IBM NeXtScale System, Planning And Implementation Manual

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IBM NeXtScale System Planning and Implementation Guide
Figure 5-18 shows more information about the capability of this rear door heat
exchanger.
Figure 5-18 Heat removal performance with a 30 kW load
Although it is possible to extract even more heat if the water is cooler, the
water temperature cannot be below the dew point in the server room or
condensation forms on the rear door.
򐂰 Some standard computer room air conditioning often is provisioned to control
humidity and enable doors to be disconnected for maintenance or other
requirements
򐂰 The reduced air conditioning requirement typically saves about 1 KW per rack
that is used to compress refrigerant and move air.
The reduction in air conditioner noise, coupled with the acoustic dampening
effect of the heat exchangers, and the decrease in high velocity cold air, has
the other benefit of making the data center environment less hostile.
The part number for the Rear Door Heat eXchanger for IBM 42U 1100 mm rack
is shown in Table 5-10 on page 143.
140
130
120
110
100
90
80
70
60
50
% heat removal as function of water temperature and flow rate for
given rack power, rack inlet temperature, and rack air flow rate
4 10 12 14
% heat remo
v
a
l
Water flow rate (gpm)
Water
temperature
12°C *
14°C *
16°C *
18°C *
20°C *
6 8
22°C *
24°C *
Airflow
(cfm) = 2500
Rack Power
(W) = 30000
Tinlet, air
(C) = 27