Demonstrating a Dual Heat Exchanger Rack Cooler “Tower” Water … · 2020-01-03 ·...
Transcript of Demonstrating a Dual Heat Exchanger Rack Cooler “Tower” Water … · 2020-01-03 ·...
Demonstrating a Dual Heat Exchanger Rack Cooler
“Tower” Water for IT Cooling
H. Coles, S. Greenberg
contact: [email protected]
October 24, 2012– Silicon Valley Leadership Group
Data Center Efficiency Summit
AMD, Sunnyvale California
PI: W. F. Tschudi
Researchers: Henry Coles, Steve Greenberg
Sponsors: California Energy Commission (CEC)
Partners: APC by Schneider Electric
Synapsense
LBNL Data Center – Building 50
Project Term: Concept July 2009/start July 2010-end Oct 2012
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Project Overview
Presentation
• Goal/Objectives
• Background/Methods
• Cooling Design Concept
• Reverse Engineering – Construct Model
• Forward Engineering – Calculate Results
• Conclusions
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Project Goal/Objective
Goal: Demonstrate the benefits of cooling IT equipment using high temperature water using a unique cooling unit.
Objectives: • Measure performance
• Develop a predictive model
• Calculate Metrics
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Background / Methods
1. Discussed concept with APC
2. APC constructs prototype
3. Install Unit at LBNL Data Center
4. Instrument Heat Exchangers, Electrical Power and Air Temperature
5. Record Thermal/Power Performance
6. Reverse Engineer Heat Exchanger/Construct Closed Form Solution
7. Calculate Metrics/Plot Results /Draw Conclusions
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APC Prototype Dual Hex Cooler
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Demonstration Installation
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IT
Equipment
Rack
Heat
Exchanger
Heat
Exchanger
IT
Equipment
Rack
IT
Equipment
Rack
IT
Equipment
Rack
IT
Equipment
Rack
APC Prototype
InRow™ Cooler
Cold Aisle
Hot Aisle
Cold Aisle
Hot Aisle
Air
Containment
Curtain
Cold Air
Going to Cold Aisle
(IT Equipment Intake)
Hot Air
From Hot Aisle
(IT Equipment Exhaust)
Function Concept
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Maximize Use of
“Tower” Water
Use Chilled
Water Only When
Required
Provides Localized WSE
Data Collection
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Tower Cooled
Water
Connection
Hot Air Entering
(from server exhausts)
Cooled Air Leaving
(to server inlets)
Air
Filter
ONICON
“Btu” Meter
Chiller Cooled
Water
Connection
ONICON
“Btu” Meter
Chilled Water
Heat Exchanger
Tower Water
Heat Exchanger
ION
Power
Meter
SynapSense
Wireless
SynapSense
Wireless
Fans
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Reverse Engineering Problem
gathered data
Heat Exchanger Performance
Not Provided
need closed form model
Reverse Engineering (cont.)
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1E = 1 – exp(-Tau * (Cmax / Cmin))
Tau = 1 – exp(-Ntu * (Cmin / Cmax))
If Cmax = Cmixed (air)
C = mass flow rate x heat capacity
1E = (Cmax / Cmin) * (1 – exp(-Tau' * (Cmin / Cmax)))
Tau' = 1 – exp(-Ntu)
If Cmax = Cmixed (water)
1Ntu = AU/Cmin
solve for AU
q (heat transferred) = E Cmin (Thot in –Tcold in)
calculate exiting temperatures (Thot out, Tcold out)
1Kays, W. M. and A. L. London. 1964. Compact Heat Exchangers, 2nd Edition. Stanford University. Page 19
Fit to Hex Theory: Cross Flow, One Fluid Mixed, Other Unmixed
[DBPP warning]
Check Closed Form Solution
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Heat Exchanger Reverse Engineering Results
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Results (forward engineering)
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1.00
1.04
1.08
1.12
1.16
1.20
26 30 34 38 42 46 50 54 58
pP
UE
IT Cooling (kW)
One Hex - Chilled Water
Two Hexes – Tower (max flow),
Add Chilled
Chilled Water Flow Starts
One Hex – Tower Only
pPUE Comparison
100 cfm / kW, Server Inlet = 72ºF, Tower Water = 68ºF, Chilled Water = 45ºF
Results (cont.)
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Compare to Chill-Off 2 Devices
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Conclusions
• Warmer (tower/economizer) water provides 30 to 50 % cooling efficiency improvements, compared to water supplied using compressor-based (chiller) cooling.
• Design minimizes compressor based cooling (individual localized economizer, lower pPUE)
• Fan energy has a significant effect on efficiency at high air flow rates.
• The prototype cooling unit compared favorably (20-30 percent improvement) to similar devices evaluated in a past PIER demonstration project (Chill-Off 2)
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End Questions?
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Backup Slides
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1.00
1.04
1.08
1.12
1.16
1.20
26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56
pP
UE
IT Power (kW)
Case 2: Tower Water Only <= 48 gpm(two heat exchangers)
Case 1: Tower Water < = 24 gpm
(two heat exchangers) Chilled Water Added as Needed
Case 4: Chilled Water Only
(one heat exchanger removed)Fan Power = 68%
Case 3: Tower Water Only
(one heat exchanger removed)Fan Power = 68%
Not able tomeet72°F
Set Point
pPUE Comparison of 4 ConfigurationsOne or Two Heat Exchangers in Series, Tower and Chilled Water Supply
Servers = 100 cfm/kW, Server Air Inlet = 72°F, Tower Water = 68°F, Chilled Water = 45°F
pPUE Includes Plant Power and Cooling Unit Power Only
Plant Model
kW / ton vs. supplied water temperature
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y = 0.0000051561x3
- 0.0008596432x2
+ 0.0327788257x+ 0.3552353121
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
40 45 50 55 60 65 70 75 80 85 90
Ele
ctri
cal P
ow
er
Ne
ed
ed
(kW
/to
n)
Cooling Water Temperature (°F)
kW/ton vs. Chilled Water Temperature (CWT)distribution pumping included
Taylor Engineering
Santa Clara CAYear Average
COP Metric Definition
COP [ kWthermal / kWelec. ] = cooling provided / power needed
power needed (kW) = (kW/ton * tons) + (kW/ton * tons) + APC Unit Power
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APC Unit
Power
cooling provided (kW) = treated water cooling + chilled water cooling – APC Unit Power
pCOP? using PUE and pPUE