Explanation:
The first job here is to determine the properties of steam at the conditions specified. A convenient reference for this task may be found at http://www.spiraxsarco.com/esc/SH_Properties.aspx, from which m = 1.6 x 10- Pa s, ρ = 1.59 kg/m3. We then need to calculate velocity and pipe dimensions in a consistent system of units. Consideration of continuity yields v = 5.82 m/s. D = 0.102 m. L = 40 m. From these data we find Re= 5.8 x 10 4. For e/d = 0.01, f = 3.9 (read from a Moody plot). The pressure drop is then found from Δp = (L/D) f ½ρ v2= 0.4 atm. Note that since the pressure drop will influence the fluid density and viscosity, a more accurate estimate might be obtained by an iterative solution using average properties over the pipe length or by integrating over short sections of pipe.
