P. 1


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### Document

Number: 

# 170 ) IV-C-137 Docket Number: 

# A-87-1 1

Printed 11/13/2008 7:21:00 AM Sheet 170 of 232P. 2 

## -DT-C-/3 7 UNITE D STATE S ENVIRONMENTA L PROTECTIO N AGENC Y

AN N ARBOR . MICHIGA N 4810 5
OFFIC E O F AI R AN D RADIATIO N 

## OC T 

## 2 0 " ^
Dr . Marce l Halberstad t Moto r Vehicl e Manufacturer s Associatio n 30 0 Ne w Cente r Building Detroit , M I 4820 2

Dea r Dr . Halberstadt : Pleas e fin

d enclose d documentatio n an d compute r cod e fo r th e evaporativ e emission s mode l discusse d a t th e publi c workshop , "Modification s t o Evaporativ e an d Refuelin g Tes t Procedure s fo r th e Contro l o f Exces s Evaporativ e Emissions " hel d o n Jun e 30 , 1988 . Thi s releas e o f th e mode l document s th e basi s fo r EP Aestimate s o f evaporativ e emissio n caniste r size s an d performanc e presente d a t th e workshop . I t wil l b e appreciate d i f yo u ca n distribut e copie s o f th e mode l documentatio n an

d compute r cod e t o you r membe r organizations .

Sincerel y yours ,

Charle s L . Gray / Jr . Directo r Emissio n Contro l Technolog y Divisio n
Enclosur e cc : Docke t A-85-2 1 Docke t A-87-1 1

6489 W 

### e w 

# *^!£ *P.3

UNITE D STATE S ENVIRONMENTA L PROTECTIO N AGENC Y

AN N ARBOR . MICHIGA N 4810 5 %«* * OFFIC E O F AI R AN D RADIATIO N 

## OC T 

## 2 0

Mr . Gregory J . Dana , Technica l Directo r Automobil e Importer s o f America , Inc . 172 5 Jefferso n Davi s Highway Suit e 100 2 Arlington , V

A2220 2

Dea r Mr . Dana : Pleas e fin

d enclose d documentatio n an d compute r cod e fo r th e evaporativ e emission s mode l discusse d a t th e publi c workshop , "Modification s t o Evaporativ e an d Refuelin g Tes t Procedure s fo r th e Contro l o f Exces s Evaporativ e Emissions " hel d o n Jun e 30 , 1988 . Thi s releas e o f th e mode l document s th e basi s fo r EPAestimate s o f evaporativ e emissio n caniste r size s an d performanc e presente d a t th e workshop . I t wil l b e appreciate d i f yo u ca n distribut e copie s o f th e mode l documentatio n an

d compute r cod e t o you r membe r organizations .

Sincerel y yours ,

Charle s L . Gray , J

1 Directo r Emissio n Contro l Technolog y Divisio n
Enclosur e 

### cc : Docke t Docke t A-85-2 1 A-87-1 1

6489 WP. 4

9 4%\ UNITE D STATE S ENVIRONMENTA L PROTECTIO N AGENC Y \5SZr > AN N ARBOR ' MICHIGA N 4810 5 '«IP«C* * OFFIC E O F AI R AN D RADIATIO N 

## OCT 

## 2 0
Ms . Caro l W . Scott , Progra mManage r Healt h & Environmenta l Affair s America n Petroleu

m Institut e 122 0 L Street , N

W Washington , D C 2000 5

Dea r Ms . Scott : Pleas e fin

d enclose d documentatio n an d compute r cod e fo r th e evaporativ e emission s mode l discusse d a t th e publi c workshop , "Modification s t o Evaporativ e an d Refuelin g Tes t Procedure s fo r th e Contro l o f Exces s Evaporativ e Emissions " hel d o n Jun e 30 , 1988 . Thi s releas e o f th e mode l document s th e basi s fo r EP Aestimate s o f evaporativ e emissio n caniste r size s an d performanc e presente d a t th e workshop . I t wil l b e appreciate d i f yo u ca n distribut e copie s o f th e mode l documentatio n an

d compute r cod e t o you r membe r organizations .

