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二氧化碳水合物导热和热扩散特性 总被引:1,自引:1,他引:0
热导率和热扩散率是天然气水合物资源开采关键性基础热物性数据,采用反应釜内壁衬有氟塑料材料,低过冷度,让水合物在反应釜内逐层生成的合成方法,获得可直接用于导热测试的二氧化碳水合物样品。采用瞬变平面热源法原位测试了温度264.68~282.04 K、压力1.5~3 MPa二氧化碳水合物热导率、热扩散率,并测试了二氧化碳水合物在268.05 K、0.6 MPa左右发生自保护效应过程中热导率、热扩散率,获得了晶态下和自保护效应过程中的二氧化碳水合物热导率、热扩散率变化特性。测试结果将为天然气水合物资源的开发利用提供基础数据和理论依据。 相似文献
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采用有限元方法对炭纤维/树脂复合材料的导热性能进行了数值模拟,分别建立一维结构和二维结构炭纤维/树脂复合材料计算分析模型,研究炭纤维含量、界面接触热阻、以及炭纤维直径对复合材料有效热导率的影响。研究结果表明炭纤维作为复合材料增强相,其含量越高复合材料的热导率越高;界面的接触热阻在10-3~10-5(m2 K)/W范围内对复合材料有效热导率有较大的影响,超出范围之后改变接触热阻对材料热导率的影响可以忽略;接触热阻比较大时,炭纤维的直径对复合材料的热导率有较大的的影响,当接触热阻比较小时,炭纤维的直径对于复合材料热导率的影响非常小。 相似文献
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四氢呋喃水合物(THF)是典形的笼形水合物,目前有关其热导率的报道较少,且都存在测量样品不是单一相、测量过程水合物发生分解等问题。采用基于飞秒脉冲激光的时域热反射法(TDTR)测量THF热导率。根据样品常温下是流体的特点,设计了可同时适用样品制备及TDTR测量的温控台,实现THF热导率非接触原位测量。获得THF热导率为0.6 W/(m?K),Al/THF界面热导为90.3 MW/(m2?K)。该实验结果有助于理解并完善固体水合物微观导热机理,明晰水分子笼子和客体分子的耦合关系。 相似文献
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摘要:制备炭黑/天然橡胶(NR)、石墨烯/NR和碳纳米管/NR复合材料,采用试验与数值模拟相结合的方法研究复合材料热导率和层间接触热阻对微波加热的影响。结果表明:炭黑、石墨烯和碳纳米管自身热导率越大,复合材料的热导率越大,层间接触热阻越小;通过增大填料用量来增大复合材料的热导率和减小层间接触热阻具有一定的局限性,需考虑复合材料的配方设计适用性和经济性;复合材料的热导率对微波加热过程中高、低温区域分布规律和微波加热效率基本无影响,但影响复合材料的温度分布均匀性。为保证微波加热硫化均匀性,多层复合材料的层间接触热阻不可忽略。 相似文献
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Rajni Agarwal N. S. Saxena Kanan Bala Sharma S. Thomas M. S. Sreekala 《应用聚合物科学杂志》2003,89(6):1708-1714
Thermal properties, such as thermal conductivity, thermal diffusivity, and specific heat, of treated and untreated oil palm fiber–reinforced PF composites were measured simultaneously at room temperature and normal pressure using the transient plane source (TPS) technique. An increase in thermal conductivity was observed in the fiber‐treated and resin‐treated composites. Surface modifications of fibers by prealkali, potassium permanganate, and peroxide treatments increased the fiber–matrix adhesion by increasing porosity and pore size of the fiber surfaces. The increase in crosslinking enhanced the thermal conductivity of a composite of resin treated with peroxide compared to other composites. Also an attempt was made to explain the temperature dependence of thermal conductivity and thermal diffusivity of amorphous polymer samples using the same technique. It was observed that at the glass‐transition peak of the polymer, thermal conductivity and diffusivity were maximum. Below and above this temperature their values decreased. This has been explained on the basis of predominant scattering processes. An empirical relationship was established for the theoretical prediction of thermal conductivity and diffusivity. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1708–1714, 2003 相似文献
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试验研究了不同种类(Al2O3、Cu、SiO2)、不同质量分数(0.05%、0.1%、0.15%)及不同粒径(10、30、50 nm)的纳米粒子对CO2水合物热导率的影响。结果表明温度为-5~5℃时,纯CO2水合物热导率为0.553~0.5861 W·m-1·K-1,具有玻璃体的变化特性。分散剂SDBS的加入,可改善CO2水合物-纳米粒子体系的导热性能。在相同的质量分数和粒径下,纳米Cu粒子对CO2水合物热导率的增强作用最好,但综合考虑水合物生成特性和溶液悬浮稳定性,选用纳米Al2O3粒子较合适。Al2O3粒子粒径越小,水合物热导率越大,15 nm比50 nm纳米粒子体系中CO2水合物热导率的增长率平均提高了12.7%。此外,CO2水合物热导率随Al2O3粒子质量分数的增大而增大,质量分数由0.05%增加到0.15%时,水合物热导率的增长率由4.2%提高到8.2%。 相似文献
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Polyamide 46 (PA 46) with carbon black (CB) has been subjected to a heat treatment. Crystallinity, specific heat capacity, crystalline melting peak temperature, thermal diffusivity, and electrical conductivity were measured. The crystallinity increases with duration of thermal treatment. The maximum value is dependent on the filler fraction. A lower CB content leads to a higher crystallinity at maximum tempering time. The crystalline melting peak temperature increases with decreasing filler fraction and duration of thermal treatment due to different crystal types and/or diverging geometric forms of the crystals. Thermal diffusivity and electrical conductivity act positively proportional to each other and increase with CB content and tempering time. The thermal diffusivity decreases with increasing temperature. The volume resistance of PA 46 is lowered by heat treatment. By CB addition in combination with a tempering process, the PA 46 can be transferred into a conductor. CB is moved by PA 46 crystals into amorphous regions forming conductive pathways. © 2019 The Authors. Journal of Applied Polymer Science published by Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48882. 相似文献
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In this paper, the thermal conductivity and thermal diffusivity of nine polymers were measured by using the transient short‐hot‐wire method. The corresponding specific heat was measured with a commercial Differential Scanning Calorimeter (DSC). The effects of temperature on the thermal conductivity, thermal diffusivity, and the product of density and specific heat are further discussed. The results show that the transient short‐hot‐wire method can be used to measure the thermal conductivity, thermal diffusivity, and the product of density and specific heat of polymers within uncertainties of 3%, 6%, and 9%, respectively. 相似文献
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《Journal of the European Ceramic Society》2019,39(1):53-58
Yttrium aluminium garnet doped with rare earth ions is one of the most common active media in solid state lasers. In high-power lasers, thermal management is crucial, requiring information on the thermal properties. In this work, the thermal diffusivity and conductivity of polycrystalline YAG ceramics doped with Yb and Er were measured by laser flash method at various temperatures ranging from room temperature to 900 °C. Transparent ceramic YAG samples were prepared by solid state reactive sintering of oxide powders under vacuum. Thermal diffusivity and conductivity showed similar trends, decreasing with increasing temperature as well as with the increase of dopant content from 0 to 20 at.%. The measured values were compared with literature data and empirical relations. Similar values were obtained both for Yb and Er doping. We thus suggest that the data of thermal diffusivity and conductivity of Yb:YAG may be used as a first approximation for Er:YAG. 相似文献