Journal of Applied and Computational Mechanics

Effect of Variable Thermal Expansion Coefficient and Nanofluid Properties on Steady Natural Convection in an Enclosure

Document Type : Research Paper

Authors

1 Department of Energy Engineering and Physics, Amirkabir University of Technology (Tehran Polytechnic), Tehran, Islamic Republic of Iran

2 University of Calgary, Canada

3 Department of Mathematics, Isfahan (Khorasgan) Branch, Islamic Azad University, Isfahan, Iran

Abstract

Steady state natural convection is numerically investigated in an enclosure using variable thermal conductivity, viscosity and thermal expansion coefficient of Al2O3–water nanofluid. This study has been conducted for a wide range of Rayleigh numbers (103≤ Ra ≤ 106), concentrations of nanoparticles (0% ≤ Φ ≤ 7%), enclosure aspect ratios (0.5 ≤ AR ≤ 2) and temperature differences between the cold and the hot walls (1≤ ∆T≤ 30). The main idea in this study is about the effect of temperature on natural convection pattern of nanofluid by changing nanoparticles concentration. Also, changing thermal expansion coefficient with temperature is considerd in this study which will have significant effects on natural convection and has not been considerd before. In low Rayleigh numbers (Ra= 103) and for cavities with AR≥1, the pattern shown in the average Nusselt number versus volume fraction of nanoparticles diagram deteriorates by increasing ∆T. However, for other cases, increasing ∆T has a positive effect on Nu-Φ diagram. The actual Nuselt number curve depicts that dispersing nanoparticles in base fluid deteriorate natural convection heat transfer which is in a good agreement with experimental works.

