تحلیل انتقال حرارت ترکیبی هدایت-تابش در عایق‌های چندلایه

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشیار، دانشکده فنی و مهندسی، دانشگاه تربیت مدرس

2 دانشجوی دکتری، دانشکده فنی و مهندسی، دانشگاه تربیت مدرس

چکیده

در تحقیق حاضر مدل‌سازی انتقال حرارت ترکیبی هدایت-تابش در عایق چندلایه انجام‌شده‌است. معادلات حاکم حل دقیق ندارند. بنابراین از حل عددی به همراه حل‌های تقریبی استفاده شدهاست. معادلات حاکم اصلی شامل معادله‌ی انرژی و معادلات دوشار می‌باشند، که به‌ترتیب با استفاده از روش‌های حجم‌محدود و اختلاف‌محدود گسسته‌سازی شده‌اند. حل عددی ابتدا با حل اوزیسیک و سپس با داده‌های منتشرشده‌ی تجربی صحت‌سنجی شدهاست. با استفاده از حل پایا، شار حرارتی و رسانش حرارتی معادل و با استفاده از حل بی‌بعد توزیع دمای بی‌بعد درحالت پایا و نسبت شار‌های بی‌بعد تابشی و هدایتی در طول نمونه به‌دست آمدهاست. در مجاورت مرز گرم شار تابشی غالب است، بنابراین پیشنهاد شدهاست، بازتاباننده‌ها نزدیک به مرز گرم قرار گیرند. برای اختلاف دماهای کم، هدایت غالب است، بنابراین وجود بازتاباننده‌ها در عایق، در رسانش معادل تاثیرگذار نیست.

کلیدواژه‌ها

عنوان مقاله [English]

Analysis of Combined Conduction-Radiation Heat Transfer In Multilayer Insulations

نویسندگان [English]

  • Mahdi Maerefat 1
  • Arash Esmaili 2
چکیده [English]

Modeling of the combined conduction-radiation heat transfer in multilayer insulation has been done. Governing equations of the problem are integro-differential and there is no exact solution for them. So numerical procedure with approximate solutions have been used. Main governing equations were energy equation and two-flux equations that respectively, using the finite volume and finite differences have been discretized. Numerical solution is validated with Ozisik’s solution and published experimental results. Total heat flux and effective thermal conductivity obtained via steady state results. Dimensionless temperature distribution and dimensionless radiative and conductive heat fluxes along sample thickness obtained. Near the hot boundary, dominating mode is radiation, so it is suggested that reflective screens to be located near hot boundary. For lower temperature differences, the dominating mode is conduction, so number of reflective screens does not influence effective thermal conductivity so much. In all steps of validation, the numerical results have good agreements with published data in references. Finally, as for radiation behavior along insulation thickness, it is suggested that just the foils near the hot boundary, to be coated with gold for sake of cost cutting. In addition, it is understood that layer density has an optimum value and this value does not changes if the boundary conditions and the material remain unchanged.

کلیدواژه‌ها [English]

  • Multilayer Insulation
  • Thermal Conductivity
  • Thermal Protection System
  • Combined-mode Heat Transfer

مراجع

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