Shaun Heldt and Tyler Merrell

Background Most common type of

cooling method Keeps CPU at a safe

operating temperature Has fan to improve

overall heat transfer of fins by introducing forced convection.

Materials

1 Intel I7-26000K Processor heat sink

1 Fluke 51 Thermometer with K-thermocouple

1 Soldering Iron 1 Hot Glue Gun

Experiment

Used glue gun and soldering iron to simulate a hot CPU

Measured temperature of the center of the heat sink and the fin tip while heating

Measured time to cool after heated Compared with theoretical calculations

to solve for Qout and the required air velocity for forced convection

Data

25

27

29

31

33

35

37

39

0 50 100 150 200 250 300 350

Tem

pera

ture

(Cel

cius

)

Time (s)

Fin and Center Temperature During Heating

Center

Fin Tip

54

55

56

57

58

59

60

61

62

0 20 40 60 80 100 120 140

Tem

pera

ture

(Cel

cius

)

Time (s)

Center and Fin Cooling

Center

Fin

Natural Convection

Solve for Qout from natural convection of the heat sink to find if cooling due to natural convection is sufficient for cooling CPUs

Note: Qin from CPU equals 80W

Therefore, Qout must be greater than or equal to 80W for natural convection to be sufficient

Natural Convection

Thermal Circuit

Compiled Calculations

Qout= 6.77WTherefore, natural convection is not sufficient

Forced Convection Used forced convection calculations to

solve for required airspeed from fans to have a Qout = 80W

Using previous calculations, an h value of 143.138 W/m2 would be required to sufficiently cool the CPU

Using Hilpert’s equation for cross flow of a square geometry and thermophysical properties we found that the required airspeed velocity is 2.913 m/s

Conclusion

Approximations were made to form the model used in calculating the presented values, however, we believe that this model was a reasonable approximation of the system.

We found that forced convection through a heat sink is necessary in CPU cooling