CELdek Tech Manual GB-0016-0400

Evaporative Cooling with CELdek® Technical Manual

Nature’s own cooling… When water evaporates the surrounding air becomes cooler and more humid. This, nature’s own cooling process, takes place without any need for an external energy supply. The CELdek® cooling concept relies on this environmentally friendly principle.

How it works Water is supplied through a pipe to a distribution pad on top. This ensures an uniform supply of the water to the cooling pad and minimizes the risk of dry spots. The water is then evaporated into the dry and warm air that passes through the pad. The heat that is needed for the evaporation is taken from the air itself. The air that leaves the pad is therefore cooled and humidified simultaneously. The water that is not evaporated is drained back to the reservoir.

High cooling efficiency To describe the unique design that's typical for the Munters cooling pads presented in this brochure, we shall use the type 7090-15 as an example. The cooling pad is manufactured by bonding together corrugated cellulose sheets with different flute angles. The first one has a flute angle of 60 degrees and the second one has a flute angle of 30 degrees. This unique cross-flow configuration creates an intense contact between the air and the water that provides exceptional evaporation. The result is a pad with a cooling efficiency hard to surpass as well as a cooling process that works in an economic and environmentally friendly way.

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…with CELdek®

Efficient wetting Our experts have developed a special impregnation and treatment procedure for the CELdek® cellulose material providing an efficient wetting of the large contact surfaces in the pad. This unique feature to absorb and disperse large quantities of water minimizes the risk of droplet carryover and keeps the humidification efficiency to a high level for long periods.

Long life The impregnation also stiffens the material enough to make it self supporting. At the same time, it is efficiently protected against decomposition and rotting caused by water and air. The pad is installed in such a way that the 60 degree angle is directed down towards the air inlet. Therefore, the water flow is directed towards the inlet side of the pad where most of the evaporation takes place. This minimizes any scaling. The design also minimizes clogging of the inlet from atmospheric dust. Conclusion: a pad with a long service life and low maintenance costs.

CELdek®, the quality choice CELdek® is the original structured cooling pad. It has been manufactured for more than 30 years, constantly improved and unbeaten by competition. CELdek® is manufactured in accordance with our high ISO-9001 quality standards. Choosing CELdek® is choosing high performance and quality. 3

Design Guide - air How to calculate the air conditions after the pad and the water evaporation rate. For this example the following basic data are assumed for a farm: Air flow q

100 m

Pad height H

2m

Pad depth D

0.1 m

Pad type Ambient conditions:

40 °C

Wet bulb temperature, t1wb,

19 °C

4. Calculate the water evaporation rate E Plot the dry bulb temperatures t1db = 40°C and t2db = 23.6°C on the line for wet bulb temperature t1wb = 19°C. Read the moisture content before and after the pad, x1 = 4.9 g/kg and x2 = 11.8 g/kg. Then, calculate the water evaporation rate E:

3. Calculate the dry bulb temperature t2db

7090-15

Dry bulb temperature, t1db,

This means that the air is cooled 16.4°C! (From 40°C to 23.6°C).

2. Read the pressure drop ∆p and the saturation efficiency  From diagram for pad type 7090-15 at page 6 you read  = 78 % and ∆p = 9 Pa at v = 1.0 m/s

720 000 m3/h

Pad length L

1. Calculate the air velocity v q v= m/s L • H • 3600 720 000 v= = 1.0 m/s 100 •2 • 3600

t2db = t1db t2db= 40 -

•(t1db - t1wb) 100

78•(40 - 19) = 23.6 100

°C

E=

°C

E=

1.2•q•(x2 - x1)

l/min

1000•60

1.2 •720 000 •(11.8- 4.9) = 99 l/min 1000 • 60

x =11.8 2

Mo istu re con ten t g/k g (dr y air)

x =4.9 1

2

3

7

6

8

10

9

11

12

13

14

17

16

15

19

18

20

10 %

50

1

5

RH

0

4

30

45

Dry bulb temperature °C

t1db

20

%

30

40

%

40

%

35

50

% 60

% 70

30

% 80%

25

t2db

20

20

We

tb

t1wb 15

15 4

C re ° u t ra pe m e t ulb

25

90% % 100

Design Guide - water How to calculate fresh water consumption and pump capacity In the water distribution system, there are five different water flows, which are defined in the illustration below.

