These levels can be achieved with normal cable exits from the rack and with a
small amount of hot air bypass at the base of the door (small amounts of hot air
might escape from the rack without being cooled by the door).
Water temperatures below 18°C (64.4°F) can be used only if the system that is
supplying the water is able to measure the room dew point conditions and is able
to automatically adjust the water temperature.
Another example of performance data is shown in Figure 20 for identical
conditions as in Figure 19, except reflecting a 20 kW heat load. Because of the
lower heat load, a specific level of cooling can be achieved with warmer water, a
lower flow rate, or both.
80
75
70
65
60
55
50
Heat removal percentage
Water flow rate (gpm)
6 7 8 9 10
Water
temperature
12 C
o
14 C
o
16 C
o
18 C
o
20 C
o
xiv10117
Figure 19. Typical performance of a rear-door heat exchanger, 32 kW heat load. Percentage
heat removal as function of water temperature and flow rate. (24°C rack inlet air, 32 kW rack
load, 1530 cfm air through the rear-door heat exchanger)
Heat removal percentage
Water flow rate (gpm)
6 7 8 9 10
Water
temperature
12 C
o
14 C
o
16 C
o
18 C
o
20 C
o
80
75
70
65
60
55
85
xiv10118
Figure 20. Typical performance of a rear-door heat exchanger, 20 kW heat load. Percentage
heat removal as function of water temperature and flow rate. (24°C rack inlet air, 20 kW rack
load, 1530 cfm air through the rear-door heat exchanger)
Chapter 10. Planning for the rear-door heat exchanger 73
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