曙/b> 晃璘偵

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mme.modares.ac.ir

1

*2

2

- 1

- 2

* -143

14115 [email protected]

25 : 1394

: 30 1395

: 18 1395

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. . .

. .

.

Investigation on effect of exhaust vents location on reduction of pollution in enclosed car parks

Javad Amnian, Mehdi Maerefat

^*

, Ghasem Heidarinejad

Mechanical Engineering, Tarbiat Modares University, Tehran, Iran.

* P.O.B. 14115-143, Tehran, Iran, [email protected]

A

RTICLE

I

NFORMATION

A

BSTRACT

Original Research Paper Received 14 February 2016 Accepted 18 April 2016 Available Online 07 May 2016

The correct placement of supply air inlets and pollution extraction outlets plays an important role in increasing indoor air quality and reducing the amount of pollution in enclosed car parks. In this paper the effect of exhaust locations, exhaust height and parking dimensions on indoor air quality of car park is investigated with numerical simulation. For this purpose conservation equations are solved with openFoam. For validation, air flow and pollution are simulated in a simple car park and compared with experimental results. In the next section, the effect of exhaust vent locations on increasing indoor air quality is investigated and compared with other solutions. The result of numerical simulation indicates that, if inlets and exhausts are located in end sides of car park and if exhaust vent locations are in the optimized height, the indoor air quality in the car park is increased. In this paper, the graph of CO concentration in different heights is explained and by using it, the optimum range for exhaust vent locations is proposed. Moreover, the standard criteria for using jet fans is expressed and the results showed that, for ventilation of car parks with length more than criterion, jet fans should be used.

Keywords:

Pollution dispersion numerical simulation air inlet position exhausts position jet fan

-1

.

. .

] [ 1 .

] [ 2

1 2

1 Supply Shaft

2 Exhaust Shaft

[ Downloaded from mme.modares.ac.ir on 2023-12-07 ]

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[ 7

.

] [ 8

4

. .

5

. ]

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.

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[ 8 .

1 Supply air inlet

2Exhaust

3 ASHRAE

4 Fluent

5

.

] [ 9 .

. -

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-2

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5

.

6

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5 reactingFoam

6 OpenFoam

(3)

Sh

Pr

t

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) ( 7 ( )

+ ( )

= + Sch +

SC

Sch

t

)

( ]

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) ( 8 ( )

+ ( )

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) ( 9

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[ 9 .

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× 2.85 3

) A2

× 2 ( 3

) A3

× 2 . ( 2

-

S1 S2 E1 . E3

14

S 15 E

[

9,8

]

.

0.2 0.4 5.6

.

Fig. 1 The studied Car park geometry [

9

] ]

1

[

9

- 3

- 1

A1

1

A2

2.4 ) -2.5

.( A2 A3

)

2

.( A2

S1 S2 E1

E3

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A1 A3 10

.

k

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.(

] 5 [ 9 .

) - 20

( .

. 20

- 3 - 2

. 1

.

1200000 .

2 - M1

. 2

1200000 .

Fig. 2 Grid size independency

2

1 Velocity Inlet

2 Pressure Outlet

1.5 2 2.5 3 3.5

0 0.2 0.4 0.6 0.8 1

H ei g h t (m )

Velocity magnitude (m/s)

8.00E+05 1.00E+06 1.20E+06 1.40E+06

(4)

- 3 - 3

) 6

] [ 4 .(

) / = 2 × 1.5/30.8 × 3.6 = 0.027 (

. - . -

] [ 13 . . . ) ( A1

. 10

20 ) 25

( .

. ] [ 9 . .

- 3 - 4

1 .

M1 M2 M3 .

-

3

-

4

-

1 M1

M2 M1 M2 20

) ( 1200 ]

[ 9 .

. 0 1200

. 3

] [ 9

.

1

] 70 [ 14 .

4 . 5

1 Idle

] [ 9

. -

] [ 15

.

. .

.