E P F B E = Evaporation B = Bleed-off F = Fresh water D = Distribution P = Pump capacity 5. Calculate the bleed-off rate B To calculate the bleed-off rate B, you need an analysis of your fresh water. If your water quality is unknown, we can help you with the analyse. Send a small sample of your water to our local representative. Depending on

7. Calculate the distribution flow rate D To get sufficient wetting and optimal performance, a minimum specific water flow per m2 top surface of the pad is needed. The specific water flow cD for different CELdek® types are: Pad type

Specific water flow, cD per m2 top surface

7060-15 7090-15 5090-15

60 l/min 60 l/min 90 l/min

Using the water quality graph, the bleed-off constant cB=0.2 Then the bleed-off rate B is calculated as:

The distribution flow rate D to the total length of the pads is calculated as follows:

B = cB • E

l/min

D = cD • L • D

B = 0.2 • 99 = 20

l/min

Our example with a CELdek® pad 7090-15, L = 100 m and D = 0.1 m gives: D = 60 • 100 • 0.1 = 600 l/min

6. Calculate the fresh water consumption F The fresh water consumption F is calculated as: F=E+ B

l/min

8. Calculate the pump capacity P The pump capacity P is calculated as: P=D+B

Our example gives: F = 99 + 20 = 119

l/min

HCO-3 mg/l 0

10 000

w at er

10 0

10

10

D ci irec rc t ul w at at 2.0 in er g 1.0 w 0.5 at er 0.2 ) 5

CO32- mg/l

100 Un su ita bl e

00 0

00

1 000

10

100

(N on

l/min

CaCO3 mg/l 2500 25000

250

10

l/min

Our example gives: P = 600 + 20 = 620

Ca2+ mg/l 1.0

l/min

1

25

Example Assume that our water analysis shows: pH value of fresh water 7.1 Bicarbonate concentration: 200 mg/l HCO-3 Calcium concentration: Ca2+ 20 mg/l

D

2.5

the water quality, a so-called bleed-off constant cB can be found in the water quality graph below.

1.0 1. 0

0.1

0.1 0.2

0.01 6

5

7

8

9 pH

Why bleed-off?

The importance of bleed-off

1. Water always contains a certain amount of dissolved minerals.

The bleed-off rate is the water flow that needs to constantly be drained off to keep the mineral concentration in the water to an optimal level. Too little bleed-off means too much scaling and clogging, and you have to change pads too often. Too much bleed-off results in high water costs but also presoftening as well as a changing of the pads more often than with an optimal bleed-off rate. It is therefore important to calculate the optimal bleed-off rate to get a long lasting pad with high performance.

2. When water evaporates, the mineral concentration in the recirculated water will increase.

3. In order to compensate for the evaporated water E, fresh water must be supplied. Then more minerals are introduced to the system.

E

E

4. To avoid a built-up of insoluble minerals on the pad surface (scaling), causing an E increase in pressure drop, some of the recirculating water must be discharged E+B and replaced with fresh water. The discharged water is called the bleed-off B.

B

Performance Curves CELdek®, Type 7090-15

CELdek®, Type 5090-15 (

CELdek®, Type 7060-15

(

15°

15° bisector angle

15°

(

Air flow

(

Air velocity v m/s 2 3 4 5

100

0.5

60°(

30°

1

2

Air velocity v m/s 3 4 5

(

D=300

80

 % Saturation efficiency

 % Saturation efficiency

90

0.5

30°

60° (

1

2

mm

Air velocity v m/s 3 4 5

D=1

50 m

D=

300

100

mm

20

0

90

 % Saturation efficiency

1

45°(

(

100

0,5

15°

90°(

90° (

Sheet angle 60° (

20

0

15

80

0

m

90

10

0

80

75 70

15

70

0

10 0

0 10

60 0,5

1

2

60 3

1

2

3

4 m/s

20

100

400

0.5

1

2

0.5

1

2 3 4 5 Air velocity v m/s

300 200 Pressure drop p Pa

30

150

Pressure drop p Pa

De pth , D= 300 mm 20 0 150 100

40

D= 300 mm 20 0 150 100

200

50 Pressure drop p Pa

0.5

4 m/s

100

50

60

50

3

4 m/s

D= 150 mm 100 50 75

70

100

40 30

60

10

20

40

5

10

20

4 3 0,5

5 1

2 3 4 5 Air velocity v m/s

10 0.5

1

2 3 4 5 Air velocity v m/s

A droplet separator should be used for air velocities within the shaded area.

