Friction Factors, Pumping and You Understanding how friction affects your bottom line.

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?