DCP & Oil immersion cooling

Performance Evaluation of Plate-fin and Pin-fin
Heat Sinks and Design Optimization of Dynamic
Cold Plate (DCP)
By
Parth Jayeshkumar Soni
MS Mechanical Engineering Graduate Student
The University of Texas at Arlington
Date:03/21/2016
Thesis Advisor: Dr. Dereje Agonafer
Committee Members: Dr. A. Haji-Sheikh
Dr. Miguel AAmaya
Parth Soni Advisor: Dr. Dereje Agonafer
1

Why Liquid Cooling…
 Power Trends
https://www.cisl.ucar.edu/nar/2006/1.0.sc.jsp
2

Focus
Study 1: Design Validation of Dynamic Cold Plate
(DCP)
Study 2: Parametric Study and Performance
Comparison of Pin-fin and Plate-fin Heat Sinks for
the Application of Oil Immersed Cooling
3

Focus
Study 1: Design Validation of Dynamic Cold Plate
(DCP)
Study 2: Parametric Study and Performance Comparison
of Pin-fin and Plate-fin Heat Sinks for the Application of
Oil Immersed Cooling
4

Original Cold Plate(OCP) vs Dynamic Cold
Plate(DCP)
 One inlet one outlet
 Same water flow for all heat generating components
5
 Separate inlet and outlet for different compartment inside cold
plate
 Different flow for different compartment

What is DCP?
Dynamic cold plate is extended
version of original cold plate
6
CAD model Fin placement
Referance heat generating platform

7
Dimensions (in mm)
ASICs – 14.71 × 13.31 ×
0.8
FPGA – 10.5 × 12.7 × 0.8
Reference Platform
Component Quantity Power(W)
Base 1 -
ASIC 1(B1) 40
ASIC 11 5
FPGA 1 5
LICA 137 0
ASIC:-Application-Specific Integrated Circuit
FPGA:-Field-Programmable Gate Array
• MCM serves as basis for design of solution
- Power dissipation of 485W over 78mm × 78mm

CFD Modeling of DCP
8

Methodology
Modeling : Solidworks
Mashing: ICEM CFD
Analysis: Ansys Fluent
9

Model of Dynamic Cold Plate
10
Dimensions cold late
Foot print : 90*90 mm
Base height: 5mm
Fin dimensions
Thickness: 0.5 mm
Height: 2mm
Length: 29mm
Pitch: 1mm
Dimensions of cover
Footprint : 90*90 mm
Height: 15mm
Ø of inlet outlet: 7mm
Dimensions from Experimental setup

Purpose of Study
 To visualize the flow in side the cold plate
 To validate of the CFD model
 For, Optimization of flow inside cold plate
 For, parametric study of DCP
11

Mesh
 Unstructured mesh
 No of elements: 11,15,321
 Shape of elements: Tetra elements
 Mesh algorithm: Robust (octree)
 top-down meshing approach
 top-down meshing approach
12

Mesh Density
 Fin surface: 0.001 m
 Fin thickness: 0.005m
 Other surfaces: 1m
13

Analysis
 Models in fluent
 Energy equation
 Turbulent model: K-epsilon turbulence model
 Materials used in the modeling
14

K-epsilon Turbulence Model
15
Turbulent kinetic energy k
Eddy Dissipation ε
10% turbulent intensity from length scale model (Fluent
user guide)

Boundary Conditions
 4 inlets: Velocity inlets
 Velocity of water: 4 lpm
(Reference experimental data)
 Temperature: Ambient
 Pressure : 3000 pa
 4 outlets: Pressure outlets
 No back pressure
16

Results
17

Particle Tracking
18

Temperature Distribution
19
• This figure shows
the heat spread on
the copper plate
• As temperature of
B1 increases
neighboring chips
also shows some
higher temperature

Pressure Drop
20
Pumping power=Pressure drop *
Flow rate
Pumping power= 2.2 W(CFD result)
Pumping power=2.76 w(Experimental result)

Validation Between Results
21
0
10
20
30
40
50
B1 B2 B3 B4 FPGA C1 C2 A1 A2 A3 A4 D1 D2
Chart Title
CFD Temp (°C) EXP temp(°C)
Experimental Data: Ruturaj kokate’s Thesis

Conclusion
 Thus, from the CFD results this model is in good agreement
with experimental results
 Hence, this model can be used for the further study of
optimization and parametric study
22

Future Work
 Study 1:
This model can be used to optimize the design of the DCP
 Cover design optimization for better flow rate
Parametric study and documentation of different fins and
different cover design
23

Focus
Study 1:Design Validation of Dynamic Cold Plate (DCP)
Study 2: Parametric study and performance
comparison of pin fin and plate fin heat sinks for the
application of oil immersed cooling
24

Study 1
Parametric study and
performance comparison of pin
fin and plate fin heat sinks for the
application of oil immersed
cooling for open compute
generation one server
25

Previous Study
 Validation of the model using the identical boundary
condition generated in experiment
 Documentation of parametric study and the performance of
the parallel plate heat sink for the oil immersed application
 Optimization of the parallel plate heat sink design
26

