共查询到18条相似文献,搜索用时 74 毫秒
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用面向对象的方法实现了最新水和水蒸气热力性质工业公式IAPWS-IF97(2007.8修订版),对其各区的计算模型进行了详细地分析并设计了相应的实现算法。实现了其所有区的基本方程、导出方程、各种属性的计算公式、反推方程。实现了2区的亚稳态蒸汽区的补充方程、B23方程和B2bc方程。给出了区域区分算法、2区子区域区分算法和3区通过压力p和温度T求密度ρ的牛顿迭代算法。详细地介绍了最新IAPWS-IF97的实现方法、注意事项、相关推导过程并且补充了等容比热容cv的计算机程序验证值。提高了B23与Ts(p)边界和B2bc与ps(T)边界的一致性。通过在造纸工业中的应用,表明该实现算法具有全面、精确、快速和自动测试等优点。 相似文献
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介绍了国际水和蒸汽协会(IAPWS)最新提出的区域3的导出及边界公式,并对导出公式与工业用水和水蒸气热力性质计算基本公式(IAPWS-IF97)在区域3的一致性进行了计算分析.通过计算和比较得到了区域3所有导出公式与基本公式间偏差的具体分布,为实际工程应用提供了参考. 相似文献
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水和蒸汽(火用)值计算模型的分析及实现 总被引:1,自引:0,他引:1
能量的交换与利用,应当从能量的"数量"和"质量"两个方面进行分析研究.(火用)作为能的"数量"和"质量"的综合指标,是对热力学体系进行热力学分析的基础之一.然而,水作为热力系统中应用最广泛的工质,其(火用)值的计算,尚有很多不清晰的地方.在IAPWS-IF97的基础上,对水和蒸汽炯值的计算方法进行了研究.编制了计算软件,实现了对水和蒸汽炯值的计算. 相似文献
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多层耐火材料结构式工业炉炉壁耐火材料的导热系数随其炉内温度的变化而不同。针对平板炉壁型、矩形截面炉壁型和圆筒形截面炉壁型3种不同形状结构的工业炉,介绍了多层耐火材料结构式工业炉炉壁耐火材料在炉内温度变化条件下炉壁温度分布的计算方法。给出了实际计算例。 相似文献
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在国家规定的热网管道的每米热损失下,其保温层厚度随着保温材料的导热系数及工质温度的不同而不同。利用导出的计算公式,通过计算,将以上四个参数的关系用图表的形式表示出来,以供在热网管道的保温中予以应用。 相似文献
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提出了一个新的CO2导热系数关联式,该关联式适用273~1 273 K,0.07~210.00 MPa,1.0~1 145.0 kg/m3。与以往CO2导热系数关联式相比,提出的关联式只需温度T和密度ρ两个已知参数,不仅在全域范围内提高了计算精度,而且解决了以往关联式在近临界区域计算精度变差的问题,便于工程应用。在整个温度压力的适用范围内,新关联式计算值与实验值的相对偏差绝对平均值为2.79%;在近临界区域内,相对偏差绝对平均值为4.94%。 相似文献
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文章对使用Visual C++开发通用的锅炉热力计算程序中所涉及到的几个关键问题进行了阐述,据此开发出的程序可适应多种计算标准、多种炉型、多种燃料和燃烧方式、多种调节方式,使锅炉热力计算程序具有良好的通用性和扩展性. 相似文献
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Semahat Barlak Ali Karaipekli Sinan Yapıcı 《Nanoscale and Microscale Thermophysical Engineering》2016,20(2):85-96
In this study, the thermal conductivity and viscosity of nanofluids, composed of a base fluid and nanoencapsulated phase change material (NEPCM), were investigated experimentally. The NEPCM was prepared by the encapsulation of n-nonadecane as phase change material with diethylenetriamine and toluene-2,4-diisocyanate using interfacial polymerization method. The NEPCM was characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC) analyses. In the preparation of the nanofluids containing NEPCM, two different base fluids, water and ethylene glycol (EG), were used. The concentration of NEPCM and the working temperature were selected as the main parameters. It was found that the viscosity of the nanofluids decreases with increasing temperature and increases with increasing solid concentration. The viscosity was also expressed as a function of the solid concentration and temperature. The thermal conductivity of the nanofluids was found to increase with increasing temperature. Thermal conductivity exhibited an increasing tendency with increasing solid concentration, but the changes in thermal conductivity according to base fluid are in the range of uncertainty of the measurement for both nanofluids with a solid volumetric fraction lower than 1.68%. 相似文献
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Khoa Bui 《Numerical Heat Transfer, Part A: Applications》2013,63(8):590-603
The effective thermal conductivity (K eff) of carbon nanotube (CNT) composites is affected by the thermal boundary resistance (TBR), the dispersion pattern, and geometry distribution of the CNTs. Traditional effective medium theories assume that CNTs are perfectly dispersed without considering TBR. In this work, we report the development of a new algorithm using CNTs with 3-D worm-like geometry and different persistence lengths. We describe how to obtain K eff using simulations of these realistic CNT configurations with off-lattice Monte Carlo simulation. The results are compared with straight cylinder models without effects of persistence length. 相似文献
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以常规热平衡方法为基础,经过严格的数学推导,首次将等效热降理论应用于供热机组热力系统循环吸热量的计算,并提出了适用于不同类型供热机组热力系统的通用数学计算模型.经实例验证,该数学模型简捷、准确,将为不同类型供热机组热力系统热经济性的定量计算和热电联产总热耗量合理分配的研究奠定良好基础. 相似文献
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首先分析了工业蒸汽锅炉出力不足的原因,阐明了锅炉热平衡计算时输出热量中应包括锅炉自用蒸汽热量的论点,随后导出了热力除氧自用蒸汽量的理论计算公式和相应的热平衡计算时输出热量的等效计算式,最后就给水采用热力除氧方式蒸汽锅炉设计计算中容易出现的误区及其所造成的计算误差通过具体计算示例予以评述. 相似文献
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Heat transfer performance utilizing nanofluids in a trapezoidal enclosure is investigated taking into account variable thermal conductivity and viscosity. Transport equations are modelled by a stream-vorticity formulation, and are solved numerically by the finite difference method. The effects of the Rayleigh number, base angle, volume fraction, and size of nanoparticles on flow and temperature patterns as well as the heat transfer rate are presented. We found that the effect of the viscosity was more dominant than the thermal conductivity, and there is almost no improvement in heat transfer performance utilizing nanofluids. 相似文献