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– Particulate Contamination• Test indicated the use of 85% (MERV 11) filter reduce article concentrations to nearly match the level found in data centers that do not use economizers
• Higher performance filter (95% or MERV 16) can be used
MERV value
Sources: ASHRAE 52.2-2007, Method of Testing General Ventilation Air-Cleaning Devices for Removal Efficiency by Particle Size
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Airside Economizer – Solutions
– Gaseous Contamination• Not enough studies in the IT industry to document the rate of corrosion with respect to gaseous pollution concentrations
• The use of real time gas monitoring systems are recommended− Highly sensitive quartz crystals microbalance sensor
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Direct Airside Economizer Update
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Airside Economizer – Mechanical Rm Design
– Size
– Location
– Structure support
– Water leak containment
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Airside Economizer – Mechanical Room & Outside Air Intake Design– Outside air intake
• Snow & Rain
• Bomb Blast resistant
• Hurricane resistant
– Airborne particulates• Generator flue
• Cooling tower water mist
• Roadway dust
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Airside Economizer – Data Room Design
– High concentration of air flow• Negative flow - Venturi Effect
• Higher raised floor
• Higher return plenum
Return air
AHUNeutral Room Air
Server
Cold Air
Mixed Warm Air
Hot Air
Raised Floor
Return Plenum
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Airside Economizer – Air Distribution Design
– Air Balance & Control• Use Computational Fluid Dynamics (CFD) modeling
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Airside Economizer – Fire Protection
– Fire Prevention • Fire rated wall
– Fire Detection • Photoelectric and ionization type smoke detectors • High sensitive aspirating type smoke detectors − VESDA
− Laser
– Fire Protection• Pre-action gaseous fire protection activation
The use of cooling tower in lieu of operating a chiller or in conjunction with operating a chiller for creating chilled water to handle a cooling load when the outdoor ambient conditions allow
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Waterside Economizer Type
– Two ways to design and utilize free cooling systems• Series waterside economizer (Partial pre-cooling + Full free cooling)• Parallel waterside economizer (Full free cooling)
Series water-side economizer Parallel water-side economizer
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Waterside Economizer – Cooling Tower
– Cooling tower selection • Approach temperature increase as wetbulb temperature decrease (Capacity drop)