تأثیر فاصلۀ هوایی بین دو پوشش شیشه‌ای بر عملکرد هواگرم‌کن‌های صفحه‌ای خورشیدی

نوع مقاله : مقاله پژوهشی

نویسندگان

بخش مهندسی مکانیک، دانشکده فنی و مهندسی، دانشگاه شهید باهنر کرمان، ایران.

چکیده

با توجه به اهمیت روزافزونِ استفاده از انرژی‌های پاک و تجدیدپذیر، یکی از ساده‌ترین مکانیزم‌های تبدیل انرژی تابشی خورشید به انرژی حرارتی، در مقیاس غیرنیروگاهی، استفاده از هوا‌گرم‌کن‌های خورشیدی است که همواره به عنوان ایده‌ای جذاب برای پژوهشگران مطرح بوده است. از این رو، پژوهش حاضر، به مطالعۀ تأثیر فاصلۀ هوایی بر عملکرد هواگرم‌کن‌های صفحه‌ای خورشیدی با دو پوشش شیشه‌ای، از طریق شبیه‌سازی‌های عددی، می‌پردازد. مطالعه‌ای که مشابه آن در مراجع تحقیقاتی مختلف تاکنون گزارش نشده است. بدین منظور، معادلات حاکم بر جریان جابجایی اجباریِ هوای عبوری از داخل کانال هواگرم‌کن و همچنین جریان جابجایی طبیعی در فاصلۀ هوایی بین دو پوشش شیشه‌ای به دلیل وجود نیروی شناوری، با بکارگیری روش المان محدود و استفاده از نرم‌افزار کامسول، حلّ عددی شده‌اند. به‌علاوه، به منظور تعیین میدان دما در اجزای جامدِ هواگرم‌کن، شامل شیشه، صفحۀ جاذب و لایۀ عایق، حل معادلات هدایت حرارتی هم‌زمان با معادلات جریان صورت گرفته است. صحت شبیه‌سازی‌های عددیِ انجام‌شده در این پژوهش، از طریق مقایسه با یافته‌های عددی و تجربیِ پژوهش‌های پیشین مورد ارزیابی قرار گرفته، که سازگاری قابل قبولی در این خصوص به دست آمده است. نتایج حاصل بیانگر تأثیر مثبت حضور لایه هوای بین دو شیشه بر عملکرد هواگرم‌کن‌های صفحه‌ای خورشیدی بوده، به‌طوری‌که با تغییر دبی جریان هوا از 2 تا 14 گرم بر ثانیه عملکرد این نوع از هواگرم‌کن‌ها در شار تابشی 1000 وات بر مترمربع در مقایسه با مدل ساده و بدون فاصلۀ هوایی افزایش راندمانی در حدود 4 تا 6 درصد را نشان داده است. همچنین، در شرایط دبی جریان ...

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Effect of Air Gap between two Glass Covers on the Performance of Plane Solar Air Heaters

نویسندگان [English]

  • Omid Deymi
  • Seyyed Abdolreza Gandjalikhan-nassab
Department of Mechanical Engineering, School of Engineering, Shahid Bahonar University of Kerman, Iran.
چکیده [English]

Due to the increasing importance of using clean and renewable energies, one of the simplest mechanisms for converting solar radiant energy into thermal energy, on non-industrial applications, is the use of solar air heaters, which has always been an attractive idea for researchers. Therefore, the present study investigates the effect of air gap on the performance of plane solar air heaters with two glass covers by means of numerical simulations. A similar study has not been yet reported in various research resources. For this purpose, the equations governing the forced convection flow of air passing through the heater duct and also the natural convection flow caused by the buoyancy force in the air gap between two glass covers are numerically solved by applying the finite element method and using COMSOL Multiphysics software. In addition, in order to determine the temperature field in the solid elements of the air heater (including glass cover, absorber plate and insulation layer), conduction heat transfer equations are simultaneously solved with the flow equations. The accuracy of the numerical simulations performed in this research has been evaluated by comparing those with the theoretical and experimental findings of previous researches, and an acceptable consistency and agreement has been obtained in this regard. The results demonstrate the desired effect of the presence of air gap between the two covers on the performance of plane solar air heaters, such that changing the air flow rate from 2 to 14 g/s, the performance of this type of air heaters ...

کلیدواژه‌ها [English]

  • Solar Radiation
  • Plane Air Heater
  • Natural Convection
  • Forced Convection
  • Thermal Performance
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