شبیه‌سازی عددی جریان مافوق‌صوت گا‌ز طبیعی گذرنده از یک لاوال نازل به منظور امکان‌سنجی رطوبت‌گیری از آن

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشکده‌ی مهندسی مکانیک، دانشگاه گیلان

2 دانشکده‌ی مهندسی مکانیک، دانشگاه صنعتی اصفهان

3 گروه حرارت و سیالات دانشکده مهندسی مکانیک، دانشگاه صنعتی اصفهان، اصفهان

چکیده

جداکننده‌ی مافوق‌صوت یک نازل همگرا-واگرا است که میعان و تغییر فاز در سرعت‌های بالاتر از صوت از خصوصیات عملکرد این دستگاه است. در این جداکننده جریان از حالت مادون‌صوت به مافوق‌صوت تبدیل شده و این تغییر رژیم جریان منجر به کاهش شدید دما و تشکیل مایع درون گاز می‌گردد. جریان سیال، انتقال جرم و حرارت در جداکننده‌های مافوق‌صوت به دلیل برهم‌کنش پیچیده جریان مافوق‌صوت و تغییر فاز به خوبی درک نشده‌است. در این پژوهش مدل‌سازی عددی چگالش بخار آب با هدف بررسی جریان سیال در جداکننده‌ی مافوق صوت انجام شده‌است. برای شبیه‌سازی جریان چند فازی از روش مخلوط بهره گرفته و مدل آشفتگی مورد استفاده،  k-ε استاندارد است. از مدل ریاضی تغییر فاز لی برای پیش‌بینی دقیق پدیده‌ی چگالش خود‌به‌خودی استفاده شده‌است. مسئله در حالت دوبعدی شبیه‌سازی و فشار ورودی و خروجی و دمای ورودی به عنوان شرایط مرزی و دیواره‌ی نازل آدیاباتیک فرض شده‌است. نتایج حاصل شده از مدل عددی به خوبی با داده‌های تجربی سازگار است. بر اساس تحلیل‌های انجام‌ شده، تغییر ‌فاز آب از بخار به مایع و رطوبت‌زدایی که هدف اصلی این پژوهش بوده‌‌است، با موفقیت حاصل شده‌است. هم چنین با 8/6 % افزایش دمای ورودی، کسر جرمی مایع بیش از 2 % کاهش یافت. با حدود 5/12 %  افزایش فشار ورودی در شرایط یکسان، بیشترین کسر جرمی مایع بیش از 19 % افزایش یافت. با در نظر گرفتن گاز طبیعی به عنوان سیال ورودی جداکننده کلیه‌ی بخار آب به مایع تبدیل شده و راندمان جداسازی بسیار بالا حاصل شده‌است.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Numerical simulation of supersonic natural gas flow passing through a Laval nozzle to assess the possibility of Dehumidification

نویسندگان [English]

  • Neda Zareei 1
  • Ramin Kouhikamali 2
  • Mohsen Emami 3
  • Seyed Amir Tayefi 2
  • Navid Sharifi 1
1 Faculty of Mechanical Engineering, University of Guilan
2 Faculty of Mechanical Engineering, Isfahan University of Technology
3 Department of Mechanical Engineering, Isfahan University of Technology, Isfahan, Iran
چکیده [English]

The Supersonic separator is a convergent-divergent nozzle with condensation and phase change at supersonic speeds. In this separator, the flow is converted from subsonic to supersonic, and this change in the flow regime leads to a sharp decrease in temperature and the formation of a liquid within the gas. Fluid flow, mass and heat transfer in supersonic separators are poorly understood due to the complex interaction of supersonic flow and phase change. In this study, numerical modeling of water vapor condensation has been carried out to investigate the fluid flow in the supersonic separator. The mixture method is used to simulate the multiphase flow and the implemented turbulence model is the standard k-ε. The Lee phase change and UDF mathematical models have been used to accurately predict the spontaneous condensation phenomenon. The problem is simulated in two-dimensional mode, the inlet and outlet pressures and the inlet temperatures are assumed as boundary conditions, and the nozzle wall is adiabatic. The results obtained from the numerical model are in good agreement with the experimental data. Based on the analysis, the phase change of water from vapor to liquid and the dehumidification, which was the main objective of this research, has been successfully achieved. Also, with an increase of 6.8% in the inlet temperature, the liquid mass fraction decreased by more than 2%. With an increase of about 12.5% in the inlet pressure under the same conditions, the maximum liquid mass fraction increased by more than 19%. Considering natural gas as the inlet fluid of the separator, all water vapor is converted to liquid and the separation efficiency is very high.

کلیدواژه‌ها [English]

  • supersonic separators
  • dehumidification
  • numerical simulation
  • laval nozzle

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