TY - JOUR
T1 - Experimental investigation of free convection in a vertical rod bundle—a general correlation for nusselt numbers
AU - Keyhani, M.
AU - Kulacki, F. A.
AU - Christensen, R. N.
PY - 1985/8
Y1 - 1985/8
N2 - Free convection in two vertical, enclosed rod bundles has been experimentally investigated for a wide range of Rayleigh numbers. A uniform power dissipation per unit length is supplied to each rod, and the enclosing outer cylinder is maintained at constant temperature. Nusselt numbers for each rod, as well as an overall value for each bundle, have been obtained as a function of Rayleigh number. Comparison of the results for air and water as the working fluid indicate that, for a fixed Rayleigh number, an increase in the Prandtl number produces a reduction in the Nusselt number. This is contrary to what has been reported for vertical cavities and is attributed to curvature effects. Furthermore, the data reveal the interesting fact that it is quite possible for the individual rods in the bundle to exchange energy with the working fluid via different but coexisting regimes at a given power dissipation. Also, as the Rayleigh number is increased, the rods each tend to assume nearly the same heat transfer coefficient. Finally, a correlation for the overall convective Nusselt number is developed in terms of Rayleigh number and geometric parameters.
AB - Free convection in two vertical, enclosed rod bundles has been experimentally investigated for a wide range of Rayleigh numbers. A uniform power dissipation per unit length is supplied to each rod, and the enclosing outer cylinder is maintained at constant temperature. Nusselt numbers for each rod, as well as an overall value for each bundle, have been obtained as a function of Rayleigh number. Comparison of the results for air and water as the working fluid indicate that, for a fixed Rayleigh number, an increase in the Prandtl number produces a reduction in the Nusselt number. This is contrary to what has been reported for vertical cavities and is attributed to curvature effects. Furthermore, the data reveal the interesting fact that it is quite possible for the individual rods in the bundle to exchange energy with the working fluid via different but coexisting regimes at a given power dissipation. Also, as the Rayleigh number is increased, the rods each tend to assume nearly the same heat transfer coefficient. Finally, a correlation for the overall convective Nusselt number is developed in terms of Rayleigh number and geometric parameters.
UR - http://www.scopus.com/inward/record.url?scp=0022111291&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0022111291&partnerID=8YFLogxK
U2 - 10.1115/1.3247468
DO - 10.1115/1.3247468
M3 - Article
AN - SCOPUS:0022111291
SN - 0022-1481
VL - 107
SP - 611
EP - 623
JO - Journal of Heat Transfer
JF - Journal of Heat Transfer
IS - 3
ER -