Stable, low cost 10kw+ Enterprise rack refrigerant pumped cooling

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ENTERPRISE HIGH
PERFORMANCE COOLING
FINAL REPORT
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PUMPED REFRIGERANT COOLING
TECHNOLOGY
Martin Pitasi/Principle Investigator

2. 2
INDEX

3. 3
1. PROPOSED COOLING TECHNOLOGY ASSESSMENT
1.1 Candidate Cooling Technologies
1.2 Evaluation Criteria
1.3 Candidate Assessment Study
2. SYSTEM DESIGN & ANALYSIS
2.1 System Concept Cooling
2.2 Feasibility Hardware Model
2.3 R-134a Flow Prediction
2.4 Pump Performance
2.5 System Design Constraints
2.6 R-134a Saturated Liquid dT/Dp
2.7 R-134a Saturated Liquid
2.8 Orifice Selection Criteria
2.9 Goals
2.10 Orifice Hardware
2.11 Pump Performance Curve
2.12 Pump Reference Data
2.13 Pump Dimensional Drawing
3. SYSTEM RESULT
3.1 Orifice Performance Results
3.2 Results
3.3 Pump Performance Summary
3.4 COP Test Results
3.5 System Pictures
4. COLD PLATE DESIGN STRATEGY
4.1 Thermal Budget
4.2 Alpha Thermal Design Specifications
4.3 Cold Plate Design Strategy
4.4 Copper Off-Set Strip Fin
4.5 Preliminary Prototype Cold Plate No. 1
4.6 Preliminary Prototype Cold Plate No. 2
4.7 Function Prototype Cold Plat No. 1
4.8 Function Prototype Cold Plat No. 2 (Not Built)
5. COLD PLATE TESTING
5.1 Cold Plate Test Fixture Block Diagram
5.2 Test Fixture Heat Balance Study
5.3 Cold Plate Power Measurement Study
5.4 Copper Cold Plate Summary of Results
5.5 Copper Cold Plate Heat Balance
5.6 Copper Cold Plate Operating Envelope
5.7 Copper Cold Plate Superheat Study
5.8 Copper Cold Plate Test Data

4. 4
6. WIRING AND CONTROLS
6.1 Level Balancing Resistor Specs.
6.2 R-134a Flow and Pressure Safety Control Schematic
6.3 Self Heated Thermistor Specifications
6.4 Quality Sensor Schematic
6.5 Start-Up Circuit
6.6 System Wiring Diagram
6.7 Instrumentation Pin-Out Table
6.8 Instrumentation Wiring Diagram Liquid
6.9 Power Switch Wiring Diagram
6.10 Data Acquisition PCB Data
7. CALIBRATION DATA
7.1 Orifice Calibration
7.2 R-134a Cold Plate Flow
7.3 R-134a Total Flow
7.4 Pressure Transducer
7.5 Cold Plate Power Transducers
7.6 Input Power Transducer
7.7 Quality Sensor
7.8 AeroQuip Quick Disconnects
8. BOM
8.1 Mechanical ID Block Diagram
8.2 Mechanical
8.2 MBOM Continued
8.3 Electrical
9. WHITE PAPER

5. 5
1. PROPOSED COOLING TECHNOLOGY ASSESSMENT

6. 6
1.1 Candidate Cooling Technologies
a. Pumped Liquid Systems d. Heat Pipes Technology
 Two Phase TF&F  Circular Heat Pipes
 Single Phase  Looped Heat Pipes
b. Vapor Compression Refrigeration  Vapor Chamber
c. Thermoelectric Devices e. Air Cooled Heat Sinks
1.2 Evaluation Criteria
a. Parasitic Power Consumption e. Cost
b. COP f. Scalability
c. Control g. Hot Swap/Modularity
 Condensation/Dew Point Mgmt h. Size/Weight
 Variable Load/no Load Operation i. Processor Interface
d. Reliability  Cold Plate/Evaporator (U*A)
1.3 Candidate Assessment Study
PUMPED LIQUID VAPOR
COMPRESSION
Two Phase Single Phase Refrigeration
TFF
Parasitic Power Consumption 340 wt 2760 wt 2133 wt
COP
Air Cooled Condenser 17 2 3.0
Water Cooled Condenser 106 12 19
Control
Condensation/Dew Point N/A N/A Difficult
Ambient Air Sink Easy Easy Difficult
Water Sink Easy Easy Difficult
Chilled Water Sink Easy Easy Difficult
Load Management None Required Easy Difficult
Reliability 50K Hrs 1 50K Hrs 1 12K/20K Hrs 2
Cost Lowest Intermediate Highest
Scalability Same Same Same
Hot Swap/Modularity Same Same Same
Package
Size Smallest Largest Intermediate
Wieght Lowest Largest Intermediate
Processor Interface
Cold Plate/Evaporator UA Highest Lowest Highest
Required Area Lowest Highest Lowest
1. Limited by pump life
2. Limited by compressor life

7. 7
2. SYSTEM DESIGN & ANALYSIS

8. 8
2.1 System Concept Cooling
2.2 Feasibility Hardware Model

9. 9
2.3 R-134a Flow Prediction
91
4 6 11
Determine R134a Flow
P = 400wts x 16 = 6400 wt. (21,843 BTU/Hr-Lb.)
m= 21843/(63-41) =992.9 Lb./Hr (16.5 Lb/Min)
Adjust flow to reflect the 17 th line (liquid level sensor line)
Total flow required= 992.9*(17/16) = 1055 pph
Assume a liquid density of R134a @ 91 F=74.3 ppcf
V =1055/(74.3*0.1337) ~ 106 gph
Flow/Processor = 106/17 ~ 6.2 gph

10. 10
2.4 Pump Performance
280
240 DP
200
Pressure (P) / in wc
Max. Allowable
160 System Resistance
120 PUMP PERFOMANCE DATA
Manufacturer….…..DTE Energy Technologies
Model………….…...809-IND
Input………………..110/120vac@60Hz
80 Impeller…………..…1.9quot; Dia
Speed…………..…..3450 RPM
Refrigerant……...….R-134a
Saturation Pres.…...102 psia
Operating Temp……91 F (33 C)
40
0
0 20 40 60 80 100 120 140 160 180 200
Volumetric Flow Rate (V) /gph
2.5 System Design Constraints
1000
PERFOMANCE DATA
Refrigerant……...….R-134a
Saturation Pres.…...102 psia
Operating Temp……91 F (33 C)
MAX ALLOWABLE
dP= 0.0235m2
Pressure (P)/in wc
100
DESIGN LIMIT
dP= 0.0154m2
10
10 100 1000
Volumetric Flow Rate (V) /gph

11. 11
2.6 R-134a Saturated Liquid dT/Dp
0.040
0.036
0.032
0.028
dT/dP (deg F/in-wc)
0.024
dT/dP = 0.47P-0.69
0.020
0.016
0.012
0.008
0.004
0.000
0 20 40 60 80 100 120 140 160 180
Pressure (psig)
2.7 R-134a Saturated Liquid
140
120
100
Temperature (F)
80
Tsat = 50.157Ln(Tsat) - 141.55
60
40
20
0
0 20 40 60 80 100 120 140 160 180 200
Pressure (psig)

