Don't Touch the Stove! Grant Evans and Marc Simonsen
What is the Temperature of My Hand Without Burning It? • Taking the core body temperature to be 37° Celsius and the thickness of skin to be 4.0 cm the skin will be 34.3° Celsius. • k(skin) = .370 W/m·K • h = 2 W/m2•K (air) • ∆x = .04 m • T∞ = 22° Celsius • Tc = 37° Celsius Temperature of Skin = 34.3° C
I Just Burned My Hand … Now What? • Assuming you just touched a hot burner we will say that the skin is now 150˚ Celsius. • This new temperature is significantly higher than the 34.3˚Celsius that was calculated earlier. • WebMD recommends running your hand under cold water to draw the heat out. • How much does the temperature of the water affect the cooling (heat extraction)?
Water at Different Temperatures • h = 200 W/m2•K (water) • T∞ = 0˚C, 5˚C, 10˚C, 15˚C, 20˚C • qconv”(0˚C) = 30,000 • qconv”(5˚C) = 29,000 • qconv”(10˚C) = 28,000 • qconv”(15˚C) = 27,000 • qconv”(20˚C) = 26,000
Conclusion • First it is assumed that the heat transfer into your body by the burned skin is negligible compared to the cooling that is taking place by the convection of cold water running over the burned skin. • There is very little difference between the ice cold water 0˚C and the quite warm tap water 20˚C. Only 4,000 W/m2•K. The difference is only 13.3% of the highest q” value. • Therefore we can conclude that it is not worth the time to get ice water to pour on your burn. • Faucet water will work fine.