صفه

صفه

بررسی جریان هوا و انتقال حرارت در نمای تهویه شده با درز باز مطالعۀ موردی: ساختمان اداری شهر اصفهان

نوع مقاله : مقاله پژوهشی

نویسندگان
1 کارشناس ارشد مرکز تحقیقات افق‌های نوین در معماری و شهرسازی، واحد نجف‌آباد، دانشگاه آزاد اسلامی، نجف‌آباد، ایران
2 استادیار مرکز تحقیقات افق‌های نوین در معماری و شهرسازی، واحد نجف‌آباد، دانشگاه آزاد اسلامی، نجف‌آباد، ایران
چکیده
اهداف و پیشینه: در پیشینۀ این پژوهش به ضرورت استفاده از سیستم‌های نوین نماسازی، به‌ویژه نماهای تهویه‌شده با درز باز، به‌منظور بهینه‌سازی مصرف انرژی در ساختمان‌ها پرداخته شده؛ چراکه در مطالعات بین‌المللی، به‌ویژه در اقلیم‌های مدیترانه‌ای، به‌طور گسترده‌ای بر اثربخشی این نماها در کاهش بار حرارتی و بهبود تهویۀ طبیعی تأکید گردیده است، اما در ایران، به‌ویژه در اقلیم گرم و خشک، آنچه مشاهده می‌شود، پژوهش‌های محدود و ناقصی در این زمینه است. هدف اصلی در این مطالعه، بررسی تأثیر درصد پوشش نمای تهویه‌شده، ضخامت لایۀ هوای بین دو پوسته و ارتفاع نصب نما بر جریان هوا، دمای سطح داخلی، و مصرف انرژی ساختمان‌های اداری در شهر اصفهان است. در این پژوهش تلاش شده تا با تکیه بر شبیه‌سازی عددی و تحلیل حساسیت، الگویی بهینه برای طراحی نمای دوپوسته در شرایط اقلیمی ایران عرضه گردد.

مواد و روشها: در این پژوهش با رویکردی کمّی و ماهیتی کاربردی، با استفاده از شبیه‌سازی عددی، عملکرد حرارتی و جریان هوای نمای تهویه‌شده با درز باز در یک ساختمان اداری واقع در اقلیم گرم و خشک اصفهان بررسی شده است. برای این منظور، از نرم‌افزار انسیس فلوئنت برای تحلیل دینامیک سیالات (CFD) و از طراحی بیلدر برای محاسبۀ مصرف انرژی استفاده شد. مدل پایه شامل ساختمانی 8 طبقه با نمای جنوبی مجهز به صفحات سرامیکی مدولار با درز باز بود که در 6 حالت درصد پوشش (از 0 تا 100٪)، دو ضخامت حفره (4 و 6 سانتی‌متر)، و سه ارتفاع مختلف (طبقات همکف، چهارم، و هشتم) تحلیل شد. نتایج شبیه‌سازی در دو بازۀ زمانی انقلاب تابستانی و زمستانی بررسی و با تحلیل حساسیت، تأثیر هر متغیر مستقل بر متغیرهای وابسته‌ای چون سرعت جریان هوا، دمای سطح داخلی، شار حرارتی، و مصرف انرژی ارزیابی شد.

نتایج و جمعبندی: نتایج پژوهش نشان داد که نمای تهویه‌شده با درز باز در اقلیم گرم و خشک اصفهان، درصورت طراحی بهینه، تأثیر چشمگیری در بهبود عملکرد حرارتی و کاهش مصرف انرژی ساختمان‌های اداری دارد. در حالت بهینه، یعنی با پوشش 60 تا 80درصدی نما و ضخامت لایۀ هوای 6 سانتی‌متر و نصب در طبقۀ چهارم، سرعت جریان هوا به محدودۀ مطلوب برای تهویۀ طبیعی رسید و دمای سطح داخلی نما کاهش یافت. همچنین، شار حرارتی در تابستان تا بیش از 50٪ کاهش و مصرف انرژی نسبت به نمای معمولی تا 46٪ در تابستان و 50٪ در زمستان صرفه‌جویی را نشان داد. تحلیل حساسیت نیز بیانگر آن بود که ارتفاع نصب نما، سطح پوشانندگی، و ضخامت لایۀ هوا به‌ترتیب بیشترین تأثیر را بر عملکرد نما دارند؛ بنابراین استفاده از این نوع نما، به‌ویژه در ساختمان‌های اداری دولتی در اقلیم‌های گرم ایران، توصیه می‌شود.
کلیدواژه‌ها
موضوعات

