Air Cleaner Systems

7/31/2019 Air Cleaner Systems

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Transient Dust LoadSimulation

for Air Cleaner Systems

Dr. Bernhard Huurdeman,MANN+HUMMEL GMBH

3rd EACC, July 05/06, 2007, Frankfurt


2/21

2refer to protection notice ISO 16016

Steady state flow simulation of air cleaners

Modeling of pleated filter elements

Simulation method for transient dust load

Examples

Application of the new Fluent 3-Volume Method

to compact filter elements

Summary

Contents


3/21


MANN+HUMMEL Automotive Products

Plastic components for air induction systems

air intake manifolds

air cleaner

turbo ducts

cylinder head covers

Air and liquid

filtration systems

Crankcase ventilation

dirty air side

clean airside

pleated filter element


4/21


Steady state 3-D flow simulation

Accurate geometry representation

Calculation of pressure loss

Improve geometry where possible

Flow Simulation of Air Cleaners

clean air housingclean air pipe

dirtyair pipe

dirty air

housing incl.filter element

resonator

filter element

as anisotropicporous media


5/21


Point 1

Point 5

Point 4

Point 3

Point 6

Point 2

Simulation Results for Unloaded Filter Element

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

fresh air

pipe 1

fresh air

pipe 2

fresh air

pipe 3

fresh air

housing

filter

element

clean air

housing

clean air

pipe

s

taticpressuredifference[kPa]

measurements

simulation

static pressure [kPa]

1 2 3 4 5 6

system pressure lossmeasurements: 1.85 kPasimulation: 1.80 kPa(filter element: 0.33 kPa)


6/21


Exact geometry of all element

pleats can not be simulated

Filter element as anisotropic

porous media

Constant porous media coefficients

dependent on pleat size and media Pressure loss dependent on

viscous loss and inertia loss

coefficients C1 and C2

Modeling of Filter Element

vbp 1C/ =2

2C

2

1v+

b

C1 and C2 can bedetermined by

measurements or

by simulation


7/21


Determination of Porosity Coefficients

2-D flow simulation of pleat geometry

Result is C1 and C2 in main flow direction

C1 and C2 parallel and perpendicular toelement pleats can be determined by simple

analytical formulas

Standardized simulation using

Web-application tool (EASA)

velocitygrid

inlet

outlet

filter mediaas isotropic

porousmaterial

main flowdirection


8/21


Pressure loss of flat filter media

depends on dust loading

This information is required for

each combination of dust and

filter media

0

5

10

15

20

25

30

35

40

45

0 5 10 15 20 25 30

added mass of dust ISO fine [g]

in

creaseinpressu

reloss

[mbar]

)( dustmedia Cfp =

mediadustdust AmC /=

Dust Load Measurements of Flat Filter Media


9/21


EASA Web-Tool Simulation of pressure loss of the

filter element with increasing

amount of dust, by increasing the

filter media pressure loss.

Simplification: Element pleat is

loaded homogenously

Result: C1 and C2 as a

function of separated dust

0.0

500.0

1000.0

1500.0

2000.0

2500.0

0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0

volume flow [m/min]

totalpressureloss[Pa]

Total pressure loss pleat Total pressure loss medium

0.0

1000.0

2000.0

3000.0

4000.0

5000.0

6000.0

7000.0

0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0

volume flow [m/min]



0.0

100.0

200.0

300.0

400.0

500.0

600.0

0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0

volume flow [m/min]



),( airmediaelement mpfp &=

p pleat

p medium

2-D Simulation of Dust Loaded Pleats

)(2,1dust

CfCC =

C1, C2 for Fluent

0.0E+00

5.0E+08

1.0E+09

1.5E+09

2.0E+09

2.5E+09

3.0E+09

dust concentration [kg/m]

C1[1/m2]

0

50

100

150

200

250

300

C2[1/m]

C1

C2


10/21


Dust Load Distribution on the Filter Element using

Particle Tracking for different Particle Diameter

1 m 3 m10 m

30 m

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

0.100 1.000 10.000 100.000

particle size [m]

volume[%]

PTI fine dust

3 m

32 %

1 m

20 %

10 m

24 %

30 m

24 %

particle size:

mass

vol %:

ISO fine dustis modeledusing fourdifferent

particle sizes


11/21


The element surface is divided into

approx. 15x15 rectangles. Then, cuboids

are defined between inlet and outlet face.

