共查询到20条相似文献,搜索用时 953 毫秒
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采用五种不同的方法计算了四种不同二元混合工质的临界温度和临界压力,研究对比不同方法在推算二元混合临界性质时的精度。其中Peng-Robinson(PR)方程和Soave-Redlich-Kwong(SRK)方程,两种状态方程结合Heidemann等提出的临界点判据计算得到的临界参数与实验结果吻合较好。两种经验公式,改进的Chueh-Prausnitz(MCP)方法和Redlich-Kister方法,以及径向基函数神经网络(RBFNN)在计算混合工质的临界性质时也都有着较高的计算精度。对于临界温度的计算,PR方程、SRK方程、MCP方程、Redlich-Kister方程以及径向基函数神经网络计算结果的绝对平均偏差的最大值分别为1.82%、1.73%、0.95%、0.17%和0.20%。对于临界压力的计算,通过PR方程、SRK方程、MCP方程、Redlich-Kister方程以及径向基函数神经网络计算的绝对平均偏差的最大值分别为6.07%、5.04%、3.49%、1.90%以及0.67%。 相似文献
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《化学工程》2017,(8)
为了更完善地认识新型制冷剂HFO-1234ze(E)的热物性,在公开发表的HFO-1234ze(E)饱和蒸气压实验数据的基础上,通过仔细分析各个实验数据的精确程度,筛选出一套由118组数据点组成的综合数据,经过拟合得到一系列蒸气压方程,对比各个方程对拟合数据的绝对偏差和相对偏差,得到一个适用范围较宽(232.990—380.002 K)且精度良好的四项Wanger型HFO-1234ze(E)蒸气压专用方程。该方程对拟合数据的平均相对偏差为-0.02%。同时,通过新方程计算得到HFO-1234ze(E)的正常沸点以及偏心因子,可以供物性计算和工程运用,具有较高的实际应用价值。 相似文献
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利用公开发表的实验数据开发了甲基叔丁基醚(MTBE)的状态方程,方程以Helmholtz自由能为显式、以温度和密度为自变量。方程计算饱和蒸气压的不确定度430 K以下为1.0%,随着温度的升高,由于缺少实验数据不确定度增大为2.0%。方程计算密度的不确定度由液相区的0.2% 变到临界区和气相区的1.0%。方程计算能量相关物性(如比热容和音速)的不确定度为0.5%。临界区,除了饱和蒸气压,方程计算所有其它热力学性质的不确定度都较高。正如文中分析,本文方程不但能准确的复现实验数据,而且方程的外推性也是合理的。文中对方程进行了详细的分析。 相似文献
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本文评价了 Frost-kalkwarf 蒸气压方程,并讨论了方程系数的三种回归方法,即 Har 法,改良 Har 法和线性回归法.建立了回归方程系数的数学模型,编制了回归系数的计算机程序,搜集了文献发表的蒸气压数据.回归出355种化合物的方程系数.适用范围是 1mmHg~临界点,与文献数据十分吻合,平均误差都小于1%,总平均误差为0.314%,能在科研和化工设计计算中使用. 相似文献
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将对应态原理与基团贡献法相结合,引入拟临界性质的概念,提出基团对应状态法(Correspounding State with Group Contribution,简称CSGC)。并将其与Riedel方程相结合用于饱和蒸气压的估算,提出新的蒸气压估算方程(CSGC-PR方程)。88种基团的参数由包括饱和烃、不饱和烃、环烃、芳烃、含氧化合物、含硫化合物、含氮化合物、含卤化合物等350种物质5255个饱和蒸气压实验数据关联获得。新模型的估算精度优于现有的对应状态法,不仅对于高碳数分子有良好的估算精度,并对非极性物质能较好地外推高压下的饱和蒸气压。 相似文献
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为了对第4代新型制冷剂R1234ze(Z)的热物性有更多认识,文中在公开发表的文献中,搜集了关于R1234ze(Z)的饱和蒸气压实验数据。对每组数据精度进行分析后,筛选得到140组实验数据。经过非线性拟合,获得了R1234ze(Z)的4项Wagner型蒸气压专用方程。该方程适用温度区间为283—413 K,压力区间为12—2 950 kPa。将拟合数据与该方程进行对比,其压力绝对偏差大部分在±2 kPa,相对偏差分布于±1%范围,平均绝对偏差为0.193%。对比文献数据与该方程,其压力相对偏差范围为-1%—2%,最大相对偏差为1.827%,平均绝对偏差为0.282%。因此,新方程对各组实验数据点都有很好的拟合度。根据此方程,计算得到R1234ze(Z)的标准沸点为284.751 K,偏心因子为0.325,可供物理性质的计算和工程实践的应用。 相似文献
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Jaygwan G. Chung 《Korean Journal of Chemical Engineering》1997,14(3):209-212
The existing vapor pressure measurements available in the literature for the liquid oxygen between the triple and critical points have been utilized to establish the constants and exponent of the modified Frost-Kalkwarf vapor pressure equation in the reduced form as follows: $$\ln P_r = 6.372408 - \frac{{6.637925}}{{T_r }} - 1.975760 \ln T_r + 0.265517T_r^5 $$ In order to calculate the vapor pressure, only the normal boiling point (Tb=90.180 K) and the critical pressure (Pc=5037.17 kPa) and critical temperature (Tc=154.33 K )are necessary to obtain an overall average deviation of 0.36 % for 540 experimental vapor pressure data. 相似文献
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A new simple equation for prediction of vapor pressure of pure substances is proposed. The equation which has the Clausius-Clapeyron
(C-C) equation form consists of three parameters: critical temperature, critical pressure and normal boiling point. Experimental
data for organic and inorganic substances have been used to calculate equation parameters in the boiling point ranges from
169.45 to 457.55 K and critical temperature ranges from 282.75 to 699.15 K. Comparison of proposed equation estimation results
with experimental data shows that the new equation has minor average error. The new equation is also 68 percent more accurate
than the C-C equation 相似文献
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XU ZHONG 《Chemical Engineering Communications》2013,200(1-4):107-123
A reduced vapor pressure equation based on the theorem of corresponding states is proposed in this work by the use of the third parameter to and the fourth parameter X. This equation yields an overall average absolute deviation of 1.09% for 111 normal fluids involving a total of 6968 vapor pressure data points, and 0.67% for 20 polar fluids involving a total of 1516 data points, respectively. A relationship of estimating acentric factors is obtained by applying the reduced vapor pressure equation at the normal boiling point. This relationship is very accurate for the prediction of the values of the acentric factor 相似文献
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The new simple extended corresponding-states principle: vapor pressure and second virial coefficient
H.W. Xiang 《Chemical engineering science》2002,57(8):1439-1449
