بررسي تجربي تاثير جريان ثانويه بر عملكرد كلكتور صفحه تخت خورشيدي با استفاده از نانوسيال

Experimental Study of the Effect of Secondary Flow on the Efficiency of Solar Flat Plate Collector Applied Nanofluid

در اﯾﻦ ﭘﮋوﻫﺶ، ﺑﻪ ﻣﻨﻈﻮر ﺑﺮرﺳﯽ اﺛﺮ ﺟﺮﯾﺎن ﺛﺎﻧﻮﯾﻪ ﺑﺮ ﺑﺎزده ﮐﻠﮑﺘﻮر ﺻﻔﺤﻪ ﺗﺨﺖ، ﯾﮏ ﮐﻠﮑﺘﻮر داﯾﺮوي ﺑﺎ ﻟﻮﻟﻪﻫﺎي ﻣﺎرﭘﯿﭻ و ﯾﮏ ﮐﻠﮑﺘﻮر ﻣﻌﻤﻮﻟﯽ ﻣﺴﺘﻄﯿﻠﯽ ﺑﺎ ﻫﻢ و ﺑﺎ ﺷﺮاﯾﻂ ﯾﮑﺴﺎن ﺳﺎﺧﺘﻪ ﺷﺪه و ﻫﻤﺰﻣﺎن ﻣﻮرد ارزﯾﺎﺑﯽ و آزﻣﺎﯾﺶ ﻗﺮار ﮔﺮﻓﺘﻪاﻧﺪ. ارزﯾﺎﺑﯽ ﺑﺮ اﺳﺎس اﺳﺘﺎﻧﺪارد ASHRAE و در ﺟﻨﻮب اﯾﺮان ﺑﻮده اﺳﺖ. آزﻣﺎﯾﺸﺎت ﺑﺮ اﺳﺎس ﺷﺮاﯾﻂ ﻣﺨﺘﻠﻒ ﻣﺤﯿﻄﯽ ﺑﺎ اﺳﺘﻔﺎده از دوﺳﯿﺎل ﻋﺎﻣﻞ آب ﻣﻌﻤﻮﻟﯽ و ﻧﺎﻧﻮﺳﯿﺎل اﮐﺴﯿﺪ روي/آب اﻧﺠﺎم ﺷﺪه اﺳﺖ. ﻧﺘﺎﯾﺞ ﺑﺮرﺳﯽ ﻧﺸﺎن ﻣﯽدﻫﺪ ﮐﻪ ﺑﺎ ﺗﻐﯿﯿﺮ در ﺷﺮاﯾﻂ ﻣﺤﯿﻄﯽ و ﻫﻤﺰﻣﺎن ﺑﺎ اﻓﺰاﯾﺶ ﺗﺎﺑﺶ و ﻫﻤﭽﻨﯿﻦ ﺑﺎ اﻓﺰاﯾﺶ دﺑﯽ ﺑﺎزده ﻫﺮدو ﮐﻠﮑﺘﻮر ﻣﺴﺘﻄﯿﻞ و داﯾﺮوي اﻓﺰاﯾﺶ ﻣﯽ ﯾﺎﺑﺪ؛ وﻟﯽ ﻋﻤﻠﮑﺮد ﮐﻠﮑﺘﻮر داﯾﺮوي ﺑﻬﺘﺮ ﮐﻪ دﻟﯿﻞ اﺻﻠﯽ آن ﺗﺎﺛﯿﺮ ﺟﺮﯾﺎن ﺛﺎﻧﻮﯾﻪ در اﻓﺰاﯾﺶ اﻧﺘﻘﺎل ﺣﺮارت از ﺟﺪار ﻟﻮﻟﻪﻫﺎ ﺑﻪ ﺳﯿﺎل ﻋﺎﻣﻞ اﺳﺖ. ﻋﻼوه ﺑﺮ اﯾﻦ ﻫﻨﮕﺎم اﺳﺘﻔﺎده از ﻧﺎﻧﻮﺳﯿﺎل ﺑﻪ ﺟﺎي آب ﺑﻪ ﻋﻨﻮان ﺳﯿﺎل ﻋﺎﻣﻞ، اﮔﺮﭼﻪ ﺑﺎزده ﻫﺮدو ﮐﻠﮑﺘﻮر اﻓﺰاﯾﺶ ﻣﯽﯾﺎﺑﺪ ﮐﻪ اﻣﺮي ﺑﺪﯾﻬﯽ و اﺛﺒﺎت ﺷﺪه اﺳﺖ، وﻟﯽ ﺗﺎﺛﯿﺮﺟﺮﯾﺎن ﺛﺎﻧﻮﯾﻪ ﺑﺮ اﻧﺘﻘﺎل ﺣﺮارت در اﺳﺘﻔﺎده از ﻧﺎﻧﻮﺳﯿﺎل ﮐﺎﻣﻼ ﭼﺸﻤﮕﯿﺮ ﺑﻮده ﮐﻪ ﺑﻪ دﻟﯿﻞ ﺣﺮﮐﺎت ذرات ﻧﺎﻧﻮﺳﯿﺎل در ﺳﻮﺳﭙﺎﻧﺴﯿﻮن اﯾﻦ ﺗﺎﺛﯿﺮ ﻣﻀﺎﻋﻒ ﻣﯽ ﺷﻮد؛ ﻫﻤﭽﻨﯿﻦ ﺣﺪاﮐﺜﺮ ﺑﺎزده ﺛﺒﺖ ﺷﺪه ﻣﺮﺑﻮط ﺑﻪ ﮐﻠﮑﺘﻮر داﯾﺮهاي ﺑﺎ اﺳﺘﻔﺎده از ﻧﺎﻧﻮﺳﯿﺎل و ﺑﻪ ﻣﯿﺰان 77/6% ﺑﻮده اﺳﺖ.

In this study in order to study the effect of secondary flow on the efficiency of solar collectors, a circular collector with helical tube and a regular collector is constructed and tested at the same time. The assessment was based on the ASHRAE standard and in southern Iran. Experiments were carried out based on different environmental conditions using normal water agent and zinc oxide/ water nanofluid. The results of this study show that with variation in ambient conditions as well as increasing the efficiency and increasing the efficiency of the efficiency of both the circular and rectangle flat plate solar collector performance, the main reason is the secondary flow effect on the enhancement of heat transfer from the tubes to the operating fluid. Also, while using nanofluid instead of water as a factor fluid, although the efficiency of both solar collector is increased, the secondary effect on heat transfer in the use of nanofluid is significantly enhanced due to the motion of particles particles in suspension. In addition, the maximum number of registered solar collector efficiency by using nanofluid was about 77.6% in circular collector.