2024.9.04
Chemistry at pirika.com > Chemistry > Chemical engineering > Reprint: gas-liquid equilibrium estimation by ASOG. > Chapter 1: Basic equations of solution theory > Chapter 2: ASOG method. > 2.3 Actual ASOG method calculation
2.3.1 Verification of 1979 examples.
The book ‘Estimating Vapour-Liquid Equilibrium by the ASOG method’, published by Kodansha in 1979, contains an example problem for the 115 system as an example. Let’s try to actually calculate the example problem.
The group interaction parameters ln akl = mkl +nkl⁄T mkl and nkl will be the parameters described in the book (we will call them MN1979). The example has 78 systems of constant pressure data and 37 systems of constant temperature data. If the system is selected in the pop-up menu, the required parameters are retrieved from the database and the values estimated by the ASOG method are compared with the measured values.
Let me explain how to use the programme.
The programme page shows the following initial screen.
Click on the component called Selector and the following menu appears.
Select the version of the group interaction parameter akl.
(The free version does not show MN2019. Here, select the earliest MN1979).
Then choose a solvent pair.
If you have made it this far, all the necessary parameters have been loaded.
Click on the triangle on the left side of the VLE Calc. to display the collapsed part.
The required parameters are already displayed in the AiSOG Result section.
All that remains is to select constant pressure or constant temperature using the radio buttons and press the Calc. AiSOG button.1979 In the case of Book Data, the pressure and temperature conditions described in the book are automatically set, so all you have to do is press the Calc. AiSOG button. The vapour-liquid equilibrium is then calculated according to the conditions and the result is added to the AiSOG Result section.
PCを使っているなら気液平衡のデータをコピーして表計算ソフトにペーストして利用するのでも良いだろう。簡単なチャートを描くプログラムも搭載してある。Chartの右三角をクリックして開く。チャートが表示されている。必要に応じて３種類のチャートをラジオボタンで選択する。
Experimental data are shown as green (light blue) circles. You can select different systems and look at the results, which were available in 1979.
What are the applications of being able to do these things?
Consider, for example, the case of CFC gases used in refrigerators and air conditioners when they are released into the atmosphere. They dissolve in the rain and return to the ground while being decomposed by ultraviolet radiation. How would they behave in the ponds and lakes into which they flow? If the vapour-liquid equilibrium with water can be calculated by ASOG, we can see whether it will continue to stay in the lake without evaporating, or whether it will diffuse into the atmosphere.
Henry’s law (Henry’s law) states. If a solution contains a small amount of a volatile solute, the partial pressure of the solute is proportional to its concentration in the solution. The proportionality constant is called Henry’s constant. A solute with a large Henry’s constant will be more willing to jump out of the solution into the gas phase than its concentration.
For example, we can estimate the vapour-liquid equilibrium between water and various ester compounds and compare the infinite dilution activity coefficient (Magules A) with the literature value of this Henry constant.
In cases where literature values are not available at all, it is common practice to estimate Henry’s constant in this way. It is an indispensable tool for environment-related research.
In the simulator created in this study, only the activity coefficients can be calculated directly.
However, these activity coefficients can provide very useful information depending on how they are used.
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