Sincerel y yours ,

< - Charle s L . Gray , ,

Directo r ' Emissio n Contro l Technolog y Divisio n
Enclosur e cc : Docke t A-85-2 1 Docke t A-87-1 1

6489 WP. 5

A \ UNITE D STATE S ENVIRONMENTA L PROTECTIO N AGENC Y AN N ARBOR . MICHIGA N 4810 5
OFFIC E O F AI R AN D RADIATIO N 

### OC T 

### 2 0 !98 8

Mr . TomCackett e Californi a Ai r Resource s Boar d P.O . Bo x 281 5 Sacramento , C A9581 2
Dea r Mr . Cackette : Pleas e fin

d enclose d documentatio n an d compute r cod e fo r th e evaporativ e emission s mode l discusse d a t th e publi c workshop , "Modification s t o Evaporativ e an d Refuelin g Tes t Procedure s fo r th e Contro l o f Exces s Evaporativ e Emissions " hel d o n Jun e 30 , 1988 . Thi s releas e o f th e mode l document s th e basi s fo r EP Aestimate s o f evaporativ e emissio n caniste r size s an d performanc e presente d a t th e workshop . Sincerel y yours ,

Charle s L . Gray , Jr . Directo r Emissio n Contro l Technolog y Divisio n Enclosur e cc : Docke t A-85-2 1 Docke t A-87-1 1

6486 WP. 6

| » A \

UNITE D STATE S ENVIRONMENTA L PROTECTIO N AGENC Y I 22r i AN N ARBOR . MICHIGA N 4810 5
OFFIC E O F AI R AN D RADIATIO N 

### OC T 

### 2 0 1988

Mr . Ro b Klausmeie r Senio r Staf f Enginee r Radia n Corporatio n 850 1 Mo-Pa c Blvd . P.O . Bo x 20108 8 Austin , T X 78720-1087 8

Dea r Mr . Klausmeie r Pleas e fin

d enclose d documentatio n an d compute r cod e fo r th e evaporativ e emission s mode l discusse d a t th e publi c workshop , "Modification s t o Evaporativ e an d Refuelin g Tes t Procedure s fo r th e Contro l o f Exces s Evaporativ e Emissions " hel d o n Jun e 30 , 1988 . Thi s releas e o f th e mode l document s th e basi s fo r EP Aestimate s o f evaporativ e emissio n caniste r size s an d performanc e presente d a t th e workshop . Sincerel y yours ,

Charle s L . Gray , Jr . Directo r Emissio n Contro l Technolog y Divisio n
Enclosur e cc : Docke t A-85-2 1 Docke t A-87-1 1

6486 WP. 7

'/A \ UNITE D STATE S ENVIRONMENTA L PROTECTIO N AGENC Y 

### A i ^gf2. 3 AN N ARBOR . MICHIGA N 48105
OFFIC E O F AI R AN D RADIATIO N 

### OC T 

### 2 0 '98 8

Mr . Samue l Leonard , Directo r Automotiv e Emissio n Contro l Environmenta l Activitie s Staf f Genera l Motor s Corporatio n 3040 0 Moun

d Roa d Warren , M I 48090-901 5

Dea r Mr . Leonard : Pleas e fin

d enclose d documentatio n an d compute r cod e fo r th e evaporativ e emission s mode l discusse d a t th e publi c workshop , "Modification s t o Evaporativ e an d Refuelin g Tes t Procedure s fo r th e Contro l o f Exces s Evaporativ e Emissions " hel d o n Jun e 30 , 1988 . Thi s releas e o f th e mode l document s th e basi s fo r EPAestimate s o f evaporativ e emissio n caniste r size s an d performanc e presente d a t th e workshop . Sincerel y yours ,

