本文選題：導熱系數(shù)　切入點：熱線法　出處：《南京航空航天大學》2015年碩士論文

【摘要】：絕熱材料的導熱系數(shù)隨材料的結(jié)構(gòu)、成分、溫度和濕度等變化很大,在一些文獻提供的物性表中基本查不到低溫下的導熱系數(shù),而低溫下絕熱材料的導熱系數(shù)又是人們關(guān)注的重點,因此研究如何快速有效地測量絕熱材料低溫下的導熱系數(shù)對于航空、航天、低溫貯存及運輸、低溫技術(shù)的發(fā)展具有重要意義。本課題是工信部高技術(shù)船舶科研計劃《新型液化天然氣船液貨圍護系統(tǒng)預先研究》項目的一部分,目的是獲取聚酰亞胺泡沫塑料在液氮溫區(qū)內(nèi),導熱系數(shù)隨溫度變化的關(guān)系,為新型液化天然氣液貨艙圍護結(jié)構(gòu)的絕熱材料選型提供依據(jù)。本文重點研究了平行熱線法測量低溫環(huán)境下絕熱材料的導熱系數(shù)。理論上根據(jù)熱線法建立了熱量傳遞的瞬態(tài)數(shù)學模型、對數(shù)學模型進行了數(shù)值模擬;試驗上,根據(jù)平行熱線法原理,搭建了導熱系數(shù)測量試驗臺。理論上分析了鉑電阻傳感器代替熱電偶測量溫度帶來的誤差,與實際測量結(jié)果進行了對比,分析了引起誤差的原因及誤差大小。分析了鉑電阻平整布置于硬質(zhì)材料之中形成的空氣薄層給導熱系數(shù)測量帶來的誤差,及減小此誤差所采取的辦法。實際測量了聚酰亞胺(軟、硬)在-160℃~25℃溫度下的導熱系數(shù),得到了測試材料的導熱系數(shù)隨溫度變化的數(shù)據(jù)。利用該測量平臺得到聚氨酯泡沫以及聚酰亞胺(軟、硬)在常溫下的導熱系數(shù),與經(jīng)國家玻璃纖維產(chǎn)品質(zhì)量監(jiān)督檢驗中心測得的鑒定值對比,其相對誤差最大不超過5%。證明本課題采用的導熱系數(shù)測量方法及數(shù)學模型有效,因此低溫環(huán)境下測量的導熱系數(shù)能應(yīng)用于實際。
[Abstract]:The thermal conductivity of adiabatic materials varies greatly with the structure, composition, temperature and humidity of the materials. However, the thermal conductivity of adiabatic materials at low temperature is the focus of attention. Therefore, how to measure the thermal conductivity of adiabatic materials at low temperature quickly and effectively for aerospace, aerospace, cryogenic storage and transportation is studied. The development of cryogenic technology is of great significance. This project is part of the project of "advance research on liquid and cargo envelope system of new type liquefied natural gas ship" in the high-tech ship scientific research project of the Ministry of Industry and Information Technology, the purpose of which is to obtain polyimide foam plastics in the liquid nitrogen temperature region. The relationship between thermal conductivity and temperature, This paper focuses on the measurement of thermal conductivity of insulating materials in low temperature environment by parallel hot wire method. In theory, heat transfer is established according to hot wire method. A transient mathematical model, The mathematical model is numerically simulated, and in the experiment, according to the principle of parallel hot wire method, the thermal conductivity measurement test-bed is built. The error caused by platinum resistance sensor instead of thermocouple in measuring temperature is analyzed theoretically. Compared with the actual measurement results, the causes and magnitude of the errors are analyzed, and the errors of the measurement of thermal conductivity caused by the thin layer of air formed by the platinum-resistance leveling arrangement in the hard materials are analyzed. The thermal conductivity of polyimide (soft and hard) at -160 鈩，

本文編號：1668238