization of high added value diatomite and has obvious economic and social benefits. Polyethylene glycol (PEG) / diatomite composite phase change energy storage materials were prepared by vacuum impregnation. Firstly, diatomite was treated with alkali, and the regular diatomite holes were carved into spongy holes. PEG was evenly impregnated into the pore structure of diatomite. The adsorption capacity is 70, an increase of 46 percent, which is the highest value in the current literature, and after 200 heating-cooling heat cycles, PEG does not leak, and has excellent morphological stability. PEG / diatomite composite phase change material has excellent energy storage density. The activation energy is 1031.85 KJ / mol, which is higher than that of pure PEG. The surface modification of Ag nanoparticles and carbon nanotubes (SWCN) on the surface of diatomite by hydrothermal reduction method and solution blending method respectively did not change the pore structure and specific surface area of diatomite. Diatomite based composite phase change energy storage materials with high stability and high thermal conductivity were obtained by re-infiltration of liquid PEG. The thermal conductivity of the composite phase change material was 0.82 W / mKand 240W / mKhigher than that of PEG when modified with nano-Ag (7.2 wt%) particle size of 3 ~ 10 nm, and the thermal conductivity of the composite PCM was 0.87 W / m ~ (k) higher than that of PEG when modified SWCN (2 wt%), the thermal conductivity of composite phase change material was 0.87 W / m ~ (k), which was 260W / m ~ (-1) higher than that of PEG itself when modified SWCN (2 wt%). With the increase of thermal conductivity, the melting time and solidification time of PEG are greatly shortened, the supercooling degree is decreased, and the heat storage density does not change. LiNO3 / diatomite and Na _ 2SO _ 4 / diatomite were prepared by melt blending method. The mild high-temperature setting composite phase change materials LiNO3 and Na _ 2SO _ 4 were uniformly impregnated into the pore structure of diatomite. After 200 heating and cooling heat cycles, no liquid phase leakage occurred. The working temperatures of LiNO3 / diatomite and Na _ 2SO _ 4 / diatomite are 240 鈩，

本文編號：2050832