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clear;
clc;
printf('FUNDAMENTALS OF HEAT AND MASS TRANSFER \n Incropera / Dewitt / Bergman / Lavine \n EXAMPLE 12.6 Page 751 \n')// Example 12.6
// Spectral , Normal emissivity en and spectral hemispherical emissivity e
// Spectral normal intensity In and Spectral emissive power
T = 2000 ;//[K] temperature of surface
wl = 1 ;//[micro-m] wavelength
stfncnstt = 5.67*10^-8; //[W/m^2.K^4] Stefan-Boltzmann constant
// From the given graph of emissivities
e1 = .3;
e2 = .6;
//From Equation 12.26 Black Body Radiation
Eb = stfncnstt*T^4; //[W/m^2]
//Equation 12.34
i1 = integrate('e1*cos(x)*sin(x)','x',0,%pi/3);
i2 = integrate('e2*cos(x)*sin(x)','x',%pi/3,4*%pi/9);
e = 2*[i1+i2];
// From Table 12.1 at wl = 1 micro-m and T = 2000 K.
I = .493*10^-4 * stfncnstt*T^5 ;//[W/m^2.micro-m.sr]
In = e1*I;
//Using Equation 12.32 for wl = 1 micro-m and T = 2000 K
E = e*%pi*I;
printf('\n Spectral Normal emissivity en = %.1f and spectral hemispherical emissivity e = %.2f \n Spectral normal intensity In = %.2e W/m^2.micro-m.sr and Spectral emissive power = %.1e W/m^2.micro-m.sr ', e1, e,In,E);
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