Question

Carbon dioxide at a temperature of 0 o c and a pressure of 600 kpa (abs) flows through a horizontal 40 mm diameter pipe with an average velocity of 2 m/s

a. determine the friction factor if the pressure drop is 235 n/m 2 per 10 m length of pipe.
b. what type of pipe might this be?
c. if you are told it is cast iron installed 20 years ago, what might explain your answer to part a.

Answer 1

To find the friction factor for the given conditions, use the Darcy-Weisbach equation and known values for carbon dioxide. If it is a cast iron pipe that was installed 20 years ago, corrosion or scaling could account for an increased friction factor.

Step-by-step explanation:

To determine the friction factor for carbon dioxide flowing through a horizontal pipe, we can use the Darcy-Weisbach equation which relates the pressure drop ΔP to the friction factor f, the length L of the pipe, the fluid velocity V, the diameter D of the pipe, and the fluid density ρ.

The equation is: ΔP = f * (L/D) * (ρ * V^2 / 2). Rearranging for the friction factor gives: f = (ΔP * D) / (L * (ρ * V^2 / 2)).

Given that the pressure drop ΔP is 235 N/m² per 10 m length of pipe, the diameter D is 0.04 m, the velocity V is 2 m/s, and the density ρ of carbon dioxide at 0°C and 600 kPa can be found in tables, we can calculate f.

If the pipe material is cast iron and has been installed for 20 years, the pipe's roughness may have increased over time due to corrosion or scaling, which would result in an increased friction factor.