Dear all

I'm Gunawan, I'm using Flex Pde 6 student version,

I try to run simulation based on the conditions below :

TITLE 'NH3 Decomposition Model'

! A <--> 0.5B + 1.5C ra

!Tube side:

{A : NH3

B : N2

C : H2}

!Shell side

{D : Argon

E : Hydrogen }

COORDINATES

Cartesian1 { default coordinate is 'X' }

SELECT

ngrid=1

errlim = 1e-3

penwidth = 3

VARIABLES

Fa (0.01)

Fe (0.01)

DEFINITIONS { parameter definitions }

Z = 1 !m

S = 314*10^(-4) ! m2

V = S*Z ! m3

l = 0 !m {axial position}

Delta= 6*10^(-6) !m

d = 0.01 ! m (tube diameter)

Rhob = 510 ! kg/m3

Epsilon = (4-2)/2 {mole amount change }

PtSweep = 1 ! atm (Shell side)

PtFeed = 36 ! atm (Tube side)

Tg = 873 !K

R = 8.314 ! J/molK

W = Rhob*V !kg

Betha = 0.674 {exponential constant}

k = 5.744*10^(19)*exp(-2.304*10^(5)/(R*Tg))! m3/kg.s

Keq = 1/10^(2250.322/Tg - 0.8534 -1.51049*l*log10(Tg) - 25.8987*10^(-5)*Tg + 14.8961*10^(-8)*Tg^2)

Fao = 2 ! mol/s

Fbo = 0 ! mol/s

Fco = 0 ! mol/s

Fdo = 2 ! mol/s

Feo = 0 ! mol/s

Xa = (Fao-Fa)/Fao

Fb = Fbo+(0.5*Fao*Xa)

Fc = Fco+(1.5*Fao*Xa)-Fe

Ft1 = Fa+Fb+Fc ! mol/s

Ft1o = Fao+Fbo+Fco ! mol/s

Qo = FT1o*R*Tg/PtFeed ! m3/s

tau = V/Qo !s

Q1 = Ft1*R*Tg/PtFeed ! m3

Fd= Fdo ! mol/s

Ft2 = Fd+Fe ! mol/s

Pao = (Fao*R*Tg)/Qo

Pbo = (Fbo*R*Tg)/Qo

Pco = (Fco*R*Tg)/Qo

Pdo = (Fdo*R*Tg)/Qo

Peo = (Feo*R*Tg)/Qo

Pa = Fa/Ft1*PtFeed ! atm

Pb = Fb/Ft1*PtFeed ! atm

Pc = Fc/Ft1*PtFeed ! atm

Pd = Fd/Ft2*PtSweep ! atm

Pe = Fe/Ft2*PtSweep ! atm

P1 = Fc/Ft1*PtFeed ! atm

P2 = Fe/Ft2*PtSweep ! atm

Qio = 3.2027*10^(-9)*exp(-6.38/R*Tg)

Qi = Qio*(P1^0.5 - P2^0.5)*S/Delta

ra = k*((Pa^2/Pc^3)^Betha- (Pb/Keq^2)*(Pc^3/Pa^2)^(1-Betha)) ! mol/kg.s {NH3 Decomposition rate}

rc = 1.5*ra {Hydrogen Production rate}

us = Q1/S ! m/s

EQUATIONS

Fa: dx(Fa+Qi) = S*Rhob*ra

Fe: dx(Fe + Qi) = 0

BOUNDARIES

region 1

start (0)

Point value (Fa) = Fao

Point value (Fe) = Feo

line to (Z)

point load(Fa) = 0

point load(Fe) = 0

PLOTS

elevation(Fa,Fe) from (0) to (Z) as "Flow rate (mol/s)" report (Fa) report (Fe) report (Xa) report (Qi) report (rc)

END

But this script can’t run, I don’t know how to solve it.

Please give me your suggestions or corrections.

Thanks in advanced