Klockjj

10 Reputation

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8 years, 32 days

MaplePrimes Activity


These are replies submitted by Klockjj

@Rouben Rostamian   ah thank you very much for spotting that big mistake for me that equation was suppose to be using an exp() instead of ln().

 

That solved most of my problems however now i am having issues with creating an array for output. I am getting this signularity error this time, would you happen to have any ideas as to what may be causing this?

 

I am trying to generate a list of values for Cprop(z), T(z) and P(z) from 0 to 5 in .5 increments.

kinetic parameter

K := exp(19.837-13636/(T(z)+273.15))

exp(19.837-13636/(T(z)+273.15))

(24)

radial disperssion Coeff

Dr := Vs*dp/(9*(1+19.4*(dp/dt)^2))

0.3135309899e-3*Vs

(25)

thermal conductivity calculations,w/m-k

Kbs := kfluid*(`εb`+(1-`εb`)/(2/3*(1+kfluid/ksolid)))

0.5937050269e-1

(26)

``

Kbd := `εb`*Cpair*Gs*dp/(9*(1+19.4*(dp/dt)^2))

0.2342976727e-3

(27)

KB := Kbs+Kbd

0.5960480036e-1

(28)

Heat of reaction (deltaH), Find heat of formation for each reactant and product--> dHrxn = heat of formation(product)-heat of formation(reactant)

Error, missing operator or `;`

 

heat of formation = A + B*T + C*T^2

Hfacrolein := -7.076*10+(-5.59*10^(-2))*(273.15+350)+3.86*10^(-5)*(273.15+350)^2

-90.60509039

(29)

Hfwater := -238.41-0.122e-1*(350+273.15)+2.76*10^(-6)*(273.15+350)^2

-244.9406781

(30)

Hfpropylene := 3.62*10+(-6.49*10^(-2))*(273.15+350)+3.049*10^(-5)*(273.15+350)^2

7.59731748

(31)

`ΔHrxn` := Hfacrolein-Hfwater-Hfpropylene

146.7382702

(32)

Solving nodified Ergun Equation

f := (1-`εb`)*(1.75+(150*(1-`εb`))*`μ_air`/(dp*Gs))/`εb`

2.191735176

(33)

``

Determining U of the wall and Ueffective

``

``

Uwall := 1/(1/hi+ln(dto/dt)/(2*kpipe)+1/ho)

255.6367103

(34)

``

Ueff := 1/(1/Uwall+(1/2)*dt/(4*KB))

8.758440965

(35)

ode1 := Gs*(diff(Cprop(z), z))/rho = -K*Cprop(z)

0.4117046714e-2*(T(z)+273.15)*(diff(Cprop(z), z))/P(z) = -exp(19.837-13636/(T(z)+273.15))*Cprop(z)

(36)

ode2 := Gs*Cpair*(diff(T(z), z)) = -K*Cprop(z)*`ΔHrxn`-4*Ueff*(T(z)-(350+273.15))/dt

1.4645*(diff(T(z), z)) = -146.7382702*exp(19.837-13636/(T(z)+273.15))*Cprop(z)-666.3198268*T(z)+415217.2000

(37)

ode3 := diff(P(z), z) = -f*Gs^2/(rho*dp)

diff(P(z), z) = -4.361346783*(T(z)+273.15)/P(z)

(38)

ode := Gs*(diff(Cprop(z), z))/rho = -K*Cprop(z), Gs*Cpair*(diff(T(z), z)) = -K*Cprop(z)*`ΔHrxn`-4*Ueff*(T(z)-(350+273.15))/dt, diff(P(z), z) = -f*Gs^2/(rho*dp)

0.4117046714e-2*(T(z)+273.15)*(diff(Cprop(z), z))/P(z) = -exp(19.837-13636/(T(z)+273.15))*Cprop(z), 1.4645*(diff(T(z), z)) = -146.7382702*exp(19.837-13636/(T(z)+273.15))*Cprop(z)-666.3198268*T(z)+415217.2000, diff(P(z), z) = -4.361346783*(T(z)+273.15)/P(z)

(39)

NULL

Ics1 := Cprop(0) = 0.3e-1

Cprop(0) = 0.3e-1

(40)

Ics2 := T(0) = 350

T(0) = 350

(41)

Ics3 := P(0) = 2.5

P(0) = 2.5

(42)

ics := Cprop(0) = 0.3e-1, T(0) = 350, P(0) = 2.5

Cprop(0) = 0.3e-1, T(0) = 350, P(0) = 2.5

(43)

NULL

``

(44)

dsolve({ics, ode}, numeric, output = array([0, .5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5]))

Warning, cannot evaluate the solution further right of .10547158e-2, probably a singularity

 

array( 1 .. 2, 1 .. 1, [( 2, 1 ) = (array( 1 .. 11, 1 .. 4, [( 1, 4 ) = (HFloat(350.0)), ( 1, 1 ) = (HFloat(0.0)), ( 1, 3 ) = (HFloat(2.5)), ( 1, 2 ) = (HFloat(0.03))  ] )), ( 1, 1 ) = (array( 1 .. 4, [( 1 ) = (z), ( 2 ) = (Cprop(z)), ( 3 ) = (P(z)), ( 4 ) = (T(z))  ] ))  ] )

(45)

NULL

NULL

``

NULL

NULL

NULL

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