Friction Factors, Pumping and You
Understanding how friction affects your bottom line
Introduction
• Sizing a pump properly saves money!
• Must overcome friction
• Watch out for cavitation!
Presentation Overview
•
•
•
•
•
•
Understanding Friction Factors
Fluid Flow Mechanics
Trends in Friction Factors
Experimental Procedure
Results
Conclusions
Understanding Friction Factors
• What are friction factors?
– Energy Balance
• What goes in must come out (sort of…)
– Bernoulli’s Equation
Work In or Out
Elevation Change
P
↓
↓
(V ) dW
 gz 

F

2
dm
↑
Pressure Change
2
↑
Velocity Change
↑
Friction Losses
Understanding Friction Factors
• Okay, but what is F?
x V 2
F  4f

D 2
↑
Friction Factor
Egads, we’ve found one!
Trends in Friction Factors
• What effects a friction factor?
– Properties of the pipe, i.e. roughness
– Fluid properties and mechanics
• Laminar vs. Turbulent Flow
Trends in Friction Factors
• Reynolds Numbers
– Accounts for velocity, geometry, density and
viscosity, and how!
• Re<2000, Laminar Flow
• 2000<Re<4000, Transition
• 4000<Re, Turbulent Flow
VD VD 4Q
Re 




D
Trends in Friction Factors
• Moody Diagrams
– Based on experimental work
– Gives Darcy friction factors by Reynolds
number and pipe roughness
– Resulting Equations for Fanning friction
factors:
• Laminar Conditions:
16
f 
Re

6


10

• Turbulent Conditions: f  0.0013751   20000 
D Re





1
3




Trends in Friction Factors
Trends in Friction Factors
• 2 Methods to determine ‘f’:
– Trust the Moody Diagram
– Physical Experimentation
• Measure pressure drop over horizontal pipe
P
(V ) dW
 gz 

F

2
dm
2
 P D
f 

2
2  V x
Experimental Procedure
• Two pipes selected with differing
roughness
• A 2%wt solution of NaCl was run
through pipes at various flowrates
• Pressure drop was measured across
10ft. sections of pipe.
Results
FrictionFactors
Factors vs.
vs. Reynolds
Number
Friction
Reynolds
Number
Galvanized
Stainless
SteelPipe,
Pipe,ε=0.005ft.
ε=0.00015ft.
0.00800
0.00700
0.00700
0.00600
0.00600
0.00500
0.00500
Friction Factor
Friction Factor
0.00900
0.01000
0.00800
0.00900
0.00400
0.00400
Moody Diagram
0.00300
0.00300
0.00200
0.00200
0.00100
0.00100
0.00000
Experimental Work
Moody Diagram
Experimental Work
0
0.00000
0
10000
20000
20000
30000
40000
50000
Reynolds Number
40000
60000 (Re) 80000
Reynolds Number (Re)
60000
70000
100000
Conclusions and Recommendations
• Overall trend of Moody diagram is very
accurate
• Moody diagram gives a good estimate
for friction factors
• Additional tests should be performed
using longer pipes
• Minimal friction is money saved
Review
•
•
•
•
•
•
Understanding Friction Factors
Fluid Flow Mechanics
Trends in Friction Factors
Experimental Procedure
Results
Conclusions
Gratitude
• Thanks to lab partners:
– Mike Mellas
– Allyson Lundberg
• Fluid mechanics theory and equations:
– Dr. Eric Eddings
– de Nevers, Noel. Fluid Mehanics for
Chemical Engineers (Third Edition). New
York: McGraw-Hill, 2005.
Q&A Time!
Questions?