【摘要】：隨著化石能源的不斷消耗,人類的不可再生資源面臨嚴重問題。與此同時,太陽能發(fā)電作為一種高效的發(fā)電方式,是一種非常有潛力的新能源發(fā)電技術(shù)。這其中涉及到兩種最常見也最主要的太陽能發(fā)電形式:光伏發(fā)電和光熱發(fā)電。太陽能熱發(fā)電最有別于光伏發(fā)電的地方在于每一個太陽能熱發(fā)電系統(tǒng)都標準配備有儲能部分,這就為用電的調(diào)峰過程提供了極大的便利。光熱發(fā)電是太陽能利用的高品位方式,通過匯集太陽能產(chǎn)生的輻射熱的形式,加熱水或者水蒸氣,推動汽輪機轉(zhuǎn)動,帶動發(fā)電機發(fā)電。太陽能轉(zhuǎn)換成電能要經(jīng)歷多次能量轉(zhuǎn)換的過程,而其中對熱能的合理利用,是光熱發(fā)電的關(guān)鍵技術(shù)。在太陽能熱發(fā)電系統(tǒng)中,傳熱儲熱工質(zhì)的選擇要面對非常多限制條件,包括低腐蝕性、較高的熱容和穩(wěn)定性、出色的導熱性能,還有重復利用性。熔鹽作為非常有前景的儲熱工質(zhì)得到了工業(yè)界的廣泛關(guān)注。本文力求在現(xiàn)有研究基礎上,探索熔融鹽在太陽能集熱蓄熱領(lǐng)域中作為蓄熱材料的可行性和可優(yōu)化性。本文將碳納米管加入鹽類等固體介質(zhì)中,形成的團簇結(jié)構(gòu)和液膜層,大幅提升新型混合物熱物性。因此提出了一種新型儲熱材料:MWCNTs-太陽鹽復合材料,即多壁碳納米管-太陽鹽復合材料。并建立了其導熱率計算公式模型,同時親手制備MWCNTs-太陽鹽復合材料,并測量其包括導熱率在內(nèi)的多種熱物性,驗證導熱率模型的準確性。本文在制造此種新材料的同時,對其導熱特性大幅提升的理論機理進行了研究分析,整合多項修正因子來推演導熱系數(shù)的計算模型。該模型充分考慮了團聚、顆粒分布、布朗運動形成的微對流(包括溫度變化對布朗運動的影響)等因素對納米流體導熱系數(shù)的影響。同時本文進行了MWCNTs-太陽鹽復合材料的制備,并對其熔融狀態(tài)下的導熱率進行測定,實際證明該模型能夠準確預測出MWCNTs-太陽鹽復合材料高溫熔融條件下導熱系數(shù)增強的趨勢,增強幅度最大可達49.1%,新的導熱率計算模型理論預測值與現(xiàn)有實驗數(shù)據(jù)平均誤差5.79%。
[Abstract]:With the constant consumption of fossil energy, human non-renewable resources are faced with serious problems. At the same time, solar power generation as an efficient power generation, is a very potential new energy generation technology. This involves two of the most common and most important forms of solar power generation: photovoltaic and photothermal power generation. The most important difference between solar thermal generation and photovoltaic power generation is that every solar thermal power generation system is equipped with a standard energy storage part, which provides great convenience for the peak regulation process. Photothermal power generation is a high-grade way of solar energy utilization. By collecting the radiation heat generated by solar energy, heating water or water vapor, the steam turbine can be driven to rotate and drive the generator to generate electricity. The process of converting solar energy to electric energy has to go through many times, and the rational utilization of heat energy is the key technology of photothermal power generation. In the solar thermal power generation system, the selection of heat transfer and thermal storage fluid has many limitations, including low corrosion, high heat capacity and stability, excellent thermal conductivity, and reusability. Molten salt, as a very promising thermal storage medium, has attracted wide attention in industry. Based on the existing research, the feasibility and optimizability of molten salt as heat storage materials in the field of solar energy collection and storage are explored in this paper. In this paper, carbon nanotubes (CNTs) were added to solid media such as salts to form clusters and liquid film layers, which greatly improved the thermal properties of the new mixture. Therefore, a new type of thermal storage material, the multi-wall carbon nanotube-solar salt composite, is proposed. At the same time, MWCNTs- solar salt composites were prepared by hand, and their thermal properties, including thermal conductivity, were measured to verify the accuracy of the thermal conductivity model. In this paper, the theoretical mechanism of the thermal conductivity is studied and analyzed while the new material is manufactured, and the calculation model of thermal conductivity is deduced by integrating several correction factors. The influence of agglomeration, particle distribution and micro-convection formed by Brownian motion (including the effect of temperature on Brownian motion) on the thermal conductivity of nanoscale fluids is fully considered in the model. At the same time, the preparation of MWCNTs- solar salt composite is carried out, and the thermal conductivity of MWCNTs- solar salt composite under melting state is measured. It is proved that the model can accurately predict the increasing trend of thermal conductivity of MWCNTs- solar salt composite under the condition of high temperature melting. The maximum enhancement amplitude can be up to 49.1, and the average error between the theoretical prediction value of the new thermal conductivity calculation model and the existing experimental data is 5.79.
【學位授予單位】：華北電力大學(北京)
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TB383.1

【參考文獻】

相關(guān)期刊論文 前10條

1 林靈楠;彭浩;丁國良;陸一凡;;表面活性劑對納米制冷劑顆粒團聚的影響[J];工程熱物理學報;2016年09期

2 駱仲泱;吳越瓊;胡倩;王濤;倪明江;;碳納米管-導熱油納米流體導熱與流變特性研究[J];高�；瘜W工程學報;2015年01期

3 賈濤;王瑞祥;;碳納米管水基納米流體導熱系數(shù)的預測方法[J];熱科學與技術(shù);2014年01期

4 汪琦;俞紅嘯;張慧芬;;太陽能光熱發(fā)電中熔鹽蓄熱儲能循環(huán)系統(tǒng)的設計開發(fā)[J];化工裝備技術(shù);2014年01期

5 莫松平;陳穎;羅向龍;劉琢瑋;;基于納米顆粒小尺度效應的納米流體有效熱導率模型[J];功能材料;2013年14期

6 王輝;;太陽能光熱發(fā)電系統(tǒng)中儲熱材料研究進展[J];科技信息;2013年03期

7 汪琦;俞紅嘯;;熔鹽加熱爐的結(jié)構(gòu)設計和熔鹽過熱的研究[J];化工裝備技術(shù);2012年05期

8 李東東;李金凱;趙蔚琳;;SiO_2-水納米流體穩(wěn)定性及導熱性能[J];濟南大學學報(自然科學版);2010年03期

9 朱冬生;李新芳;汪南;王先菊;李華;楊碩;;Al_2O_3-H_2O納米流體的導熱性能[J];華南理工大學學報(自然科學版);2008年11期

10 蔡艷華;馬冬梅;王金剛;俞海軍;朱根華;;納米流體的制備及傳熱性能研究的現(xiàn)狀[J];材料研究與應用;2007年04期

相關(guān)碩士學位論文 前4條

1 楊迪;納米制冷劑管內(nèi)強化換熱研究[D];東北電力大學;2014年

2 吳迪;基于太陽能熱發(fā)電系統(tǒng)的納米顆粒提升熔鹽儲熱特性的研究[D];華北電力大學;2014年

3 胡倩;導熱油納米流體基礎熱物性及對流換熱特換熱特性實驗研究[D];浙江大學;2013年

4 徐淼;納米流體的熱物性及在波壁管內(nèi)流動特性研究[D];大連理工大學;2010年

，

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