4.4 Amount of Heat Removed from the Head Form for Thermal Equilibrium
99
4.4.1.1 Conduction (K)
According to Eq. 3.8 as given in Sect. 3.8
F cl = Ratio of surface area of clothed body to nude body
1.05
A d = DuBois body area for an adult (of weight 70 kg and height 1.73 m) 1.84 m 2
ν = Decimal fraction of unclothed body area exposed to conduction
0.05
ψ = Decimal fraction of clothing exposed to conduction
0.05
R s = Thermal resistance of the supporting object (approximated average) 0.3125 m 2 K/W
I cl = Overall clothing thermal resistance
0.74 Cl o
T sk = Temperature of the skin
307 °K
T a = Ambient temperature
301 °K
Using the above equation and the value of each parameter as shown above the
calculated value for conduction (K) = 15.5 W.
4.4.1.2 Radiation (R)
According to Eq. 3.10 as given in Sect. 3.8
σ = Stefan-Boltzmann constant
5.67 × 10 −8 W/m 2
K 4
f eff = Adjusted DuBois body area to give more accurate result for the radiant
heat transfer with the environment
0.71 m 2
f cl = Ratio of surface area of clothed body to nude body
1.05
A d = DuBois body area for an adult (of weight 70 kg and height 1.73 m)
1.84 m 2
ε sk = Emissivity of the skin
0.97
ζ = Proportion of the unclothed body exposed to radiation
0.05
ξ = Proportion of the clothed body exposed to radiation
0.95
ε cl = Emissivity of clothing
0.97
T sk = Temperature of the skin
307 °K
T a = Ambient temperature
301 °K
T cl = Temperature of the outside surface of the clothing
303 °K
Using the above equation and the value of each parameter as shown above the
calculated value for radiation (R) = 18.3 W.
4.4.1.3 Convection (C)
According to Eq. 3.9 as given in Sect. 3.8