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Installed cooler Design Guide
How to Choose the Evaporative Air Coolers

¢ñ. Selection of Air Cooler

Green evaporative air cooler has various products series, including Miracle
Mobile Series, Demeanor Mobile Series, Wind Marshal Series, Wind Charisma
Series, Wind Supremo Series, Wind Domination Series, Wind Superior Series and
Wind Emperor Series (details in catalogue). The case of Miracle Mobile Series
and Demeanor Mobile Series is made of plastic, with beautiful design, small
airflow and suitable for residential applications. The case of Wind Marshal
Series, Wind Charisma Series, Wind Supremo Series and Wind Domination Series is
also made of plastic, with beautiful design, compact structure, large airflow
and high cost efficiency. Wind Superior Series and Wind Emperor Series use
centrifugal fan, with larger airflow and long drive distance than axial one,
suitable for large areas and commercial applications. Correct selection of air
cooler should take several points into consideration, including application
area, people density, heat productivity and place of installation.

¢ò. Using psychrometric chart to confirm air supply temperature

First, confirm the outdoor state point W according to local meteorologic
conditions, outdoor state from W points along the line in such enthalpy 85% (air
cooler saturated efficiency.

¢ó. Selection of air cooler quantity

Entire Ventilation

Calculation in theory

Calculate the cooling load, moisture load and airflow of the using room
according to conventional air conditioning load calculation formula, and then
calculate the whole cooling capacity that air cooler can provide. And then you
may decide the quantity and model no. that you want. The total cooling capacity
of air cooler should be larger than that required by the using room, the margin
can be 10%. Total cooling capacity of evaporative air cooler can be calculated
in theory as follows:

Total cooling capacity: S=LρCp{e•£¨tg£­ts£©+tn£­tg}/3600

in which: L------actual air supply capacity of air cooler £¨m3/h£©

ρ------air density of air outlet£¨kg/m3£©
Cp------ air specific heat£¨kJ/kg•K£©
e------saturation efficiency of air cooler, normally in 85%

£¨tg£­ts)------wet-bulb depression£¨¡æ£©
£¨tn£­tg£©------temperature difference between indoor and outdoor£¨¡æ£©
Set ¡÷t1=£¨tg£­ts£©, ¡÷t2=£¨tn£­tg£©, ¡÷t1 should be positive value, ¡÷t2 can be both
positive or negative value.

Total cooling capacity S=LρCp£¨e•¡÷t1+¡÷t2£©, ρ¡¢Cp¡¢e are constant, we can see that
total cooling capacity relates to actual air output, wet-bulb depression and
temperature difference between indoor and outdoor. ¡÷t1 and ¡÷t2 are uncertain
values and change according to outside environment conditions, so the formula of
total cooling capacity is only use for qualitative analysis.
Calculate in experience

Calculate the quantity of air cooler needed in a space according to air changes,
which is a commonly used method in actual engineering design.

(1) Definition of air changes: air changes (times/hour)=total air output L/
(room area S ×the height of air supply outlet or exhaust outlet(take the large
one H))

(2)Usually, air change is 25¡«30 times/ hour

(3) In some crowd public areas, air change is 30¡«40 times/ hour

(4) In some workshop with heat appliance, air change is 40¡«50/hour

(5) air change can increase properly in some wet areas, and decrease in hot and
dry areas.
Calculate as follows:


(1) Calculate the areas that needs to be cooled, confirm the height of air
supply outlet and exhaust outlet and take the large one H

(2) Confirm air change according to actual condition


(3) The volume of cooling space V×air change N, and get the total air supply
capacity that the space needs.                  

(4) Total air supply capacity divide actual airflow of independent unit L1, and
get the quantity of air cooler that you need.

¢ô.Design of ventilating duct

1. Basic terms
air flow
calculating method of round duct
L=900§Ýd2v  £¨m3/h£©
d------inner diameter of the duct  £¨m£©
v------speed    £¨m/s£©

calculating method of rectangle duct
L=3600abv   £¨m3/h£©
a¡¢b------the net width and height of cross section of the duct(m)  

 

Resistance of duct system

The resistance include the friction and local resistance, the formula is as
follows:
¡÷P=¡÷Pm+¡÷Pj
¡÷P-----total resistance of the system (Pa)
¡÷Pm----- friction resistance (Pa)
¡÷Pj-----local resistance  (Pa)

The calculation of friction resistance
¡÷Pm=¡÷pm•L
¡÷pm----- on-way resistance (Pa/m)
L-----length of the duct section (m)

Loss of local resistance
¡÷Pj=ξ•v2ρ/2
ξ------local resistance coefficient
v------air velocity of the space where local resistance loss
occurs £¨m/s£©
ρ------air density£¨kg/m3£©
2. Points for designing Aolan air cooler duct


£¨1£©The material of ducts should be galvanized sheets, or glass steel, plastic,
aluminum foil sheets, etc.

£¨2£©Grilles or diffusers should be installed at the places where cooling is
needed. The specification can be decided according to airflow and air speed. The
material could be aluminum, wood etc., and the type could be selected according
to actual situations. We recommend Double Deflection Air Grille with 3-6m/s
airflows speed, and an airflow adjusting valve is recommended.


£¨3£©The dimension of the duct is usually assumed as follows: the wind velocity is
6-8m/s in the main duct, 4-5 m/s in the branches, and 3-4 m/s at the end.

£¨4£©The design of the duct system is supposed to be economical, low resistance
and low noise to make the maximum airflow of “Aolan” air cooler. In order to
reduce the resistance, the curvature radius of the elbow should not be less than
1.5 times of the width of the elbow.

£¨5£©It is much better to make the duct go straight, avoiding corners and
branches, to reduce resistance.

£¨6£©Both auto swing air grilles and duct can be used for side discharge air
coolers.

£¨7£©According to different airflows, the duct should be designed with sections of
different specifications to be connected together. The reducing ducts should not
be too many, usually no more than 4 ducts in a whole system, and the length
is≥2£¨D-d£©.

£¨8£©The connection between duct and air cooler should be hose, with no
temperature preservation design.