A new simple extended corresponding-states principle has been developed to represent and predict the thermophysical properties of fluids. The extended corresponding-states principle only requires the substance-dependent critical parameters and acentric factor which enhances the corresponding-states principle of Pitzer et al. to include the behavior of substances whose force fields deviate strongly from spherical symmetry. The additional corresponding-states parameter defined in terms of the deviation of the critical compression factor of a real molecule from that of spherical molecules is independent of experimental data for any specific property. The new simple extended corresponding-states principle presented here remarkably improves the representation of the vapor pressure from the triple point to the critical point and the second virial coefficient from the triple point to the highest temperatures over which experimental data exist. Accurate results for these two well-understood properties are given for simple, normal, polar, hydro-bonding and associating compounds. The results also show that the new simple extended corresponding-states principle is more reliable and accurately predicts the vapor pressure and second virial coefficient of a strongly nonspherical fluid than any other existing methods. 相似文献
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Thermodynamic data on solid, liquid, and gaseous carbon have been carefully selected from the literature or estimated, and vapor pressure have been calculated up to the critical point. Using certain assumptions about the properties of liquid carbon and nonideal gas corrections for carbon vapor, our calculations show the triple point and critical point to be 4765 and 6810°K, respectively, with critical density 0·64 g/cm3, and critical pressure 2200 atm. The dominant vapor species above ~ 2000°K is C3, while C7 is also of importance from 4500 to 6810°K. Coexistence curves which summarize the densities and enthalpies of solid, liquid, and vapor carbon are plotted. The density of liquid carbon is assumed to be 20% less than that of graphite at the triple point. The enthalpy of fusion is given as 30 kcal/g-atom C. Sublimation enthalpies are found to be 50–66 kcal/g-atom C at 3000–4765°K, and vaporization enthalpies about 20 kcal/g-atom C at 4765–6000°K. 相似文献
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Monika Thol Stefan Herrig Roland Span Eric W. Lemmon 《American Institute of Chemical Engineers》2021,67(9):e17326
A fundamental equation of state is presented for the calculation of thermodynamic properties of chlorine. It is expressed in terms of the Helmholtz energy with the independent variables temperature and density. Based on the available experimental data from the literature, the equation is valid from the triple point temperature 172.17–440 K with a maximum pressure of 20 MPa. The quality of the equation is evaluated by comparisons with experimental measurements. Since the equation was developed in part for use in mixture models relevant for carbon capture and storage applications, special focus was also given to correct extrapolation behavior. 相似文献
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A reduced vapor pressure relationship of the following form has been developed: The optimum value of n was established to be 8.00 from vapor pressure data for n-heptane. A method was developed for the determination of the constants A, B, C and D from one reliable vapor pressure point. By this procedure vapor pressures were calculated for 33 hydrocarbons, including saturated and unsaturated paraffins, naphthenes, and aromatics, and were compared with corresponding experimental values. For these substances the overall average deviation between calculated and actual vapor pressure was 0.38% (1879 points). This relationship was also applied to seven additional hydrocarbons not included in its development, and for these substances the resulting average deviation was 0.36% (99 points). 相似文献
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A new generalized equation of state for polar and non-polar fluids based on the corresponding states theorem is developed, f n addition to two critical parameters, four parameters are required; two for the calculation of volumetric properties and two for the calculation of pressure and departure functions. Parameteres for more than 100 polar and non-polar fluids are given. Comparison with the existing generalized state equations showed that the new method, in general, shows a better agreement with the experimental data. The absolute average deviation is 0.48% for the vapor pressure and 0.32% for the saturated liquid volume. 相似文献