Precision Cooling Architecture Flashcards
7 cards from real ATP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Precision Cooling Architecture flashcards as text
A data center with a PUE of 1.2 means that for every 1 kW consumed by IT equipment, what is the total facility power draw?
Answer: 1.2 kW total (0.2 kW overhead)
PUE = Total Facility Power ÷ IT Equipment Power; a PUE of 1.2 means 1.2 kW is consumed for every 1.0 kW of IT load, with 0.2 kW going to cooling, lighting, and power conversion.
Air-side economizers improve data center cooling efficiency by:
Answer: Bringing in outdoor air directly to cool IT equipment when outside conditions are favorable
Air-side economizers use outdoor air when temperature and humidity are within acceptable ranges, bypassing mechanical refrigeration entirely for 'free cooling.'
Water-side economizers differ from air-side economizers primarily because they:
Answer: Use outdoor air to cool a water loop via a cooling tower, which then cools the data center without running chillers
Water-side economizers cool the chilled water loop using a cooling tower when outdoor wet-bulb temperatures are low enough, eliminating or reducing chiller compressor operation.
Which outdoor weather metric is most critical for determining cooling tower and water-side economizer effectiveness?
Answer: Wet-bulb temperature
Wet-bulb temperature determines the minimum temperature a cooling tower can achieve through evaporative cooling, directly setting the economizer switchover threshold.
ASHRAE recommends maintaining data center relative humidity within what range to balance static electricity risk and condensation risk?
Answer: 20–80% RH
ASHRAE A1 class allows 20–80% RH, with the lower bound preventing electrostatic discharge and the upper bound preventing condensation on equipment.
In precision cooling, 'free cooling hours' refers to the number of annual hours when:
Answer: Mechanical refrigeration can be reduced or eliminated using outdoor ambient conditions
Free cooling hours are the annual period when outdoor temperatures are low enough to cool the data center without running mechanical compressors, directly reducing energy cost.
Which refrigerant phase transition principle allows DX (direct expansion) precision cooling units to absorb server heat?
Answer: Evaporation absorbs heat as refrigerant changes from liquid to gas
In the evaporator coil, liquid refrigerant absorbs heat from the warm return air and evaporates into a gas, carrying the heat away from the data center space.