Fig. 3 CO generation in car park 3

Fig. 4 Comparison of numerical simulation and measurement results, position M1

4 M1

Fig. 5 Comparison of numerical simulation and measurement results, position M2

5

M2

2.23

2.78

2 2.2 2.4 2.6 2.8 3

0 300 600 900 1200

C O G en er at io n ( g /s )

Time (s)

0 5 10 15 20

0 200 400 600 800 1000 1200

C O ( p p m )

Time (s) Experiment [8]

Present Study

0 5 10 15 20

0 200 400 600 800 1000 1200

C O ( p p m )

Time (s) Experiment [8]

Present Study

(5)

-

3

-

4

-

2 M3

] [ 9 ) M3

( 1

) 2 ( 7200

5 . 8

2 . 6

] [ 9 300

. ) 900

( 15

. .

5 8

. 1

] [ 9 . 7

] [ 9 .

)

. ( 6

Fig. 6 CO generation in car park base geometry

6 1

Table 1 Air mass flow rate to the car park in different modes

Fig. 7 Comparison of numerical results and ref. [9], Position M3 ] 7

[ 9 M3

-4

. .

- 4 - 1

1 ]

1

[ 16 . . .

-

. 2

. 7

5 8

. 1

.

) 3 5

8

7 .( 10

/ = (10/7) = 2.91 .

( )

8 5

.

- :

] [ 16 .

2

] 2 , 1 , 3 [ 17

Table 2 pollution and air change limits in standards [1,3,17]

1 Local Ventilation

2 Fully mixed flow

4.6

0.7 3.6

4.4

3.1

2.6 2.5

0 1 2 3 4 5

0 900 1800 2700 3600 4500 5400 6300 7200

C O G en er at io n ( g /s )

Time (s)

0 10 20 30 40 50 60

0 900 1800 2700 3600 4500 5400 6300 7200

C O C o n ce n tr at io n ( p p m )

Time (s)

5 ACH, Ref. [8] 5 ACH, Base Geometry 8 ACH, Ref. [8] 8 ACH, Base Geometry

/

5

8

A1 2.4 m³/s

2.4 m³/s

A2 -2.5 m³/s

-2.5 m³/s

1.95 m³/s

3.84 m³/s

-4.45 m³/s -7.6 m³/s

) ) (

ppm

)

(1 8 )

(35 9 7.5 lit s^-1m²

8

35 -

8

50 6-10 ACH

8

25 7.5 lit s^-1m²

- -

3.8 lit s^-1m²

(6)

1

.

2

.

] , 18 [ 19 . 1

( ) .( )

. S1

E1 E2

E3 S2

) (

. A2

.

A1 2.4

A2 -

7 1.96

.

) (

. . 5 . 6

M3

( )

. 9 5

M3 M3

. .

( )

) (

.

10 5

8

( )

.

Fig. 8 Car park with improved outlet 8

1 Longitudinal Ventilation

2 Displacement Ventilation

Fig. 9 Comparison of base and modified outlet results, Position M3

9 M3

) 1.75

t=2 hour

(

. 5

8 40

26

ppm . 20

a b

. 5 8

50 ppm . 33

.

10

)

. ( 8

] [ 6

. ) % 35

.(

)

3

( 12

4

) ( 13

] , 6 [ 20 .

Cexit

Caverage

Cmax

Cmin

.

3 CO removal effectiveness

4 CO removal efficiency

0 10 20 30 40 50 60

0 900 1800 2700 3600 4500 5400 6300 7200

C O C o n ce n tr at io n ( p p m )

Time (s)

ASHRAE

5 ACH, Base Geometry Improved Outlet

) ( 12

=

) ( 13

=

(7)

Fig. 10 CO distribution, height= 1.75 m, time= 2 hour 10 1.75

t=2 hour

. 3

. .

. 4

5 8 .

8

.

- 4 - 2

. .

.

. 1

8 . 11

11

H

_ND

=

h/H

h H

H

ND

.

1 ) 2.5

-

H

_ND

0.27

. ( 0.7

1

) 16

) ( 12

11 16

12 .(

] 3 [ 20 Table 3 Ventilation flow categories [20]

4

Table 4 CO removal effectiveness and removal efficiency

0-1 0- 50%

1

50%

1-2

50- 100%

2 100%

5 0.56

27.3%

8 0.88

41.5%

1.72 83%

(8)

Fig. 11 CO concentration versus non dimensional height 11

0.6 0.65

.

11

. .