27
 Evaluate the performance of pin fin and plate fin heat
sink
 Compare the thermal resistance of both the heat sinks
with current heat sink in use for open compute server
Motivation

Methodology
 Place plate fin and pin fin heat sink in place of the parallel
plate heat sink on the validated model
 Parametric study of heat sinks for same condition as
experimental set up
 Base height
 Pin thickness and radius
 Flow rate
 Documentation of the performance of both heat sinks
28

Types of Heat Sinks
29
http://img.diytrade.com/cdimg/720673/627215
7/0/1214899819/pin_fin_heat_sink.jpg
http://www.enertron-
inc.com/images/resources/forged/forged_2.JPGhttp://www.newegg.ca/Product/Product.aspx?Ite
m=N82E16816101827
Parallel plate heat sink Pin fin heat sink Plate fin heat sink

30 Material Properties
PCB, Ram- FR-4 epoxy resin
 Density- 1900 kg/m3
 Thermal conductivity – 0.17 W/m K
 Specific heat – 749 J/kg K
 Heat sink - Aluminum
 Density- 2700 kg/m3
 Thermal conductivity-218 W/m K
 Specific heat- 900 J/Kg K

Mineral Oil Properties31
𝜇 = 𝐶1 ∗ 𝐸𝑥𝑝
2797.3
𝑇 + 273.2
STE Oil Company data sheets and
MSDS:http://www.steoil.com/msds-tech-data
 Density – 1680 Kg/m3
 Thermal conductivity – 0.13 J/kg K
 Specific heat – 1680
 Re: 4.6

32 Flow Conditions
• Inlet temperature: 30˚C
• Volume rate : 1 lpm
• Velocity : 0.00115 m/s
• Pressure : 6 psi
• Re : 13.6
Volume flow rate = Area of inlet ×
Velocity
Re=
𝜌𝑣𝐷
𝝁
𝐷 =
2𝑔ℎ
𝑔+ℎ
g= channel width
h=fin height
Pumping power= pressure drop * mass
flow rate

CFD Set Up
33
Heat sink data:
• Foot print- 10 cm ×7 cm
• Base height – 0.6 cm
• Total height – 3.1 cm
• Number of fins – 25
• Fin radius – 0.6 cm
Model data
Cabinet
Footprint: 35*35 cm
Ram
Dimension: 14*3*8 cmHeat sink data:
• Foot print- 10 cm ×7 cm
• Base height – 0.6 cm
• Total height – 3.1 cm
• Number of fins – 25
• Fin thickness – 0.4 cm

Why Fixed Flow Rate
Pressure drop in air cooling application is around 4
Pa
For parallel plate heat sink in in oil cooling
application pressure drop around 0.9 Pa
Where as, in oil cooling application pressure drop is
around 0.032 Pa
34
Pumping power=Pressure drop * Flow rate
Advantage of fix Flow rate concept
• Less time consuming
• Easy to use

Results
35

Grid independent Study
36
Inlet Temperature - 30° C
Volume rate – 1 lpm
0
0.05
0.1
0.15
0.2
0.25
0.3
0 50000 100000 150000 200000 250000 300000
Thermalresistance(c/kg.k)
No of nodes
Chart Title
Plate fin pin fin

Flow Rate vs Thermal Resistance
37
0
0.05
0.1
0.15
0.2
0.25
0.3
0 0.5 1 1.5 2 2.5
Flow rate(lpm)
Flow rate vs Thermal resistance
pin fin
plate fin

Base Height vs Thermal Resistance
38
Volume rate – 1 lpm
0.935
0.94
0.945
0.95
0.955
0.96
0.965
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
Base height (cm)
Base height vs Thermal resistance

Fin Height and Fin Radius vs Thermal Resistance
for Pin Fin Heat Sink
39

Fin Height And Fin Thickness vs Thermal
Resistance for Plate fin heat sink
40
2.5
3
3.5
4
4.5
5 0.4
0.5
0.6
0.7
0.8
0.9
1
0.1
0.12
0.14
0.16
0.18
0.2
0.22
0.24
0.26
0.28
0.3
0.32
'C:UsersParthDesktopNew folder (2)project-16resultPin fin2.dat'
Height of fin (cm)
Thickness of fin (cm)
0.1
0.12
0.14
0.16
0.18
0.2
0.22
0.24
0.26
0.28
0.3
0.32

Conclusion
 Base height: Optimize base height can be 0.6cm as after
that the thermal resistance is not varying much.
 Fin height: Fin height shows the optimum result at 2.5 to 3 cm
as after that flow passes through lease
resistance path
 Fin radius or thickness:
 recommended thickness of the fin can be 0.4mm to 0.6 mm
(Plate fin) as after that resistance increases and performance
decreases
 Recommended radius of the fin can be 0.5 to 0.6 mm as after
that flow resistance increases and performance decreases
41

Future Work
Performance of the other available heat sinks can be
documented for the same model as well as higher
generation servers
This same can be studied for the fix pumping power
method
42

43 Thank You
Questions?...

DCP & Oil immersion cooling

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