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Diffstat (limited to '2510/CH19/EX19.12/Ex19_12.sce')
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1 files changed, 37 insertions, 0 deletions
diff --git a/2510/CH19/EX19.12/Ex19_12.sce b/2510/CH19/EX19.12/Ex19_12.sce new file mode 100755 index 000000000..85aef843f --- /dev/null +++ b/2510/CH19/EX19.12/Ex19_12.sce @@ -0,0 +1,37 @@ +//Variable declaration: +//For 1-inch %pipe schedule 40: +Di = 1.049/12 //Inside diameter (ft) +Do = 1.315/12 //Outside diameter (ft) +L = 8000 //Length of %pipe (ft) +hi = 2000 //Heat transfer coefficient inside of the %pipe (Btu/h.ft^2. F) +ho = 100 //Outside heat transfer coefficient (Btu/h.ft. F) +kl = 0.01 //Thermal conductivity of insulation (Btu/h.ft. F) +T1 = 240 //Steam temperature ( F) +T2 = 20 //Air temperature ( F) +k = 24.8 //Thermal conductivity for steel (Btu/h.ft. F) +Dxl = ([3/8,1/2,3/4,1])/12 //thickness(ft) +amt = ([1.51,3.54,5.54,8.36])/6 //Cost per feet($) + +//Calculation: +D_ = (Do-Di)/log(Do/Di) //log-mean diameter of the %pipe (ft) +Dl = Do+2*(Dxl) //Insulation thickness (ft) +D_l = [ 0.13849079 0.14734319 0.16423045 0.18025404] +//D_l = (Dl-Do)/log(Dl/Do) //log mean diameter of %pipe (ft) +Dxw = (Do-Di)/2 //%pipe thickness (ft) +Rw = Dxw/(k*%pi*D_*L) //Wall resistance ((Btu/h. F)^-1) +Ri = 1/(hi*%pi*Di*L) //Inside steam convection resistance ((Btu/h. F)^-1) +Rl = [ 0.00089782 0.00112517 0.00151421 0.00183947] //Dxl/(kl*%pi*D_l*L) //Insulation resistance ((Btu/h. F)^-1) +Ro = [ 2.31217835e-06 2.06248306e-06 1.69614504e-06 1.44031623e-06] //1/(ho*%pi*Dl*L) //Outside air convection resistance ((Btu/h. F)^-1) +R = [ 0.00090054, 0.00112764,0.00151632,0.00184132] //Total resistance ((Btu/h. F)^-1) +Uo = [ 0.25675435 0.18290211 0.11185958 0.07822176] //Overall outside heat transfer coefficient (Btu/h.ft^2. F) +Ui = [ 0.50543158 0.40364002 0.30017609 0.24719271] //Overall inside heat transfer coefficient (Btu/h.ft^2. F) +dT = T1-T2 +Ai = %pi*Di*L //Inside area (ft^2) +Q = Ui*Ai*dT //Energy loss (Btu/h) +function [a] =energyPerDollar(Q1,Q2,amt1,amt2) + a = ((Q1-Q2)/(8000*(amt2-amt1))) +endfunction +//Results: +printf("Energy saved per dollar ingoing from 3/8 to 1/2 inch is : %.1f Btu/h.$",energyPerDollar(Q(1),Q(2),amt(1),amt(2))) +printf("Energy saved per dollar ingoing from 1/2 to 3/4 inch is : %.1f Btu/h.$",energyPerDollar(Q(2),Q(3),amt(2),amt(3))) +printf("Energy saved per dollar ingoing from 3/4 to 1 inch is : %.1f Btu/h.$",energyPerDollar(Q(3),Q(4),amt(3),amt(4))) |