1. Average fluid temp necessary to
calculate the thermal input to the
system.
The thermal input to the system used
to determine heat removed by system,
losses and heat transfer coefficient.
Heat transfer coefficient tells of the
heat removal capabilities of the
system.
Reynolds number gives insight to flow
conditions existing in the channels.
The Nusselt number gives insight to
increases in convective heat transfer.
Heat Transfer Coefficient
Equation 3
Bulk Fluid Temperature
Equation 1
Thermal Input
Equation 2
High Heat Flux Electronic Cooling
Industry Advisor: Ioan Sauciuc
Faculty Advisor: Frank Kreith
Team:Andrew Bornstein, Elliot Clymer, Bradley Cooper, Ian Cullimore,Adam Wolf
Conclusions
• Achieved heat transfer coefficients 3 times higher
than standard forced convection (Figure 1)
• Achieved heat transfer coefficients 1600 times higher
than standard free convection of air (Figure 1)
References
1. Kreith, Frank, R. M. Manglik, and Mark Bohn. Principles of
Heat Transfer. 7th ed. Stamford, CT: Cengage Learning, 2011.
Print.
2. Koomey, Jonathan G., Christian Belady, Michael Patterson,
Anthony Santos, and Klaus-Dieter Lange. "ASSESSING TRENDS
OVER TIME IN PERFORMANCE, COSTS, AND ENERGY USE FOR
SERVERS." Intel.com. Stanford, 17 Aug. 2009. Web. 13 Apr.
2011. <http://www3.intel.com/assets/pdf/general/
servertrendsreleasecomplete-v25.pdf>.
Objectives and Project Requirements
Overview
• Moore’s Law: Exponential increase in computational power and heat
• Improper heat dissipation could lead to system failure
• Computational cooling costs can be 10% of total business expenses
(2)
Project Objectives
• Improve single phase water cooling efficiency
• hc = 50,000 W/m2K
Constraints
• Budget = $1,250
• Duration = 2 semesters
Heat Transfer Basics (1)
Convection Heat Transfer (qc)
• Forced convection using water
• Heat transfer depends on heat transfer
coefficient (hc), heated area, and the
difference between the surface and bulk
fluid temperatures
• Figure 1 (right) represents an order of
magnitude approximation of the heat
transfer possible with common fluids
Coldplate Photos
Pressure Transducer
• Input/Output Pressure
• Head losses through
geometry
Flow Meter
• Measures flow rate
mL/min
Pump
• Increases flow rate in
the system, increasing
heat transfer
Reservoir
• Water at ambient temperature
Thermocouples
• Temperature at various points in the
experiment, used to calculate heat transfer.
Valve
• Used to manually vary flow rate
Coldplate
• Novel flow design,
proprietary and thus
not disclosed
Opened Coldplate
(right) Partially exploded
view of the coldplate
assembly.
Experimental Setup
(left) The coldplate flow
channels.
Heat Transfer Calculations (1)
Future Work and Recommendations
• Reach two phase flow through use of vacuum pump
• Observe and photograph sub-cooled boiling and
measure the associated heat transfer
Experimental Schematic
Figure 2
Figure 1 – Range of heat transfer coefficients for different heat transfer modes
Nusselt Number
Equation 5
Reynolds Number
Equation 4
Special Thanks
• Greg Potts
• Darren McSweeney
• Nick Stites
Results and Graphs
Variable Flow Rate
Figure 4
• Increased flow rate
leads to increase in
heat transfer
coefficient
• Magnitude of the heat
transfer coefficient is
within goal range
GOAL hc
GOAL hc
Figure 3 – Physical apparatus