Carbon Canister Modeling. Jon Brown Staff Engineer Exhaust Aftertreatment & Emissions CLEERS Workshop 2017

Transcription

1 Cabon Caniste Modeling Jon Bown Staff Enginee Exhaust Afteteatment & Emissions CLEERS Wokshop 2017

2 Agenda Cabon caniste and EVAP system oveview Motivation, Backgound, and Objective Adsoption isothem Reaction Rate Model Results Conclusions

3 Cabon Caniste and EVAP System Oveview The cabon caniste is the cente piece of the evapoative emission contol system, efeed to as EVAP fo OBD2 Adsobs fuel vapo fom fuel tank, and desobs to the intake system when puged with ai The hydocabon (HC) mass escaping the EVAP system is egulated SHED test with diunal tempeatue cycle [1] Refeence fo figue: A Fuel Vapo Model (FVSMOD) fo Evapoative Emissions System Design and Analysis, Lavoie, G., Imai, Y., Johnson, P., 1998, SAE

4 Motivation Many ecent equests, despite being old technology OEMs, supplies, consultants, and univesities Reasons LEV III zeo fuel-hc emissions vehicle test equiement [2] Moe complex puge contol system equiements fo tubo-chaged GDI engines [3], and design tade-offs fo plug-in hybid applications Refeence fo figue: "EVAP System Fluid-Dynamics and Chemisty Modelling fo EMS Puge Contol Development and Optimization," Smith, L., Hussain, A., Pautasso, E., Sevetto, E., Gaziano, E., Bown, J., 2015, SIA Powetain Confeence.

5 Backgound and Objective "Cabon Caniste Modeling fo Evapoative Emissions: Adsoption and Themal Effects," Lavoie, G., Johnson, P., and Hood, J., 1996, SAE [4] Model and measuements, focused on equilibium state, but we need kinetic ates, site density, etc. Othes have used linea diving foce models typically in 3D CFD [5,6,7] The objective was to use steady-state adsoption isothem data to develop tansient kinetics fo a fast 1D, pedictive, and adaptable model fo diffeent fuels and caniste types Minimize the numbe of equied calibation vaiables Standad afteteatment modeling components in GT-SUITE

6 Adsoption Isothem

7 Adsoption Isothem Standad measuement steady-state adsoption isothem

8 Lavoie et al Adsoption Isothem Fitting Function Relative adsobed volume, v V v V Whee Vadsobed volume, V * satuation volume * Equivalent to coveage Fee enegy of adsoption pe unit liquid volume, f f ( ρ RT ) L W ln Whee ρ L liquid density, Rgas constant, Ttempeatue, Wmolecula weight, p sat satuation pessue, p vap vapo pessue Polanyi, Dubinin, et al type adsoption theoy [4,8], simila appoach to Pihl and Daw [9], but the fuel is assumed to adsob as liquid p p sat vap Function of tempeatue and concentation

9 Lavoie et al Adsoption Isothem Fitting Function Lavoie et al e-plotted the adsoption isothem data, and fit the data using two functions, one is elevant fo expected ange v V V n f * f 1 A e ; * f f * A * f 1 85 J/mL f * 4 J/mL n1.2 V * 0.83 ml/gc at T20 C

10 Reaction Rate

11 Deive the Net Reaction Rate The goal is to deive a net ate using tansient fowad and evese ates in tems of coveage θ and eactant concentation {C} The expected ate fom at equilibium: Substitute f into the fitting function, eplace v with θ, solve fo p vap, and convet p vap to {C eq }: ( ) } {, C d a θ ( ) 0 } { } { eq d a C C k { } n L A R T W f sat d a e T R P multi des C k 1 1 * ln _ θ ρ

12 Known and Unknown Vaiables Only 3 unknown vaiables to be calibated: k is an oveall ate multiplie, units of 1/s des_multi is a desoption multiplie, unit-less, nea 1 Enthalpy of fomation fo the stoed fuel coveage (h vap + bond) Popeties of the fuel ae known: W, ρ L, and p sat function of T fom Antoine Equation Remaining ae known fom fitting the adsoption isothem: f 1, A*, and n ae adsoption isothem fitting function paametes Site density (mol/m 3 ), ρ app Appaent cabon bed density (gc/ml) { } n L A R T W f sat d a e T R P multi des C k 1 1 * ln _ θ ρ 3 * 2933 _ m mol W V Density Site L app ρ ρ

13 Cabon Caniste Model Results

14 Cabon Caniste Model, Loading Tests 50/50, 20/80, and 10/90 mixtues by volume of n-butane C 4 H 10 with N 2 Expeiment 50% 20% 10% Avg. standad space velocity h Avg. RT Facto (<1 faste than RT) Maste dt0.1 s Fuel Vapo N 2 T 1/6 T 5/6 T 2/6 T 4/6

15 Caniste Loading vs. Time Vaied n-butane Inlet Concentation

16 Caniste Loading vs. Axial Location Compaison to Lavoie et al 1996, Loading 50/50

17 Caniste Bed Tempeatue vs. Time, Loading, 50/50 Paasitic heat tansfe not modeled, but negligible effect fo mass loading since no C 4 H 10 at these locations at this these times

