1. A Heat Transfer Investigation of Sleeping Bags
Tyler Campbell and Curtis Rands

2. Sleeping Bags Portable “bed and blankets” in one
Insulates and protects body from elements
Available with very low temperature ratings
A Heat Transfer Investigation of Sleeping Bags

3. How does a sleeping bag prevent different modes of heat transfer?
Conduction
Convection
Radiation
A Heat Transfer Investigation of Sleeping Bags

4. How does a sleeping bag prevent different modes of heat transfer?
Conduction
Hinders conduction from body to cold ground surface. This is enhanced with a foam sleeping pad
Good insulators often solid/gas matrix; conduction is slowed due to small contact area; internal convection is slowed due to small size of air pockets. Ex: Hollowfill® polyester, goose down
Convection
Radiation
A Heat Transfer Investigation of Sleeping Bags

5. How does a sleeping bag prevent different modes of heat transfer?
Conduction
Convection
Adds to thermal resistance between body and outside air to decrease convection around body
Decreases temperature gradient for convection
Even when forced convection is negligible, natural convection can occur
Radiation
A Heat Transfer Investigation of Sleeping Bags

6. How does a sleeping bag prevent different modes of heat transfer?
Conduction
Convection
Radiation
Decreases temperature gradient
Specially designed interior shell material can reflect body heat
Low-emissivity outer surface keeps radiative heat loss to a minimum
A Heat Transfer Investigation of Sleeping Bags

7. Experimental Data Low-Temp Mummy Bag, Reflective Liner
Performed consistently better than flannel-lined bag in all tests
No noticeable difference with pad (temperature gradient, surface)
Mild-Temp Rectangular Bag, Flannel Liner
Good insulator, flannel lining non-reflective
No noticeable difference with pad (temperature gradient, surface)
A Heat Transfer Investigation of Sleeping Bags

8. Observations in Research
Very little standardized research on sleeping bags
One ASTM document which used heated manikin
Many other significant factors, such as tent style, metabolism, clothing, moisture, sleeping bag shape & size
A Heat Transfer Investigation of Sleeping Bags