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Journals / Isı Bilimi ve Tekniği Dergisi / 2020 / Cilt: 40 - Sayı: 2

NATURAL CONVECTION OF ETHYLENE GLYCOL AND WATER MIXTURE BASED AL2O3 NANOFLUIDS BETWEEN VERTICAL CONCENTRIC CYLINDERS

DİK KONSANTRİK SİLİNDİRLER ARASINDAKİ AL2O3-ETİLEN GLİKOL VE SU KARIŞIM BAZLI NANOAKIŞKANLARIN DOĞAL KONVEKSİYONU

Kamil KAHVECİ
Elif ÖĞÜT
Pages
237–250
Publication Date
2020-10-31
DOI
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AI Summary & Key Takeaways

AI Insight
⚡ TL;DR(Too Long; Didn't Read)

The results show that the average Nusselt number shows a considerable increase with an increase in the Rayleigh number and radius ratio.

📌 3 Key Takeaways

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Objective & Hypothesis:Natural convection of ethylene glycol (EG) and water mixture based Al2O3 nanofluids between vertical concentric circular cylinders heated from the inner wall and cooled from the outer wall was investigated numerically in this study.
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Key Findings & Data:The computations were carried for the Rayleigh numbers of 104, 105, 106, and 107, nanoparticle volume fractions of 0%, 4% and 8%, ethylene glycol (EG) to water volume ratios of 0:100 %, 50:50%, and 100:0%, the radius ratios of 2, 3 and 4, and aspect ratios of 0.5, 1, and 2.
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Conclusion & Impact:The results show that the average Nusselt number shows a considerable increase with an increase in the Rayleigh number and radius ratio.
🔬Design:Modeling & Simulation
📍Scope:Comprehensive Sample
⚙️Variables:Doğal konveksiyon · konsentrik silindirler · nanoakışkan

Abstract

Natural convection of ethylene glycol (EG) and water mixture based Al2O3 nanofluids between vertical concentric circular cylinders heated from the inner wall and cooled from the outer wall was investigated numerically in this study. The computations were carried for the Rayleigh numbers of 104, 105, 106, and 107, nanoparticle volume fractions of 0%, 4% and 8%, ethylene glycol (EG) to water volume ratios of 0:100 %, 50:50%, and 100:0%, the radius ratios of 2, 3 and 4, and aspect ratios of 0.5, 1, and 2. The Brinkman model was used to predict the viscosity and the Yu and Choi model for the thermal conductivity of nanofluid. The results show that the average Nusselt number shows a considerable increase with an increase in the Rayleigh number and radius ratio. The results also show that the average Nusselt number shows a medium increase with increasing nanoparticle volume fraction and a slight increase with increasing volume ratios of EG to water. Furthermore, the results show that the average Nusselt number experiences first an increase then a decrease with an increase in the aspect ratio except for the low Ra numbers. Finally, the average Nusselt number experiences a slight increase with the aspect ratio for the low Rayleigh numbers.

Özet

Bu çalışmada iç duvardan ısıtılan ve dış duvardan soğutulan dikey eş merkezli dairesel silindirler arasında etilen glikol (EG) ve su karışım bazlı Al2O3 nanoakışkanların doğal konveksiyonu sayısal olarak incelenmiştir. Hesaplamalarda Rayleigh sayıları 104, 105, 106 ve 107, nanoparçacık hacim fraksiyonları % 0,% 4 ve % 8, etilen glikol (EG) - su hacim oranları %0:100, % 50:50 ve % 100: 0, yarıçap oranları 2, 3 ve 4 ve görünüş oranları 0.5,1 ve 2 olarak alınmıştır. Nanoakışkanın termal iletkenliği için Yu ve Choi modeli ve vikozitesi içinde Brinkman modeli kullanılmıştır. Sonuçlar, ortalama Nusselt sayısının Rayleigh sayısı ve yarıçap oranındaki artışla önemli miktarlarda arttığını göstermektedir. Sonuçlar ayrıca ortalama Nusselt sayısının artan nanoparçacık hacim fraksiyonu ile orta seviyede bir artış ve EG-su hacim oranı artışı ile küçük bir artış sergilediğini göstermektedir. Sonuçlar ayrıca, ortalama Nusselt sayısının düşük Ra sayıları dışında, görünüş oranındaki artışla önce artmakta sonra bir azalma göstermektedir. Son olarak, ortalama Nusselt sayısı düşük Rayleigh sayıları için artan görünüş oranıyla küçük bir artış göstermektedir

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Cite This Article

KAHVECİ, K., ÖĞÜT, E. (2020). NATURAL CONVECTION OF ETHYLENE GLYCOL AND WATER MIXTURE BASED AL2O3 NANOFLUIDS BETWEEN VERTICAL CONCENTRIC CYLINDERS. Isı Bilimi ve Tekniği Dergisi, Cilt: 40 - Sayı: 2, 237–250. https://ajindex.com/articles/133232

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