Airborne endotoxin was significantly (p = 0.04) and positively associated with
absolute humidity in a mixed-effect model adjusting for a random home effect and fixed effect of sampling month and home characteristics.
Placing the living wall's calculated
absolute humidity and enthalpy on a psychrometric chart (Figure 6), we can easily conclude the remaining air properties:
Substituting experimental results into Equations 9-14, the gasket infiltration load is estimated as [Q.sub.ing] = 0.44 [+ or -] 0.19 W (1.50 [+ or -] 0.64 Btu/h) for a temperature difference between freezer and room of [DELTA]T = 47.2 [+ or -] 0.3[degrees]C (85.0 [+ or -] 0.5[degrees]F) and an
absolute humidity difference between the cavity and the surroundings of [DELTA]W = 0.015 [kg.sub.w]/[kg.sub.a] (0.015 [lb.sub.w]/[lb.sub.a]).
To evaluate the effects of relative humidity and
absolute humidity, two groups of measurement are done.
Figure 4c shows the behavior of the duct air
absolute humidity obtained through simulation.
Comparison of the bottom three rows of Table 1 for each variable shows that models produce climate change values exceeding both natural variability of the 20th century and inter-model variability in projected climate change for drybulb temperature, dew-point temperature, and
absolute humidity, but not for cloud cover, relative humidity, and surface pressure.
For all the data in Figure 6, the
absolute humidity of the PI and RI streams was 0.0133 kg/kg, while the PO and RO streams were 0.0053 and 0.0212 kg/kg, respectively.
The principle of operation is as follows: Ambient air is drawn into a common intake and through a pre-cooling coil which cools the air stream and reduces the
absolute humidity. Beyond the cooling coil, the air stream splits into four separate 12" x 12" (0.3m x 0.3m) ducts with individual dampers to control volume flow through each circuit.
The wet bulb temperature was set at 0.6 [degrees] C (33 [degrees] F), which yielded an entering relative humidity of about 82% and an
absolute humidity of 0.0035 kg-water/kg-air during the experiments.
The difference in
absolute humidity ([omega]) between the incoming outdoor air and supply air leaving the unit represents the amount of condensation that occurs.
Ideally, humidity controls are configured to control
absolute humidity (humidity ratio or dew point), rather than relative humidity, since relative humidity is temperature dependent and temperatures can vary significantly from one location to another in data centers (e.g., hot aisles versus cold aisles).
Since relative humidity depends on both pressure and temperature, the relative humidity varies during the pressure and temperature sensitivity tests; however, the
absolute humidity remained constant.
The actual amount of water collected depends on parameters such as the
absolute humidity level, total airflow and coil bypass ratio.
HVAC Operating Modes Operating Mode Number of Percent of Hours Per Year Year Mix of outside and return air 8200 hours 93% Direct evaporative cooling 45 0.5% Direct evaporative cooling and chilled water 38 0.4% coil Chilled water coil 510 6% For over 90% of the hours in a year, the indoor conditions can be met by mixing outside and return air (the psychrometric process of this mode is shown by the arrows in Figure 5, which is to first order along lines of constant
absolute humidity, since there is negligible latent load in the HPC).
Dew-point (
absolute humidity) maximums of 63[degrees]F (17[degrees]C) for Class I and 70[degrees]F (21[degrees]C) for Class II data centers would set the upper limit for the delivery condition off the adiabatic cooler/humidifier system.
