IBM 8408-44E Site And Hardware Planning page 86

– Minimum: 22.7 liters (6 gallons) per minute
– Maximum: 56.8 liters (15 gallons) per minute
Heat exchanger performance
A heat removal of 100% indicates that an amount of heat that is equivalent to that generated by the
devices has been removed by the heat exchanger and the average air temperature leaving the heat
exchanger is identical to that entering the rack (27°C (80.6°F) in this example). Heat removal in excess of
100% indicates that the heat exchanger not only removed all of the heat that was generated by the
devices, but further cooled the air so that the average air temperature that is leaving the rack is actually
lower than air temperature that is entering the rack.
To help maintain optimum performance of the rear door heat exchanger and provide proper cooling for
all rack components, you must take the following precautions:
v Install filler panels over all unoccupied bays.
v Route signal cables at the rear of the rack so that they enter or exit the cabinet through the top and
bottom air baffles.
v Bundle signal cables together in a rectangle so that the upper and lower air-baffle sliders are closed as
far as possible. Do not bundle signal cables together in a circular formation.
Figure 44. Typical performance of the heat exchanger, 20 kW heat load
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Site and hardware planning