申論題

3. (20%) Please find the surface temperature and mean air temperature at the exit of a circular pipe with D = 0.1 m, ε/D = 0.01, and L = 1m. The air flow in the circular pipe is assumed thermally and hydraulically fully developed at the inlet with Tinlet = 20℃ and V = 15.16 m/s. The uniform heat flux is applied to the tube surface with a value of 1310W/ m². Please apply the following values for the physical properties of air at one atmosphere: Pr = 0.71, density = 1.2041 kg/m³,ν kg/mos and k = 0.02514W/m.K. The following equations are used to determine the heat transfer coefficient of turbulent flow in a circular pipe. The definition of Reynolds number and Nusselt number listed below: