Infrared absorption in polymers
Beer-Lambert Law
Ioe^(-ac)=I, a=absorption coefficient, c=amount
Solar scattering -> reflection
IR absorption -> high emission
Black body radiation map for human body
Temperature of sun >> Temperature of human body
Air
Human body gets radiation from the sun and environment and emits radiation to environment.
Temperature of human body > ambient temperature
Energy absorption in human body
Energy emission from human body
Stefan-Boltzman Law
θ
Human body (surface 1.8m2) was assumed as a rectangular.
Projected area : 0.1cosθ + 0.4sinθ (m2)
Irradiated sunlight : (0.1cosθ +0.4sinθ) (m2) x 1000 (W/m2) = 100cosθ + 400sinθ (W)
0.4m2
0.1m2
Radiation energy from the sun
Simulation of solar energy radiated on human body according to solar position. Human body was assumed as a rectangular which has a 1.8m2 surface area (average value for adult).
-Plank’s law (black bodt radiation) -> spectral intensity by wavelength (T is fixed), Wien Law (T and wavelength)
-Stefan Boltmann Law -> Energy by T
1kcal/hr = 1.16W
Thermal comfort?
Steady state thermal transfer model
-incoming eneryg = outcoming energy
-To simplyfy the equation, resistance of thermal transfers are utilized in terms of thermal-delaying parameters.
(moisture transfer resistance,
thermal conductive resistance,�covective resistance,�radiative resistance)
R=1/h (h = thermal coefficient)
h : W/m2K
Q=deltaT/h
Temp. is the perfect indicator?
D. P. Wyon et al., J. Hyg.. Camb.. 1972, 70, 203.
Skin temps are various.
J. Hardy, PNAS 1937
Steadman, R. G. J. Appl. Meteor. 1979, 18, 861.
ex) Can you predict the temperature of graphite ball (or graphene, CNT ball) under the sunlight?
Degree C
Solar energy (W/m2)
Ta = 23 degree C
Plank’s law or Stefan Boltzman Law
ex) Can you predict the temperature of your textile under the sunlight?
Polymetylpentene: PMP