TY - JOUR
T1 - Natural convection heat transfer of alumina-water nanofluid in vertical square enclosures
T2 - An experimental study
AU - Ho, C. J.
AU - Liu, W. K.
AU - Chang, Y. S.
AU - Lin, C. C.
N1 - Funding Information:
The present study is supported by the National Science Council of ROC in Taiwan through the projects: NSC93-2212-E006-013, NSC94-2212-E006-101, and NSC95-2212-E006-232. The constructive comments of the reviewer are sincerely appreciated.
PY - 2010
Y1 - 2010
N2 - An experimental study has been undertaken concerning natural convection heat transfer of a nanofluid in vertical square enclosures of different sizes, whose dimensions, width × height × length (mm), are 25 × 25 × 60, 40 × 40 × 90, and 80 × 80 × 180, respectively. The nanofluid formulated in the present experiment is water dispersed with various volumetric fractions of the alumina (Al2O3) nanoparticles ranging from 0.1 vol.% to 4 vol.%. The Rayleigh number varies in the range of 6.21 × 105-2.56 × 108. A correlation analysis based on the thermophysical properties of the nanofluid formulated shows that efficacy of applying the nanofluid for natural convection heat transfer enhancement in enclosure is inferred to be generally infeasible. The experimental results for the average heat transfer rate across the three enclosures appear generally consistent with the assessment based on the changes in thermophysical properties of the nanofluid formulated, showing systematic heat transfer degradation for the nanofluids containing nanoparticles of c v ≥ 2 vol.% over the entire range of the Rayleigh number considered. However, for the nanofluid containing much lower particle fraction of 0.1 vol.%, a heat transfer enhancement of around 18% compared with that of water was found to arise in the largest enclosure at sufficiently high Rayleigh number. Such enhancement cannot be explained simply based on the net influence due to relative changes in thermophysical properties of the nanofluid containing such low particle fraction, thus strongly suggesting other factors may come into play.
AB - An experimental study has been undertaken concerning natural convection heat transfer of a nanofluid in vertical square enclosures of different sizes, whose dimensions, width × height × length (mm), are 25 × 25 × 60, 40 × 40 × 90, and 80 × 80 × 180, respectively. The nanofluid formulated in the present experiment is water dispersed with various volumetric fractions of the alumina (Al2O3) nanoparticles ranging from 0.1 vol.% to 4 vol.%. The Rayleigh number varies in the range of 6.21 × 105-2.56 × 108. A correlation analysis based on the thermophysical properties of the nanofluid formulated shows that efficacy of applying the nanofluid for natural convection heat transfer enhancement in enclosure is inferred to be generally infeasible. The experimental results for the average heat transfer rate across the three enclosures appear generally consistent with the assessment based on the changes in thermophysical properties of the nanofluid formulated, showing systematic heat transfer degradation for the nanofluids containing nanoparticles of c v ≥ 2 vol.% over the entire range of the Rayleigh number considered. However, for the nanofluid containing much lower particle fraction of 0.1 vol.%, a heat transfer enhancement of around 18% compared with that of water was found to arise in the largest enclosure at sufficiently high Rayleigh number. Such enhancement cannot be explained simply based on the net influence due to relative changes in thermophysical properties of the nanofluid containing such low particle fraction, thus strongly suggesting other factors may come into play.
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U2 - 10.1016/j.ijthermalsci.2010.02.013
DO - 10.1016/j.ijthermalsci.2010.02.013
M3 - Article
AN - SCOPUS:79957544319
SN - 1290-0729
VL - 49
SP - 1345
EP - 1353
JO - International Journal of Thermal Sciences
JF - International Journal of Thermal Sciences
IS - 8
ER -