FACSIMILE

Arsineh Hecobian

Jaemeen Baek

Index Important Functions of Facsimile Model Run Examples Application: HONO Reaction Conclusion

Overview A user-friendly computer program for modeling

chemical kinetics and transport Develop useful models rapidly, with specific

facilities for modeling chemical kinetics Handle very stiff ordinary differential equations

with the robust numerical integrator a predictor-corrector technique The values of the solution vector at the end of a step

are first predicted, and are then corrected to satisfy the differential equations by a few Newton iterations

Important Functions of Facsimile 4 Model Types

Homogeneous chemical reaction scheme Chemistry with flow and diffusion Fitting model to data 2-Dimensional flow with diffusion

Reaction Database Thousands of reactions from many database

(NIST Chemical Kinetics, NDRL/NIST Solution Kinetics, SGTE pure element, etc.)

Homogeneous chemical reaction

Illustrates simple chemical reaction

kf kr H2 = H + H 10 1

H + O2 = OH + O 200 2

Chemistry with flow and diffusion Simulates chemical kinetics, plug flow (1-D) and

diffusion along a pipe

c: A species concentration t: time

x: The distance along the pipe Q: The net production/destruction rate of the species due to the chemical reaction D: The species diffusion constant u: The flow velocity

x

cu

x

cDQ

t

c

2

2

Fitting model to data Fits unknown parameters in the model to

experimental data (A B) time A B

0.2 2.019 8

0.3 0.907 9.1

0.4 0.408 9.6

0.5 0.183 9.8

The reaction equation for data

=> find kkAdt

dA

2-Dimensional flow with diffusion Similar to the Advection-Diffusion model Simulates transport through a two-

dimensional matrix Reactants can flow from one cell to the

next in either dimension From a cell (x, y) to (x,y+1) or (x+1,y), and

can diffuse to any adjacent cell ie from (x,y) to (x,y+1), (x,y-1), (x-1,y) and (x+1,y)

Model Run – Main Menu

Main Menu

ModelWizard

Model Run – Homogeneous Rxn

% k1db : O3 + O = O2 + O2;% k2db : O2x + O3 = O + O2 + O2;% k3db : Ox + O3 = O + O + O2;% k4db : Ox + O3 = O2 + O2;% k5db : O3 + M = O + O2;% k6db : H + O3 = OH + O2;% k7db : H + O3 = OH + O2;% k8db : O3 + OH = HO2 + O2;% k9db : HO2 + O3 = OH + O2 + O2;% k10db : O3 + M = O + O2;% k11db : O + O3 = O2 + O2;% k12db : OH + O3 = HO2 + O2;% k13db : HO2 + O3 = OH + O2 + O2;% k14db : O + O2 = O3;% k15db : O + O2 + M = O3 + M;

*.fac

Model Run – Homogeneous Rxn

Initial concentration

Time steps

Model Run – Homogeneous Rxn

Homogeneous Reaction* Generated by FACSIMILE Reaction Wizard - Tuesday, November 25, 2003 ;

EXECUTE OPEN 8 "C:\ESRI\homo.out";

PARAMETERTEMP 298 ;

PARAMETERk1db k2db 2.30E+09 k3db 7.20E+13 k4db 7.20E+13 k5db k6db 1.60E+13 k7db k8db k9db 1.21E+09 k10db k11db 2.35E+13 k12db 1.93E+10 k13db 7.83E+10 k14db 1.69E+09 k15db 8.90E+09 k16db 1.05E+14 ;

VARIABLEH HO2 M O Ox O2 O2x O3 OH ;

COMPILE INSTANT;HO2 = 0.00000001 ;M = 0.0005 ;O2 = 0.0001 ;**;

COMPILE INITIAL;k1db = 5.20E+12 * EXP(-2090/TEMP) ;k5db = 4.60E+16 * TEMP@(-0.44) * EXP(-11930.0/TEMP) ;k7db = 9.00E+12 * TEMP@(0.5) * EXP(-2010.0/TEMP) ;k8db = 7.80E+11 * EXP(-960/TEMP) ;k10db = 4.60E+16 * TEMP@(-0.44) * EXP(-11930.0/TEMP) ;**;

