نویسنده

پژوهشکده انرژی، پژوهشگاه علوم و تکنولوژی پیشرفته و علوم محیطی، دانشگاه تحصیلات تکمیلی صنعتی و فناوری پیشرفته، کرمان

چکیده

در این مقاله شبیه‌سازی عددی جریان و انتقال حرارت نانوسیال اکسید آلومینیوم/ آب، در سه هندسه مختلف لوله مستقیم، لوله دارای خم °90 و لوله دارای خم °180 تحت شرایط شار حرارتی دیواره ثابت انجام‌ شده است. معادلات انرژی و ناویر- استوکس تراکم‌ناپذیر و آرام با درنظر گرفتن مدل تک ‌فاز برای نانوسیال، در یک سیستم مختصات منطبق بر جسم با استفاده از برنامه نوشته شده توسط نویسندگان بر مبنای روش حجم‌کنترلی حل شده‌اند در حالی که تمام خصوصیات ترموفیزیکی نانوسیال تابع دما درنظر گرفته شده‌اند. اثر کسرهای حجمی‌ مختلف نانوذرات و همچنین نیروی گریز از مرکز برروی میدان دما و فشار مورد مطالعه قرار گرفته ‌است. تطابق نتایج عددی با داده‌های آزمایشگاهی موجود، بیانگر صحت مدل‌سازی عددی به‌کار رفته برای شبیه‌سازی جریان و انتقال حرارت داخل لوله خمیده و همچنین صحت مدل تک ‌فاز ارائه شده برای نانوسیال است. با توجه به نتایج به‌دست آمده، وجود لوله خمیده و همچنین استفاده از نانوسیال‌ها باعث بهبود چشم‌گیر مشخصه‌های انتقال حرارت می‌شوند، در حالی‌که افت فشار قابل توجهی نیز ایجاد می‌کند. نتایج نشان می‌دهند که برای شرایط بهینه عملکرد نانوسیال، متغیرهای مختلفی چون افزایش انتقال حرارت و افت فشار را باید به‌صورت هم‌زمان مدنظر قرار داد. در انتها روشی برای انتخاب نانوسیال و هندسه مناسب برای کاربردهای خاص ارائه شده است.

کلیدواژه‌ها

عنوان مقاله [English]

Comparative Study of Laminar Convective Heat Transfer and Pressure Drop of Nanofluids through Curved Geometries

نویسنده [English]

  • E. Ebrahimnia-Bajestan

چکیده [English]

In this paper, numerical simulation of flow and heat transfer of Al2O3/water nanofluid has been carried out through three different geometries involving a straight pipe, a 90o curved pipe and a 180o curved pipe under constant heat flux condition. Employing singe-phase model for the nanofluid, the Navier-Stokes and energy equations for an incompressible and laminar flow have been solved in a body fitted coordinate system using a homemade code based on control-volume approach, while all thermophysical properties of the nanofluid are dependent on considered temperature. The effects of different nanoparticle concentration and centrifugal forces on the temperature and pressure field have been examined in detail. The accordance of numerical results with experimental data expresses the accuracy of the  employed numerical method for simulating flow and heat transfer in the curved pipes, as well as the accuracy of the single-phase model of the nanofluid. The Presented results indicated that both the nanoparticle and curvature effects improve the heat transfer characteristics dramatically, but at the expense of considerable increase in pressure drop. Furthermore, the results showed that in order to obtain the optimum operating conditions of nanofluids, different parameters such as heat transfer enhancement and pressure drop must be considered simultaneously. Finally, a method has been proposed to indicate the proper nanofluid and flow geometry for special practical applications.

کلیدواژه‌ها [English]

  • Numerical solution
  • convective heat transfer
  • Nanofluid
  • Curved pipe
  • Pressure drop
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