12. Sensor Line
180 in wc 17
6.2.0 gph
Liquid Level
2.9 Goals
Sensor
6.2.0 gph 16
400 wts
6.2.0 gph 400 wts 15
6.2.0 gph 14
2.8 Orifice Selection Criteria
400 wts
6.2.0 gph 4
Quality = 30%
400 wts
~
~ ~
~
6.2.0 gph 400 wts
3
17/ 0.047 “ Orifices
6.2.0 gph
400 wts
2
6.2.0 gph
400 wts
1
230 in wc
6.2.0 gph
400 wts
PUMP 0
12
106 gph

13. 13
2.10 Orifice Hardware

14. 14
2.11 Pump Performance Curve

15. 15
2.12 Pump Reference Data

16. 16
2.13 Pump Dimensional Drawing

17. 17
3. SYSTEM RESULT

18. Sensor Line
170 inwc
7.1 gph 17
Liquid Level
Sensor
3.2 Results
7.2 gph 16.
400 wts
7.3 gph 15
400 wts
Orifice ID = 0.052”
7.4 gph 14
400 wts
3.1 Orifice Performance Results
7.5 gph 13
400 wts
~
~ ~
~
4
24% < x < 27%
6.6 gph
400 wts
3
6.7 gph
400 wts
2
6.8 gph
400 wts
220 inwc 1
6.9 gph Orifice ID = 0.047”
400 wts
18
0
PUMP
120gph

19. 19
3.3 Pump Performance Summary
280
240
200 DP
OP
Pressure (P) / in wc
160 System Design
Resistance
120
PUMP PERFOMANCE DATA
Manufacturer….…..DTE Energy Technologies
Max. Allowable Model………….…...809-IND
System Resistance Input………………..110/120vac@60Hz
80
Impeller…………..…1.9quot; Dia
Speed…………..…..3450 RPM
Refrigerant……...….R-134a
Saturation Pres.…...102 psia
40 Operating Temp……91 F (33 C)
0
0 20 40 60 80 100 120 140 160 180 200
Volumetric Flow Rate (V) /gph
3.4 COP Test Results
3.4 COP TEST RESULT
Input # Total Ancillary1 Htr COP Air COP Liquid
Power Power Power Condenser Condenser
(wt) (wt) (wt)
1 1590 54 1536
2 1189 25.5 1164
3 1526 0 1526
4 1510 4.82 1505
Total 5731
AC Fans 576 192 9.1 106.1
DC Fan 285 95 16.9 106.1
1 Pump, Controls, Relays, Pilot Lights, etc.

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3.5 System Pictures

21. 21
4. COLD PLATE DESIGN STRATEGY

22. 22
4.1 Thermal Budget
Location Temperature Temperature Thermal UA
Difference Resistance
(C/F) (deg C/deg F) (deg C/wt) (Btu/hr-F)
Junction 85/185
Junction to case 45/81 0.225
Case 40/104
Interface 5./9. 0.025
Wall 35/95
Boiling dT 2.2/4 0.011 178.7
Saturation Temp 32.8/87.8
Log Mean Temp. 3.5/6.3 0.0175 3467
Ambient 25/77
Cond. Discharge Air. 31.6/88.9
4.2 Alpha Thermal Design Specifications
COMPAQ
SPECIFICATIONS
A
200 wt. 200 wt.
A
200 wt
T = 85 º C
j
T J ? 85 ? C
T C ? 40 ? C
T = 40 º C
c
SECTION A-A

23. 23
4.3 Cold Plate Design Strategy
B B
Fram
Distributed Flow
Discharge Pool
SECTION B-B 28.3 C
Supply 30%
Reservoir
6.2 Gp L @ 26 C
Manifold
Convoluted Fin
Null Cavity
200 WT 200 WT
In Line Cu Strip 0.10”HX2.00”WX6.50”L
∆P
0
1.00
∆ P/ ∆ P
0
0.1
0.01
0
Qu
30
ality
(%
15
0

24. 24
4.4 Copper Off-Set Strip Fin
0.10” X 2.00” X 6.50” (20 FINS/INCH)
4.5 Preliminary Prototype Cold Plate No. 1
4.6 Preliminary Prototype Cold Plate No. 2

25. 25
4.7 Function Prototype Cold Plat No. 1
LID
ALUMINUM
COLD PLATE
FRAME
SUPPLY RESERVOIR
MANIFOLD CONVOLUTED
FIN DISCHARGE
POOL
NULL CAVITY
4.8 Function Prototype Cold Plat No. 2 (Not Built)

26. 26
5. COLD PLATE TESTING

27. 27
5.1 Cold Plate Test Fixture Block Diagram

28. 28
5.2 Test Fixture Heat Balance Study
DATA
PM1000 Heater 2
CASE PH Vol Tfi Tfo Power Tht Volts Amps Thr
(psig) (gpm) (deg C) (deg C) (watts) (deg C) (VRMS) (IRMS) (deg C)
1D 100.3 0.88 18.0 21.1 805.0 41.0 100.9 3.6 39.6
2D 101.0 0.60 18.2 21.5 710.0 38.4 92.5 3.3 36.4
3D 100.3 0.48 18.3 21.8 590.0 35.9 84.2 3.1 34.4
4D 100.3 0.30 18.9 22.4 360.0 32.2 63.9 2.3 31.6
5D 100.6 0.50 18.1 21.7 651.0 36.4 87.4 3.2 34.9
6D 99.8 0.90 17.9 21.1 840.0 41.8 101.9 3.7 44.3
RESULTS
PM1000 Heater 2 Heat
CASE PH Mass Tfi Tfo M*Cp*dT Power Tht Power Thr
(psig) (pph) (deg C) (deg C) (wts) (watts) (deg C) (wts) (deg C)
1D 100.3 438.2 64.4 69.9 706.1 805.0 105.8 364.2 103.2
2D 101.0 298.8 64.7 70.7 525.2 710.0 101.1 308.1 97.5
3D 100.3 239.0 65.0 71.2 434.2 590.0 96.6 257.6 93.9
4D 100.3 149.4 66.1 72.3 271.4 360.0 89.9 147.6 88.8
5D 100.6 249.0 64.6 71.0 466.9 651.0 97.5 275.2 94.8
6D 99.8 448.2 64.3 69.9 735.3 840.0 107.2 371.9 111.7
900
800 No Thermal Insulation
700
600
MCp(To-Ti) /wt.
IDEAL
500
ACTUAL
400
300
200
100
0
0 100 200 300 400 500 600 700 800 900
Measured Input Power / wt.