COMPILE EQUATIONS ; % k1db : O3 + O = O2 + O2;% k2db : O2x + O3 = O + O2 + O2;% k3db : Ox + O3 = O + O + O2;% k4db : Ox + O3 = O2 + O2;% k5db : O3 + M = O + O2;% k6db : H + O3 = OH + O2;% k7db : H + O3 = OH + O2;% k8db : O3 + OH = HO2 + O2;% k9db : HO2 + O3 = OH + O2 + O2;% k10db : O3 + M = O + O2;% k11db : H + O3 = OH + O2;% k12db : O + O3 = O2 + O2;% k13db : OH + O3 = HO2 + O2;% k14db : HO2 + O3 = OH + O2 + O2;% k15db : O + O2 = O3;% k16db : O + O2 + M = O3 + M;**;

SETPSTREAM 1 8 ;TIME ;H HO2 M O Ox O2 O2x ;O3 OH ;**;

COMPILE OUT ;PSTREAM 1 ;**;

WHENEVER TIME=20 * (+0.5) 0 % CALL OUT;**;

BEGIN;STOP;

VARIABLEH HO2 M O Ox O2 O2x O3 OH

k1db = 5.20E+12 * EXP(-2090/TEMP) ;k5db = 4.60E+16 * TEMP@(-0.44) * EXP(-11930.0/TEMP) ;k7db = 9.00E+12 * TEMP@(0.5) * EXP(-2010.0/TEMP) ;k8db = 7.80E+11 * EXP(-960/TEMP) ;

PARAMETERTEMP 298

PARAMETERk1db k2db 2.30E+09 k3db 7.20E+13 k4db 7.20E+13 k5db k6db 1.60E+13 k7db k8db k9db 1.21E+09 k10db k11db 2.35E+13 k12db 1.93E+10

Model Run – 2-D Flow & Diffusion

Model Run – 2-D Flow & Diffusion

Model Run – 2-D Flow & Diffusion

Model Run – 2-D Flow & Diffusion

Application: HONO Reaction Production of HONO (Nitrous Acid) from

mixing OH and NO This experiment was used to make a

known amount of HONO (in lab) to be used to calibrate an LIF (Laser Induced Fluorescence) instrument which will be used to measure ambient HONO concentrations

Experimental setup

Hg Lamp

OH +H, N

2

H2O + N2

NO NO

NO, OH, H, O2, H2O, H2O2, HO2

O3, HNO3, O, NO2, N2,…LIF

2”

Reactions Main Reaction

OH + NO + [M] HONO + [M]

Other Reactions OH + OH + [M] H2O2 + [M]

OH + OH H20 + O

OH + HOOH H2O + H02

OH + HO2 H2O + O2

And more…

Facsimile model setup Set Conditions:

T = 293K P = 1013 mb

29 reactions and their rate constants were used in this model

Using (H2O + hv OH + H) J value, the flow rate of 1 slpm(standard liter per meter) for water vapor and N2 and manufacture’s specifications for the intensity of the Hg Lamp, the amount of OH and H produced were calculated and put as initial values in the model

Facsimile model setup Model Type

Chemistry with flow and diffusion model Reactions were selected from the reaction

database

Initial Values OH = 7.4 x 1011 molecules cm-3

H = 7.4 x 1011 molecules cm-3

NO = 5 x 1012 molecules cm-3 (from a 10 ppb cylinder)

Results of the model

Snapshot graphs

Conclusions The data from this model agreed with the

experimental data and data from another model in MATLAB

Advantages A very fast and very easy model setup for

different applications No need to arrange bundle of differential

equations Correct model results

Model scripts in text files Easy to edit The model wizard adds comments

automatically

Further Improvement Bunch of errors

Using special character ‘*’ in reaction database Hard to debug

The more powerful debugging tool The more detailed error messages

Weak graphic functions No axis scaling is available Graphs are not compatible with windows cut and

paste

Further Improvement Hidden limitations

The pipe length Maximum values for some parameters

Not best-fitted for atmospheric chemistry Photochemical decomposition rates are missing 150 lines to define 20 x 20 grid model Limitations may not be larger enough to define

atmospheric chemical reaction system