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An expression to predict the values of the latent heat of vaporization of pure compounds at their normal boiling point has been developed. A knowledge of the critical temperature, critical pressure, normal boiling point and acentric factor of the compound coupled with the use of generalized correlations for second virial coefficient and liquid molar volume allows to obtain good estimates, particularly for alcohols and ketones. Results for 71 various substances are compared with experimental values and with the results of eight other equations available in the literature. The possibility of using the calculated heats of vaporization at the normal boiling point to estimate values at other temperatures is discussed. 相似文献
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正常沸点下液体汽化热的计算 总被引:1,自引:0,他引:1
本文从修正Clapeyron方程出发,提出一个新的计算正常沸点下液体汽化热的方程。并提出一个校正沸点的方法。用本文方法对160种物质汽化热进行计算,经同文献方法比较,本方法计算误差为最小。 相似文献
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沸点蒸发焓估算的基团拓扑空间方法 总被引:2,自引:0,他引:2
本文提出了有机物正常沸点蒸发焓估算的基团拓扑空间方法。给出了沸点蒸发焓的估算表达式和相应的基团参数值。沸点蒸发焓估算的平均相对偏差为1 052%。把本方法和广泛应用的其它方法进行了比较,结果表明本方法有更高的准确度和可靠性。 相似文献
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本文提出了一个由液体密度和正常沸点下蒸发焓数据推算物质临界参数的新方法。本方法所需数据为:液体密度、ZRA值及正常沸点下蒸发焓。采用本文方法对有代表性的近100种有机物和16种无机物的Pc和Tc值进行了估算,结果表明本文方法稳定、可靠。 相似文献
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Hildo B. Krop Martin J. M. v. Velzen John R. Parsons Harrie A. J. Govers 《Journal of the American Oil Chemists' Society》1997,74(3):309-315
Fat models frequently use input parameters that are defined at environmental conditions. In a recently developed gas-liquid
chromatography method (GC-VAP), vapor pressures, heats of vaporization, and heat capacity differences (gas-liquid) of fatty
acid esters are determined over a large temperature range that includes environmental temperatures. This method also allows
an accurate determination of the normal boiling point temperature of a substance. Literature values of vapor pressure, boiling
point temperature, and heat of vaporization at 298.15 K for the chosen esters are all in excellent agreement with those determined
with the developed method. Correlations between carbon number and heat of vaporization are high. 相似文献
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应用八十年代提出的新R-K状态方程式,改进纯物质常沸点汽化热的剩余函数预测法,推导出纯物质常沸点汽化热的新计算方程式。并应用该方程式,由最基本的物性数据T_b,T_c和P_c,预测了400种各类物质的常沸点汽化热,与实验值比较,预测准确度优于其它方程。 相似文献
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ZHI-YONG LIU 《Chemical Engineering Communications》2013,200(1):221-228
A new method is proposed to estimate the heat of vaporization of pure liquid at its normal boiling temperature. The properties required include the boiling temperature, critical temperature and critical pressure. For monohydric alcohol and monohydric organic acid, an adjusting-boiling-temperature strategy is proposed to reduce the calculation errors. The method is tested for 160 substances including many groups of compounds. The results show that the proposed method is better than the literature methods, especially for monohydric alcohol and monohydric acid. 相似文献
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Zhi-Yong Liu 《Chemical Engineering Communications》2001,184(1):221-228
A new method is proposed to estimate the heat of vaporization of pure liquid at its normal boiling temperature. The properties required include the boiling temperature, critical temperature and critical pressure. For monohydric alcohol and monohydric organic acid, an adjusting-boiling-temperature strategy is proposed to reduce the calculation errors. The method is tested for 160 substances including many groups of compounds. The results show that the proposed method is better than the literature methods, especially for monohydric alcohol and monohydric acid. 相似文献
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一个蒸发焓的估算方程——CSGC—MHW方程 总被引:2,自引:0,他引:2
一个蒸发焓的估算方程CSGC-MHW方程*李平马沛生朱晨(天津大学化学工程系,天津300072)关键词基团贡献蒸发焓流体物性估算1引言蒸发焓(ΔVH)是物质的重要热力学性质,是化工过程计算、分析及设计的重要基础物性数据之一。由于目前已发表的蒸发焓实测... 相似文献
