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clear;
clc;
printf('FUNDAMENTALS OF HEAT AND MASS TRANSFER \n Incropera / Dewitt / Bergman / Lavine \n EXAMPLE 3.6 Page 122 \n'); //Example 3.6
// Heat conduction through Spherical Container
k = .0017; //[W/m.K] From Table A.3, Silica Powder at Temp 300K
h = 5; //[W/m^2.K]
r1 = 25*10^-2; //[m] Radius of sphere
r2 = .275; //[m] Radius including Insulation thickness
//Liquid Nitrogen Properties
T = 77; //[K] Temperature
rho = 804; //[kg/m^3] Density
hfg = 2*10^5; //[J/kg] latent heat of vaporisation
//Air Properties
Tsurr = 300; //[K] Temperature
h = 20 ;//[W/m^2.K] convection coefficient
Rcond = (1/r1-1/r2)/(4*%pi*k); //Using Eq 3.36
Rconv = 1/(h*4*%pi*r2^2);
q = (Tsurr-T)/(Rcond+Rconv);
printf("\n\n (a)Rate of Heat transfer to Liquid Nitrogen %.2f W",q);
//Using Energy Balance q - m*hfg = 0
m=q/hfg; //[kg/s] mass of nirtogen lost per second
mc = m/rho*3600*24*10^3;
printf("\n\n (b)Mass rate of nitrogen boil off %.2f Litres/day",mc);
//END
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