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A Heat Transfer Approach to Sleeping Bag Ratings

A Heat Transfer Approach to Sleeping Bag Ratings. Moises Alcevedo Jordan Ryskamp. Modes of heat transfer. Factors. Different Standards. Ratings are given as a temperature Manufacturers pick their ratings Many are “optimistic” No recognized standards Make different assumptions

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A Heat Transfer Approach to Sleeping Bag Ratings

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  1. A Heat Transfer Approach to Sleeping Bag Ratings Moises Alcevedo Jordan Ryskamp

  2. Modes of heat transfer

  3. Factors

  4. Different Standards • Ratings are given as a temperature • Manufacturers pick their ratings • Many are “optimistic” • No recognized standards • Make different assumptions • Young male in a tent wearing thermals • Older larger female sleeping under the stars

  5. Our Project • Use heat transfer principles to compare bags • All bags are limited by the amount of insulation • Approximate as cylinder Air out (To, Rair out)

  6. Properties and Assumptions Fillings of sleeping bags • Feathers k=0.02 mK / W • Polyguard Delta k= .041 mK / W • h= 5 • Why? Rcond < Rconv = 1/ h • No radiation • Why? Low temperature

  7. Thermal Circuit Ti To Rair in Rcond Rair out • Rtotal = Rair in + Rcond + Rair out • Rair in = 1/hA = 1/h2RbodyL • Rcond = Ln(Rout s.b./Rin s.b.) / 2kL • Rair out = 1/hA = 1/h2Rout s.b.L

  8. Solution and Conclusion • qV = ∆T / Rtotal = Ti -To / Rtotal To= Ti - qVRtotal Model does not give accurate results. However, it does give a good method of comparison. Currently found online at www.littlegreendesigns.com/Sleepingbags.aspx

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