نویسندگان
دانشگاه آزاد اسلامی سمنان
چکیده
در این پژوهش بررسی عددی انتقال حرارت جابه جایی اجباری فروسیال در داخل یک لوله مسی مدور تحت یک میدان مغناطیسی متناوب انجام شده است. جریان از یک لوله تحت شار حرارتی یکنواخت و با رژیم آرام عبور می کند. شدت بخشیدن به انتقال ذرات و آشفتگی در لایه مرزی با استفاده از اثر میدان مغناطیسی بر روی نانوذرات به منظور افزایش انتقال حرارت بیشتر، هدف اصلی بوده است. رژیم ها ی همرفت پیچیده ناشی از فعل و انفعالات میان نانوذرات مغناطیسی تحت شرایط مختلف مورد مطالعه قرار گرفتند. فرآیند انتقال حرارت با غلظ ت ها و حجم های مختلف، تحت فرکانس های مختلف میدان مغناطیسی بررسی شدهاند. ضریب انتقال حرارت جابه جایی آب مقطر و فروسیال محاسبه و تحت شرایط مختلف با یکدیگر مقایسه شدهاند. اثر میدان مغناطیسی بر ضریب انتقال حرارت جابه جایی در درصدهای حجمی و اعداد ر ینولدز مختلف مورد بررسی قرار گرفتند. افزایش فرکانس میدان مغناطیسی متناوب و کسر حجمی، به افزایش بهتر انتقال حرارت منجر شده است. میدان مغناطیسی در اعداد رینولدز کم، تأثیر بیشتری را نشان داده است. هماهنگی خوبی بین نتایج حل عددی و دادههای تجربی وجود دارد و حداکثر خطای روش عددی انجام شده کمتر از 10 % بوده است .
کلیدواژه‌ها
عنوان مقاله [English]
Numerical Study of Ferrofluid Forced Convection Heat Transfer in Tube with Magnetic Field
نویسندگان [English]
- M. Falsafi
- H. Kargarsharifabad
چکیده [English]
This research study presents a numerical study on forced convection heat transfer of an aqueous ferrofluid passing through a circular copper tube in the presence of an alternating magnetic field. The flow passes through the tube under a uniform heat flux and laminar flow conditions. The primary objective was to intensify the particle migration and disturbance of the boundary layer by utilizing the magnetic field effect on the nanoparticles for more heat transfer enhancement. Complicated convection regimes caused by interactions between magnetic nanoparticles under various conditions were studied. The process of heat transfer was examined with different volume concentrations and under different frequencies of the applied magnetic field in detail. The convective heat transfer coefficient for distilled water and ferrofluid was measured and compared under various conditions. The results showed that applying an alternating magnetic field can enhance the convective heat transfer rate. The effects of magnetic field, volume concentration and Reynolds Number on the convective heat transfer coefficient were widely investigated, and the optimum conditions were obtained. Increasing the alternating magnetic field frequency and the volume fraction led to better heat transfer enhancement. The effect of the magnetic field in low Reynolds numbers was higher. The results showed that the modeling data were in a very good agreement with experimental data. The maximum error was around 10%.
کلیدواژه‌ها [English]
- ferrofluid
- nanoparticles
- convective heat transfer
- alternating magnetic field
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