本文選題：碳酸鹽　切入點(diǎn)：相變潛熱　出處：《武漢理工大學(xué)》2015年碩士論文

【摘要】：太陽能熱利用技術(shù)是能源領(lǐng)域的主要發(fā)展方向,但太陽能在時(shí)間和空間上都缺乏連續(xù)性,因此儲(chǔ)熱傳熱技術(shù)及材料的研究顯得非常重要。本文在前期研究無機(jī)鹽相變儲(chǔ)熱材料的基礎(chǔ)上,對(duì)以K2CO3-Na2CO3-Li2CO3為基鹽的多元碳酸鹽添加不同種類不同含量的硝酸鹽、碳酸鹽以及高導(dǎo)材料,擇優(yōu)選擇綜合性能最佳的多元混合無機(jī)鹽并研究其在600℃高溫下與316L不銹鋼和304不銹鋼的相容性。利用差示掃描量熱法(DSC)、熱重分析(TG)、微量熱儀法、電子掃描探針(EPMA)等測(cè)試方法,重點(diǎn)研究了多元碳酸鹽的相變潛熱、相變溫度、分解溫度、比熱容及腐蝕性等。通過DSC測(cè)試添加10%、20%、30%的硝酸鹽和碳酸鹽的多元混合無機(jī)鹽的相變潛熱、相變溫度。測(cè)試結(jié)果表明,與硝酸鹽作為添加劑進(jìn)行對(duì)比,碳酸鹽作為添加劑能夠更好的形成共晶、更大程度的提升基鹽的相變潛熱、降低基鹽的熔點(diǎn)。添加劑的種類和含量都對(duì)相變潛熱有影響,且隨著含量的增加,相變潛熱反而減小,從晶格能、靜電作用力的角度對(duì)比分析硝酸鹽和碳酸鹽作為添加劑對(duì)相變潛熱和相變溫度的影響。擇優(yōu)選取綜合性能較好的多元混合無機(jī)鹽,通過TG分析測(cè)試其分解點(diǎn),得出了不同試樣的分解溫度所在的溫度范圍,發(fā)現(xiàn)碳酸鋇、碳酸鍶、碳酸錳作為添加劑時(shí),對(duì)基鹽分解點(diǎn)的提高有更為明顯的幫助,分解點(diǎn)最高的為添加10%BaCO3、10%SrCO3、和20%SrCO3的混合鹽,均達(dá)到820℃。在此基礎(chǔ)上計(jì)算多元碳酸鹽在高溫下可能會(huì)發(fā)生化學(xué)反應(yīng)的吉布斯自由能變,分析了高溫下影響熔鹽不穩(wěn)定性的主要因素。添加10%、20%和30%BaCO3到基鹽K2CO3-Na2CO3-Li2CO3中,測(cè)試其比熱容,結(jié)果表明,從100℃~300℃,隨著溫度逐漸的升高,無機(jī)混合鹽的比熱容曲線緩慢的上升,且比熱容的穩(wěn)定的平均值隨著添加劑的增多而減少。在K2CO3-Na2CO3-Li2CO3-10%BaCO3基鹽中添加5%、10%、20%、30%的膨脹石墨、粒狀石墨和碳纖維及其混合物,測(cè)試其相變潛熱、熔點(diǎn)以及熱導(dǎo)率。測(cè)試結(jié)果表明,膨脹石墨、粒狀石墨和碳纖維的加入降低了無機(jī)混合鹽的相變潛熱,但在很大的程度上提高了其熱導(dǎo)率。添加膨脹石墨對(duì)熱導(dǎo)率的提升幅度最明顯,最大可以達(dá)到4.04W/(m·K)。利用靜態(tài)腐蝕實(shí)驗(yàn)法研究了基鹽K2CO3-Na2CO3-Li2CO3-10%BaCO3在600℃熔融態(tài)時(shí)與316L不銹鋼和304不銹鋼的相容性,利用光學(xué)顯微法、電子掃描探針對(duì)經(jīng)過192h浸蝕后的試樣進(jìn)行線掃描,發(fā)現(xiàn)兩種不銹鋼都只是被輕微腐蝕,腐蝕層并未出現(xiàn)坑或者凸起,也沒有腐蝕產(chǎn)物的堆積。利用XRD分析可知浸蝕層僅有微弱的Li、O元素,其余的主要是奧氏體相和馬氏體相。通過分析不銹鋼浸蝕的動(dòng)力學(xué)曲線可知,基鹽K2CO3-Na2CO3-Li2CO3-10%BaCO3與316L不銹鋼和304不銹鋼的相容性較好。
[Abstract]:The use of solar thermal technology is the main development direction in the field of energy, but solar energy in time and space are lack of continuity, therefore it is very important to study the technology of heat transfer and heat storage materials. This paper based on the previous studies of inorganic salt phase-change material, adding different content of nitrate on multiple carbonate by K2CO3-Na2CO3-Li2CO3 as the base of salt, carbonate and high conductivity materials, compatibility selection the best comprehensive performance of mixed inorganic salt and study the stainless steel and 316L at 600 degrees Celsius and 304 stainless steel. By using differential scanning calorimetry (DSC), thermogravimetric analysis (TG), electronic scanning calorimetry method. Probe (EPMA) and other test methods, focusing on the latent heat, multiple carbonate phase transition temperature, decomposition temperature, specific heat and corrosion resistance. Through the test of DSC added 10%, 20%, 30% of nitrate and carbonate Latent heat, mixed inorganic salt phase change temperature. The test results show that compared with nitrate as additive, carbonate as additive can form