Improving the natural convective heat transfer of a rectangular heatsink using superhydrophobic walls: A numerical approach

Document Type : Research Paper

Authors

Department of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran

Abstract

The effect of utilizing superhydrophobic walls on improving the convective heat transfer in a rectangular heatsink has been studied numerically in this paper. The vertical walls were kept at isothermal hot-and-cold temperatures and horizontal walls were insulated. The boundary condition on the walls was: no-slip for regular, and slip (with slip length of 500 µm) for superhydrophobic walls. By changing the heatsink aspect ratio (AR, height/width) from 0.1 to 10, it was observed that regardless of the wall slip, the optimum AR is 1, i.e. square enclosure. For a square heatsink, using the nanofluid with  = 3% could enhance the heat transfer (quantified by Nusselt number) by up to 9.8%. For the same enclosure filled with pure water, applying superhydrophobic horizontal walls could increase the heat transfer by 4.45%. The joint effect of using superhydrophobic walls and nano-particles enhanced the heat transfer by up to 14.75%. The results of this paper may open a new avenue for high performance cooling systems.

Keywords


[1] Lim K.O., Lee K.S., Song T.H., Primary and Secondary Instabilities in a Glass-Melting Surface, Numerical Heat Transfer, Part A, Applications (2010).
[2] Patil P. M., Kulkarni P. S., Effects of Chemical Reaction on Free Convective Flow of a Polar Fluid through a Porous Medium in the Presence of Internal Heat Generation, The  International Journal of Thermal Sciences (2008) 47(8):1043–1054.
[3] Lamsaadi M., Naïmi M., Hasnaoui M., Mamou M., Natural Convection in a Vertical Rectangular Cavity Filled with a Non-Newtonian Power Law Fluid and Subjected to a Horizontal Temperature Gradient, Numerical Heat Transfer, Part A, Applications (2006).
[4] Singh S., Sharif M. A. R., Mixed Convective Cooling of a Rectangular Cavity with Inlet and Exit Openings on Differentially Heated Side Walls, Numerical Heat Transfer: Part A Applications (2003) 44(3):233–253.
[5] Iwanik P. O., Chiu W. K. S., Temperature Distribution of an Optical Fiber Traversing through a Chemical Vapor Deposition Reactor, Numerical Heat Transfer: Part A Applications (2003) 43(3):221–237.
[6] Saha L. K., Hossain M. A., Gorla R. S. R., Effect of Hall Current on the MHD Laminar Natural Convection Flow from a Vertical Permeable Flat Plate with Uniform Surface Temperature,Journal of Thermal Science (2007) 46(8): 790–801.
[7] Yan Y. Y., Zhang H. B., Hull J. B., Nmrical Modeling of  Electrohydrodynamic (EHD) Effect on Natural Convection in an  Enclosure, Numerical Heat Transfer: Part A Applications (2004) 46(5): 453–471.
[8] Incropera F. P., Convection Heat Transfer in Electronic Equipment Cooling, The Journal of Heat Transfer (1988) 110(4b):1097.
[9] Go J. S., Kim S. J., Lim G., Yun H., Lee J., Song I., Pak Y. E., Heat Transfer Enhancement Using Flow-Induced Vibration of a Microfin Array, Sensors and Actuators A: Physical (2001) 90(3):232–239.
[10] Air Cooling Technology for Electronic Equipment. CRC Press (1996).
[11] Wang X. Q., Mujumdar A. S., Heat Transfer Characteristics of NanoFluids: A Review, The  International Journal of Thermal Sciences (2007) 46 (1): 1–19.
[12] Hamilton R. L., Crosser O. K., Thermal Conductivity of Heterogeneous Two-Component Systems (2002).
[13] Wasp E.J., Kenny J.P., Gandhi R.L., Solid–Liquid Slurry Pipeline Transportation, Bulk Material Handling Trans Tech Publications (1999).
[14] Xuan Y., Roetzel W., Conceptions for Heat Transfer Correlation of Nanofluids, International Journal of Heat and Mass Transfer (2000) 43(19): 3701–3707.
