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clear;
clc;
printf('FUNDAMENTALS OF HEAT AND MASS TRANSFER \n Incropera / Dewitt / Bergman / Lavine \n EXAMPLE 1.6 Page 26 ')// Example 1.6
// Find Skin Temperature & Heat loss rate
A=1.8; // [m^2] Area for Heat transfer i.e. both surfaces
Ti = 35+273; //[K] - Inside Surface Temperature of Body
Tsurr = 297; //[K] - Temperature of surrounding
Tf = 297; //[K] - Temperature of Fluid Flow
e=.95; // Emissivity of Surface
L=.003; //[m] - Thickness of Skin
k=.3; // Effective Thermal Conductivity
h=2; //[W/m^2.k] - Natural Thermal Convectivity from body to air
stfncnstt=5.67*10^(-8); // [W/m^2.K^4] - Stefan Boltzmann Constant
//Using Eq 1.5
Tsa=305; //[K] Body Temperature Assumed
i=-1;
while(i==-1)
hr = e*stfncnstt*(Tsa+Tsurr)*(Tsa^2+Tsurr^2); //[W/m^2.K] - Radiative Heat transfer Coeff on assumption
//Using Eq 1.8 & Eq 1.9 k(Ti-Ts)/L = h(Ts - Tf) + hr(Ts - Tsurr)
Ts = (k*Ti/L + (h+hr)*Tf)/(k/L +(h+hr));
c=abs(Ts-Tsa);
if(c<=0.0001)
i=1;
break;
end
Tsa=Ts;
end
q = k*A*(Ti-Ts)/L; //[W]
printf("\n\n (I) In presence of Air")
printf("\n (a) Temperature of Skin = %.2f K",Ts);
printf("\n (b) Total Heat Loss = %.2f W",q);
//When person is in Water
h = 200; //[W/m^2.k] - Thermal Convectivity from body to water
hr = 0; // As Water is Opaque for Thermal Radiation
Ts = (k*Ti/L + (h+hr)*Tf)/(k/L +(h+hr)); //[K] Body Temperature
q = k*A*(Ti-Ts)/L; //[W]
printf("\n\n (II) In presence of Water")
printf("\n (a) Temperature of Skin = %.2f K",Ts);
printf("\n (b) Total Heat Loss = %.2f W",q);
//END
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