The chiller efficiency is relatively low during the charging period as the chiller works at the lower water/glycol supply temperature of 25[degrees]F (-4[degrees]C) instead of 45[degrees]F (7[degrees]C) although the wet bulb temperature
and consequently the condensing water temperature is relatively low during that period.
The effectiveness of an evaporative cooling process depends on the "Wet bulb Depression", which is the difference between the dry bulb and wet bulb temperatures
of the airstream.
1,wb] is the wet bulb temperature
of the entering air (Figure 1a).
The format of the energy performance curves in heating mode is similar to cooling mode, simply replacing the zone wet bulb temperature
and the weighted average indoor wet-bulb temperature with the zone dry bulb temperature and the weighted average indoor dry-bulb temperature.
Equations 2 and 6 make use of indoor inlet wet bulb temperature
and only provide total cooling capacity for wet coils.
The capacity is around 60 tons at a supply chiller water temperature of 25 [degrees]F, varying with the condenser entering/or leaving water temperature that is typically related to the wet bulb temperature
of the outdoor air.
An analysis was done of the stated uncertainties in the measurements of common variables (such as dry bulb temperature, wet bulb temperature
, refrigerant line temperatures, refrigerant pressures, airflow, and power) as measured in the laboratory, by EM&V teams, by participants in maintenance programs, and by typical contractors.
Average wet bulb temperature
was found to exhibit the best correlation; the results are shown below for different cooling systems, assuming an electrical PUEe of 1.
Based on the hourly records of saturated condensing temperature, cooling water temperature leaving and returning to chillers, and outdoor wet bulb temperature
, the performance of the condensing-side can be evaluated using three temperature differentials (dT).
The server inlet air requirements are typically expressed as a dry bulb temperature and either a wet bulb temperature
, relative humidity, or dew point.
The format of energy performance curves in heating mode is similar to the cooling mode, simply replacing the zone, wet bulb temperature
and the weighted average, indoor, wet-bulb temperature with the zone, dry bulb temperature and the weighted average, indoor, dry-bulb temperature.
1 [degrees] C), for outdoor wet bulb temperature
is [+ or -] 1 [degrees] F (0.