Evaporative Cooling
with CELdek
®
Nature’s own cooling…
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 evapo-rated 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.
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
…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 sur-faces in the pad. This unique feature to absorb and disperse large quantities of water minimizes the risk of droplet carry-over 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 manufac-tured for more than 30 years, constantly improved and un-beaten by competi-tion. CELdek® is
manufactured in
How to calculate the air condi-tions after the pad and the water evaporation rate.
For this example the following basic data are assumed for a farm:
1. Calculate the air velocity v
v = 720 000 = 1.0 m/s 100 •2 • 3600
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
3.Calculate the dry bulb
temperature t2db
t2db= 40
-78•(40 - 19)
= 23.6 °C 100
This means that the air is cooled 16.4°C! (From 40°C to 23.6°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:
E = 1.2 •720 000 •(11.8- 4.9)
1000 • 60 = 99 l/min
Design Guide - air
0 12 13 14 15 16 17 18 19 20 1 2 3 4 5 6 7 8 9 10 11 50 45 40 35 30 25 20 15 20 15 25 30
Moisture content g/kg (dry air)
Dry bulb temperature
° C 90% 100% 80% 70% 60% 50% 40% 30% 20% 10% RH Wet bulb tempe rature °C x1=4.9 x2=11.8
t
1dbt
2dbt
1wb t2db= t1db-•(t1db- t1wb) °C 100 v = q L • H • 3600 m/s E = 1.2•q•(x2- x1) l/min 1000•60 Air flow q 720 000 m3/h Pad length L 100 m Pad height H 2 m Pad depth D 0.1 m Pad type 7090-15 Ambient conditions:Dry bulb temperature, t1db, 40 °C
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 = 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
the water quality, a so-called bleed-off constant cBcan be found in the water quality graph below.
Example
Assume that our water analysis shows:
Using the water quality graph, the bleed-off constant cB=0.2
Then the bleed-off rate B is calculated as:
B = 0.2 • 99 = 20 l/min
6.Calculate the fresh water
consumption F
The fresh water consumption F is calculated as:
Our example gives:
F = 99 + 20 = 119 l/min
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 cDfor different CELdek®types are:
The distribution flow rate D to the total length of the pads is calculated as follows:
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
8.Calculate the pump capacity P
The pump capacity P is calculated as:
Our example gives:
P = 600 + 20 = 620 l/min
Design Guide - water
E
F
B
D
P
1.0 0.5 0.25 0.1 2.0 1.0 2.5 25 250 2500 25000 CaCO3 mg/l Ca2+ mg/l 10 100 1.0 10 100 1 000 10 0 00 HCO3 mg/l CO 3 2- mg/l 0.1 1.0 10 100 1 000 10 000 -Dir ect water (Non cir culating water) Unsuitable water 0.2 B = cB• E l/min D = cD• L • D l/min P = D + B l/min F = E + B l/minpH value of fresh water 7.1 Bicarbonate concentration:
HCO3- 200 mg/l
Calcium concentration:
Ca2+ 20 mg/l
Pad type Specific water flow, cD
per m2top surface
7060-15 60 l/min 7090-15 60 l/min 5090-15 90 l/min
Why bleed-off?
1. Water always contains a certain amount of dissolved minerals. 2. When water evaporates, the mineral concentra-tion in the recircu-lated 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.
4. To avoid a built-up of insoluble minerals on the pad surface (scaling), causing an increase in pressure drop, some of the recirculating water must be discharged and replaced with fresh water. The discharged water is called the bleed-off B.
B
E+B
E
E
E
The importance
of bleed-off
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 scal-ing and cloggscal-ing, 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 calcu-late the optimal bleed-off rate to get a long lasting pad with high performance.
80 90 100 D=300 mm 200 150 10 0 10 0 15 0 20 0 Depth , D= 30 0 mm 60 70 100 50 40 30 20 10 5 4 3 5 4 3 2 1 0,5 5 4 3 2 Air velocity v m/s 1 0,5 % Saturation efficiency Pressure drop p Pa m/s 4 3 2 1 0,5 Air velocity v m/s 80 90 100 D=300 mm 200 150 10 0 10 0 15 0 20 0 D=3 0 0 mm 60 70 200 150 100 50 40 30 20 10 5 5 4 3 2 1 0.5 5 4 3 2 Air velocity v m/s 1 0.5 % Saturation efficiency Pressure drop p Pa m/s 4 3 2 1 0.5 Air velocity v m/s 80 90 100 D=150 mm 100 75 50 5 0 75 10 0 D=150 mm 60 70 400 300 200 100 60 40 20 10 5 4 3 2 1 0.5 5 4 3 2 Air velocity v m/s 1 0.5 % Saturation efficiency Pressure drop p Pa m/s 4 3 2 1 0.5 Air velocity v m/s
Performance Curves
CELdek®, Type 7060-15 CELdek®, Type 7090-15 CELdek®, Type 5090-15
( ( ( ( Sheet angle 60° 45° 15° 15° bisector angle 60° 90° 90° 60° 30° 30° ( ( ( ( 15° 15° ( ( ( ( Air flow
Product Specification
CELdek
®Cooling Pad
Each cooling pad type is available in standard heights and depths. The standard width is 600 mm.
To understand the order-ing key in greater detail let us take the type 7090-15 as an example.
CELdek
®Water Distribution Pad
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 elimina-ted. 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.
Ordering key (Water Distr. Pads)
CELdek 70120 - 0 - W x D x H
Width, mm Depth, mm Height, mm
Standard depths, see under cooling pad.
Height of cooling
and distribution
pad
If distribution pads are used, do not forget to include the height in your framework.
W D
H
Flute height
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 Type 7 0 9 0 - 15 Flute height, mm Sheet angle, deg. Bisector angle, deg.
( ( ( ( 60° 30° Sheet angle, 90° 15° Bisector angle
Standard heights
H, mm 500 600 900 1000 1200 1500 1800 2000Standard heights
H, mm 30 50Standard depths
Type D, mm 7060-15 7090-15 5090-15 50 • 75 • 100 • • • 150 • • • 200 • • 300 • •Wijkström & Co, Danderyd 2000 08-753 66 88 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 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
UNITED KINGDOM Munters Ltd. Blackstone Road
Huntingdon Cambs PE18 6EF Tel: +44 1480 432 243 Fax: +44 1480 411 332
Munters Europe AB - HumiCool Division Homepage: www.munters.com