Jun

How To Control Relative Humidity In Data Centers

The following guide provides instructions on how to change the strategy of air-handling controls in data center so they can meet the recommended range of ASHRAE and save energy in cooling and humidification. This means that moisture is not controlled by the outside air handler.

Reducing the supply of fresh air to the computer room with the minimum pressurization and ventilation.
Measure the temperature of air entering the IT equipment.
Resolve each hot spot (which affects the air going into other IT equipment) plates with bleach, floor gratings moving, removing the glass doors of the racks, etc..View other blogs on air performance.
Increase setpoints of the air handlers. If possible, increase the set point of the return air, but be sure to keep the air supply to the IT equipment within the limits recommended by ASHRAE (18 ° C / 64.4 F 27 ° C / 80.6 ° F ). Ideally it would be best to change the control strategy CRAC return air to supply air control so that the constant air temperature is provided.
The next step is to adjust the setpoints of relative humidity of the air handlers. For humidification, it should be kept above 5.5 ° C / 41.9 ° F dew point air (DP). This is done by aligning set point with return air setpoint relative humidity (RH) as follows: 24 ° C / 75.2 ° F (30% RH), 26 ° C / 78.8 ° F (27% RH), 28 ° C / 82.4 ° F (24% RH), 30 ° C / 86 ° F (21% RH) and 32 ° C / 89.6 ° F (19% RH). Keep in mind that these set points of HR are much lower than those normally used in traditional facilities, but still meet the ASHRAE recommended range.
To de-humidify, the dew point must be below 15 ° C / 59 ° F (for temperatures, air-supplied IT equipment from 23 ° C / 74.4 ° F and 27 ° C / 80.6 ° F). Since in most refrigeration systems the dew point of the device (ADP) will be well below these values, de-humidification necessary will take place anyway in the battery cooling air handler. Therefore, there is normally no further action necessary to have separate trays and condensate piping in air handlers.
However, if there is an important source of external humidification due to high humidity, and de-active humidification is necessary, then the relative humidity should be regulated according to the return temperature to keep the dew point below 15 ° C / 59 ° F as follows: 24 ° C / 75.2 ° F (57% RH), 26 ° C / 78.8 ° F (51% RH), 28 ° C / 82.4 ° F (45% RH ), 30 ° C / 86 ° F (40% RH) and 32 ° C / 89.6 ° F (36% RH).
PERIODICALLY, you should monitor the temperature of dry bulb and dew point of incoming air to the IT equipment.