Mitsubishi Electric PQHY-P250YHM-A, Data Book

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5. Setting the Air conditioners
(1) Air-Conditioning 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 heat load.
2) Unlike the outdoor air, computer heat 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
(2) Sample Selection of Air Conditioners
(2-1) Conditions
(2-2) Building Conditions
1) Coefficient of Overall Heat Transmission U (W/m
2
·K)
2) Internal Load
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
Computer-generated heat 20.9kW
Number of workers 5
Lighting 20W/m
2
Temperature and humidity
Indoor °CDB/Indoor WBT: 24°C/17°C
°CDB of the air going into the computer: 18°C
Frequency 60Hz
Windows (W: 4.5m, H: 1.5m) × 2
Inside Measurement Ceiling height 2.2m
Surroundings Upstairs room, downstairs room, heat and air conditioning
Outer Walls Summer 3.6, Winter 3.8
Inner Walls 2.05
Ceiling Downward convection 3.36, upward convection 3.3
Floor (free access) Downward convection 3.05, upward convection 4.56
Floor Downward convection 2.42, upward convection 3.3
Windows Summer 5.93, Winter 6.5
Window