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clear;
clc;
//Example 2.31
//Calculate:(a) Heat loss per unit length
//(b)Reduction in heat loss
//Given
hi=10 //W/sq m.K
h0=hi //W/sq.m.K
r1=0.09 //m
r2=0.12 //m
t=0.05 //thickness of insulation [m]
k1=40 //W/m.K
k2=0.05 //W/m.K
T1=473 //K
T2=373 //K
Q_by_L=2*%pi*(T1-T2)/(1/(r1*hi)+log(r2/r1)/k1+1/(r2*h0)); //W/m
printf("Ans (a) Heat loss=%f W/m ",Q_by_L)
//After addition of insulation:
r3=r2+t; //radius of outer surface of insulaiton
Q_by_L1=2*%pi*(T1-T2)/(1/(r1*hi)+log(r2/r2)/k1+log(r3/r2)/k2+1/(r3*h0)); // W
Red=Q_by_L-Q_by_L1 //Reduciton in heat loss in [W/m]
percent_red=(Red/Q_by_L)*100 //% Reduction in heat loss
printf("Ans (b) Percent reduction in heat loss is %f percent",percent_red)
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