eutectic better, enhance the latent heat based salt greater degree, reduce the base salt melting point. The kinds and contents of additives have the effect on the latent heat, and with the the increase of the content of latent heat decreases, the lattice energy, contrast analysis of electrostatic interaction effects of nitrate and carbonate as additive on the latent heat and phase transition temperature. The preferred mixed inorganic salt selected good comprehensive properties, through the TG analysis to test its decomposition, the decomposition temperature of the temperature range of different samples. Found, barium carbonate, strontium carbonate, manganese carbonate as an additive, has a more obvious help to improve the base salt decomposition point, the highest point for adding 10%BaCO3,10%Sr decomposition CO3, a mixture of salt and 20%SrCO3, have reached 820 degrees. On the basis of calculation of multiple carbonate under high temperature may occur chemical reaction Gibbs free energy, analyzes the main factors influencing the stability of high temperature molten salt is added. 10%, 20% and 30%BaCO3 to salt based K2CO3-Na2CO3-Li2CO3, to test the specific heat, the show that from 100 DEG ~300 DEG, with the temperature gradually increased, rising heat inorganic mixed salt volume curve slowly, and the average specific heat stable value decreases with the increase of additive. Adding 5%, in the K2CO3-Na2CO3-Li2CO3-10% BaCO3 based in salt 10%, 20%, 30% of the expanded graphite, graphite and carbon fiber and granular the mixture, test its latent heat, melting point and thermal conductivity. The test results show that the expanded graphite, granular graphite and carbon fiber decreased with the latent heat of inorganic salt mixture, but increased to a great extent The thermal conductivity. Adding the expanded graphite on thermal conductivity increases most obviously, the maximum can reach 4.04W/ (M - K). The compatibility between the static corrosion test method of salt based K2CO3-Na2CO3-Li2CO3-10%BaCO3 at 600 DEG C melting state and 316L stainless steel and 304 stainless steel, using optical microscopy, scanning electron microprobe of samples after 192h after etching of line scanning, found two kinds of stainless steel are slight corrosion, corrosion layer does not appear a pit or bulge, there is no accumulation of corrosion products. The analysis shows that the etching layer only weak Li, using the XRD O element, the rest is mainly austenite and martensite phases. The kinetic curves of stainless steel etching base, salt K2CO3-Na2CO3-Li2CO3-10%BaCO3 and 316L stainless steel and 304 stainless steel has good compatibility.

【學(xué)位授予單位】：武漢理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TB34

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