عنوان مقاله English

Investigating Air Flow and Heat Transfer in An Open-Joint Ventilated Façade; The case of an Office Building in Isfahan

نویسندگان English

Najmeh Malekipour 1
Narges Dehghan 2
1 M.A. Advancement in Architecture and Urban Planning Research Center, Na.C., Islamic Azad University, Najafabad, Iran
2 Assistant Professor, Advancement in Architecture and Urban Planning Research Center, Na.C., Islamic Azad University, Najafabad, Iran
چکیده English

Background and Objectives: The background of this research emphasizes the need to adopt innovative façade systems—particularly open joint ventilated façades—to optimize energy consumption in buildings. International studies, especially those conducted in Mediterranean climates, have widely confirmed the effectiveness of these façades in reducing thermal loads and enhancing natural ventilation. However, in Iran—particularly in hot and dry climates—related studies have been limited and incomplete. The main objective of this study is to investigate the impact of three key parameters: the percentage of ventilated façade coverage, the air cavity thickness between the two skins, and the installation height of the façade on airflow, interior surface temperature, and energy consumption in office buildings located in Isfahan. Relying on numerical simulation and sensitivity analysis, this research aims to provide an optimized model for designing double-skin façades adapted to Iran’s climatic conditions.
Materials and Methods: This study follows a quantitative and applied approach using numerical simulation to analyze the thermal Performance and airflow behavior of an open joint ventilated façade in an office building located in the hot and dry climate of Isfahan. For this purpose, ANSYS Fluent was used for Computational Fluid Dynamics (CFD) analysis, and DesignBuilder was used to evaluate seasonal energy consumption. The base model consisted of an 8-story building with a south-facing façade covered with modular ceramic panels featuring open joints. Six façade coverage ratios (0%, 20%, 40%, 60%, 80%, and 100%), two cavity thicknesses (4 سانتی‌متر and 6 سانتی‌متر), and three vertical installation levels (ground floor, fourth floor, and eighth floor) were defined and analyzed. Simulations were performed for two key timeframes: summer solstice (June 21) and winter solstice (December 21). Through sensitivity analysis, the individual impact of each independent variable on dependent parameters—such as air velocity, interior surface temperature, heat flux, and overall energy consumption—was thoroughly evaluated.
Results and Conclusion: The findings revealed that open joint ventilated façades, when optimally designed, significantly improve thermal Performance and reduce energy consumption in office buildings in hot and dry climates like Isfahan. In the optimal case—60% to 80% façade coverage, 6 سانتی‌متر cavity thickness, and installation at the fourth floor—air velocity fell within the ideal range for natural ventilation, and the interior surface temperature was noticeably reduced. Heat flux in summer decreased by more than 50%, and energy consumption was reduced by up to 46% in summer and 50% in winter, compared to a standard single-skin façade. Sensitivity analysis indicated that installation height, coverage ratio, and cavity thickness were, respectively, the most influential variables. It was also found that excessive height or cavity thickness could negatively affect airflow and increase energy demand. Based on these results, the use of open joint ventilated façades is strongly recommended, especially for governmental and office buildings in hot Iranian climates.

کلیدواژه‌ها English

Open-joint ventilated façade
Energy saving
Building envelope
Heat transfer
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  • تاریخ دریافت 16 دی 1400
  • تاریخ بازنگری 13 مرداد 1403
  • تاریخ پذیرش 03 خرداد 1404