Keywords

Main Subjects

[1] Vahl Davis, G.D. Natural convection of air in a square cavity, a benchmark numerical solution, Int. J. Numer. Methods Fluids, 3, 1962, pp. 249–264.
[2] Fusegi, T., Hyun, J.M., Kuwahara, K. Farouk, B. A numerical study of three-dimensional natural convection in a differentially heated cubical enclosure, Int. J. Heat Mass Transfer, 34, 1991, pp. 1543–1557.
[3] Barakos, G. Mitsoulis, E. Natural convection flow in a square cavity revisited: laminar and turbulent models with wall functions, Int. J. Numer. Methods Fluids, 18, 1994, pp. 695–719.
[4] Choi, U.S. Enhancing thermal conductivity of fluids with nanoparticles, ASME Fluids Engineering Division, 231, 1995, pp. 99–103.
[5] Xuan, Y., Roetzel, W. Conceptions for heat transfer correlation of nanofluids, Int. J. Heat Mass Transfer, 43, 2000, pp.3701–3707.
[6] Khanafer, K., Vafai, K. Lightstone, M. Buoyancy-driven heat transfer enhancement in a two-dimensional enclosure utilizing nanofluids, Int. J. Heat Mass Transfer, 46, 2003, pp. 3639–3653.
[7] Gosselin, L. da Silva, A.K. Combined heat transfer and power dissipation optimization of nanofluid flows, Appl. Phys. Lett., 85, 2004, pp.4160–4162.
[8] Brinkman, H.C. The viscosity of concentrated suspensions and solutions, J. Chem. Phys., 20, 1952, pp.571–581.
[9] Polidori, G., Fohanno, S. Nguyen, C.T. A note on heat transfer modeling of Newtonian nanofluids in laminar free convection, Int. J. Thermal Sciences, 46, 2007, pp. 739–744.
[10] Ho, C.J., Chen, M.W. Li, Z. W. Numerical simulation of natural convection of nanofluid in a square enclosure: Effects due to uncertainties of viscosity and thermal conductivity, Int. J. Heat and Mass Transfer, 51, 2008, pp. 4506–4516.
[11] Maiga, S.E.B., Nguyen, C.T., Galanis, N., Roy, G. Heat transfer behaviors of nanofluids in a uniformly heated tube, Superlattices and Microstructures, 35, 2004, pp. 543–557.
[12] Aminossadati, S.M. Ghasemi, B. Natural convection of water–CuO nanofluid in a cavity with two pairs of heat source–sink, Int. Comm. in Heat and Mass Transfer, 38, 2011, pp. 672-678.
[13] Koo, J. Kleinstreuer, C. A new thermal conductivity model for nanofluids, J. Nanoparticle Research, 6(6), 2004, pp. 577–588.
[14] Koo, J. Kleinstreuer, C. Laminar nanofluid flow in micro heat-sinks, Int. J. Heat and Mass Transfer, 48(13), 2005, pp. 2652–2661.
[15] Abu-Nada, E., Masoud, Z., Oztop, H.F. Campo, A. Effect of nanofluid variable properties on natural convection in enclosures, Int. J. Thermal Sciences, 49, 2010, pp. 479–491.
[16] Nnanna, A.G.A., Fistrovich, T., Malinski, K. Choi, S.U.S. Thermal transport phenomena in buoyancy-driven nanofluids, Proc. ASME Int. Mech. Eng. Congress RDD Expo., IMECE2004-62059, Anaheim, CA, 2004, pp. 1-8.
[17] Nnanna, A.G.A. Routhu, M. Transport phenomena in buoyancy driven nanofluids Part II, Proc. ASME Summer Heat Transfer Conf., SHTC— 72782, San Francisco, CA, 2005, pp. 1–8.
[18] Putra, N., Roetzel, W. Das, S.K. Natural convection of nanofluids, Heat Mass Transfer, 39, 2003, pp. 775–784.
[19] Wen, D. Ding, Y. Formulation of nanofluids for natural convective heat transfer applications, Int. J. Heat and Fluid Flow, 26, 2005, pp. 855–864.
[20] Wen, D. Ding, Y. Natural convection heat transfer of suspensions of titanium dioxide nanoparticles (nanofluids), IEEE Trans. Nanotechnol., 5(3), 2006, pp. 220–227.
[21] Li, C.H. Peterson, G.P. Experimental studies of natural convection heat transfer of Al2O3/DI water nanoparticle suspensions (nanofluids), Advances in Mechanical Engineering, 2010, Article ID 742739.
[22] Hu, Y., He, Y., Wang, S., Wang, Q. Schlaberg, H.I. Experimental and numerical investigation on natural convection heat transfer of Tio2–Water nanofluids in a square enclosure, ASME Journal of Heat Transfer, 136, 2014, Article ID 022502.
[23] Nnanna, A.G.A. Experimental model of temperature-driven nanofluid, ASME Journal of Heat Transfer, 129, 2007, pp.697–704.
[24] Ho, C.J., Liu, W.K., Chang, Y.S. Lin, C.C. Natural convection heat transfer of alumina-water nanofluid in vertical square enclosures: An experimental study, Int. J. Thermal Sciences, 49, 2010, pp.1345–1353.
[25] Corcione, M. Heat transfer features of buoyancy-driven nanofluids inside rectangular enclosures differentially heated at the sidewalls, Int. J. Thermal Sciences, 49, 2010, pp.1536–1546.
[26] Kestin, J., Sokolov, M. Wakeham, W.A. Viscosity of liquid water in the range -8 °C to 150 °C., J. Phys. Ref. Data, 7(3), 1978, pp. 941–948.
[27] Sharqawy, M.H. New correlations for seawater and pure water thermal conductivity at different temperatures and salinities, Desalination, 313, 2013, pp. 97–104.
[28] Patankar, S.V. Numerical Heat Transfer and Fluid Flow, Hemisphere Publishing Corporation, Taylor and Francis Group, New York, 1980.
[29] Versteeg, H.K. Malalasekera, W. An Introduction to Computational Fluid Dynamic: The Finite Volume Method, John Wiley Sons Inc., New York, 1995.
[30] Fusegi, T. Hyun, J.M. Laminar, Transitional natural convection in an enclosure with complex, realistic conditions, Int. J. Heat Fluid Flow, 15, 1994, pp. 258–268.
[31] Abu-Nada, E. Effects of variable viscosity and thermal conductivity of Al2o3–water nanofluid on heat transfer enhancement in natural convection, Int. J. Heat and Fluid Flow, 30, 2009, pp. 679–690.
[32] Abu-Nada, E. Chamkha, A.J. Effect of nanofluid variable properties on natural convection in enclosures filled with a CuO-EG-Water nanofluid, Int. J. Thermal Sciences, 49, 2010, pp. 2339–2352.
Journal of Applied and Computational Mechanics
Volume 3, Issue 4
October 2017
Pages 240-250