مدل‌سازی ترمودینامیکی جذب سطحی گازهای خالص و مخلوط‌های دوتایی و سه تایی گازی با استفاده از مدل دانسیته موضعی ساده شده

نوع مقاله: مقاله پژوهشی

نویسندگان

دانشکده مهندسی شیمی، دانشگاه علم و صنعت ایران

چکیده

در این مطالعه از مدل دانسیته موضعی ساده شده (SLD) به منظور بیان جذب سطحی چندین گاز خالص و مخلوط‌های دوتایی و سه تایی تشکیل شده از اجزای مذکور استفاده شده است. خواص سیال به کمک معادلات حالت PR و ESD محاسبه شده است . سه حالت مختلف در تعیین پارامترهای مدل مورد ارزیابی قرار گرفته است. در حالات 1 و 2 به ترتیب مدل دارای 2 و 1 پارامتر قابل تنظیم است. در حالت 3، هیچ یک از پارامترهای مدل تنظیم نشده‌اند. در همه موارد تنها از اطلاعات اجزای خالص در پیش‌بینی جذب مخلوط‌ها استفاده شده است. نتایج نشان می‌دهد که اگرچه برازش پارامترها نتایج مدل را برای مواد خالص نسبتاً بهبود می‌بخشد، اما برای مخلوط‌ها تأثیر چشمگیری ندارد و حتی در برخی موارد اثر معکوس دارد. بنابراین با برازش نکردن آنها نیز نتایج مدل با دقت خوبی قابل قبول است. متوسط خطای مطلق محاسبات جذب اضافی گاز برای مواد خالص با استفاده از معادله حالت PR به ترتیب برابر 6/6%، 0/10% و 6/11% برای حالات 1، 2 و3 به دست آمده است. متوسط خطای مطلق محاسبات برروی همین مواد با معادله حالت ESD برای حالات 1، 2 و 3 به ترتیب 1/8%، 4/10 % و 9/15% است. برای مخلوط‌های دو جزئی متوسط خطای مطلق جذب اضافی گاز با معادله حالت PR برابر 7/2، 9/3 و 2/4% و با معادله حالت ESD برابر 7/4%، 5/3% و 8/4% برای حالات 1، 2 و 3 به دست آمده است. محاسبات جذب اضافی برای یک محلول سه جزئی از متان، اتان و اتیلن در حالات 1، 2 و 3 نیز خطایی معادل 5%، 4% و 6/15% برای معادله حالت PR و 9/6%، 9/8% و 4/17% برای معادله ESD دارد. محاسبات نشان می‌دهد که در مجموع، معادله حالت PR نتایج بهتری نسبت به معادله حالت ESD ارائه می‌دهد.

کلیدواژه‌ها


عنوان مقاله [English]

Thermodynamic Modeling of Adsorption of Pure Gases and Binary and Ternary Mixtures of Gases with Simplified Local Density Model

نویسندگان [English]

  • Sajad Abbariki
  • Farzaneh Feyzi
Thermodynamics Research Laboratory, School of Chemical Engineering, Iran University of Science and Technology
چکیده [English]

In this work, the SLD model is used to investigate the adsorption of pure gases and binary and ternary mixtures of them on solids. The volumetric properties of the fluid phase are described by PR and EDS equations of state. Three different procedures are used to estimate the parameters of the model. In the first and second procedures, the model is considered to have 2 and 1 adjustable parameters respectively. However, in the third procedure, none of the parameters are adjusted. In all the three cases, only the data of the pure compounds are used. The results show that although the adjustment of the parameters improves the results for pure compounds, it does not necessarily improve the prediction of the model for the mixture of gases, and even in some cases, less reliable results are observed. As a result, good predictions are observed without fitting the parameters of the model. The average absolute percentage of deviation for the calculation of excess adsorption for pure gases with PR EOS is 6.6%, 10.0%, and 11.6% for procedures 1, 2, and 3 respectively. The corresponding values for ESD EOS are 8.1, 10.4, and 15.9. For binary gas mixtures, the errors are 2.7%, 3.9%, and 4.2% for procedures 1, 2, and 3 respectively in case of using PR EOS; ESD EOS results in errors of 4.7%, 3.5%, and 4.8% for procedures 1, 2, and 3 respectively. A ternary gas mixture composed of methane, ethane, and ethylene is also examined; the average absolute percentages of deviations are 5, 4, and 15.6 in case of PR EOS and 6.9, 8.9, and 17.4 with ESD EOS for procedures 1, 2, and 3 respectively. The comparison of the equations of state used show that PR equations of state generally produce better results.

کلیدواژه‌ها [English]

  • SLD Model
  • Adsorption
  • Active Carbon
  • Equation of State
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