2 replies to this topic

[moverduin]

Air flows through a pipe at 270 CFM with inlet temp of 30 F, and pressure of 105 psi. The pipe is copper, 1 ft in length and 1 inch in diameter. The copper pipe is twisted in a helical manner. Height of each twist is approximately 1/5 inch.

How would you calculate pressure drop? roughness factor?


thanks!

[sheiko]

A hint: absolute roughness is not calculated. It is a data you can find in various handbook such as Perry.

Now you can do your homework.

[demank]

Air flows through a pipe at 270 CFM with inlet temp of 30 F, and pressure of 105 psi. The pipe is copper, 1 ft in length and 1 inch in diameter. The copper pipe is twisted in a helical manner. Height of each twist is approximately 1/5 inch.

How would you calculate pressure drop? roughness factor?


thanks!

There are 2 points that you must consider before calculating pressure drop:
1. moody friction factor, use a chart or equation (exist in many book)
2. Helical shape. Do you dare to ignore the Equivalent Length (elbow, fitting, valve, etc have this equivalent length) of this helical shape? (regarding it just a shor pipe 1 ft).