FRICTION FACTOR AND NUSSELT NUMBER IN FLAT TUBES WITH ROUNDED EDGES

This paper is aimed at presenting a fluid flow and heat transfer analysis in flat rectangular ducts with rounded edges. The differential momentum and energy equations are numerically solved by a finite difference technique for a fluid in steady-state, laminar flow with constant wall temperatures. The two-dimensional (2-D) velocity and temperature profiles are so determined, and the friction factors and the Nusselt numbers are predicted for different aspect ratios (O less than or equal to alpha less than or equal to 0.5) for Newtonian and slug flows. The results show that the differences in friction factor and Nusselt number between round-edged ducts and rectangular ducts increase when the aspect ratio increases. Very accurate results are predicted by simple polynomial expressions.