Survival Time in Freezing Water By Wendy Lee & Dan Morgan ME 340 Winter 2010

Derivation

Properties Used Properties (Water at 290 K) ν = 1.081 x 10-6 cp = 4184 J/kg*K μ = 1080 x 10-6 k = 0.598 W/m*K Pr = 7.56 Properties (Average Human Body) ρ = 1010 kg/m3 k = 0.5 W/m*K r = 0.25 m As = 2 m2 To = 37 oC Tcore, final = 28 oC qgen = 100 W cp = 4000 J/kg*K

Results

Results

Conclusions In freezing water (about 0 °C ), the expected survival time is only about a half hour. We found that survival time increases if you are more obese (more insulation), or are more fit (more efficient qgen). As water temperature increases, survival time increases exponentially.

Assumptions For Conduction we assumed the person was curled up into a spherical shape. Assumed the water was only moving 1 m/s which would be inaccurate if they were swimming. Assumed constant heat generation, but most likely heat generation would decline as body temperature declined. Our person was wearing only thin clothing. The survival time would increase with thicker clothing and more layers.

References Works Cited Lavine, Adrienne, David DeWitt, Frank Incropera, and Theodore Bergman. Fundamentals of Heat and Mass Transfer. 6th ed. John Wiley & Sons Inc, 2006. Print. Nave, R. "Conduction and Convection: Cooling Mechanisms for Human Body." Conduction and Convection: Cooling Mechanisms for Human Body. Web. <http://hyperphysics.phy- astr.gsu.edu/HBASE/thermo/bodcon.html 1 of>. TARLOCHAN, F., and S. RAMESH. "HEAT TRANSFER MODEL FOR PREDICTING SURVIVAL TIME IN COLD WATER IMMERSION." BIOMEDICAL ENGINEERINGAPPLICATIONS, BASIS & COMMUNICATIONS 17.August (2005): 159-66. Print. "Cold Water Survival." Cold Water Survival. Search & Rescue Task Force. Web. <http://www.ussartf.org/cold_water_survival.htm>.