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//Variable declaration:
m = 1 //Mass flowrate (lb)
cP = 1 //Heat capacity (Btu/lb. F)
//From figure 21.3:
T1 = 300 //Temperature of hot fluid leaving exchanger ( F)
T2 = 540 //Temperature of hot fluid entering exchanger ( F)
T3 = 60 //Temperature of cold fluid leaving exchanger ( F)
T4 = 300 //Temperature of cold fluid entering exchanger ( F)
//Calculation:
DSh = m*cP*log((T1+460)/(T2+460)) //Entropy for hot fluid (Btu/ F)
DSc = m*cP*log((T4+460)/(T3+460)) //Entropy for cold fluid (Btu/ F)
DSa = DSh+DSc //Entropy for one exchanger (Btu/ F)
DSt = DSa*2 //Total entropy change (Btu/ F)
//Result:
printf("The entropy chage is : %.4f Btu/ F .",DSt)
if (DSt>0) then
printf("There is a positive entropy change.")
else
printf("There is a negative entropy change.")
end
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