29. 29
5.3 Cold Plate Power Measurement Study

30. 30
5.4 Copper Cold Plate Summary of Results

31. 31
5.5 Copper Cold Plate Heat Balance
V = 6.2 gphL @ 26.6 ºC T HTR 2
COLD HTR 3 T3 = 28.3
THT THT
T T
HTR 2 HTR 3
Indium/Gallium Interface
Wall
Th3= 33.9 ºC
Th2 = 33.6 ºC Q2=198.5 wt Q3=198.5 wt
RCU =0.017 Cu COLD PLATE
Cu COLD PLATE
d C/Wt
T3 = 28.3 ºC
FINS FINS
M~61 pph T2’ = 28. 3ºC T2’ = 28.3 ºC x = 30 %
Cp =0.18 WT-Hr/Lb-ºC
Cu COLD PLATE Cu COLD PLATE
QL=Negligible QL=Negligible
TS = TBD
33.6 ºC 33.9 ºC
28.3 ºC 28.3 ºC
T
T
Q2 Q3
Q1
26.5 ºC 26.5 ºC
Q1 = (61*0.18*(28.3-26.6)) = 18.7 wt R 2-S = (33.9-28.3)/198.5 = 0.028 deg. C/Wt
Q2 = (198.5-18.7) =179.8 R s-wall = 0.028-0.017 = 0.011 deg C/Wt
Qave = (18.5/2) + 179.8 =189.1 wt
189.1/198.5 = (Ts-26.5)/ (28.3-26.5) = 28.2 ºC
R 2-S = (33.6-TS)/198.5=0.0269 deg C/wt
R s-wall = 0.027-0.017 = 0.010 deg C/Wt
Sub-Cooled Saturated
Liquid Vapor

32. 32
5.6 Copper Cold Plate Operating Envelope

33. 33
5.7 Copper Cold Plate Superheat Study

34. 34
DATA 5.8 Copper Cold Plate Test Data
Case # Initial 101 102 103 104 105 106 107 AVE
Elapse Time (min) 0 30 50 70 90 110 170
Heaters 4 & 5
Htr 4 Volts (VAC) 57.6 115.2 95.9 95.5 93.4 93.8 93.9 93.5 94.5
Current (AAC) 0.0 0.0 3.6 3.4 3.4 3.4 3.4 3.4 3.4
Htr 5 Volts (VAC) 58.0 115.2 95.9 95.4 93.7 94.0 94.4 93.5 94.7
Current (AAC) 0.0 0.0 3.5 3.5 3.4 3.4 3.4 3.4 3.4
Water Vol (gpm) 0.0 0.0 0.9 0.8 0.85
Ti (C) 22.6 23.2 18.7 18.7 18.7
To (C) 21.9 22.4 21.4 21.4 21.4
Heaters 2,3,4 & 5
Water otal Vol (gpm) 0.0 0.0 1.7 1.7 1.6 1.6 1.6 0.8 1.6
Ti (C) 22.6 23.2 18.4 18.4 18.4 18.4 18.4 18.7 18.4
To (C) 21.9 22.4 20.8 20.7 20.8 20.8 20.8 21.4 20.8
System P1(psig) 75.0 88.5 101.0 100.0 100.0 100.0 100.0 100.0 100.2
dP1(in wc) 0.0 130.0 90.0 90.0 80.0 85.0 85.0 130.0 86.0
Cold Plate Vol (gpm) 0.0 5.9 6.5 6.2 6.0 6.2 6.0 6.4 6.2
dP4 (in wc) 10.0 9.0 10.0 10.0 10.0 10.0 9.7 10.5 9.9
T2 (C) 24.4 24.3 26.7 26.5 26.6 26.6 26.7 27.1 26.6
T3 (C) 23.1 24.1 28.6 28.4 28.5 28.4 28.4 26.9 28.5
THTR2 (C) 22.9 24.1 34.1 34.1 33.9 33.7 33.9 27.2 33.9
THTR3 (C) 22.9 26.5 C ( 79. 34.4 34.4 34.2 34.0 34.2 27.1 34.2
TCP2 (C) 22.9 24.1 33.9 33.8 33.7 33.5 33.6 27.1 33.7
TCP3 (C) 22.9 24.1 33.8 33.7 33.6 33.4 33.5 27.1 33.6
dP5 (in wc) 0.0 200.0 210.0 210.0 190.0 210.0 200.0 200.0 204.0
VOLTS (rms) 44.0 28.3 C (82 64.4 63.9 63.2 62.8 63.2 108.0 63.5
AMPS (rms) 0.0 0.0 6.4 6.4 6.3 6.3 6.3 0.0 6.3
C. Flow
PM1000 Power Meter (wts) M~61 pph
Instrumentation 10.2 10.2
Instrumentation+Pump 45.6 45.6
Total 1089.4 1232.0 1252.0 1214.0 1204.0 728.2
RESULTS
Water Properties
Density (ppcf) 62.4
Cp (Btu/lb-F) 1.0
System
Heat Balance
Htr 2 Htr 3 Htr 4 Htr 5 Htr 4&5 Htr2,3,4,&5 Htrs2,3
I*E (wts) 201.4 201.4 323.6 325.1 648.7 1051.5 402.8
M(pph) 423.3 811.7 388.4
MCpdT (wt) 341.0 0.0 -341.0
%diff 47.4 100.0 184.7
Copper Cold Plate
Thermal Resistance
Saturated Liquid Conditions Measred Calc. Ref. %diff
dP1 (psia) 111.80
T(C) 28.5 30.1 -5.66
Cp (BTU/lb-F) 0.34
Density (ppcf) 74.3
SG 1.19
Htr 2 Ref. Calc. (Based on Sat Temp)
Vol (gph) 4.36
M (pph) 43.07
MCpdT (wt) 8.01
Hfg(wt) 193.40
Htr2 201.41
T2AVE (C) 28.44