8 .

.

hvent

H

exh

=

hvent

/H .

16 . 12 -

10

.

. 13

.

) H

exh

( 0.5 - 0.7

. 0.5 0.7

. -

14 0.5 0.7

.

ppm 52

. . 15

-

.

Fig. 12 CO measurement points 12

Fig. 13 CO concentration in different heights 13

0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70

22 24 26 28 30 32 34 36 38 40 42 44 46 H

ND

Average CO Concentration (ppm)

Base Case

Improved Outlet

0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70 0.75 0.80 0.85 0.90

20 25 30 35 40 45 50 55 60

H

ND

CO concentration (ppm)

Hexh = 0.1 Hexh = 0.2

Hexh = 0.3 Hexh = 0.4

Hexh = 0.5 Hexh = 0.6

Hexh = 0.7 Hexh = 0.8

(9)

Fig. 14 Effect of exhaust height on average CO concentration 14

Fig. 15 Effect of exhaust height on CO removal efficiency and effectiveness

15

- 4 - 3 .

] [ 21 . 54

54 . 54

)

) ]

[ 4 .( 75

] [ 21 60

30 2.85

) .( 16

80

% 25

) ( 20

] , 4 [ 17 . 6

0.4 1 6 0.8

1.4 . 16

[1]

. )

(

N

) (

E

)

) (

A

(

T

) (

C

) ( 14

% 75 % 90

( )

] [ 4 . . 5

18.96

] [ 1 . 16

( )

20 0.1

0.25

3.16 70

) .(

2

. 16

ppm . 54

ppm ) 42

16

ppm .( 60

. .

.

) 2

( [3]

)

1.75

.(

. .

) 5 ( 14

Table 5 Amount of parameters of equation 14

)N (

- 20

)E (

g/min

18.96

E0

) (

g/(h.m²)

26.7

)A (

m²

1800

)C (

) lit/s)/(m²/s (

0.000481

)T (

s 120

qvent

)

( lit/(s.m²)

2.73

)ACH (

- 3.45

qexhaust

) (

m³/s 5.8

20 25 30 35 40 45 50 55

0 0.2 0.4 0.6 0.8 1

A v er ag e C O ( p p m )

H

_exh

30 40 50 60 70 80 90 100

0.7 0.9 1.1 1.3 1.5 1.7 1.9

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

C O r em o v al E ff ic in cy

C O r em o v al E ff ec ti v en es s

H

_exh

effectiveness efficiency )

( 14 q = C T N E × 60

A E × 100

(10)

Fig. 16 CO distribution in car park, h=2 m, t=60 min

16 t=60 min 2

5 14

. ]

[ 22 . -

100 5

. 0.05

. . 90

1

2.2 . 200

1 . 0.4

2 3

. 16

. .

1 Induced fan

2 Pressure jump

3 Fan boundary condition

ppm 20 ppm

. 31 .

1.04 . 1.65

%

% 49 80

-5

k- .

-

. .

.

. . 2.91

-

% . 35

:

0.5 0.7 .

:

. 54

%

% 49 . 80

-6 ) A

m²

(

C1 , C2

Ci

c’i

i

Cµ

C_P

)

J.kg^-1K^-1

(

(11)

)

D m²s^-1

(

E, E

0

)

gmin^-1

(

)

h Jkg^-1

( ) (

m

)

H

(

m

H

exh

)

k m²s^-2

( )

kgs^-1

(

N )

P J.s^-1

(

)

p kgm^-1s^-2

(

Pr

t

)

Q m³s^-1

(

Sch

_t

SG

)

kg m^-2s^-2

(

Sh

)

kg m^-1s^-3

(

Sij

)

s^-1

(

) T (

K

)

t

(

s

U_i

)

ms^-1

(

u’i

) i

ms^-1

(

xi

)

i

(

m

x_j

)

j

(

m

-7

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)

eff m²s^-1

(

)

m²s^-3

(

)

t m²s^-1

(

µ

eff

)

kgm^-1s^-1

(

µ

t

)

kgm^-1s^-1

(

)

m²s^-1

( )

t m²s^-1

(

)

kgm^-3

(

k

‘

¯

average

exhaust

exit

inlet

max min

ND vent