Your task Is to evaluate the effects of hair and hats on the rate of heat loss f

Question

Your task Is to evaluate the effects of hair and hats on the rate of heat loss from a persons head. Model the head as a hemisphere with D=9inches. Model hair as a covering of thickness between zero and 2 inches with thermal conductivity between 0.02 and 0.2W/mK. Model a hat as a covering of thickness varying between zero and 1 inch with thermal conductivity varying between 0.01 and 0.1W/mK. Make the appropriate comparisons and plot your results. It the convective heat transfer cofficient vary between 5 and 50 w/m^2 degree K Let the skin temperature be 35 degree C and the surrounding air temperature be 10 degree C

Explanation / Answer

Rate of heat loss from person head(without hair or hat) = 5*25*2*3.14*0.1143*0.1143

                                                                                          = 10.255 W

Rate of heat loss from person head(without hair or hat) = 50*25*2*3.14*0.1143*0.1143

                                                                                          = 102.55 W

=> It varies between 10.255 - 102.55 W

Reduction in heat loss by hair = 0.0508*25*0.02

                                                 = 0.0254 W

=> Reduction in heat loss by hair varies between 0.0254 - 0.254 W

Reduction in heat loss by hat = 0.0254*25*0.01

                                                 = 0.00635 W

=> Reduction in heat loss by hat varies between 0.00635   - 0.0635 W

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