Free convective heat transfer to fluids in the near-critical region from vertical surfaces with uniform heat flux

Abstract

Numerical predictions are made for laminar free convective heat transfer to fluids in the nearcritical region from a vertical flat plate with uniform surface heat flux. The variation of all the thermophysical properties have been taken into consideration. The governing equations are integrated using the Patankar-Spalding implicit finite difference scheme. Computations are made for carbon dioxide at pressures of 75 ( P P cr = 1.015 ), 80 ( P P cr = 1.083 ) and 100 ( P P cr = 1.354 ) bar and for water at pressures of 225 ( P P cr = 1.018 ) and 245 ( P P cr = 1.108 ) bar, for various values of wall-heat flux ranging from 1000 W/M 2 to 50 000W/M 2. Based on the results obtained, a correlation has been proposed to evaluate the local heat-transfer coefficient for a wide range of Rayleigh numbers ( Ra ∞ = 5 × 10 6−5 × 10 10).