35. 35
DATA
Case # Initial 111 112 113 114 115 116 117 AVE
Elapse Time (min) 0 30 50 70 90 110 170
Heaters 4 & 5
Htr 4 Volts (VAC) 94.31 93.60 92.98 94.20 94.90 93.60 93.92
Current (AAC) 3.35 3.38 3.17 3.39 3.42 3.37 3.34
Htr 5 Volts (VAC) 93.90 93.36 91.65 94.30 94.60 94.03 93.48
Current (AAC) 3.47 3.45 3.41 3.41 3.43 3.39 3.43
Water Vol (gpm) 0.00 0.85 0.90 0.88
Ti (C) 23.6 18.9 19.0 18.94
To (C) 22.7 21.4 21.4 21.44
Heaters 2,3,4 & 5
Water otal Vol (gpm) 1.60 1.69 1.65 1.65 1.65
Ti (C) 18.4 18.4 18.4 18.4 18.43
To (C) 20.7 20.8 20.8 20.8 20.78
System P1(psig) 73.3 87.0 100.6 100.0 99.5 100.6 100.8 100.6 100.2
dP1(in wc) 0.0 120.0 115.0 65.0 60.0 70.0 70.0 110.0 66.3
Cold Plate Vol (gpm) 0.0 7.5 7.0 7.5 7.0 7.7 7.6 7.2 7.5
dP4 (in wc) 0.0 No Data 3.5 3.7 3.5 4.0 4.1 3.5 3.8
T2 (C) 23.5 24.1 27.1 26.6 26.5 26.7 26.7 27.1 26.6
T3 (C) 23.5 23.9 26.9 28.2 28.2 28.5 28.4 26.9 28.3
THTR2 (C) 23.5 23.9 27.1 33.2 32.9 33.4 33.4 27.1 33.2
THTR3 (C) 23.5 26.5 C ( 79. 27.1 33.5 33.1 33.6 33.7 27.1 33.5
TCP2 (C) 23.6 24.1 27.1 33.1 32.7 33.2 33.2 27.1 33.1
TCP3 (C) 23.6 24.1 27.1 32.9 32.6 33.1 33.1 27.1 32.9
dP5 (in wc) 0.0 210.0 200.0 200.0 180.0 200.0 210.0 200.0 197.5
VOLTS (rms) 0.0 28.3 C (82 0.0 60.34 59.38 60.55 61.41 0.0 60.4
AMPS (rms) 0.0 0.0 0.0 6.00 5.93 6.10 6.08 0.0 6.0
C. Flow
PM1000 Power Meter (wts) M~61 pph
Instrumentation 10.2 10.2
Instrumentation+Pump 47.1 47.1
Total 740 1178 1121 1184 1186 727
RESULTS
Water Properties
Density (ppcf) 62.4
Cp (Btu/lb-F) 1.0
System
Heat Balance
Htr 2 Htr 3 Htr 4 Htr 5 Htr 4&5 Htr2,3,4,&5 Htrs2,3
I*E (wts) 182.1 182.1 313.7 320.2 633.9 998.0 364.2
M(pph) 435.7 820.4 384.7
MCpdT (wt) 319.2 564.2 245.0
%diff 49.6 43.5 32.7
Copper Cold Plate
Thermal Resistance
Saturated Liquid Conditions Measred Calc. Ref. %diff
dP1 (psia) 112.53
T(C) 28.3 30.3 -6.94
Cp (BTU/lb-F) 0.34
Density (ppcf) 23.5
SG 0.38
Htr 2 Ref. Calc. (Based on Sat Temp)
Vol (gph) 52.53
M (pph) 164.18
MCpdT (wt) 28.17
Hfg(wt) 153.92
Htr2 182.09
T2AVE (C) 28.21

36. 36
DATA
Case # Initial 121 122 123 124 125 126 127 AVE
Elapse Time (min) 25 50 65 80 95 110 170
Heaters 4 & 5
Htr 4 Volts (VAC) 96.28 95.08 95.52 95.36 95.86 96.06 96.45 95.70
Current (AAC) 3.47 3.43 3.44 3.44 3.47 3.43 3.47 3.45
Htr 5 Volts (VAC) 97.10 95.67 95.40 95.52 95.37 95.65 96.45 95.49
Current (AAC) 3.52 3.47 3.46 3.46 3.48 3.45 3.50 3.46
Water Vol (gpm) 1.00 1.06 1.03
Ti (C) 19.2 19.2 19.19
To (C) 21.6 21.6 21.58
Heaters 2,3,4 & 5
Water otal Vol (gpm) 1.80 1.84 1.81 1.85 1.85 1.84
Ti (C) 19.1 19.1 19.1 19.1 19.1 19.07
To (C) 21.1 21.1 21.1 21.1 21.1 21.11
System P1(psig) 100.3 99.6 99.8 99.4 100.3 100.6 99.4 100.0
dP1(in wc) 125.0 50.0 55.0 55.0 60.0 65.0 95.0 58.8
Cold Plate Vol (gpm) 6.0 7.0 7.0 7.0 7.2 7.7 7.0 7.2
dP4 (in wc) 2.0 3.5 3.8 3.5 4.0 4.4 3.2 3.9
T2 (C) 26.8 26.4 26.5 26.4 26.5 26.6 26.8 26.5
T3 (C) 26.7 28.3 28.2 28.2 28.3 28.3 26.8 28.2
THTR2 (C) 26.8 33.8 33.7 33.5 33.9 34.2 26.9 33.8
THTR3 (C) Ti =26.5 C ( 79. 34.2 34.2 34.1 33.8 34.3 34.5 34.1
TCP2 (C) 26.8 33.6 33.4 33.4 33.7 34.1 27.0 33.6
TCP3 (C) 26.8 33.4 33.3 33.3 33.6 33.8 26.9 33.5
dP5 (in wc) 210.0 190.0 190.0 185.0 200.0 205.0 180.0 195.0
VOLTS (rms) To = 28.3 C (82 64.10 63.75 63.93 64.84 65.23 0.0 64.4
AMPS (rms) 0.0 6.43 6.26 6.35 6.44 6.41 0.0 6.4
C. Flow
M~61 pph
PM1000 Power Meter (wts)
Instrumentation 0.0
Instrumentation+Pump 0.0
Total 769.0 1211 1245 1249 1260 1271 758
RESULTS
Water Properties
Density (ppcf) 62.4
Cp (Btu/lb-F) 1.0
System
Heat Balance
Htr 2 Htr 3 Htr 4 Htr 5 Htr 4&5 Htr2,3,4,&5 Htrs2,3
I*E (wts) 205.1 205.1 329.7 330.6 660.3 1070.4 410.1
M(pph) 512.9 915.0 402.1
MCpdT (wt) 359.0 547.3 188.4
%diff 45.6 48.9 54.1
Copper Cold Plate
Thermal Resistance
Saturated Liquid Conditions Measred Calc. Ref. %diff
dP1 (psia) 112.60
T(C) 28.2 30.3 -7.44
Cp (BTU/lb-F) 0.34
Density (ppcf) 74.3
SG 1.19
Htr 2 Ref. Calc. (Based on Sat Temp)
Vol (gph) 5.10
M (pph) 50.36
MCpdT (wt) 8.78
Hfg(wt) 196.29
Htr2 205.07

