Lecture 3
Lecture 3
Lecture 3
Note:
is the density at the average pressure
When the pressure drop is greater than 10% incompressible flow
cannot be assumed.
Example 5
A gasoline storage tank drains by gravity to a tank truck. The pipeline
between the tank and the truck is 200 ft of 1-in schedule 40
commercial steel pipe. Both tank and truck are open to the
atmosphere, and the level in the tank is 20 ft above the level in the
truck. What is the flow rate of the gasoline? Ans. 12.6 gal/min
Example 6
We wish to transport 500 cu. ft/min of air horizontally from an air
conditioner to an outbuilding 800 ft away. The air is a 40 degF and 0.1
psig (the atmospheric pressure is 14.7 psia). At the outbuilding the
pressure is to be 0.0 psig. We will use a circular sheet-metal duct with a
roughness of 0.00006 in. The viscosity of air can be taken as 0.017 cP at
the given temperature. Find the required duct diameter. Ans. 8.15 in
Effect of Heat Transfer on Friction
Factor
•
For non-circular conduits
• We use the hydraulic radius
• Churchill Equation
Empirical Relations
• Churchill equation (for any type of flow)