8-5 Setting the Air conditioners
33
20.9kW
5
20W/m
2
60Hz
Computer-generated heat
Number of workers
Lighting
Temperature and humidity
Frequency
Indoor ˚CDB/Indoor WBT : 24˚C/17˚C
˚CDB of the air going into the computer : 18˚C
(1) Air-Conditioning Load
(2) Sample Selection of Air Conditioners
(2-1) Conditions
Windows
Inside Measurement
Surroundings
(W: 4.5m, H: 1.5m)
✕
2
Ceiling height 2.2m
Upstairs room, downstairs room, heat and air conditioning
(2-2) Building Conditions
1
Coefficient of Overall Heat Transmission U (W/m
2
·K)
Summer 3.6, Winter 3.8
2.05
Summer 5.93, Winter 6.5
Floor (free access)
Outer Walls
Inner Walls
Ceiling
Floor
Windows
Downward convection 3.36, upward convection 3.3
Downward convection 3.05, upward convection 4.56
Downward convection 2.42, upward convection 3.3
2
Internal Load
1
Once the floor plan is made and the conditions for the air-conditioning system are set, air conditioning
capacity has to be determined by calculating the load.
2
Unlike the outdoor air, computer load remains constant throughout the year. However, it is possible
that there are considerable fluctuations within a day. This is due to the fact that, depending on the time
of the day, there are changes in the number of computers that are turned on and that the different
computer systems are in operation.
3
If there is a plan to expand the current computer system in the future, it is important to include the
load for the units to be added in the future when calculating the thermal load because it is practically
impossible to keep the computers off for days on end during the installation of the new units.
4
The following items need to be checked before calculating the unit capacity:
· Floor area of the computer room (m
2
)
· Total quantity of heat generated by computers
Number of People in the Room 5
Lighting
20W/m
2
Calculator
20.9kW
Draft
0.2 times/h
3
Volume of Outdoor Air Intake
25m
3
/h·person
Window