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在分析了文献上计算汽化热的主要公式的基础上,解Clapeyron方程;并将上限延伸到临界点的温度和压力,再引进参数K_1,K_2值,提出了计算液体汽化热的新公式,即 r_b=K_2{[T_bT_c/(T_c-T_b)]+K_1}logP_c式中 参数K_2则考虑不同分子结构提出不同的数值,以有助于计算的准确性。 本文用此新公式验算了31类共157种纯物质的液体汽化热,与实测值相比,平均误差为1.65%。 相似文献
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本文提出一种专用于硅化合物的分子蒸发热(沸点时,一大气压下)估计法。 本文试将Joshi沸点-折射关系式应用于硅化合物的分子R_T值的计算,并求出若干原子团及键的R_T值。 相似文献
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Douglas Ambrose Brian E. Broderick Roger Townsend 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1974,24(6):359-372
Critical temperatures and pressures of some organic compounds were measured. There is good agreement between the observed critical pressures and values obtained by extrapolation of equations representing the variation of vapour pressure with temperature in the region of the normal boiling point. An incremental scheme relating critical temperatures to normal boiling points is described and is used for the correlation of the critical temperatures, obtained in this and other investigations, of more than 150 compounds. 相似文献
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本文以图论法为基础,提出了一个预测异构烷烃和链烯烃常沸点汽化热的计算方程式:应用该式对50种饱和烷烃和25种链烯烃的汽化热分别进行了预测。结果表明,预测的精确度和简便性都是令人满意的。 相似文献
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Published flash point prediction methods are evaluated for accuracy against experimental data from the DIPPR ® 801 database. The most accurate methods require a vapor pressure correlation, which is often not available. Two new methods are presented, one that uses the vapor pressure, and one based on the normal boiling point and enthalpy of vaporization at the normal boiling point. The vapor pressure method shows little improvement over the previous methods unless group contributions are implemented. The boiling point method predicts the flash point within an absolute average deviation of 1.3% when compared with data for more than 1000 compounds. The previous most accurate method that was not based on vapor pressure exhibited an absolute average deviation of 1.84% for the same test set. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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Charles H. Fisher 《Journal of the American Oil Chemists' Society》1995,72(10):1101-1105
Heats of vaporization at both 25°C and normal boiling points are given for then-fatty acid methyl and ethyl esters and then-alkyl acetates. The validity of the reported heats of vaporization is supported by: (i) their agreement with those estimated
by alternate methods, and (ii) the equations correlating heats of vaporization with homolog carbons have the proper slopes
(approximately 4.96). Equations also are given for correlating heats of vaporization with boiling points, and boiling points
and molar volumes with homolog chainlength. 相似文献
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引 言在作者先前的工作[1]中 ,已由液体混合的热力学模型导得一个比Scatchard -Hildebrand正规溶液理论更加严格的过量Gibbs自由能表达式 .据此 ,定义了一个新的溶解度参数Δ =λ/m =δ2 /λ (1 )式中 δ2 =ΔVap Um/Vm,为液体的内聚能密度 ;λ =p1/2i ,为液体内压的平方根 ;m =piVm/ΔVapUm,为Hildebrand参数 .不难看出 ,当m =1时 ,Δ =δ ,故传统的Hildebrand溶解度参数δ只是式( 1 )的一种特殊情况 ,由于一般液体的m不等于1 ,故Hildebrand溶解度参数必须… 相似文献
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The vaporization times of small (12 mg.) drops of a binary liquid on a flat plate were measured in the maximum (critical) heat flux region of boiling heat transfer. The binary system studied was water-1-pentanol, the mixture previously shown by other workers to exhibit the most pronounced concentration effect on critical heat flux. Evaporation curves are reported in the critical region for pure water, pure pentanol and a number of mixtures in the concentration range 1.0 to 2.5 weight % pentanol in water. It was confirmed that drop lifetimes can be obtained in the critical heat flux region by comparatively simple techniques and that there is a concentration effect on drop lifetime that is very similar to that observed during critical heat flux boiling studies. A minimum drop lifetime is observed at 1.8 weight % pentanol in water, the same concentration at which maximum critical heat fluxes were obtained in pool boiling studies at one atmosphere by S. J. D. Van Stralen and co-workers. 相似文献