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Product Specification CELdek® Cooling Pad

CELdek® Water Distribution Pad

Each cooling pad type is available in standard heights and depths. The standard width is 600 mm. To understand the orderBisector angle ing key in greater detail let us 15° take the type 7090-15 as an example.

The distribution pad has a special angle arrangement to disperse the water and thus ensure a uniform supply of water to the cooling pads. In this way, the risk of dry spots that may occur in case of an uneven water flow is eliminated. A distribution pad is always advised. The distribution pad has to be ordered by itself and is available in standard heights and depths. The standard width is 600 mm.

(

Type 7 0 9 0 - 15

Ordering key (Water Distr. Pads)

Sheet angle, 90° (

(

Flute height, mm Sheet angle, deg. Bisector angle, deg.

CELdek 70120 - 0 - W x D x H 60°(

30°

Width, mm Depth, mm Height, mm

Ordering key (Cooling Pads) CELdek X X X X - XX - H x D x W Type 7060-15 Type 7090-15 Type 5090-15 Height, mm Depth, mm Width, mm

D H

Standard heights H, mm 30 50 Standard depths, see under cooling pad.

Standard heights H, mm 500 600 900 1000 1200 1500 1800 2000

Height of cooling and distribution pad If distribution pads are used, do not forget to include the height in your framework.

ht heig e t Flu

Standard depths Type 7090-15

D, mm 7060-15 50 75 100 • • 150 • • 200 • • 300 • • •= Available in these depths

5090-15 • • • •

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W

Wijkström & Co, Danderyd 2000 08-753 66 88

Munters Europe AB - HumiCool Division Homepage: www.munters.com FINLAND Munters Oy PL 4 FIN-01301 Vantaa Tel: +358 9 83 860 330 Fax: +358 9 83 860 336

FRANCE Munters S.A 142-176 Av. de Stalingrad Bâtiment 5 F-92712 Colombes Cedex Tel: +33 1 41 19 24 51 Fax: +33 1 41 19 00 17

GERMANY Munters Euroform GmbH Division HumiCool Postfach 1089 D-52011 Aachen Tel: +49 241 8900 0 Fax: +49 241 8900 189

ITALY Munters S.r.l Division HumiCool P O Box 73 I-20090 ASSAGO Tel: +39 02 488 67 81 Fax: +39 02 488 11 71

ITALY Munters euroemme S.p.A Strada Piani, 2 I-18027 CHIUSAVECCHIA (Imperia) Tel: +39 0183 52 11 Fax: +39 0183 52 13 33

KINGDOM OF SAUDI ARABIA Hawa Munters Co. Ltd P O Box 3790 Riyadh 11481 Tel: +966 1 477 1514 Fax: +966 1 476 0936

SCANDINAVIA AND EXPORT Munters Europe AB HumiCool Division P O Box 434 S-191 24 Sollentuna Tel: +46 8 626 63 00 Fax: +46 8 754 56 66

SOUTH AFRICA Munters (Pty) Ltd. P O Box 4539 Edenvale 1610 Tel: +27 11 455 2550 Fax: +27 11 455 2553

SPAIN Munters Spain S.A Europa Empresarial, Ed. Londres c/Playa de Liencres no. 2 E-28230 Las Rozas de Madrid Tel: +34 91 640 0902 Fax: +34 91 640 1132

UNITED KINGDOM Munters Ltd. Blackstone Road Huntingdon Cambs PE18 6EF Tel: +44 1480 432 243 Fax: +44 1480 411 332

The Humidity Expert HC/MEX/CGB-0016-04/00