This paper presents a systematic experimental method of studying the heat transfer behavior of buoyancy-driven nanofluids. The presence of nanoparticles in buoyancy-driven flows affects the thermophysical properties of the fluid and consequently alters the rate of heat transfer. The focus of this paper is to estimate the range of volume fractions that results in maximum thermal enhancement and the impact of volume fraction on Nusselt number. The test cell for the nanofluid is a two-dimensional rectangular enclosure with differentially heated vertical walls and adiabatic horizontal walls filled with 27 nm – nanofluid. Simulations were performed to measure the transient and steady-state thermal response of nanofluid to imposed isothermal condition. The volume fraction is varied between 0% and 8%. It is observed that the trend of the temporal and spatial evolution of temperature profile for the nanofluid mimics that of the carrier fluid. Hence, the behaviors of both fluids are similar. Results shows that for small volume fraction, the presence of the nanoparticles does not impede the free convective heat transfer, rather it augments the rate of heat transfer. However, for large volume fraction , the convective heat transfer coefficient declines due to reduction in the Rayleigh number caused by increase in kinematic viscosity. Also, an empirical correlation for as a function of and Ra has been developed, and it is observed that the nanoparticle enhances heat transfer rate even at a small volume fraction.
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e-mail: nnanna@calumet.purdue.edu
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Technical Papers
Experimental Model of Temperature-Driven Nanofluid
A. G. Agwu Nnanna
A. G. Agwu Nnanna
Department of Mechanical Engineering, Micro- and Nano-scale Heat Transfer Laboratory,
e-mail: nnanna@calumet.purdue.edu
Purdue University Calumet
, Hammond, IN 46323-2094
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A. G. Agwu Nnanna
Department of Mechanical Engineering, Micro- and Nano-scale Heat Transfer Laboratory,
Purdue University Calumet
, Hammond, IN 46323-2094e-mail: nnanna@calumet.purdue.edu
J. Heat Transfer. Jun 2007, 129(6): 697-704 (8 pages)
Published Online: September 12, 2006
Article history
Received:
September 6, 2005
Revised:
September 12, 2006
Citation
Nnanna, A. G. A. (September 12, 2006). "Experimental Model of Temperature-Driven Nanofluid." ASME. J. Heat Transfer. June 2007; 129(6): 697–704. https://doi.org/10.1115/1.2717239
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