37. 37
DATA
Case # Initial 131 132 133 134 135 136 137 AVE
Elapse Time (min) 25 50 65 80 95 110 170
Heaters 4 & 5
Htr 4 Volts (VAC) 87.55 87.66 87.66 87.66 87.66 87.66 87.86 87.66
Current (AAC) 3.20 3.16 3.17 3.11 3.14 3.19 3.16 3.15
Htr 5 Volts (VAC) 87.32 86.98 87.78 87.88 87.30 88.10 87.88 87.61
Current (AAC) 3.12 3.16 3.19 3.17 3.17 3.19 3.19 3.18
Water Vol (gpm) 0.75 0.75 0.75
Ti (C) 19.3 19.2 19.25
To (C) 21.8 21.8 21.81
Heaters 2,3,4 & 5
Water otal Vol (gpm) 1.60 1.60 1.60 1.60 1.60 1.60
Ti (C) 19.1 19.2 19.2 19.2 18.9 19.11
To (C) 21.2 21.3 21.3 21.3 21.2 21.27
System P1(psig) 90.0 100.2 100.7 100.4 100.4 100.7 100.90 100.48
dP1(in wc) 120.0 120.0 65.0 70.0 70.0 65.0 70.0 78.00
Cold Plate Vol (gpm) 7.0 7.2 7.5 7.7 7.2 7.2 7.5 7.36
dP4 (in wc) 4.0 4.2 4.6 4.2 4.1 4.5 4.30 4.32
T2 (C) 26.8 26.6 26.6 26.6 26.5 26.5 27.0 26.54
T3 (C) 26.6 28.3 28.3 28.2 28.2 28.2 26.9 28.26
THTR2 (C) Ti =26.5 C ( 79. 33.5 33.6 33.4 33.4 33.5 27.1 33.49
THTR3 (C) 26.8 33.8 33.8 33.7 33.7 33.8 27.1 33.78
TCP2 (C) 26.8 33.4 33.4 33.3 33.3 33.3 27.1 33.34
TCP3 (C) 26.8 33.3 33.2 33.1 33.1 33.3 27.1 33.19
dP5 (in wc) To = 28.3 C (82 195.0 205.0 200.0 200.0 200.0 200.0 200.00
VOLTS (rms) 0.0 64.10 63.75 63.93 64.84 65.23 0.0 64.37
AMPS (rms) C. Flow 6.43 6.26 6.35 6.44 6.41 0.0 6.38
M~61 pph
PM1000 Power Meter (wts)
Instrumentation 0.0
Instrumentation+Pump 44.9 44.9
Total 640.0 1108 1123 1099 1111 1116 644
RESULTS
Water Properties
Density (ppcf) 62.4
Cp (Btu/lb-F) 1.0
System
Heat Balance
Htr 2 Htr 3 Htr 4 Htr 5 Htr 4&5 Htr2,3,4,&5 Htrs2,3
I*E (wts) 205.3 205.3 276.5 278.2 554.7 965.3 410.6
M(pph) 373.5 796.7 423.3
MCpdT (wt) 279.6 503.2 223.5
%diff 49.6 47.9 45.5
Copper Cold Plate
Thermal Resistance
Saturated Liquid Conditions Measred Calc. Ref. %diff
dP1 (psia) 112.36
T(C) 28.3 30.3 -7.10
Cp (BTU/lb-F) 0.34
Density (ppcf) 74.3
SG 1.19
Htr 2 Ref. Calc. (Based on Sat Temp)
Vol (gph) 5.19
M (pph) 51.30
MCpdT (wt) 8.74
Hfg(wt) 196.53
Htr2 205.28
T2AVE (C) 28.22

38. 38
6. WIRING AND CONTROLS

39. 39
6.1 Level Balancing Resistor Specs.

40. 40
6.2 R-134a Flow and Pressure Safety Control Schematic
CIRCUIT DESIGN
BLOCK DIAGRAM

41. 41
6.3 Self Heated Thermistor Specifications

42. 42
6.4 Quality Sensor Schematic
+24 vdc T
100 Ω
75 Ω
0
500 Ω 10K Ω
0.80/1.00vdc
OUT

43. START CIRCUIT
OVERPRESSURE EMERGANCE OFF
110 VAC N
PRESSURE SWITCH
6.5 Start-Up Circuit
12 VDC 24 VDC FLOW & PRESSURE
PS PS CONTROL
PUMP
BUSS
CNT’L
BUSS
110 VACL
110 VACN
PUMP -12VDC +12 VDC -12VDC
+ 12 VDC
-12 VDC
FLOW PSI*
CNT’L CNT’L
+12 VDC
HTR
CNT’L
HEATERS -12VDC
43
*50 PSI < P<150 PSI
30 July, 2002

44. 44
6.6 System Wiring Diagram

45. 45
6.7 Instrumentation Pin-Out Table
Function Patch Panel Connector 5 Connector 1 Connector 7 Connector 4
Coolant Flow 20 3 10
R-134a Flow 21 2 11
CldPlt Flow 22 10 3 11
Pump Disc. Pressure 23 1 8 10
CldPlt Disc. Pressure 24 18 2
CldPlt dP 25 11 1
Input Power 26 15 -
CldPlt Power 27 7 -
Quality 28 17 - 9
Open 29 19
No Pin 4
No Pin 5
No Pin 6
Common 8 7 7
No Pin 9
No Pin 10
No Pin 12
Liquid Level 13
Liquid Level
No Pin 16
Over Press. Switch 4
Over Press. Switch 5 1
Ground 6
-12vdc (Common) 7
+12 vdc (Common) 9
+12vdc (Pump) 12
-24 vdc (Solinoid) 13
+24 vdc (Solinoid) 14(2 Cnt'l)
+24 vdc (Solinoid) 15(15 Cnt'l)
+24 vdc (Solinoid) 16(5 Cnt'l)
Thermistor Quality 17 8
No Pin 18
Thermistor Quality 14 19
110VAC N Buss 2
Power Controller Pot 3&4
0 5 1
12 4
110VAC L Buss 13

46. CldPlt Pwr
Tran
N 110 VAC L
CONN 1 CONN 5
CldPlt ∆P 1 1 Patch Panel 23 (Volts)
Pump Disc P 2 Patch Panel 21 (Amps)
2
CldPlt Flow 3 3 Patch Panel 20 (Amps)
OVERPRES. 4 4 Qly Sig (Volts)
SWITCH 5 5
6 6
7 Common 7 Patch Panel 27 (Amps)
CldPlt Disc P 8 Common
8
Sys Stdby
9 +12 vdc 9
Coolant Flow 10 10 Patch Panel 22 (Amps)
R-134 a Total Flow 11 11 Patch Panel 25 (Amps)
Pump 12 +12 vdc 12
Common
13 13
Solenoid 2
14 +24 vdc 14 Patch Panel 29 (Amps)
Solenoid 3 15 Patch Panel 26 (Amps)
+24 vdc 15
Solenoid 1
16 +24 vdc 16
Qlt Trans Patch Panel 28 (Amps)
6.8 Instrumentation Wiring Diagram Liquid
17 17
18 18 Patch Panel 24
19 19
Input Pwr
Tran.
+24
Cntl
LOAD
CONN 7 1 2 3 4 5 6 7 8 9 10 11 12 13 14
CldPlt Flow
Emergency Hour Meter
Off Quality Signal
Quality Transducer
46
LEG 3 POWER
Common
CONTROL
29 August, 2002

47. 110 vac G
21 22
11
6 5 PIN 13 Solenoid/102 psig
+24 vdc 1 2 PIN 15 Solenoid/100 psig
16 15 PIN 14 Solenoid/101 psig
CONNECTOR 1
-24 vdc 14
6.9 Liquid Condenser Flow Control Wiring Diagram
9 10
WATLOW CONT’L
Model 988A-22FD-JARG
Comm +12 vdc
Pump Disc
Pressure Transducer
47
5/12/2002

