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首页> 外文期刊>Fluid Phase Equilibria >Vapour-liquid equilibria of aroma compounds in hydroalcoholic solutions: Measurements with a recirculation method and modelling with the NRTL and COSMO-SAC approaches
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Vapour-liquid equilibria of aroma compounds in hydroalcoholic solutions: Measurements with a recirculation method and modelling with the NRTL and COSMO-SAC approaches

机译：水醇溶液中香气化合物的气液平衡：采用再循环方法进行测量并使用NRTL和COSMO-SAC方法进行建模

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Aqueous solutions of aroma compounds are commonly encountered in the food and biofuel industries, and the knowledge of their thermodynamic properties is very important for process design. Here, we report the measurements of the vapour-liquid equilibria of water-ethanol solutions containing 13 aroma compounds (alcohols, aldehydes and esters), for temperatures between 351 and 366 K, and ethanol concentration ranging from 10 to 90% (v/v). The new data were obtained with a recirculation apparatus and are represented with the non-random two liquid (NRTL) activity coefficient model. It is observed that the partition coefficients of the aroma compounds can decrease of several orders of magnitude by increasing the proportion of ethanol. The COSMO-SAC (conductor-like screening model-segment activity coefficient) model provides reasonable predictions of the new data for alcohols and aldehydes, but underestimates the partition coefficients of the long ethyl esters. It is observed that the COSMO-SAC predictions depend a lot on the molecular conformations used to generate the sigma profiles, in agreement with previous studies. The COSMO-SAC predictions can be empirically improved by changing the real space cut-off distance employed in the ab initio calculations. The COSMO-SAC model is then reliable not only at infinite dilution but also over a whole composition range. The model is used to define a limit of validity for the infinite dilution approximation. (c) 2008 Elsevier B.V. All rights reserved.
机译：芳香族化合物的水溶液在食品和生物燃料行业中很常见，其热力学性质的知识对于工艺设计非常重要。在这里，我们报告了在351至366 K之间的温度以及10至90％（v / v）的乙醇浓度范围内，包含13种香气化合物（醇，醛和酯）的水-乙醇溶液的汽-液平衡的测量结果。 ）。新数据是通过再循环设备获得的，并用非随机两种液体（NRTL）活度系数模型表示。观察到，通过增加乙醇的比例，芳香化合物的分配系数可以降低几个数量级。 COSMO-SAC（类似导体的筛分模型-段活度系数）模型为酒精和醛类的新数据提供了合理的预测，但低估了长乙酯的分配系数。可以观察到，COSMO-SAC的预测在很大程度上取决于用于生成sigma轮廓的分子构象，这与以前的研究一致。通过更改从头算中使用的实际空间截止距离，可以凭经验改进COSMO-SAC预测。这样，COSMO-SAC模型不仅在无限稀释下而且在整个组成范围内都是可靠的。该模型用于定义无限稀释近似值的有效极限。 （c）2008 Elsevier B.V.保留所有权利。

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