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A new semi-theoretical method based on Enskog's hard sphere theory for dense fluids and the principle of corresponding states is presented for predicting viscosity of pure organic liquids. The viscosities of 75 organic liquids—37 acyclic and 38 cyclic hydrocarbons—were calculated using this method which requires critical properties and normal boiling point as input data. The predictions were compared with empirical data and other prediction methods. Highly satisfactory results were obtained over a wide range of temperatures (0.45 < Tr< 0.80). 相似文献
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A new method based on the Effective Carbon Number is presented for the prediction of the thermal conductivity of liquids and liquid mixtures. The Effective Carbon Number for each substance of interest can be calculated from its thermal conductivity at a reduced temperature of 0.6. The thermal conductivities of isoalkanes, cycloalkanes, aro-matics, alkanes, carboxylic acids, ketones, esters and aldehydes over a range of temperatures were predicted using this method and the results were compared with experimental values. The thermal conductivities of defined mixtures were also predicted using a quadratic mixing rule for the Effective Carbon Number. Lastly, the thermal conductivities of undefined mixtures such as crude oil fractions were calculated by treating each fraction as a single pseudocompo-nent. In all cases studied, calculated results compared favorably with experimental values. 相似文献
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精确计算不同温度下液体导热系数的新方法 总被引:3,自引:2,他引:3
根据液体微观结构的特点和热传导机理,发展了一种计算液体导热系数的新方法。对273种物质6271个数据点的计算结果表明,该方法在很宽的温度范围(熔点到沸点以上温度)内具有很高的准确度,平均误差仅0.292%,计算精度优于文献方法。 相似文献
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By applying a model of a randomly mixed packing of spheres of two sizes to binary liquid mixtures, the thermal conductivity of the mixture is related to the physical properties of each component through the number of contact points. Further, two parameters are introduced to account for the effect of the hydrogen bond and are correlated with the Lennard-Jones (6-12) parameters σ and ?, or the boiling temperature. In comparing the calculated values with the experimental data for 13 aqueous liquids and 21 non-aqueous liquid systems, the present equation turns out to be more accurate than previous ones. 相似文献
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We have recently developed an extension of the three parameter corresponding states principle based on the properties of two non-spherical reference fluids for the viscosity of liquids and liquid mixtures. We extend the method here to the thermal conductivity. We have tested the method for a large number of binary liquid mixtures using the two pure components in each case as our reference fluids. Good agreement between predicted and experimental thermal conductivities was obtained using only the data for the pure components. This agreement becomes excellent if a single binary interaction consta independent of temperature and composition, is used in the mixture calculations. If the pure component reference properties are not available, then the may he obtained from the properties of two similar fluids. 相似文献
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Dezhi Zheng Yiwang Bao Detian Wan Shuai Yi 《International Journal of Applied Ceramic Technology》2019,16(6):2299-2305
Thermal conductivity is a crucial parameter for evaluating the quality and thermal effects of ceramic coatings, especially for thermal barrier coatings. However, measurement by conventional method involves two problems: (a) it is difficult to peel off a ceramic coating from a substrate; (b) even if the coating can be peeled off, it is still hardly used as standard specimen in test. Therefore, the relative method was proposed to evaluate the thermal conductivity of ceramic coating. An analytical relationship among the thermal conductivities of the coating, the substrate, and the coating/substrate composite was established. Experiments on TA4 coated with YSZ coatings were carried out to demonstrate the feasibility of this novel method and to investigate the impact of temperature on the thermal conductivity of YSZ coatings. The experimental results demonstrated the validity and convenience of the relative method. With the increasing testing temperature, the thermal conductivity value of YSZ coatings displayed nonlinearity feature, that is, decreased from 1.4 to 1.3 (W m−1 K−1) in the temperature range of 32-300°C and then increased up to 1.58 W m−1 K−1 at 1000°C. 相似文献
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Ahmad Mohaddespour Hossein Abolghasemi Meisam Torab Mostaedi Sajjad Habibzadeh 《应用聚合物科学杂志》2010,118(2):1042-1050