48. 48
6.10 Power Switch Wiring Diagram
Notes:
Radio Shack SN 900-7813 Red Illuminated
Rocker Switch 3P SPST ON-Off/10 A 125 VAC Red
White
LOAD
60 Hz
Black
1
2
3
6.11 Data Acquisition PCB Data
PCI-DAS-TC Thermocouple Board
• 16 Thermocouple Inputs
• On-Board Processor
• Utilizes Noise-Immune V/F Converter
• J, K, E, T, R, S, B Thermocouple Types
PCI-DAS1602-16 I/O Board
• Model 16-Bit Analog Input Resolution
• 330 kHz Sample Rate (PCI-DAS1602-16)
• On Board Sample FIFO
• Dual High Speed Analog Outputs
• 24-Bits High Drive I/O (for PCI-DAS1602-16)
• Fully Plug-and-Play

49. 49
7. CALIBRATION DATA

50. 50
7.1 Orifice Calibration

51. 51
7.2 R-134a Cold Plate Flow
100
Notes:
90
Flow Meter No.……………..2
Fluid…………………....Water
80 Temp……………….……...70F
Press………………...120 psia
70 Orientation…………. ..Vertical
Mass Flow Rate (pph)
Flow Meter Sn…… .1391358
Range………………. ..0-2 psid M = 76.6Ln(ma) - 128.1
60
50
40
30
20
10
0
1 10 100
Flow Meter Output (ma)
7.3 R-134a Total Flow
300
Notes:
Flow Meter No……………….3
250 Fluid …………………... Water
Temp……… …….....…..70 F
Pressure………...... .120 psia
Orientation……...….Horizontal
Mass Flow Rate (pph)
200 Transducer Sn……....1405480
Range………………. ...0-2 psid
M = 142.7Ln(ma) - 177.4
150
100
50
0
1 10 100
Flow Meter Output (ma)

52. 52
7.4 Pressure Transducer
280
240
200
Pressure (psig)
160
120
80
40
0
4 8 12 16 20
Transducer Output (ma)
7.5 Differential Pressure Transducers
7.6 2.4
2.0
Pressure Drop (psid)
1.6
1.2
0.8
0.4
0.0
4 8 12 16 20 24
Transducer output (ma)

53. 53
7.7 Power Transducer
3200
2800
2400
2000
Power (wt)
1600
1200
800
400
0
4 8 12 16 20 24
Transducer Output (ma)

54. 54
8. BOM

55. 55
8.1 Mechanical ID Block Diagram
5/
1/ 8 (2
4 (2 x Pl
x Pl 5/ ac
1/ ac 8 es H
4 es x ea
x 1/ te
1/
1/
4
H D
E St
A iff
T
E
R
S T
U E he
B- H xt r
A ea en m
S te si

56. 56
8.2 Mechanical
ITEM NO. QTY DESCRIPTION STATUS P/N PRICE COST
Test TFF Compaq Spares
100 1 1 0 PUMP/MOTOR IN HOUSE 001-100
110 1 1 0 MANIFOLD SUB ASS'Y TBB* 002-100 $50.00 $50.00
120 1 1 0 SEPARATOR SUB ASS'Y TBB* 003-101 $100.00 $100.00
130 1 1 0 CONDENSER/SUB ASS'Y IN HOUSE 004-101 $0.00 $0.00
140 1 1 0 RECEIVER SUB ASS'Y TBB* 005-100
141 1 1 24quot;L X 3quot;D COPPER TUBE TBB* 005-101 $0.00 $0.00
142 2 2 3quot; X 3' X 5/8quot; COPPER TEE TBB* 005-102 $0.00 $0.00
143 2 2 3quot; D END CAPS TBB* 005-103 $0.00 $0.00
150 0 1 0 SAFETY LINE TBB* 006-000
151 0 0 1 0 5/8 PRESSURE RELIEF VALVE PURCHASE 006-101 $54.64 $54.64
160 3 16 16 DISTRIBUTION LINES TBB* 006-202
161 0 32 32 4 1/4quot; BALL VALVES PURCHASE 006-303 $22.22 $1,422.08
162 0 16 16 4 1/4quot; TEEquot; ACCESS VALVE PURCHASE 006-404
163 3 16 16 3 1/4quot; SIGHT GLASSES PURCHASE 006-505 $10.38 $394.44
170 3 16 16 0 HEATER SUB ASS'Y TBB* 007-100
171 32 32 1/4quot; X 1/4quot; X 1/4quot; TEES PURCHASE 007-101 $1.25 $125.00
172 32 32 5/8quot; X 5/8quot; X 1/4quot; TEES PURCHASE 007-102 $2.00 $200.00
173 16 16 5/8quot; X 3 quot; TUBES PURCHASE 007-103 $0.00 $0.00
174 16 16 5/8quot; X 1/4quot; FPT ADAPTERS COMPAQ 007-104 $0.00 $0.00
177 32 32 5/8quot; D Heater Extension TBB* 007-107 $1.13 $36.00
178 32 32 1/4quot;D X 2.5 quot; Stiffener TBB* 007-108 $0.24 $7.60
180 3 16 16 3 ORIFICE SUB ASS'Y TBB 008-100
181 16 16 1/4quot; ORIFICES PURCHASE 008-101 $4.50 $72.00
181 16 16 1/4quot; ORIFICE ADAPTERS TBB 008-102 $0.92 $14.72
190 NA 1 NA FLOW METER SUB ASS'Y TBB* 009-000
192 6 6 3/8 ' X 3/8quot; X 1/4quot; TEES TBB* 009-002 $0.00 $0.00
193 2 2 1/4 Metering Valves PURCHASE 009-003 $47.60 $95.20
193 2 2 FLOW METERS PURCHASE 009-003 $265.00 $530.00
200 NA TUBE + FITTINGS + VALVES
220 2 2 5/8' FLEX LINE SUB ASS'Y IN HOUSE 010-001 $0.00 $0.00
221 36' 36' 1/4quot; TUBING PURCHASE 010-002 $1.23 $44.16
222 6' 6' 3/8 quot; TUBING PURCHASE 010-003 $1.81 $10.87
223 12' 12' 5/8 quot; D TUBING IN HOUSE 010-004 $0.00 $0.00
224 6' 6' 2quot; TUBING IN HOUSE 010-005 $0.00 $0.00
225 2 2 2quot; CAPS PURCHASE 010-006
226 1 1 2quot;X2quot;X5/6quot; TEE'S PURCHASE 010-007
228 1 1 5/8quot; BALL VALVE IN HOUSE 010-009 $0.00 $0.00
229 5 5 3/8quot; BALL VALVE IN HOUSE 010-010 $49.80 $99.60
230 0 1 0 0 RACK ASSEMBLY
231 0 1 0 0 Frame PURCHASE 011-001 $269.46 $269.46
232 0 1 0 0 Panel PURCHASE 011-002 $110.86 $110.86
233 0 2 0 0 Side 55 PURCHASE 011-003 $95.42 $190.84
234 0 1 0 0 Top 18 PURCHASE 011-004 $58.27 $58.27
235 0 1 0 0 P-B166 100 mm base PURCHASE 011-005 $95.31 $95.31
236 0 1 0 0 Casters PURCHASE 011-006 $67.99 $67.99