18 Cabon Caniste Model, Puging Tests N 2 at 10, 20, and 30 L/min puge flow ates Expeiment 10 L/min 20 L/min 30 L/min Avg. standad space velocity h Avg. RT Facto (<1 faste than RT) Maste dt0.01 s Fuel Vapo N 2 T 5/6 T 1/6

19 Caniste Puging vs. Time Vaied Puge Flow Rate Measuement eo appeas to be pesent in the Indiect Measuements, scales with the volumetic flow ate, wheeas the model consistently conseves mass

20 Caniste Puging vs. Axial Location Compaison to Lavoie et al 1996, Puging 20 L/min

21 Caniste Bed Tempeatue vs. Time, Puging, 20 L/min

22 Going Full Cicle, Veification of Adsoption Isothem Steady-state loading, geat match at T20 C

23 Conclusions Developed a net eaction ate that chaacteizes the cabon caniste behavio Successfully pedicts the tansient loading and puging of fuel vapo Successfully epoduces the steady-state adsoption isothem Can be used to pedict cabon caniste woking capacity, beak-though mass, and fo EVAP contol system development Same appoach can be used fo othe adsoption/ desoption devices ai intake system HC taps, wate adsoption, fuel adsoption

24 Acknowledgements Thomas Payet-Buin Fome inten at Gamma Technologies Ed Bissett

25 Refeences [1] A Fuel Vapo Model (FVSMOD) fo Evapoative Emissions System Design and Analysis, Lavoie, G., Imai, Y., Johnson, P., 1998, SAE [2] ARB LEV III Attachment A-5: "CALIFORNIA EVAPORATIVE EMISSION STANDARDS AND TEST PROCEDURES FOR 2001 AND SUBSEQUENT MODEL MOTOR VEHICLES," 2012, [3] "EVAP System Fluid-Dynamics and Chemisty Modelling fo EMS Puge Contol Development and Optimization," Smith, L., Hussain, A., Pautasso, E., Sevetto, E., Gaziano, E., Bown, J., 2015, SIA Powetain Confeence. [4] "Cabon Caniste Modeling fo Evapoative Emissions: Adsoption and Themal Effects," Lavoie, G., Johnson, P., and Hood, J., 1996, SAE [5] "Modeling and Simulation of N-butane Adsoption/Desoption in a Cabon Caniste," Bai, X., Isaac, K. M., Banejee, R., Klein, D., Beig, W., and Olive, L., 2004, SAE [6] "Adsoption and Desoption Simulation of Cabon Caniste Using n-butane as Model Compound of Gasoline," Sato, K., Kobayashi, N., 2011, Jounal of Japan Petoleum Institute, 54, (3), [7] "Vehicula Emission Pefomance Simulation," Lin, J., Dong, M., Ali, S., Hipp, M., and Schneppe, C., 2012, SAE [8] Stoage of Chemical Species in Emission Contol Systems: The Role of Mathematical Modeling, Koltsakis, G., Stamatelos, A., 2001, Global Powetain Congess. [9] "NH3 Stoage Isothems: A Path Towad Bette Models of NH3 Stoage on Zeolite SCR Catalysts," Pihl, J., Daw, S., 2014, CLEERS Wokshop.

26 Questions?

27 Additional Infomation

28 Cabon Caniste Model Infomation 1D Packed Bed Reacto Model Fontal Aea3330 mm^2 Total Bed Length300 mm Total Bed Volume1 L Void Faction0.366 Paticle Diamete0.677 mm C f and Nu/Sh functions of Re paticle fom classical efeences dx5 mm (60 sub-volumes) dt 0.1 s loading /0.01 s puging Paasitic heat loss between chambes not modeled Flow ate too low fo QS Implicit solution with d/dt tems

29 Deive the Net Reaction Rate The goal is to have a net eaction ate in tems of coveage θ and eactant concentation {C} ( θ, { C} ) Only infomation available is isothem data fo a geneal equilibium state g At equilibium the following must be tue a d g( v, pvap ) ( θ,{ C}) f ( T ) g( v, p ) vap 0

30 Deive the Net Reaction Rate Reaanging v(f) f(v) and setting equal to the oiginal adsoption enegy tem f f 1 ln ( ρ RT ) Single adsobing species, fuel vapo A v * 1 n L W p vap { C} RT ln p p sat vap Solving fo the equilibium concentation { C eq } psat RT e f1w ln LRT ρ * A v 1 n

31 Deive the Net Reaction Rate The expected ate fom is: Plug in {C eq } Replace v with θ (intoduce desoption multiplie tem) Mathematically flip ln() tem fo potection if θ 0 Final fom: ( ) 0 } { } { eq d a C C k { } n L A R T W f sat d a e T R P multi des C k 1 1 * ln _ θ ρ

32 Reaction Rate Paametes and Constants Calibated inputs, and calculated site density Fo tunove ate in 1/s, multiply site density by ate_multiplie Fuel popeties and adsoption fitting function paametes Refeence fo the constants ae fom [4]: Cabon Caniste Modeling fo Evapoative Emissions: Adsoption and Themal Effects, Lavoie, G., Johnson, P., Hood, J., 1996, SAE