بهینه‌یابی انرژی گنبدهای آب انبارها؛ نمونه موردی: گنبدهای شهر قزوین

آب‌انبارها علاوه بر مناطق گرم و خشک، در مناطق سرد کشورمان نیز مورد استفاده عموم قرار می‌گرفته است. یکی از اصلی‌ترین عنصر آب‌انبارها پوشش مخزن آن‌هاست، که از طاق‌های آجری گوناگون مانند آهنگ، کلنبو با خیز و فرم‌های متفاوت ساخته ‌شده است. هدف از این پژوهش شناخت میزان دریافت تابش خورشید در سطوح و جریان حرارت در داخل گنبد آب‌انبارهای قزوین می‌باشد که منجر به شناخت بهینه‌ترین فرم پوشش مخزن آب‌انبار در بین نمونه‌های مطالعه شده می‌گردد. برای انجام این تحقیق چهار نمونه از آب انبارها با ساختار متفاوت گنبد در شهر قزوین انتخاب، سپس گنبدها در نرم افزار revit 2016 مدلسازی شد و میزان دریافت تابش خورشید گنبدها در سردترین روز سال و در ساعات 13، 14و 16 با استفاده از پلاگین‌های honeybee ladybug با موتور انرژی پلاس مشخص گردید. برای اعتبارسنجی با استفاده از نرم‌افزار comsol تحلیل جریان هوای یکسان cfd در گنبدهای خیز بلند و کم انجام شد. نتایج آنالیزها نشان دادند که میزان دریافت تابش در سطوح گنبد آب‌انبارها متفاوت است و در گنبدهای خیز کم و سطح تماس زیاد نسبت به تابش خورشید، عملکرد دریافت حرارت نسبت به گنبدهای خیز بلند، بیشتر است. زیرا این گنبدها سطوح بیشتری در معرض تابش خورشید قرار می‌دهند. در تحلیل جریان cfd در هنگام ظهر و گرمای شدید روز، در قسمت بالای گنبد خیز بلند گردابه‌ی گرما ایجاد می‌گردد که از گرم شدن بیش از حد داخل گنبد جلوگیری می‌نماید. بنابرین مناسب‌ترین گنبد برای آب‌انبارهای اقلیم سرد قزوین، گنبدهای خیز کم می‌باشند.

energy optimization of the ab-anbar domes; case study: domes of qazvin city

background and objectives: traditionally, the public has used abanbars (water reservoirs) in hot and dry areas and also in cold regions of iran. one of the main elements of abanbar is the reservoir coverage (reservoir lining), which is made of various brick vaults such as barrel and colombo vaults with different rises and forms. due to the dry weather in most parts of iran and insufficient rainfall in more than six months of the year in most places, which has resulted in the seasonality of rivers and the lack of access to water, various arrangements have been established for freshwater supply in dry seasons. the construction of the abanbar (water reservoir and cistern) is one of the innovative ways to supply drinking water. in this regard, the abanbar, as its name implies, is used to store water in rainy seasons to be used for the rest of the year. the main structure of the abanbar consists of an underground storage tank and a dome to cover it. in some areas in iran, a wind catcher is added to this structure to keep the water cool in summer. the construction material used for abanbars was a special mortar called sarooj, which was made of sand, clay, lime, goat hair, egg whites, and ash in specific proportions, depending on the location and climate of the place. some abanbars had rectangular storage tanks, and some tanks had a cylindrical shape. this study aims to determine the amount of solar radiation received on the surfaces and heat flow inside the abanbar domes of qazvin, which leads to recognizing the most optimal form of reservoir coverage for abanbars among the studied samples. methods: the data, including dry and humid temperature, air, radiation, and current radiation situation of qazvin city weather station, were prepared over a tenyear period (19962006). the library documents also provided the map of the abanbar domes. in order to conduct the research, four samples of abanbars with different dome structures in qazvin city were selected. after that, the domes were modeled in revit 2016, and the amount of solar radiation received by the domes on the hottest day of the year, at 14, 16, and 18 o’clock, were determined using honeybee ladybug plugins with energy plus engine. comsol software, and the cfd airflow analysis, were performed for validation in highrise and lowrise domes. findings: the results of the analyses showed that lowrise domes with large surface contact receive more heat than highrise domes with a small surface contact, and the area of the domes is effective in receiving the sun radiation. sardar kouchak (little commander) dome, a lowrise dome, is approximately exposed to its total surfaces and solar heat by 84.3% at 14 o’clock. in comparison, the highrise dome next to the grand mosque is exposed by 52.5% at 14 o’clock. the lowrise dome is exposed by 74.7%, while the highrise dome is exposed by 53.5% at 16 o’clock. finally, the lowrise dome is exposed by 62.4%, and the highrise dome is exposed by 43.2% at 18 o’clock. therefore, lowrise domes in the cold climate are more efficient in receiving solar radiation than highrise ones.conclusion: the airflow inside the domes was graphically performed for validation using cfd analysis on a hot day. the results are consistent with the outputs from honeybee ladybug plugins. lowrise domes can retain more heat than highrise domes, and the vortex of hot air created in lowrise domes is less than in highrise domes, which leads to more heat gain inside the dome. therefore, the most suitable dome for abanbar in the cold climate of qazvin are lowrise domes.