57. 57
8.3 MBOM Continued
237 1pk PANEL NUTS PURCHASE 011-007
240 HEATERS
241 16 4 500 WT/120 VOLT/ 4 quot; L PURCHASE 007-109 $28.04 $560.80
242 16 2 400 WT/120 VOLT/ 4 quot; L PURCHASE 007-110 $28.10 $505.80
243 4 500 WT/120yVOLT/ 4 quot; L WITH J TC
Q g PURCHASE 007-111 $76.50 $306.00
$50 00
250 PRESSURE SWITCH
251 1 1 PURCHASE 012-001 $47.00 $94.00
260 MISC.
261 120 FRONT FERRULS PURCHASE 013-001 $0.26 $31.20
262 1 ORIFICES PURCHASE 014-000 $4.95 $4.95
263 1 ORIFICES PURCHASE 014-001 $4.95 $4.95
264 3 30# CANISTERS OF R-134A PURCHASE 015-000 $125.00 $375.00
265 20 1/4quot; SAE FLARE NUTS PURCHASE 015-001 $0.34 $6.80
266 20 1/4quot; FLARE SWEAT ADAPTERS PURCHASE 015-002 $0.61 $12.20
267 20 1/4quot; 90 DEG. ELLS PURCHASE 015-003 $1.23 $24.60
268 1 HAND BLIND RIVIT TOOL PURCHASE 015-004 $45.50 $45.50
269 2 BX BLIND RIVITS PURCHASE 015-005 $11.80 $23.60
270 1 BX BLIND RIVITS PURCHASE 015-006 $11.95 $11.95
271 1 BX BLIND RIVITS PURCHASE 015-007 $28.49 $28.49
272 1 1/4quot;D X 72quot; L SS ROD PURCHASE 015-008 $15.80 $15.80
273 2 TOOLING & CONSTRUCTION BALLS PURCHASE 015-009 $12.10 $24.20
274 6 7/32 quot; DIA. BRASS ROD PURCHASE 015-010 $0.55 $3.31
275 4 1/8 quot; DRILL BITS PURCHASE 015-011 $0.84 $3.36
276 1 7/32quot; D TRANSFER PUNCH PURCHASE 015-012 $1.59 $1.59
277 2 7/32 quot; DRILL BITS PURCHASE 015-013 $1.42 $2.84
278 2 1/4' COUNTER BORE PURCHASE 015-014 $5.77 $11.54
279 2 CARBIDE DEBURING BIT PURCHASE 015-015 $7.69 $15.38
280 6 1/4quot; BRASS BARE PURCHASE 015-016 $0.63 $3.78
281 1 1/16quot;TX2 1/2quot; W X 24quot;L C-1018 STELL PURCHASE 015-017 $18.55
282 1 1quot; X 1quot; X 1quot; AL CHANNEL 1/8' WALL PURCHASE 015-018 $18.40
283 1 3/4quot; X 3/4quot; X 6 FT BRASS BAR PURCHASE 015-019 $35.04
284 2 1/16quot; T X 1/2quot;W X 6' L BRASS BAR PURCHASE 015-020 $4.73 $9.46
285 4 1quot; X 1quot; X 8'L AL ANGLE 1/8quot; WALL PURCHASE 015-021 $14.48 $ $57.92
,
* TBB TO BE BUILT

58. 58
8.4 EBOM
ITEM NO. QTY DESCRIPTION STATUS P/N
500 4 AC POWER SUPPLY SYSTEM IN HOUSE 001-100
501 4 20 AMP CIRCUIT BREAKER TBB* 001-101
502 4 140/20 AMP VARIAC IN HOUSE 001-102
503 4 20 AMP CONTACTERS IN HOUSE 001-103
510 4 HTR BANK TBB* 002-100
511 16 5 AMP FUSS HOUSINGS TBB* 002-101
512 16 5 AMP FUSSES TBB* 002-102
513 16 0.5 kW /120 VAC CARTRIDGE HTS TBB* 002-103
514 16 MECH. THERMOSTATS TBB* 002-104
515 16 5 AMP TOGGLE SWITCHE/LIGHTS TBB* 002-105
520 4 POWER INSTRUMENTATION TBB* 003-100
521 4 20 AMP CONTACTERS PURCHASE 003-101
522 1 WATT METER IN HOUSE 003-102
523 1 4 POSITION ROTARY SWITCH IN HOUSE 003-103
524 1 2 POSITION ON/OFF SWITCH IN HOUSE 003-104
525 1 110/120 VAC TO 48 VDC PWR SUPPLY IN HOUSE 003-105
530 1 PRESSURE CONTROL SYSTEM/ALARM TBB* 004-100
531 1 CONDENSER FAN/MOTOR IN HOUSE 004-101
532 1 IRON-CONSTANTAN TC ASSEMBLY PURCHASE 004-102
533 1 TEMP/PRESSURE CNT'L PURCHASE 004-103
534 1 ? AMP CONTACTER PURCHASE 004-104
535 2 LIGHT/NOISE ALARMS PURCHASE 004-105
540 1 LIQUID LEVEL CONTROL TBB* 005-000
541 1 LIQUID LEVEL CONTROL SENSOR PURCHASE 005-001
542 1 100 AMP CONTACTER PURCHASE 005-002
543 1 ? AMP CONTROLLER PURCHASE 005-003
550 1 AMBIENT ALARM + SAFETY TBB* 006-000
551 1 AMBIENT TEMP. SENSOR PURCHASE 006-001
552 1 100 AMP CONTACTER PURCHASE 006-002
553 1 ? AMP CONTROLLER PURCHASE 006-003
554 1 ALARM (VISUAL+NOISE) PURCHASE 006-004
560 MISC. SWITCHES 007-000
561 1 FAILSAFE PRES. SWITCH PURCHASE 007-001
562 1 HIGH PRES. SAFETY SWITCH PURCHASE 007-002
563 1 SYSTEM POWER SWITCH PURCHASE 007-003
564 1 START/STOP SWITCH PURCHASE 007-004
570 MISC. HARDWARE 008-000
571 TBD NEMA BOXES PURCHASE
572 TBD WIRE PURCHASE
573 TBD WIRE NUTS PURCHASE
574 TBD ETC PURCHASE

