Forced and mixed convection heat transfer to supercritical CO{sub 2} vertically flowing in a uniformly-heated circular tube

• Published in: Experimental thermal and fluid science 2010-11, Vol.34 (8)
• Main Authors: Bae, Yoon-Yeong, Kim, Hwan-Yeol, Kang, Deog-Ji
• Format: Article
• Language: English
• Subjects: CARBON DIOXIDE; CONVECTION; CORRELATIONS; DATA COVARIANCES; ENGINEERING; EXPERIMENTAL DATA; FORCED CONVECTION; FUEL ASSEMBLIES; GENERAL STUDIES OF NUCLEAR REACTORS; HEAT FLUX; MASS; NUSSELT NUMBER; PRESSURE RANGE MEGA PA 01-10; REACTOR COOLING SYSTEMS; REYNOLDS NUMBER; Supercritical pressure; SUPERCRITICAL STATE; TUBES; Vertical flow
• ISSN: 0894-1777; 1879-2286
• DOI: 10.1016/J.EXPTHERMFLUSCI.2010.06.001

An experiment of heat transfer to CO{sub 2}, which flows upward and downward in a circular tube with an inner diameter of 6.32 mm, was carried out with mass flux of 285-1200 kg/m{sup 2} s and heat flux of 30-170 kW/m{sup 2} at pressures of 7.75 and 8.12 MPa, respectively. The corresponding Reynolds number at the tube test section inlet ranges from 1.8 x 10{sup 4} to 3.8 x 10{sup 5}. The tube inner diameter corresponds to the equivalent hydraulic diameter of the fuel assembly sub-channel, which is being studied at KAERI. Among the tested correlations, the Bishop correlation predicted the experimental data most accurately, but only 66.9% of normal heat transfer data were predicted within {+-}30% error range. The Watts and Chou correlation, which is claimed to be valid for both the normal and deteriorated heat transfer regime, showed unsatisfactory performance. A significant decrease in Nusselt number was observed in the range of 10{sup -6}