Author:
Zhen Qi,Tana ,Sun Yunfeng,Yan Caixia,Wang Hongzhi
Abstract
AbstractThe work numerically investigated laminar natural convection heat transfer from the single sphere with a constant heat flux surface in air over the wide range of Grashof number ($$10 \le Gr \le 10^{7}$$
10
≤
G
r
≤
10
7
). The more efficient and precise numerical method based on Bejan et al. was employed here, the accuracy of which has been confirmed through validation against a single sphere case. The heat transfer characteristics were systemically analyzed in terms of isothermal contours and streamlines around the sphere, dimensionless temperature and velocity profiles. Additionally, local Nusselt number as well as local pressure and friction drag coefficients were studied with different Grashof number. In comparison to the sphere with uniform heat flux surface, the heat transfer from the isothermal sphere was found to be enhanced attributable to a more robust buoyancy force and a steeper temperature gradient. Moreover, the average Nusselt number for the sphere with a constant heat flux between 60.4 and 98.6% of the isothermal sphere’s value, this range being contingent upon the specific Grashof number. What’s more, the proposed correlation addresses a notable void in the predictive understanding of heat transfer from the sphere with uniform heat flux, which is scenario prevalent in various engineering applications, particularly for the cooling of electrical and nuclear systems, and offer values for academic research.
Funder
Natural Science Foundation of Inner Mongolia
Basic Research Fund Project for Directly Affiliated Universities of Inner Mongolia
Publisher
Springer Science and Business Media LLC
Reference40 articles.
1. Baek, S. I., Moon, J. Y. & Chung, B. J. Natural convective heat transfer influence between two spheres in a packed bed. Int. Commun. Heat Mass Transf. 139, 106430 (2022).
2. Noah, O. O., Slabber, J. F. & Meyer, J. P. Investigation of natural convection heat-transfer phenomena in packed beds: Lead-way toward new nuclear fuel design. ASME J. Nucl. Eng. Rad. Sci. 1(4), 041014 (2015).
3. Zhu, J. & Chen, F. A CFD method for thermal-hydraulic calculation of pebble bed HTGRs. In Proceedings of 29th International Conference on Nuclear Engineering, (ICONE 29) Vol. 86434, V008T08A015 (2022).
4. Chen, R. et al. Numerical analysis of the granular flow and heat transfer in the ADS granular spallation target. Nucl. Eng. Des. 330, 59–71 (2018).
5. Bejan, A. Convection Heat Transfer (Wiley, 2013).