59. 59
9. WHITE PAPER

60. 60
To: Joe Marsala
From: Marty Pitasi
Subject: Pumped Two-Phase Cooling Paper
Date: 18 December, 2008
References:
a. Refrigerant 134a (R-134a), “2001 ASHRAE Handbook of Fundamentals” pages 20.16 &
20.17
b. Pump curve, “hy/save 809-IND Performance Curve” for 60 HZ, 3450 PRM, 1.95”D impeller
c. Quick disconnects AeroQuip Corporation “P/N AE71406B, Coupling Half, Modular, and P/N
AE71572B, Coupling Half, Rack.”
d. Pump Reliability, Hy-Save Energy Conservation Technologies letter, Subject “Refrigerant
Pump Reliability,” date August 23,2001
Enclosures:
1. R-134a PUMPED (2Φ) COOLING SYSTEM FLOW DESIGN
2. PROTOTYPE COLD PLATE FLOW CONCEPT
3. PROPOSED COLD PLATE
4. SYSTEM PERFORMANCE
5. HARDWARE INTERGRATION
6. COLDPLATE PERFORMANCE SUMMARY
1. Summary
A new and versatile high performance, isothermal-cooling design, currently capable of cooling 6.4
kW at 33°C (91°F) with a COP of 100 is discussed. The system is a pumped liquid two-phase
(2Φ) cooling design that uses a 1/20 HP motor-hermetic pump prime mover. The fluid is
refrigerant 134a (R-134a), an ecologically friendly refrigerant used in car air conditioners. The
design consists of pumping R-134a through a series of metered distribution lines that delivers
refrigerant to heat exchangers/cold plates (evaporators). Heat is absorbed by the refrigerant
changing it from a liquid to a vapor. The vapor is then converted back to a liquid via an air or
liquid cooled condenser.
This technique is scalable. A simplified 0.5kw system was built as a demo. Specifics of the design
are similar to those discussed in the paper.
2. Introduction
In anticipation of a 200wt. ALPHA processor (or equivalent) for the next generation of Enterprise
Computer, Compaq Computer’s Alpha Server Division surveyed all available cooling technology.
Their goal was to establish a cooling strategy that would be applicable for future system and
component cooling needs. As a result of the survey a pumped liquid 2Φ cooling system was
identified and developed. This system is able to meet all design constraints including envelope
size, cabinet integration, reliability, parasitic power limits, cooling demands, and control issues.
The proof of concept flow diagram (enclosure 1) shows the R-134a fluid being pumped into a
distribution manifold. Flow metering orifices uniformly distribute the R-134a into 16 parallel ¼” D
lines. Custom 400 wt heaters simulate 2 x 200 wt processor packages converting the liquid to
vapor. To enhance the system performance the vapor is discharged into a vapor-liquid separator
where gravity causes the saturated liquid to displace the vapor to the condenser. Sub-cooled
fluid flowing from the condenser mixes with the saturated fluid prior to the pump.
To prevent heat exchanger burn out, orifices are sized to deliver flow at rates that guarantee a
vapor quality not to exceed 30%.
Enclosure 1 shows an additional line. Line 17 is at the top of the system and is used to monitor
the refrigerant charge.
The thermal budget limited the heat exchanger‘s case-to-sink thermal resistance to 0.011°C/wt.
Flow analysis of the problem showed that an inline convoluted strip fin design with a pitch of 10

61. 61
fins/ inch and measuring 0.10”H x 2.00”W would meet the 0.011°C/wt requirement. The
subsequent design shown in enclosure 2 depicts the heat exchanger flow components. Flow
enters the heat exchange via a ¼” D line and pools behind a distribution manifold, then uniformly
flows across the fins into a vapor reservoir prior to discharge via 1/2” D line. To ensure a uniform
flow across the fins, therefore uniform cooling, and the manifold flow loss is designed as the
primary loss exceeding the fin, fluid expansion, and entrance and exit effect. The heat exchanger
accommodates 2/200wt processor packages approximately 2” W x 2” D, resulting in an overall
proof-of-concept cold plate size of approximately 2 7/8” W x 8 5/8’” L x 5/8” H. A sketch of the
proposed final deign is shown in enclosure 3.
Briefly, the two goals are to build and demonstrate: (1) a proof-of-concept pumped liquid, two-
phase (2Φ) cooling system capable of uniformly cooling 16/400 wt (6.4kw.) loads at temperatures
below 33°C, and (2) a heat exchanger with a sink-to-case thermal resistance ≤ 0.011°C/wt.
3. Results
A diagram of the proof-of-concept hardware is shown in enclosure 1. As described earlier the
primary system components of motor-pump, distribution manifold, orifices, vapor/liquid separator,
and condenser are clearly visible. Other support hardware such as reservoir, liquid level sensor,
and sight glasses are also shown.
Specifics regarding the system design point were extracted from the R-134a phase diagram
(Reference a) and the pump performance curve (Reference b). The vapor enthalpy (hfg ) for 30%
quality and 33°C (91°F) produces approximately 6.4 wt-Hr/Lb. Combining this value with an overall
load of 6.4kw and adjusting for the 17th leg results in a total flow requirement of 100 gph. Using the
pump performance curve, figure 1 of enclosure 4, a maximum allowable design pressure of 7.6 psi
was extracted and used to determine the orifice sizes. As shown in figure 2 of enclosure 4, a
minimum of 5.9 gph of R-134a at 33°C is required for each leg. However, in practice with off-the-
shelf orifices, the flows ranged from 6.6 to 7.5 gph, thus, resulting in a maximum vapor quality of
27%.
The assembled system integrated into Compaq GS-320 19” cabinet is shown in enclosure 5.
Note both air and liquid condensers included. Coefficient-of-Performance (COP) test results
+
range from 17 to 100 for air and liquid cooled condenser, respectively.
To determine the thermal performance of the heat exchanger a heat balance was performed. Two
2” x2” film heaters simulate the package envelope, dissipating 200 wt each. They were mounted
to the cold plate via an indium/gallium amalgam interface material. Thermal insulation was placed
over the heaters to eliminates loses. Input power, flow, and critical temperatures were measured.
The resulting maximum heat transfer coefficient extrapolated from the data was 0.011°C/wt.
Enclosure 6 summarizes the data used to evaluate the analysis.
4. Discussion of Results
Test data from twenty-one (21) separate tests were used to statistically determine the heat
exchanger’s sink-to-case thermal resistance. Values ranged from of 0.009 °C/wt to 0.011°C/wt.
Enclosure 5 shows the proof-of-concept system integrated into a typical Enterprise cabinet. The
design requires approximately 5% of the cabinet volume and doesn’t encroach into the sensitive
electronics envelope. Not show, is the design strategy that allows for quickly hot swapping a
board using quick disconnects (reference c)
By operating the system at 33 °C ambient, condensation issues are avoided. Any leakage takes
the form of a non-contaminating gas. The 1/20 HP motor-hermetic pump moves 6.4 kW at 33 °C
and has a documented minimum MTBS of 50,000 hours (reference d). Control is inherent in the

62. 62
design. R-134a operating temperatures are managed by the condenser performance, and load
variability is managed at the receiver/separator.
+
Coefficient of performance (COP) values range from 17 to 100 for air and liquid cooled
condensers, respectively. The only difference between the two is the fan power needed for the
air-cooled condenser.

63. 63

64. 64

65. 65

66. 66

67. 67