شبیه‌سازی عددی انتقال گرمای جریان آشفته نانو سیال غیرنیوتنی در مبدل گرمایی دولوله‌ای مارپیچ

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشیار و عضو هیئت علمی گروه مکانیک- دانشکده فنی- دانشگاه گیلان

2 دانشکده فنی مکانیک ، دانشگاه گیلان، رشت، ایران

3 دانشکده فنی مکانیک، دانشگاه گیلان، رشت ایران

چکیده

در این پژوهش رفتار گرمایی و هیدرودینامیکی جریان آشفته نانوسیال غیرنیوتنی در آرایش جریان مخالفدر یک مبدلگرمایی دولولهای مارپیچ به صورت عددی شبیه‌سازی شده است. از محلول پودرکربوکسی متیل سلولز در آب با درصد جرمی 1/0% همراه با نانوذره آلومینیوم‌اکسید به عنوان سیال عامل استفاده شده است. از نرم افزار دینامیک سیالات محاسباتی فلوئنت جهت حل معادلات استفاده شده که نتایج این حل عددی با داده‌های تجربی پیشین مطابقت خیلی خوبی داشته است. نقش و تأثیر پارامترهای مهم مانند انحنای مارپیچ، عدد رینولدز و درصد حجمی نانوذرات آلومینیوماکسید روی انتقال گرما مورد بررسی قرار گرفته است. نتایج نشان می‌دهد با افزایش نسبت انحنا در اعداد دین ثابت، عدد ناسلت و ضریب اصطکاک افزایش می‌یابد. نیروی گریز از مرکز ناشی از انحنای لوله‌های مارپیچ سبب ایجاد جریان ثانویه در مبدل شده به طوری که میزان انتقال گرما و افت فشار به ترتیب تا 35% و 30% نسبت به لوله‌های مستقیم افزایش پیدا کرده است. نتایج نشان می‌دهد که اضافه کردن نانوذرات آلومینیوم‌اکسید به سیال پایه برای جریان با عدد رینولدز و عدد دین ثابت، باعث افزایش انتقال گرما و افزایش افت فشار جریان در لوله‌های مارپیچ می‌شود. اثر روش‌های افزایش انتقال گرما بر شاخص هیدرودینامیکی نیز بررسی شد به طوری که در کویل‌های مارپیچ با کاهش نسبت انحنا و افزایش غلظت حجمی نانوذرات مقدار شاخص هیدرودینامیکی نیز بیشتر شده است.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Numerical Simulation of Heat Transfer Turbulent Flow for Non-Newtonian Nanofluid in a Double Pipe Helical Heat Exchanger

نویسندگان [English]

  • Kourosh Javaherdeh 1
  • Seyed Shahab Mozafarie 2
  • zeinab Zare Talab 3
1 Instructor of Department of Mechanical Engineering, Faculty of Engineering, University of Guilan
2 Faculty of Mechanical Engineering, University of Guilan, Rash, Iran
3 Faculty of Mechanical Engineering, University of Guilan, Rasht, Iran
چکیده [English]

In this research, the thermal and hydrodynamic behavior of a non-Newtonian nanofluid turbulent flow in the counterflow arrangement in a double pipe helical heat exchanger is numerically simulated. A solution of carboxymethyl cellulose powder in water with a mass percentage of 0.1% with a nanoparticle of aluminum oxide as a working fluid has been used. The computational fluid dynamics commercial software Fluent was used to solve the governing equations, the results were in a good agreement with experimental data. The effect of important parameters such as curvature, Reynolds number and volume percentage of aluminum oxide nanoparticles on the heat transfer has been investigated. The results show that as the curvature ratio increases in constant Dean (Dn) numbers, the Nu number and the coefficient of friction increase. The addition of nanoparticles of aluminum oxide to the base fluid for the flow with the constant Reynolds and Dn number increases the heat transfer and increases the pressure drop in the helically coiled tubes. The centrifugal force generated by the curvature of the coiled tubes results in a secondary flow in the heat exchanger so that the heat transfer and pressure drop increased up to 35% and 30%, respectively, compared to the straight tubes. The effect of heat transfer enhancement methods on the hydrodynamic index has also been studied, so that in the helical coils, the amount of hydrodynamic index increased with decreasing curvature ratio and increasing the volume concentration of nanoparticles.

کلیدواژه‌ها [English]

  • Double pipe helical heat exchanger
  • numerical simulation
  • heat transfer
  • Nanofluid
  • Turbulent flow
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