Below illustrations highlight the significance of air cooling with open space cooling system in workspace settings:
The example given here is based on a set of temperature conditions recorded in year 2008.
With open space cooling, the reduction in workspace temperature is significant C equals to an average reduction of 5-6 outdoor temperature. The temperature reduction is even more significant when compared to the workspace temperature C an average reduction of 8-10 inside the workspace area. By taking advantage of the wind-chill factor, the temperature reduction capability of open space cooling is illustrated by an example workspace setting that is equipped with open space cooling and wind-chill effect, the temperature is cooled from 36.5 to 25.9 (i.e. a net reduction of 10.6). |
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| |
| Factory with No Cooling |
|
| Outside Dry Bulb Temp |
|
33.5 | |
|
| Outside Wet Bulb Temp |
|
26.5 | |
|
|
|
|
|
|
|
| Increase in Temperature |
|
3.0 | | |
|
Dry Bulb Temp 33.5
Wet Bulb Temp 26.5 |
 |
Inside Temp Sensation: 36.5
Increase in Temp: 3 | | | |
| |
| Factory with Open Space Cooling |
|
| Outside Dry Bulb Temp |
|
33.5 | |
|
| Outside Wet Bulb Temp |
|
26.5 | |
|
|
|
|
| Supply Air Temperature |
|
27.9 | |
|
| Inside Temp before cooling |
|
36.5 | |
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| Reduction in Temperature |
|
8.6 | | |
|
Dry Bulb Temp 33.5
Wet Bulb Temp 26.5 |
 |
Inside Temp Sensation: 27.9
Reduction in Temp:8.6 | | | |
| |
| Factory With Open Space Cooling and Wind-Chill Effect |
|
| Outside Dry Bulb Temp |
|
33.5 | |
|
| Outside Wet Bulb Temp |
|
26.5 | |
|
|
|
|
| Supply Air Temperature |
|
27.9 | |
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| Inside Temp Before Cooling |
|
36.5 | |
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| Workers Temp Sensation |
|
25.9 | |
|
| Reduction in Temperature Sensation |
|
10.6 | | |
|
Dry Bulb Temp 33.5
Wet Bulb Temp 26.5 |
|
Worker Temp Sensation: 25.9
Reduction in Temp:10.6 | | | |
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| Supply Air Temperature |
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|
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| The Supply Air Temperature depends on the "dryness" of the outside air at that time. The drier the outside air, the lower is the wet bulb temperature. The lower the wet bulb temperature, the more temperature depression can be achieved. Table beside illustrates the Supply Air Temperature at several actual occasions in the Guangdong Province. |
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| Supply Air Temperature |
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| Outside Dry Bulb Temp |
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31.9 |
|
32 |
|
33.5 |
|
38.2 | |
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| Outside Wet Bulb Temp |
|
26.8 |
|
28 |
|
26.5 |
|
27.2 | |
|
| Psychrometric difference |
|
5.1 |
|
4 |
|
7 |
|
11 | |
|
| Supply Air Temp |
|
27.8 |
|
28.8 |
|
27.9 |
|
29.4 | |
| Dry bulb temperature is the actual temperature of the air in the atmosphere.
Wet bulb temperature is the temperature of the air if water is allowed to
evaporate into the air. | |
| |
| The Wind-Chill Effect |
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| Wind-Chill Effect is the secondary cooling effect when air passes over human skin (similar to a fan created effect) thereby causing a lower temperature sensation. The Wind-Chill Effect depends on both the Supply Air Temperature and the air velocity. As an example, supply air temperature of 28C at 10 m/s velocity can create a sensation of 25.6C. |
|
| Wind-Chill Effect |
|
Air Velocity
m/s |
|
Supply Air Tempetature |
|
| 25 |
|
26 |
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27 |
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28 |
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29 |
|
30 |
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| Equivalent Temperature Sensation on human | |
|
| 8 |
|
21.7 |
|
23.3 |
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24.4 |
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26.1 |
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27.2 |
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28.9 | |
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| 9 |
|
21.7 |
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22.8 |
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24.4 |
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26.1 |
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27.2 |
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28.9 | |
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| 10 |
|
21.1 |
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22.8 |
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24.4 |
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25.6 |
|
27.2 |
|
28.9 | |
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| 11 |
|
21.1 |
|
22.8 |
|
23.9 |
|
25.6 |
|
27.2 |
|
28.3 | |
|
| 12 |
|
21.1 |
|
22.8 |
|
23.9 |
|
25.6 |
|
27.2 |
|
28.3 | | | |
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| Supply Air Effective Temperature |
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|
| |
The Supply Air Effective Temperature table here takes into consideration the Wind-Chill Effect of an average cooler sensation of 2C.To predict the Inside Supply Air Effective Temperature, decide the Outside Air Dry-Bulb Temperature first. The column of values below that provides the temperature range. As to what is the actual Inside Supply Air Effective Temperature, it depends on the outside air dryness shown on the left hand column.
This zone is not applicable as
in reality when the temperature is
relatively high, RH is predominantly low |
|
| Supply Air Effective Temperature |
|
Outside Air
RH(%) |
|
Outside Air Dry-Bulb Temperature |
|
| 30 |
|
31 |
|
32 |
|
33 |
|
34 |
|
35 |
|
36 |
|
37 |
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38 |
|
39 |
|
40 | |
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| 35 |
|
21 |
|
21 |
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22 |
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23 |
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24 |
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25 |
|
25 |
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26 |
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27 |
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28 |
|
29 | |
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| 40 |
|
22 |
|
22 |
|
23 |
|
24 |
|
25 |
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26 |
|
26 |
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27 |
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28 |
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29 |
|
30 | |
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| 45 |
|
22 |
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23 |
|
24 |
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25 |
|
26 |
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27 |
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27 |
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28 |
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29 |
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30 |
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| 50 |
|
23 |
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24 |
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25 |
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26 |
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27 |
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27 |
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28 |
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29 |
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30 |
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| 55 |
|
24 |
|
25 |
|
26 |
|
27 |
|
27 |
|
28 |
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29 |
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30 |
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| Supply air temperature is taken at immediate downstream of fan. | |
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