Submerged PC Cooling

By: Patrick HagueGeoffrey ClarkChristopher Fitzgerald

Group 11

History of PC Cooling

Early personal computers did not require active cooling

Increasing demand for computer technology requires cooling improvements

Today’s smaller devices require more complex analysis and design for cooling

Cooling Methods In Use

Aluminum heat sinks The cumulative

energy consumption worldwide of both manufacturing the heat sinks and operating the fans is an estimated 109 kW hours per year!

…Other Methods

Heat pipes are a very effective method of removing the heat from the surface of the processor

Water cooling using water blocks requires the use of a pump and radiator

Objectives

Reduce power consumption of system Increase cooling potential Reduced noise pollution

Why Submersion?

Lower velocity for heat migration required

The ability to remove the heat from the components, and dissipate it in a general location

Enclosure Design

Sizing Specifications: 1. Fit inside case with

components 2. House all the pc

boards 3. Must be water tight 4. Modular design

Enclosure Design (cont.)

¼ inch acrylic enclosure for visibility

Vertical cable orientation

3 gallon capacity

Components

CPU: AMD Athlon XP 2000+ = 60 Watts Max

GPU: ATI x700 Pro = 33 Watts Full Load Memory, Motherboard = 60 Watts Total Heat Output expected = 153 Watts

(safety factor included)

Initial Setup

Designing Heat sink

Must dissipate 153 Watts Should fit as cover over the enclosure Cannot interfere with case components Fins must be spaced far enough apart to

allow proper natural convection cooling Heat sink must contact fluid

Heat Transfer Analysis

Ensure the CPU and GPU temperatures are within specifications.

Maintain a stable operating environment, no hot pockets of fluid.

Keep the fluid at a temperature relative to a typical air cooled case.

Heat Transfer Solution

CPU/GPU Calculations:

Enclosure Heat sink Calculations:

otb

b

RR

TTq

,

1

, 11

f

t

ftot A

NAAhR

31

21

2

PrRe664.02w

w

w

kh

c

cf mL

mLtanh

fft hANq bhAϴb + ϴb

TThA

q

bf

ff

mLmkhmL

mLmkhmLMq f sinh)/(cosh

cosh/sinh

CPU/GPU

Calculate the base temperature of both CPU and GPU

Use extended fin equations in natural convection

Enclosure Heat Sink

Use the CPU/GPU fluid temperature as a given

Determine the surface area required to dissipate the total 153 Watts

Surface Area Affects on Heat Rate

50

70

90

110

130

150

170

190

210

230

12 16 20 24 28 32

Number of Fins

He

at

Ra

te o

f S

ink

Finished Heat Sink

Results Idle Temperatures

20

25

30

35

40

45

50

55

60

65

70

0 50 100 150 200 250 300 350

Time (min)

Te

mp

era

ture

(C

)

CPU Temp

Fluid Temp

Conclusions

Case can be cooled with passive cooling Power consumption has been reduced by

approximately 5 Watts Case is effectively silent

Where to go from here?

Commercial applications on larger scaleServer applications have high power densityMore fluid yields greater results

Questions?

Thank You