Numerical Predictions of Laminar Forced Convection Heat Transfer with and without Buoyancy Effects from an Isothermal Horizontal Flat Plate to Supercritical Nitrogen

Numerical predictions are made for Laminar Forced convection heat transfer with and without buoyancy effects for Supercritical Nitrogen flowing over an isothermal horizontal flat plate with a heated surface facing downwards. Computations are performed by varying the value of ΔT from 5 to 30 K and P_∞/P_cr ratio from 1.1 to 1.5. Variation of all the thermophysical properties of supercritical Nitrogen is considered. The wall temperatures are chosen in such a way that two values of T_w are less than T* (T* is the temperature at which the fluid has a maximum value of C_p for the given pressure), one value equal to T* and two values greater than T*. Three different values of U_∞ are used to obtain Re_∞ range of 3.6 × 10⁴ to 4.74 × 10⁵ for forced convection without buoyancy effects and Gr_∞/Re²∞ range of 0.011 to 3.107 for the case where buoyancy effects are predominant. Six different forms of correlations are proposed based on numerical predictions and are compared with actual numerical predictions. It has been found that in all six forms of correlations, the maximum deviations are found to occur in those cases where the pseudocritical temperature TT*lies between the wall temperature and bulk fluid temperature.