The document describes a project to implement aisle pressure management at a client's data center site in Rocklin, CA. Sensors and active fan tiles were used to control cold aisle pressure to be slightly positive, addressing underfloor distribution issues. This allowed the site to run at N+1 redundancy instead of N+2, raised CRAC setpoints, and reduced top-of-rack temperatures by an average of 5 degrees F. Further study of moving temperature control to the underfloor and testing lower redundancy configurations was suggested.

1. Contained Aisle Pressure Management
Rocklin, CA site
Feb 24, 2012
www.AdaptivCOOL.com
wally.phelps@adaptivcool.com

2. Background
Product Concept
• Understood implications of cold aisle containment on servers
• Developed sensor, control algorithms and performed in-house lab tests mid 2011
Client site Rocklin, CA
• Legacy Site with meat locker type cold aisle containment recently added
• Approx 97% contained - still ~3% leakage, especially at roof fire safety mechanism
• Typical underfloor obstructions
• DX cooling N+2 redundancy
• Negative pressure in some aisles, curtains bowing inwards
• CRAC setpoints not able to be safely optimized
• During CRAC maintenance some severe overheating (Even at N+1)
CEETHERM Collaboration
• Nov 2011, live testing of “Aisle Pressure Management” concept
• Cooperative spirit = rapid development and test cycles
Customer Implementation
• Jan 23 thru Feb 3 2012
www.AdaptivCOOL.com

3. Aisle Pressure Management concept
Control cold aisle pressure to be “slightly positive”,
regardless of underfloor distribution issues
using network of sensors and active fan tiles.
www.AdaptivCOOL.com

4. Client Data Center
Underutilized
CRAC Critical
CRAC
Critical
CRAC
11 contained cold aisles Underutilized
CRAC
Some aisles critical due to IT load,
underfloor distribution and proximity to CRACs
www.AdaptivCOOL.com

5. Implementation
Δp
Aisle Pressure Sensor
01 10 30
02 01 50
Δp
03 31 Fan Tile 1200CFM Max
05 04 11 02
32
06 Δp 33 Contained Cold Aisle
12 Δp
06 Δp
15 (by customer)
60 03
Δp 16 07
08 04
Δp
40 17 13 09 Δp
05
Δp Under Floor Pressure
42 18 14 10 Sensor (reference only)
19 36 51
43
Δp 20
Δp
37 Δp
34
98 top of rack temperature
Δp 21 38
Δp
50
44 22 35 sensors (reference only)
45 23 39
24 underfloor temperature
45kW IT 40kW IT sensors (reference only)
CRACs fully instrumented
(reference only)
Higher density aisles www.AdaptivCOOL.com
use more fan tiles

6. Pressure Management Results
Example of 2 aisles
Aisle Pressure Management during various CRAC Failures
100 0.014
Fan Tile Speed %
Aisle 14A Speed
90 0.012
80 0.010
Asile 12A Speed
70 0.008
60 0.006 UnderFloor Pressure
Pressure "wc
50 0.004
Aisle 14A Pressure
40 0.002
30 0.000 Aisle 12A Pressure
2015 hours elapsed test time 3 minute sampling
-0.002
moving average of 8 samples
Aisle Pressure Control set to 0.002”wc
www.AdaptivCOOL.com

7. Findings
• Average of 5ºF reduction in top of rack temperatures after install
• CRAC failure/maintenance fully robust, location independent
• Run site normally at N+1 instead of N+2. N is possible
• All curtains bowed out, visual indication of positive pressure
• Top of rack temperatures held within +2ºF of underfloor temperatures
• CRAC setpoints now raised +5ºF to 85-86ºF.
• @50% DX cooling - underfloor = 75ºF top of racks = 77ºF
• Moved humidification sensors to cold aisle. 40%RH = 22%RH at CRACs
www.AdaptivCOOL.com

8. Further Study
• Move CRAC temperature control to underfloor
• Test N or N-1 redundancy performance
• CEETHERM testing indicated fan tiles increase CRAC flow
• Higher CFM fan tiles, Current Tiles limited to 10KW IT load per tile
www.AdaptivCOOL.com

9. Questions?
Thank You!
Wally Phelps
Director of Engineering
AdaptivCool
18 Meadowbrook Drive
Milford, NH 03055
wally.phelps@adaptivcool.com
(603)913-3453
www.AdaptivCOOL.com