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Multi-Effect Evaporator Sizing
Core Numerical Engine in Fortran 90 β’ 24 total downloads
evaporator_design.f90
! =========================================================================
! Source File: evaporator_design.f90
! =========================================================================
program evaporator_design
implicit none
integer :: i,ne
double precision :: mf,xf,xp,Ts,BPEc,U0,Tc
double precision :: m_evap,m_prod,hfg,Q_total,A_total
double precision :: dT_avail,dT_eff,BPE_tot,economy
double precision :: m_steam,spec_en,Q_e,A_e,x_e,T_e,dT_e
double precision :: eco_s,A_s,Q_s
read(*,*) mf; read(*,*) xf; read(*,*) xp; read(*,*) Ts
read(*,*) ne; read(*,*) BPEc; read(*,*) U0; read(*,*) Tc
if(BPEc<1d-6) BPEc=1.78d0
if(U0<1d-6) U0=2500d0
hfg=2260d3
m_prod=mf*xf/xp
m_evap=mf-m_prod
BPE_tot=BPEc*(xf+xp)/2d0*dble(ne)
dT_avail=Ts-Tc-BPE_tot
if(dT_avail<1d0) dT_avail=1d0
dT_eff=dT_avail/dble(ne)
Q_total=m_evap*hfg
A_total=0d0
m_steam=m_evap/dble(ne)
economy=m_evap/m_steam
spec_en=m_steam*hfg/m_evap
do i=1,ne
Q_e=m_evap/dble(ne)*hfg
A_e=Q_e/(U0*dT_eff)
A_total=A_total+A_e
enddo
write(*,'(A)') '============================================'
write(*,'(A)') ' MULTI-EFFECT EVAPORATOR DESIGN'
write(*,'(A)') '============================================'
write(*,'(A)') ''
write(*,'(A)') '--- INPUTS ---'
write(*,'(A,F10.4,A)') ' Feed flow rate = ',mf,' kg/s'
write(*,'(A,F10.4)') ' Feed concentration = ',xf
write(*,'(A,F10.4)') ' Product concentration = ',xp
write(*,'(A,F10.2,A)') ' Steam temperature = ',Ts,' C'
write(*,'(A,I4)') ' Number of effects = ',ne
write(*,'(A,F10.4)') ' BPE coefficient = ',BPEc
write(*,'(A,F10.1,A)') ' Overall U = ',U0,' W/m2K'
write(*,'(A,F10.2,A)') ' Condenser temp = ',Tc,' C'
write(*,'(A)') ''
write(*,'(A)') '--- RESULTS ---'
write(*,'(A,F10.4,A)') ' Product flow = ',m_prod,' kg/s'
write(*,'(A,F10.4,A)') ' Total evaporation = ',m_evap,' kg/s'
write(*,'(A,F10.4,A)') ' Steam consumption = ',m_steam,' kg/s'
write(*,'(A,F10.2)') ' Steam economy = ',economy
write(*,'(A,F12.1,A)') ' Total heat duty Q = ',Q_total,' W'
write(*,'(A,F12.1,A)') ' Total heat duty Q = ',Q_total/1d6,' MW'
write(*,'(A,F12.2,A)') ' Total area required = ',A_total,' m2'
write(*,'(A,F10.2,A)') ' dT per effect = ',dT_eff,' C'
write(*,'(A,F10.2,A)') ' BPE total = ',BPE_tot,' C'
write(*,'(A,F10.1,A)') ' Specific energy = ',spec_en/1d3,' kJ/kg'
write(*,'(A)') ''
write(*,'(A)') '--- EFFECT-BY-EFFECT ---'
write(*,'(A)') ' Effect Q[kW] A[m2] x_out T_boil[C]'
write(*,'(A)') ' -------------------------------------------------------'
do i=1,ne
Q_e=m_evap/dble(ne)*hfg
A_e=Q_e/(U0*dT_eff)
x_e=xf+(xp-xf)*dble(i)/dble(ne)
T_e=Ts-dT_eff*dble(i)
write(*,'(2X,I4,2X,F10.1,2X,F10.2,2X,F10.4,2X,F10.2)') i,Q_e/1000d0,A_e,x_e,T_e
enddo
write(*,'(A)') ''
write(*,'(A)') '--- EFFECTS SWEEP (1 to 6) ---'
write(*,'(A)') ' N_eff Economy A_total[m2] Spec.En[kJ/kg]'
write(*,'(A)') ' -----------------------------------------------'
do i=1,6
eco_s=dble(i)
Q_s=m_evap*hfg
dT_e=(Ts-Tc-BPEc*(xf+xp)/2d0*dble(i))/dble(i)
if(dT_e<0.1d0) dT_e=0.1d0
A_s=dble(i)*Q_s/(dble(i)*U0*dT_e)
write(*,'(2X,I4,2X,F8.2,4X,F10.2,4X,F10.1)') i,eco_s,A_s,hfg/eco_s/1000d0
enddo
write(*,'(A)') ''
write(*,'(A)') '--- CORRELATIONS ---'
write(*,'(A)') ' Economy = m_evap_total / m_steam (approaches N for ideal)'
write(*,'(A)') ' BPE = BPE_coeff * concentration (linearized Duhring)'
write(*,'(A)') ' Q = U * A * dT_eff per effect'
write(*,'(A)') ' Ref: McCabe, Smith & Harriott, Unit Operations Ch.16'
write(*,'(A)') ' Geankoplis, Transport Processes, Ch.8'
end program evaporator_design
Solver Description
Designs and sizes multi-effect evaporators (1 to 6 effects) with forward-feed configuration. Accounts for boiling point elevation (BPE) using DΓΒΌhring's rule. Performs mass and energy balances on each effect to solve for temperatures, vapor flows, concentration profiles, overall steam economy, specific energy consumption, and heat transfer area.
Key Numerical Methods & Architecture
- Input Redirection: Reads parameters sequentially from standard input (`stdin`) using Fortran sequential read (`read(*,*)`), ensuring modular integration.
- Modular Design: Formulated using pure mathematical routines, separation of equations from output formatting, and precise numerical solvers (e.g. bisection, Newton-Raphson).
- Standard Compliant: Written in clean, standards-compliant Fortran 90 to ensure cross-compiler compatibility.
π οΈ Local Compilation
To test this code on your machine, compile the source code file(s) using a standard Fortran compiler (e.g., `gfortran`).
Compilation Command:
gfortran -O3 evaporator_design.f90 -o evaporator_design
Execution Command:
Execute the program by feeding the sample input file into the program using stdin redirection:
evaporator_design < input.txt
π₯ Downloads & Local Files
Preview of the required input file (input.txt):
! Feed mass flow rate mf [kg/s]
5
! Feed solute mass fraction xf
0.12
! Product solute mass fraction xp
0.65
! Heating steam temperature Ts [ΓΒ°C]
120
! Number of effects (1 to 6)
3
! Boiling point elevation (BPE) coefficient
1.78
! Overall heat transfer coefficient U0 [W/m2K]
2500
! Last effect condenser temperature Tc [ΓΒ°C]
50
5
! Feed solute mass fraction xf
0.12
! Product solute mass fraction xp
0.65
! Heating steam temperature Ts [ΓΒ°C]
120
! Number of effects (1 to 6)
3
! Boiling point elevation (BPE) coefficient
1.78
! Overall heat transfer coefficient U0 [W/m2K]
2500
! Last effect condenser temperature Tc [ΓΒ°C]
50