Transcript FACIMILE - Georgia Institute of Technology
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 H2 = H + H kf 10 H + O2 = OH + O 200 kr 1 2
Chemistry with flow and diffusion
Simulates chemical kinetics, plug flow (1-D) and diffusion along a pipe
c
t
Q
D
2
c
x
2
u
c
x
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
Fitting model to data
Fits unknown parameters in the model to experimental data (A B) time A B 0.2 2.019
0.3 0.907
0.4 0.408
0.5 0.183
8 9.1
9.6
9.8
The reaction equation for data
dA
kA dt
=> find k
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 Model Wizard
Model Run – Homogeneous Rxn
*.fac
% 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;
Model Run – Homogeneous Rxn
Initial concentration Time steps
Model Run – Homogeneous Rxn
Homogeneous Reaction
* Generated by FACSIMILE Reaction Wizard Tuesday, November 25, 2003 ; ; TEMP 298 k7db k8db k9db 1.21E+09 k10db k11db 2.35E+13 k12db 1.93E+10 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;
VARIABLE
;
O3 OH
COMPILE INSTANT; % k15db : O + O2 = O3; % k16db : O + O2 + M = O3 + M;
H HO2 M O Ox O2 O2x
SETPSTREAM 1 8 ; TIME ; HO2 = 0.00000001 ; H HO2 M O Ox O2 O2x ;
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) ;
k1db = 5.20E+12 * EXP(-2090/TEMP) ;
k8db = 7.80E+11 * EXP(-960/TEMP) ;
O3 OH ; **; COMPILE OUT ; **; k7db = 9.00E+12 * TEMP@(0.5) * EXP(-2010.0/TEMP) ; WHENEVER TIME= k8db = 7.80E+11 * EXP(-960/TEMP) ; k10db = 4.60E+16 * TEMP@(-0.44) * EXP(-11930.0/TEMP) ; **; 20 * (+0.5) 0 % CALL OUT; **; BEGIN;
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
NO NO, OH, H, O 2 , H 2 O, H 2 O 2 , HO 2 O 3 , HNO 3 , O, NO 2 , N 2 ,… H 2 O + N 2 2” Hg Lamp LIF
Reactions
Main Reaction OH + NO + [M] HONO + [M] Other Reactions OH + OH + [M] OH + OH H 2 0 + O OH + HOOH H 2 O + H0 2 OH + HO And more… 2 H 2 H 2 O 2 + [M] O + O 2
Facsimile model setup
Set Conditions: T = 293K P = 1013 mb 29 reactions and their rate constants were used in this model Using (H 2 O + hv OH + H) J value, the flow rate of 1 slpm(standard liter per meter) for water vapor and N 2 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 10 11 molecules cm -3 H = 7.4 x 10 11 molecules cm -3 NO = 5 x 10 12 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