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

Öz

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

Anahtar Kelimeler

• Doğal konveksiyon
• konsentrik silindirler
• nanoakışkan
• Al2O3
• etilen glikol
• su
• Rayleigh sayısı
• Nusselt sayısı

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

Öz

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.

Anahtar Kelimeler

• Natural convection
• concentric cylinders
• nanofluid
• Al2O3
• ethylene glycol
• water
• Rayleigh number
• Nusselt number

Kaynakça

1. Alawi O.A., Sidik N.A.C. and Dawood H.K., 2014, Natural Convection Heat Transfer in Horizontal Concentric Annulus Between Outer Cylinder and İnner Flat Tube using Nanofluid, Int. Comm. in Heat and Mass Transfer, 5765–5771.
2. Abu-Nada E., Masoud Z. and Hijazi A., 2008, Natural Convection Heat Transfer Enhancement in Horizontal Concentric Annuli using Nanofluids, Int. Comm. in Heat and Mass Transfer, 35, 657–665.
3. Brinkman, H.C., 1952, The Viscosity of Concentrated Suspensions and Solutions, J. Chem. Phys., 4, 571–581.
4. Cabaleiro D, Colla L., Agresti F., Lugo L. and Fedele L. 2015, Transport Properties and Heat Transfer Coefficients of ZnO/(ethylene glycol + water) Nanofluids, Int. J. of Heat and Mass Transfer, 89, 433–443.
5. Chen W.C., Chen Y.F. and Cheng W.T., 2016, Numerical Simulation on Forced Thermal Flow of Nanofluid in the Gap between Co-axial Cylinders with Rotational inner Spindle, Int. J. of Heat and Mass Transfer, 102,971–979.
6. Cianfrini M., Corcione M. and Quintino A., 2011, Natural Convection Heat Transfer of Nanofluids in Annular Spaces between Horizontal Cconcentric Cylinders, Appl. Thermal Engineering, 3,14055-4063. Davis G. de Vahl and Thomas R. W., 1969, Natural Convection between Concentric Vertical Cylinders, Physics of Fluids 12, 198- 207.
7. Dawood H.K., Mohammed H.A., Sidik N.A.C., Munisamy K.M. and Alawi O.A., 2017, Heat Transfer Augmentation in Cconcentric Elliptic Annular by Ethyleneglycol Based Nanofluids, Int. Comm. in Heat and Mass Transfer, 82, 29–39.
8. Fuchs, L. and Eguchi, Y. 1988, On the Accuracy of Finite-Difference and Finite-Element Methods for the Simulation of Some Incompressible Flows. Computational Mechanics 4, 105–114.

9. Haq R.U., Shahzad F Al-Mdallal. and Q.M., 2017, MHD Pulsatile Flow of Engine Oil Based Carbon Nanotubes Between Two Concentric Cylinders, Results in Physics, 7, 57–68.
10. Hajmohammadi M.R., 2017, Cylindrical Couette Flow and Heat Transfer Properties of Nanofluids; Single-Phase and Two-Phase Analyses, J. of Molecular Liquids, 240, 45–55
11. Heris S.Z., Shokrgozar M., Poorpharhang S., Shanbedi M. and Noie S.H., 2014, Experimental Study of Heat Transfer of a Car Radiator with Cuo/Ethylene Glycol-Water as a Coolant, J. Disper. Sci. Technol., 35, 677–684.
12. Hinge H., Chaudhri P. E., Barhatte S. H. and Dhokane N. 2017, Boiling Heat Transfer Enhancement of Heat Pipe Using Nanofluid , Int. Journal of Curr. Engineering and Technol., 7, 244-251.
13. Jiajan W., 2010, Solution to Incompressible Navier Stokes Equations by using Finite Element Method, Ms Thesis, The University of Texas at Arlington, USA.
14. Keblinski P., Phillpot SR, Choi S.U.S. and Eastman J.A., 2002, Mechanisms of Heat Flow in Suspensions of Nano-Sized Particles (Nanofluids), Int. J. Heat Mass Transfer 45, 855–863.
15. Maghlany W.M.E. and Elazm M.M.A., 2016, Influence of Nanoparticles on Mixed Convection Heat Transfer in an Eccentric Horizontal Annulus with Rotating İnner Cylinder, J. of the Taiwan Institute of Chemical Engineers, 63,259–270.
16. Mitra S.K, Chakraborty S., 2011, Microfluidics and Nanofluidics Handbook, 2 Volume Set 1st Edition, CRC Press Published, September 20.
17. Özdemir K. and Öğüt E. 2019, Hydro-Thermal Behaviour Determination and Optimization of Fully Developed Turbulent Flow in Horizontal Concentric Annulus with Ethylene Glycol and Water Mixture Based Al2O3 Nanofluids, Int. Comm. in Heat and Mass Transfer, 109,1-13. Öztuna S., Kahveci K. and Tanju B.T., 2011, Natural Convection of Water-Based CuO Nanofluid Between Concentric Cylinders, Recent Advances in Fluid Mechanics and Heat & Mass Transfer, Florence, Italy, 164-169.
18. Said Z., Sajid M.H., Alim M.A., Saidur R.and Rahim N.A., 2013, Experimental Investigation of The Thermophysical Properties of Al2O3-Nanofluid and its Effect on a Flat Plate Solar Collector, Int. Comm. in Heat and Mass Transfer, 48, 99–107.
19. Sasmal C., 2017, Effects of Axis Ratio, Nanoparticle Volume Fraction and its size on The Momentum and Heat Transfer Phenomena from an Elliptic Cylinder in Water-Based CuO Nanofluids, Powder Technology, 313, 272–286.
20. Selimefendigil F. and Öztop H.F., 2017, Conjugate Natural Convection in Nanofluid Filled Partitioned Horizontal Annulus Formed by Two Isothermal Cylinder Surfaces under Magnetic Field, Int. J. of Heat and Mass Transfer, 108, 156–171.
21. Srinivasacharya D. and Shafeeurrahman Md., 2017, Hall and Ion Slip Effects On Mixed Convection Flow of Nanofluid Between Two Concentric Cylinders, J. of the Association of Arab Universities for Basic and Applied Sciences, 24, 223–230.
22. Togun H., Abu-Mulaweh H.I., Kazi S.N. and Badarudin A., 2016, Numerical Simulation of Heat Transfer and Separation Al2O3/Nanofluid Flow in Concentric Annular Pipe, Int. Comm. in Heat and Mass Transfer, 71, 108–117.
23. Turkyilmazoglu M., 2015, Anomalous Heat Transfer Enhancement by Slip Due To Nanofluids in Circular Concentric Pipes, Int. J. of Heat and Mass Transfer 85, 609–614.
24. Wu W., Zhou Z., Aubry N., Antaki J.F. and Massoudi M., 2017, Heat Transfer and Flow of a Dense Suspension Between Two Cylinders, Int. J. of Heat and Mass Transfer, 112, 597–606.
25. Xuan, Y. and Roetzel, W., 2000, Conceptions for Heat Transfer Correlation of Nanofluids, Int. J. Heat Mass Transfer, 43,3701–3707.
26. Yu W. and Choi S.U.S., 2003, The Role of Interfacial Layer in The Enhanced Thermal Conductivity of Nanofluids: a Renovated Maxwell Model, J Nanoparticles Res,, 5, 167–171.
27. Yu Z., Xu X., Hu Y., Fan L. and Cen K., 2012, A Numerical Investigation of Transient Natural Convection Heat Transfer of Aqueous Nanofluids in a Horizontal Concentric Annulus, Int. J. of Heat and Mass Transfer, 55, 1141–1148