Heat%20Transfer%20and%20The%20Human%20Head

1
Heat Transfer and The Human Head

• Brad Elmer
• John Pearson

2
Introduction

• Problem
• Find the effects of wearing a beanie on a bald
  head
• Varying wind speeds in cold weather

3
Assumptions

• Average Head Circumference 58cm
  (www.thehatesite.com)
• Radiation neglected (same for all cases)
• Flesh Properties Same as Water
• Constant Core Temperature
• Transition region where hat ends very small

4
Setup

• Conditions
• Air at 20 F
• Core at 97.8 F
• Test 1
• Bald, no wind
• w/Beanie, no wind
• Test 2
• Bald, 20 mph wind
• w/Beanie, 20 mph wind
• Test 3
• Bald, category 5 hurricane 156mph wind
• w/Beanie, category 5 hurricane 156mph wind

5
Solution

• Test 1
• Free convection
• Gr gtgtRe2
• Test 2
• Forced convection
• Some error expected
• Re gt 7.6e4
• Test 3
• Forced convection
• Some error expected
• Re gt 7.6e4

6
Results
Head Surface Temperatures
Test 1 0 mph Test 2 20 mph Test 3 156 mph
Bald 91.5 F 65.9 F 43.2 F
With Beanie 93.2 F 86.8 F 84.9 F
7
Recommendations

• Wear a beanie especially when there are category
  five hurricane winds and its
• 20F outside
• Do not shave your head bald in a cold climate

8
Appendix

• Formulas used
• Free convection
• 9.12
• 9.25
• 9.35
• Forced convection
• 7.56

9
Appendix