High density polyethylene– and polypropylene–clay nanocomposites are synthesized by melt blending, in which polyethylene glycol and polypropylene glycol are used as compatibilizers to increase the space of galleries. The morphology properties of nanocomposites are explored by X‐ray diffraction and transition electron microscopy. The thermal conductivity coefficient (K) of nanocomposites is also measured along with the thermal stability. A conventional model based on developed Maxwell‐Garnett formula is also established to predict the thermal conductivity of polymer/clay nanocomposites with clay loading. Morphology results indicate that two intercalated and exfoliated structures are formed. The established model satisfactorily predicts the K values of nanocomposites for low range of clay content. Thermogravimetric analysis shows remarkable thermal stability of nanocomposites with 10 wt % of clay content. The deviation of our model from experimental result for 10 wt % of clay can be attributed to the intercalated structure of layered silicates into the matrices. Although the K values do not considerably increase in 5 wt % with respect to the increase occurs for 10 wt % of clay, but it increases about 28 and 37% at 50°C for high density polyethylene– and polypropylene–clay nanocomposites, respectively. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 相似文献
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The molecules with the mono‐ and bi‐function at the sides in the acrylic PLC mixtures were aligned by the rubbing method. The alignment was immobilized by the photo polymerization to result the homogeneous acrylic films, which have good alignment with the higher order parameters. The thermal conductivity along the molecular long axis direction showed the larger magnitude of 0.62 W/m · K, which is independent on ratio of the main chain and the side chain fractions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3169–3174, 2007 相似文献
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A new theoretical equation that describes the thermal conductivity of two‐phase composite materials has been proposed. The Cheng‐Vachon equation has been modified by introducing a new parameter named Pd max, permitting the new equation to describe the thermal conductivity of composite materials for a wide variety of filler shapes and states of dispersion. The new equation can describe the thermal conductivity of two‐phase materials more accurately than any of the previous equations. Furthermore, this new equation will make it possible to evaluate the dispersion state of the discontinuous phase by measuring the thermal conductivity of the filled polymers or the polymer blends. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 1689–1697, 1999 相似文献
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Masatoshi Hasegawa Noriaki Suyama Naoyuki Shimoyama Hisashi Aoki Takehiko Nunokawa Tohru Kimura 《Polymer International》2011,60(8):1240-1247
Polybenzoxazole (PBO) model compounds consisting of benzoxazole mesogenic units linked with long alkyl chains via ether or ester groups were prepared from flexible dicarboxylic acids with two kinds of bis(o‐aminophenol)s, i.e. 4,4′‐diamino‐3,3′‐dihydroxybiphenyl (p‐HAB) and 3,3′‐diamino‐4,4′‐dihydroxybiphenyl (m‐HAB). The results revealed that the use of p‐HAB completely erased the thermotropic liquid crystallinity and that the m‐HAB‐based ether‐linked model compound was much more advantageous for the formation of a stable liquid crystal phase than the corresponding ester‐linked one. However, the relevant high‐molecular‐weight PBOs showed quite opposite results. Only the m‐HAB‐based ester‐linked C10 PBO system showed a liquid crystal‐like texture among various semi‐aliphatic PBO systems examined. A very high thermal conductivity of 1.79 W m?1 K?1 along the thickness direction for the m‐HAB‐based ester‐linked C10 PBO film was achieved by heat treatment in the liquid crystalline state under a strong magnetic field of 10 T. Copyright © 2011 Society of Chemical Industry 相似文献
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为了提高煤中氮含量的测试效率,采用GB/T 19227—2008《煤中氮的测定方法》中的半微量开氏法和红外热导法测定煤中的氮,并对测试结果进行了分析对比。结果表明:2种测试方法测试结果准确,精密度不存在显著性差异,均能满足测试要求,但红外热导法测定煤中氮操作简便,自动化程度高,安全性好。 相似文献
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Liang Xu Lei Su Hongjie Wang Hongfei Gao De Lu Kang Peng Min Niu Zhixin Cai 《Journal of the American Ceramic Society》2022,105(2):1548-1557
Thermal barrier coating materials with proper thermal expansion coefficient (TEC), low thermal conductivity, and good high-temperature stability are of great significance for their applications in next-generation turbine engines. Herein, we report a new class of high-entropy (La0.2Sm0.2Er0.2Yb0.2Y0.2)2CexO3+2x with different Ce4+ contents synthesized by a solid-state reaction method. They exhibit different crystal structures at different Ce4+ content, including a bixbyite single phase without Ce4+ doping (x = 0), bixbyite-fluorite dual-phase in the RE2O3-rich region (0 < x < 2), and fluorite single phase in the stoichiometric (x = 2) and CeO2-rich region (x > 2). The high-entropy (La0.2Sm0.2Er0.2Yb0.2Y0.2)2CexO3+2x exhibit tailorable TECs at a large range of 9.04 × 10–6–13.12 × 10–6 °C–1 and engineered low thermal conductivity of 1.79–2.63 W·m–1·K–1. They also possess good sintering resistance and high-temperature phase stability. These results reveal that the high-entropy (La0.2Sm0.2Er0.2Yb0.2Y0.2)2CexO3+2x are promising candidates for thermal barrier coating materials as well as thermally insulating materials and refractories. 相似文献
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应用密度泛函理论(DFT),在B3LYP/6-31+G(d)水平上对含有5~24个碳原子的部分液相链烷烃进行结构优化和量化计算其分子中各个原子间空间拓扑距离,并构建拓扑距离矩阵。结合分子中各原子的支化度,应用原子的平衡电负性对分子图进行着色,得到新型结构拓扑指数PXm(m=1,2,3)。采用多元线性回归技术建立液相链烷烃热导率λ与PXm(m=1,2,3)的定量关系拓扑模型,并用该模型对热导率λ进行预测与估算,结果表明实验值与预测值、估算值均很吻合。同时,采用留一法(leave-one-out)和外检验方法测试模型的内部稳定性和外部预测能力。与文献结果比较,本文所用参数少,计算简便,为液相链烷烃导热的研究提供了一种新方法。 相似文献