Data Center Cooling Flashcards
7 cards from real CDCP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Data Center Cooling flashcards as text
What is the primary benefit of rear-door heat exchangers (RDHx) attached to server rack doors?
Answer: They capture and remove heat directly at the rack exhaust, preventing hot air from entering the room environment
Rear-door heat exchangers use chilled water coils in the rack rear door to absorb server exhaust heat before it enters the room, effectively creating a rack-level heat sink.
In a data center's cooling hierarchy, which of the following represents the correct order from most to least localized cooling?
Answer: Chip-level → Rack-level → Row-level → Room-level
Modern cooling approaches progress from chip-level (most localized, highest efficiency) through rack, row, and finally room-level (least localized, lowest efficiency per watt removed).
What does the term 'sensible heat ratio' (SHR) mean for data center precision cooling units?
Answer: The fraction of total cooling capacity dedicated to removing sensible (temperature) heat versus latent (humidity) heat
SHR indicates how much of a cooling unit's capacity handles temperature reduction (sensible) versus dehumidification (latent)—data center units have high SHR (~0.9–1.0) since servers generate mostly sensible heat.
What is the function of a variable frequency drive (VFD) on cooling system fans and pumps?
Answer: To vary motor speed to match cooling output to actual load, saving energy during partial-load conditions
VFDs allow fans and pumps to run at reduced speeds during lower load conditions, and since power consumption scales with the cube of speed, small speed reductions yield large energy savings.
Which cooling approach is most appropriate for ultra-high-density computing pods exceeding 100 kW per rack, such as AI GPU clusters?
Answer: Direct liquid cooling (DLC) or immersion cooling delivering liquid directly to components
At densities above 30–50 kW per rack, air cooling becomes impractical; direct liquid cooling (cold plates or immersion) is necessary to efficiently remove the extreme heat loads in AI/GPU deployments.
What is the purpose of computational fluid dynamics (CFD) modeling in data center cooling design?
Answer: To simulate and visualize airflow patterns and temperature distribution to identify hot spots before deployment
CFD modeling uses fluid dynamics simulation to predict airflow behavior and thermal conditions in a data center, enabling engineers to optimize cooling before physical installation.
According to ASHRAE TC 9.9 guidelines, what is the maximum recommended relative humidity for IT equipment inlet air to prevent electrostatic discharge (ESD) issues?
Answer: 60% RH
ASHRAE TC 9.9 recommends maintaining relative humidity between 20–80% RH (with a dew point below 15°C) to prevent both ESD at low humidity and condensation at high humidity.