本文關鍵詞：脂肪酸復合相變材料的制備及其在日光溫室中的應用　出處：《西北農(nóng)林科技大學》2015年碩士論文　論文類型：學位論文

  更多相關文章： 脂肪酸 定形相變材料 日光溫室 相變蓄熱墻板 應用

【摘要】：日光溫室是我國重要的農(nóng)業(yè)生產(chǎn)設施,在我國的農(nóng)業(yè)發(fā)展中有著極其重要的作用。然而在實際的生產(chǎn)過程中,尤其在北方寒冷地區(qū),日光溫室常常難以確保作物安全越冬,還需要消耗能源對溫室進行加熱來提高最低溫度,因而就增加了生產(chǎn)運行的成本。近年來相變蓄熱材料的研究,給節(jié)能日光溫室的研究提供了新的思路。將相變儲能技術應用于溫室,將在降低能源消耗,改善溫室熱環(huán)境,優(yōu)化日光溫室墻體結構等方面,有著非常重要的意義。本研究的主要內(nèi)容如下：(1)開發(fā)了適用于日光溫室的三元脂肪酸定形復合相變材料：月桂酸-肉豆蔻酸-癸酸／膨脹石墨,并對其性能進行了測試。研究結果表明：該定形復合相變材料的相變溫度為21.82℃,相變潛熱為121.5J/g。膨脹石墨在定形復合相變材料中所占質(zhì)量分數(shù)為8%。在表面張力和毛細作用下,相變材料被固定到膨脹石墨的微觀孔隙中,在融化情況下也沒有材料泄露現(xiàn)象發(fā)生。經(jīng)1000次加速冷熱循環(huán)之后,定形復合相變材料熔點變化了-0.22℃,潛熱變化了-2.3%,變化幅度極小,表現(xiàn)出了良好的熱穩(wěn)定性和化學穩(wěn)定性。定形復合材料的導熱系數(shù)為1.79W/(m-K),相比于純相變材料提高了近6.5倍,極大地改善了脂肪酸材料導熱性能差的問題。(2)將定形復合相變材料與菱鎂墻板結合,設計出一種相變蓄熱墻板,并進行了應用效果分析。通過選取典型天氣條件下室內(nèi)的氣溫、20cm深處地溫、墻體溫度、墻體熱流等環(huán)境數(shù)據(jù)進行分析對比,所得主要結論如下：晴天天氣條件下,裝有相變蓄熱墻板的溫室白天的最高氣溫平均比對照低0.9℃,最大可低3.4℃,夜間最低氣溫比對照溫室要高出2.3℃,最大可高2.9℃；20cm深處的地溫比對照溫室高0.8～1.1℃；白天相變蓄熱墻板的累計吸熱量為6.18MJ/m2,比對照磚墻高2.05MJ/m2；夜晚相變蓄熱墻板的累計放熱量為2.24MJ/m2,比對照磚墻高101MJ/m2。在陰天天氣條件下,相變蓄熱溫室的氣溫比對照溫室要高出1.1～1.7℃；20cm深處的地溫比對照高0.9-1℃；白天相變蓄熱墻板累計吸熱量0.79 MJ/m2,高于對照磚墻0.14 MJ/m2；夜間相變蓄熱墻板夜間累計放熱量為0.53 MJ/m2,比對照墻體高出03MJ/m2。相變蓄熱墻板的應用明顯地提高了日光溫室的蓄熱量,降低白天溫室內(nèi)的過高的溫度,提升夜間室內(nèi)的最低溫度,對室內(nèi)熱量起到了“削峰填谷”的調(diào)節(jié)作用。該研究為進一步改善溫室熱環(huán)境,降低溫室內(nèi)能源消耗,提供了一定的參考價值。
[Abstract]:Solar greenhouse is an important agricultural production facilities in China, plays an important role in the development of agriculture in our country. However, in the actual production process, especially in the northern cold area, the greenhouse is often difficult to ensure the safety of crops in winter, also need to consume energy to heat the greenhouse to raise the minimum temperature, thus increasing the production cost of running. In recent years the research on phase change materials, provides a new way for the research of energy saving solar greenhouse. The phase change energy storage technology in greenhouse, will reduce energy consumption, improve the greenhouse thermal environment, optimize the structure of wall in solar greenhouse, has a very important significance. The main contents of this the research is as follows: (1) three yuan of fatty acid composite phase change material developed for greenhouse: lauric acid and myristic acid and capric acid / expanded graphite, and its properties were tested. The results show that the phase transition temperature of composite phase change material is 21.82 DEG C, latent heat for 121.5J/g. graphite in composite phase change material in the mass fraction of 8%. in surface tension and capillary effect, the phase change material is fixed to the micro pores of expanded graphite, in case there is no leakage of material melting phenomenon 1000. After accelerated thermal cycling. The composite phase change material melting point changes -0.22 C, heat change -2.3%, change amplitude is very small and showed good thermal stability and chemical stability. The thermal conductivity of composite materials for 1.79W/ (m-K), compared to the pure phase change materials increased nearly 6.5 times, greatly to improve the thermal conductivity of the fatty acid material is poor. (2) the combination of amorphous composite phase change material and magnesite wall, design a kind of phase change wallboard, and the application effect analysis. By choosing the indoor temperature under typical weather conditions, 20cm deep soil temperature, wall temperature, wall heat flux and environmental data were analyzed, the main conclusions are as follows: sunny weather conditions, the highest temperature with phase change wallboard greenhouse in average 0.9 lower than the control temperature, the maximum can be 3.4 lower than the control temperature, the minimum temperature at night the greenhouse is up to 2.3 degrees, the maximum temperature 2.9 DEG C higher than the control; 20cm inside the greenhouse is higher 0.8 ~ 1.1 DEG C; the cumulative amount of heat during the day phase change wallboard is 6.18MJ/m2 than the control 2.05MJ/m2 high brick wall; phase change thermal storage wall night accumulated heat release is 2.24MJ/m2, than the control brick high 101MJ/m2. in cloudy weather conditions under greenhouse temperature phase change than the control of greenhouse is up to 1.1 to 1.7 DEG C; 20cm deep temperature higher than the control at 0.9-1 during the day; phase change wallboard cumulative heat absorption of 0.79 MJ/m2 high. In the control of brick 0.14 MJ/m2; the night phase change wallboard night accumulated heat release is 0.53 MJ/m2, higher than the control wall using 03MJ/m2. PCM Wallboard can obviously improve the heat storage of solar greenhouse, reducing daytime greenhouse temperature, raising the minimum temperature during nighttime, the adjustment function of "peak" the indoor heat. The research to further improve the greenhouse thermal environment, reduce greenhouse energy consumption, to provide a certain reference value.

【學位授予單位】：西北農(nóng)林科技大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TB34

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本文編號：1404833