[15] Khanafer K., Vafai K., Lightstone M., Buoyancy-Driven Heat Transfer Enhancement in a Two-Dimensional Enclosure Utilizing Nanofluids, International Journal of Heat and Mass Transfer (2003) 46(19): 3639–3653.
[16] Einstein A., Investigations on the Theory of the Brownian Movement. Courier Corporation (1956).
[17] Brinkman H. C., The Viscosity of Concentrated Suspensions and Solutions, The Journal of Chemical Physics (1952) 20 (4): 571.
[18] Hwang K. S., Lee J.-H., Jang S. P., Buoyancy-Driven Heat Transfer of Water-Based Al2O3 Nanofluids in a Rectangular Cavity, International Journal of Heat and Mass Transfer (2007) 50(19–20): 4003–4010.
[19] Fattahi E., Farhadi M., Sedighi K., Nemati H., Lattice Boltzmann Simulation of Natural Convection Heat Transfer in Nanofluids, The International Journal of Thermal Sciences (2012) 52(1): 137–144.
[20] Panitapu B., Reddy K. K. T., Ramesh M., Reddy K. S., Heat Transfer Enhancement in Natural Convection Using Water Based Fe3O4 Nanofluid Inside a Square Cavity. International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics (2014).
[21] Afrand M., Toghraie D., Sina N., Experimental Study on Thermal Conductivity of Water-Based Fe3O4 Nanofluid: Development of a New Correlation and Modeled by Artificial Neural Network, International Communications  in  Heat  and  Mass Transfer (2016) 75: 262–269.
[22] Betz A. R., Jenkins J., Kim C.-J., Attinger D., Boiling Heat Transfer on Superhydrophilic, Superhydrophobic, and Superbiphilic Surfaces, International Journal of Heat and Mass Transfer(2013)57(2): 733–741.
[23] Li F. C., Kawaguchi Y., Yu B., Wei J. J., Hishida K., Experimental Study of Drag-reduction Mechanism for a Dilute Surfactant Solution Flow, International Journal of Heat and Mass Transfer (2008) 51(3–4): 835–843.
[24] Choi C., Kim M., Wettability Effects on Heat Transfer (2010).
[25] McHale G., Shirtcliffe N. J., Newton M. I., Contact-Angle Hysteresis on Super-Hydrophobic Surfaces, Langmuir (2004) 20(23):10146–10149.
[26] Nakajima A., Hashimoto K., Watanabe T., Takai K., Yamauchi G., Fujishima A., Transparent Superhydrophobic Thin Films with Self-Cleaning Properties, Langmuir (2000) 16(17): 7044–7047.
[27] Bhushan P. B., Jung Y. C., Lotus Effect : Surfaces with Roughness- y y Self-Cleaning g Induced Superhydrophobicity , and Low Adhesion Prof Bharat Bhushan Biomimetics- examples from nature.
[28] Zheng S., Li C., Fu Q., Hu W., Xiang T., Wang Q., Du M., Liu X., Chen Z., Development of Stable Superhydrophobic Coatings on Aluminum Surface for Corrosion-Resistant, Self-Cleaning, and Anti-Icing Applications, Materials & Design (2016) 93: 261–270.
[29] Goharkhah M., Ashjaee M., Effect of an Alternating Nonuniform Magnetic Field on Ferrofluid Flow and Heat Transfer in a Channel, The Journal of Magnetism and Magnetic Materials (2014) 362: 80–89.
[30] Xu X., Yu Z., Hu Y., Fan L., Cen K., A Numerical Study of Laminar Natural Convective Heat Transfer Around a Horizontal Cylinder Inside a Concentric Air-Filled Triangular Enclosure, International Journal of Heat and Mass Transfer (2010) 53(1): 345–355.
[31] Sojoudi A., Saha S. C., Xu F., Gu Y. T., Transient Air Flow and Heat Transfer Due to Differential Heating on Inclined Walls and Heat Source Placed on the Bottom Wall in a Partitioned Attic Shaped Space (2016) 113:39–50.
[32] De Vahl Davis G., Natural Convection of Air in a Square Cavity: A Bench Mark Numerical Solution, The International Journal for Numerical Methods in Fluids (1983) 3(3): 249–264.
[33] Incropera F. P., DeWitt D. P., Introduction to Heat Transfer, 6th Edition, New York: J. Wiley (1990).