مدل‌سازی و بررسی آزمایشگاهی کاهش تبخیر سطحی آب توسط پوشش‌های شناور با حضور جریان سطحی

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشگاه صنعتی شاهرود-دانشکده مهندسی مکانیک

2 دانشکده مهندسی مکانیک و مکاترونیک، دانشگاه صنعتی شاهرود، شاهرود، ایران

3 دانشکده مهندسی عمران، دانشگاه صنعتی اصفهان، اصفهان، ایران

چکیده

امروزه حفظ منابع آب شیرین به‌دلیل رشد جمعیت، تغییرات اقلیمی و خشکسالی از اهمیت ویژه‌ای برخوردار است.در نواحی خشک، بخش قابل‌توجهی از آب‌های ذخیره‌شده به‌دلیل تبخیرازبین می‌روند که پوشاندن سطح مخازن با اجسام شناور، راهکاری ساده و قابل‌اطمینان برای کاهش تبخیر به‌شمار می‌آید. علی‌رغم مطالعات گسترده روی پوشش‌های شناور، تاثیر آن‌ها درحضور جریان‌های سطحی تاکنون مورد بررسی دقیق قرار نگرفته است. لذا در این مطالعه به مدل‌سازی و بررسی آزمایشگاهی تاثیر جریان سطحی بر میزان تبخیر مخازن آب پوشیده با اجسام شناور پرداخته‌ می‌شود. بدین‌منظور از توپ‌های سیاه‌ و سفید برای پوشش‌دهی مخزن واز یک پمپ جهت ایجاد جریان سطحی ً با استفاده‌شده است. نتایج آزمایش‌ها نشان می‌دهد که میزان تبخیر تا یک دبی مشخص (دبی بهینه)، کاهش و مجددا افزایش دبی، افزایش می‌یابد.همچنین در تمامی شرایط وجود/عدم‌ وجود جریان، کمترین میزان تبخیر در پوشش‌دهی با توپ‌های سفید رخ می‌دهد. درضمن پوشش‌دهی به‌صورت مخلوطی مساوی از توپ‌های سیاه‌و سفید و پوشش با توپ‌هایسیاهبه‌ترتیبدررتبه‌هایبعدیکاهشتبخیرقراردارند (بیشترینتبخیرمربوطبه‌حالت بدون‌پوشش می‌باشد(. همچنین نتایج حاصل از مدل‌سازی انرژی نشان می‌دهد که روابط حاکم برمدل‌سازی،دقت قابل‌قبولی در تخمین میزان تبخیربرای تمامی حالت‌های بدون‌پوشش/پوشش‌دهی همراه با وجود/عدم‌وجود جریان‌سطحی خواهد داشت.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Modelling and Experimental Investigation of the Evaporation Suppression Using Floating Covers in the Presence of Surface Flows

نویسندگان [English]

  • amir rezzazadeh 1
  • Pooria Akbarzadeh 2
  • Milad Aminzadeh 3
1 Department of Mechanical and Mechatronics Engineering, Shahrood University of Technology, Shahrood
2 Department of Mechanical and Mechatronics Engineering, Shahrood University of Technology, Shahrood
3 Department of Civil Engineering, Isfahan University of Technology, Isfahan, Iran
چکیده [English]

The increase in fresh-water demand due to the rapid population growth and climate changes with severe droughts highlights the protection of limited fresh-water resources. In arid regions, evaporation accounts for a significant fraction of losses from water reservoirs. Among different methods for suppressing evaporative loss, the use of modular floating elements offers a simple and reliable technique. Despite numerous studies on application of floating elements, performance of this method in the presence of surface flows is not yet addressed comprehensively. Hence, the present study aims to investigate the effect of surface flows on evaporation from covered reservoirs. For this purpose, a 500-liter water reservoir was covered with white and black balls and a water-pump provided surface flows at different rates. The results show that evaporation decreases monotonically with increasing surface flow rate until a specific flow rate, called optimal flow rate. The increase in surface flow more than this optimal rate results in increase in evaporative loss. Regardless of surface flow condition, the results indicate that the lowest water evaporation occurs for the coverage with white balls while coverage using a mixture of black and white balls and only with black balls showed higher evaporation rates, respectively (the highest evaporation is of course for the uncovered surface). The experimental findings demonstrate that surface flows with appropriate rates can effectively enhance evaporation suppression efficiency of floating elements. Comparison of the modeling results with experimental outputs highlights application of the physically-based energy balance model in estimating surface evaporation for covered and uncovered water surfaces with and without surface flow conditions.

کلیدواژه‌ها [English]

  • Surface water evaporation
  • Surface flows
  • Floating balls
  • Optimal flow rate
  • Energy balance

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نشریه مهندسی مکانیک امیرکبیر
دوره 52، شماره 7
مهر 1399
صفحه 1193-2010

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