friction factors, pumping and you understanding how friction affects your bottom line
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Friction Factors, Pumping and YouUnderstanding 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
FdmdWVzgP
2)( 2
Pressure Change
↓
↑
Elevation Change
↑Velocity Change Friction Losses
↑
Work In or Out↓
Understanding Friction Factors
• Okay, but what is F?
24
2VDxfF
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
DQVDVD 4Re
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:
• Turbulent Conditions:
Re16
f
31
6
Re10200001001375.0
Df
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
FdmdWVzgP
2)( 2
xD
VPf
22
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
Friction Factors vs. Reynolds NumberStainless Steel Pipe, ε=0.00015ft.
0.00000
0.00100
0.00200
0.00300
0.00400
0.00500
0.00600
0.00700
0.00800
0.00900
0 20000 40000 60000 80000 100000
Reynolds Number (Re)
Fric
tion
Fact
or
Moody DiagramExperimental Work
Friction Factors vs. Reynolds NumberGalvanized Pipe, ε=0.005ft.
0.000000.001000.002000.003000.004000.005000.006000.007000.008000.009000.01000
0 10000 20000 30000 40000 50000 60000 70000
Reynolds Number (Re)
Fric
tion
Fact
or
Moody DiagramExperimental Work
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?
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