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//Variable declaration:
//From table 16.5:
t2 = 75.0 //Temperature of water leaving the shell ( C)
t1 = 35.0 //Temperature of water entering the shell ( C
T2 = 75.0 //Temperature of oil leaving the tube ( C)
T1 = 110.0 //Temperature of oil entering the tube ( C)
mw = 1.133 //Mass flowrtae of water (kg/s)
cpw = 4180.0 //Heat capacity of water (J/kg.K)
cpo = 1900.0 //Heat capacity of oil (J/kg.K)
p = 850.0 //Density of oil (kg/m^3)
Di = 0.01905 //Inside diameter of tube (m)
V = 0.3 //Average velocity of oil flow inside the tube (m/s)
Np = 2.0 //Number of passes
Uc = 350.0 //Overall heat transfer coefficient for clean heat exchanger (W/m^2)
Rf = 0.00027 //Fouling factor (m^2.K/w)
pi = %pi
//Calculation:
Cw = mw*cpw //Water capacitance rate (W/K)
Q = Cw*(t2-t1) //Heat load (W)
Co = Q/(T1-T2) //Oil capacitance rate (W/K)
mo = Co/cpo //Total flowrate of oil (kg/s)
if (Cw<Co) then
Cmin = Cw //Minimum capacitance rate (W/K)
Cmax = Co //Maximum capacitance rate (W/K)
else
Cmin = Co //Minimum capacitance rate (W/K)
Cmax = Cw //Maximum capacitance rate (W/K)
end
m_ot = p*V*(pi/4.0)*Di**2 //Oil flowrate per tube (kg/s)
Nt = mo/m_ot //Number of tubes per pass
N = Nt*Np //Number of tubes
DT1 = T2-t1 //Temperature driving force 1 ( C)
DT2 = T1-t2 //Temperature driving force 2 ( C)
DTlm1 = ((DT1-DT2)/log(DT1/DT2)) //Log mean temperature driving force for ideal countercurrent heat exchanger ( C)
P = (t2-t1)/(T1 - t1) //Dimensionless parameter P
R = (T1-T2)/(t2-t1) //Dimensionless parameter R
//From figure 16.7:
F = 0.81 //Correction factor
DTlm2 = F*DTlm1 //Log mean temperature driving force for shell and tube exchanger ( C)
Ud = 1.0/(1.0/Uc+Rf) //Dirty overall heat transfer coefficient (W/m^2.K)
A = Q/(Ud*DTlm2) //Required heat transfer area (m^2)
L = A/(N*pi*Di) //Tube length (m)
N = round(N*10**-1)/10**-1
//Result:
printf("1. The mass flow rate of the oil is : %.2f kg/s .",mo)
printf("2. The minimum and maximum heat capacity rate is : %.0f and %.1f W/K",Cmin,Cmax)
printf("3. The heat load, Q is : %.0f W .",Q)
printf("4. The total number of tubes is : %f ",N)
printf("5. The tube length is : %.1f m .",L)
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