Optimal Design Of The Concentric Annulus For The Solar Collectors And Energy Storage

Amina Hmoud Alikhan; Khaleel  Saleem Jebur Al-Ogaili; Hadi  Obaid Mery; Osamah  Malik Mohammed; Mohammed  Arkan Al-attabbi

doi:10.31185/ejuow.Vol12.Iss3.570

Authors

Amina Hmoud Alikhan Wasit University
Khaleel Saleem Jebur Al-Ogaili
Hadi Obaid Mery
Osamah Malik Mohammed
Mohammed Arkan Al-attabbi

DOI:

https://doi.org/10.31185/ejuow.Vol12.Iss3.570

Keywords:

Natural convective flow; isothermal concentric cylinders; Silica sand; Radius ratios; Heat transfer; Rayleigh number

Abstract

Heat exchangers with uniform heating ensure even heat distribution, improving heat transfer efficiency and lowering thermal stress. It contributes to increasing the effectiveness of solar energy conversion into thermal energy in solar collectors, improving system performance and sustainability. It is essential for enhancing performance in both home and industrial applications because of these advantages. An experimental investigation was conducted to study the natural convective flow between two isothermal concentric cylinders filled with porous media (silica sand) and equipped with annular fins attached to the inner cylinder. The fins varied in length (Hf = 3, 7, and 11 mm), and the radius ratios (Rr) between the cylinders were also considered during the study. This work examines and discusses the effects of independent characteristics, such as fin height (Hf), radius ratio (Rr), and Rayleigh number (Ra) from 10 to 500, on heat transfer outcomes. As the distance between the two cylinders expands, the average Nu remains relatively constant for low values of Ra. However, as Ra approaches 100, the average Nu increases. These values also rose when Rr decreased for the hot cylinder and vice versa for the cold cylinder. The average Nusselt number versus Ra was analyzed in graphical form to show the effect of the fin number on the average Nusselt number. The analysis includes a range of fin numbers. It is found that as the amount of fins increases from n = 12 to n = 23 and eventually to n = 45, there is a decrease in the average Nusselt number. The decrease in average Nusselt number can range from 19.2% to 26.6% for the same value of Ra.

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