Amount of dust in each cuboid is

computed using a particle tracking method

Porous media coefficients

are determined from the interpolated

local amount of mass of dust

Transient Simulation with particle trackingfor every 10th time step. Then update of

the porous media coefficients

See also SAE paper 2006-01-1316

rectangle

cuboid

)(,21 dust

CfCC =

C1, C2 for Fluent

0.0E+00

5.0E+08

1.0E+09

1.5E+09

2.0E+09

2.5E+09

3.0E+09

dust concentration [kg/m]

C1[1/m2

]

0

50

100

150

200

250

300

C2[1/m]

C1

C2

3-D Simulation Method for Element Loading


12/21


3-D Simulation of Dust Loaded Element

dust distribution in the filter element with10x15 cuboids (here: 400 tets per cuboid). interpolated dust distribution

interpolateddistribution ofC1 and C2(good

convergencebehaviour)

C1

C2

cuboid


13/21


Example: Dust Distribution at End of Simulation

10 m 30 m

1m 3 m


14/21


0

2

4

6

8

10

12

14

16

18

20

0 50 100 150 200 250 300

dust load per filter surface area [g/m]

pressureloss[mbar]

filter element

air cleaner

Example: Animation of dust and velocity

velocity normal to element accumulated dust

pressure loss offilter element andair cleaner


15/21


Air Cleaner Simulation with Different Types of Dust

0

10

20

30

40

5060

70

80

90

100

1 10 100

particle size [m]

volumesum

[%]

PTI fine

SF500 4 m

SF300 10 m

W6 40 m

Cumulative Volume

SimulationGrid

Three different types of dust with mean

particle diameter of 4, 10, and 40 m

Measurements of flat filter media and of

complete air cleaner

dust concentration

increaseinp

ressureloss

4 dust

10 dust

40 dust

Measured Pressure loss on flat filter media


16/21


small particle size large particle size

halfloaded

fullyloaded

Air Cleaner with Different Types of Dust

mass ofdust


17/21



small particle size

large particle size


18/21


no load half load full load

0

5

10

15

20

25

0 20 40 60 80 100 120 140

dust concentration [g/m]

pressureincreas

e[mbar]

Test 4mu

Test 10 mu

Test 40 mu

Simulation 4 mu

Simulation 10 mu

Simulation 40 mu


Good correlation of pressure

loss increase, but strongly

dependent on dust modeling.

Velocity near air mass meter

helps to evaluate the influence

of the dust load during element

life time

4 m

10 m

40 m

Here, a nearly dust

load independentvelocity distributionshows an uncriticalinfluence of the dustload on the air mass

meter signal.


19/21


Filter Element Modeling for Compact Elements

Instead of pleats, compact filter elements

consist of long alternately closed channels

The assumption, that the dust will distribute

homogenously along the channel, is here

not applicable anymore.

The usage of an isothermal and dust sizedependent version of the Fluent 3-Volume model

for DPF is assumed to be an attractive approach.

porous media source termsdirty air

clean air

V1

V2dirty air clean air

three overlappingvolumes with equal grids

Using source terms, the dirty and

clean air mass is exchangedbetween the two volumes.solid


20/21


Velocity Distribution and Dust Load with the

3-Volume Model

filter elementvelocity distributiondirty air volume

velocity distributionclean air volume

dust distribution7 %

dust load

100 %

dust load

scale

5 - 15 %

scale90 -110 %


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A flow simulation method for air cleaner systems has been presented which

takes dust loading into account during the lifetime of a filter element.

When compared to measurements, simulation produced reasonably accurate

dust distribution in filter element surface.

The simulation method will be useful to improve air cleaner design regarding

the quality of the air mass meter signal during element life time.

Furthermore, the dust hold capacity of air cleaner systems can be compared,

which will help to find the most suitable design variant.

The new 3-volume method developed by Fluent is a promising approach

especially for compact filter elements. The possibility to simulate an inhomogeneous dust distribution along the main

filter direction, may also improve the dust load simulation method for pleated

filter elements.

Summary

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