Determining heat load capacities
The total airflow required by the equipment installed in each server rack must be compared with the total available supply from the MCS 5042, so it is not exceeded. The fans in the MCS 5042 are speed controlled to reduce the airflow in case the maximum cooling capacity is not demanded from the MCS 5042. Table 10 provides a few examples of the approximate fan speeds by the demanded cooling capacity from the MCS 5042.
Table 10: Approximate fan step at certain cooling capacity
Approximate cooling capacity | Approximate fan speed |
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~9 kW | |
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~16 kW | |
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~24 kW | |
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~32 kW | |
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>40 kW | 100% |
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A minimum heat load is necessary for operating the MCS 5042 properly. This minimum depends on the water supply temperature as shown in Table 11.
Table 11: Minimum heat load at different water supply temperatures and server air intake temperature
| Server air intake temperature | Water supply temperature | Minimum heat load | ||
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| 7ºC (45°F) | 9 kW | ||
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| 20°C (68ºF) | 10ºC (50°F) | 7 kW | ||
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13ºC (55°F) | 6 kW | ||||
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| 16ºC (61°F) | 6 kW | ||
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| 16 kW | |||
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| 25°C (77ºF) | 16ºC (61°F) | 14 kW | ||
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| 18ºC (64°F) | 10 kW | ||
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Note:
When the minimum heat load is not provided to the MCS 5042, it can cause unstable control of the temperatures and flow rates of the MCS 5042.
Consult with your HP representative for further information.
The charts in Figures 32 and 33 offer a guideline for determining the approximate amount of heat that can be removed from MCS 5042 based on 20°C (68°F) and 25° C (77°F) server intake air temperatures (in degrees Celsius) and flow rates (liters per minute (lpm) or in US gallons per minute (gpm)) being delivered to the unit.
Note:
The term “water” in the following charts refers to the coolant described in “Water quality requirements” section.
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