Charle s L . Gray' , Jr Directo r Emissio n Contro l Technolog y Divisio n

Enclosur e cc : Docke t A-85-2 1 Docke t A-87-1 1

6486 WP.8

UNITE D STATE S ENVIRONMENTA L PROTECTIO N AGENC Y AN N ARBOR . MICHIGA N 4810 5 OFFIC E O F AI R AN D RADIATIO N 

## OC T 2 o 

## m Mr . Wal t Krueche r Environmenta l an

d Safet y Engineerin g Staf f For d Moto r Compan

y Th e America n Roa d Dearborn , M I 4812 0

Dea r Mr . Kruecher : Pleas e fin

d enclose d documentatio n an d compute r cod e fo r th e evaporativ e emission s mode l discusse d a t th e publi c workshop , "Modification s t o Evaporativ e an d Refuelin g Tes t Procedure s fo r th e Contro l o f Exces s Evaporativ e Emissions " hel d o n Jun e 30 , 1988 . Thi s releas e o f th e mode l document s th e basi s fo r EP Aestimate s o f evaporativ e emissio n caniste r size s an d performanc e presente d a t th e workshop . Sincerel y yours ,

Charle s L . Gra } Directo r Emissio n Contro l Technolog y Divisio n

Enclosur e cc : Docke t A-85-2 1 DoO&e t A-87-1 1

6486 W- « N -<» - » H I !• < I UNITE D STATE S ENVIRONMENTA L PROTECTIO N AGENC Y

A N N ARBOR , MICHIGA N 4B10 3
OFFICIA L BUSINES S PENALT Y FO R PRIVAT E USE . S30 0 A N EQUA L OPPORTUNIT Y EMPLOYE R



# ft <££ . ~%. %



## 0

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### P T Evaporativ

e Emissions Mode

l Description an

d User s Guid e

September , 198 8

Davi d B
. Bartu s Standard s Developmen t

an d Suppor

t Branc h Emissio n Contro l Technolog y Divisio n Offic e o f Mobil e Source s Offic e o f Ai r an d Radiatio n U.S
. Environmenta l Protectio n Agenc y 

## IV-D-/3 7

kpi-i^' j • _P.1 1

I Introductio n 1 I I Mode l Descriptio n 3 A ) Introductio n 3 B ) InputDat

a 3 1 ) Scala r Dat a3 a ) Tan k Size 3 b ) Caniste

r Size 4 c ) Initia l Caniste r Loa d 4 d) Maximu

mPurge Rat

e 4 e) Diurna l Caniste r Loa d 4 f ) Hotsoak

Caniste r

Loa d 5 g ) Purg e Dela

y 5 h) Horsepowe

r Correlatio n Parameters 5 i ) Driv e Schedul e Dat aFile Nam

e 5 j ) Vapo r Generatio n Dat aFil e Name s 5 k ) Even t Dat aFile Nam

e 6 1 ) Lo g Outpu

t File Nam e 6 m ) Plot Outpu t Fil e Nam e 6 n ) Purg e Typ e Ra g 6 2 ) Tabula r Dat a6 a ) Driv e Schedul e Tabl e .... 6 b ) Caniste

r Purg e Table 6 c ) Vapo r Generatio n Tabl e 7 3 ) Even t Dat a7 a ) Diurna l Events 7 b ) Hotsoa k Event s 8 c ) Driv e Event s 8 C ) Mode

l Operatio n and Structur e 1 0 1 ) Mode l Operatio n 1 0 2 ) Mode l Structur e 1 2 3 ) Componen

t Descriptio n 1 4 a ) Ptdih s 1 4 b ) Ptdrive 1 4 c ) Getpurg e 1 5 d ) Getspeed 1 6 e ) Geth p 1 6 f ) Getfue l 1 6 g ) Getvp r

1 7 h ) Dopurg e 1 7 II I User s Guid e 1 9 A ) Overvie w 1 9 B ) Dat aFil e Preparatio n 1 9 1 ) Inpu t Dat aPreparatio

n 1 9 2 ) Tabula r Dat aPreparatio

n 2 1 a ) Driv e Schedul e Tabl e 2 1 b ) Caniste

r Purg e Table 2 1P.1 2

c ) Vapo r Generatio n Tabl e 2 2 3 ) Even t Dat aPreparatio

n 2 4 C ) Progra m Us e 2 5 1 ) Runnin g the Mode

l 2 5 3 ) Outpu t Descriptio n 2 7 a ) Termina l Outpu t 2 7 b ) Lo g Fil e Outpu

t 2 9 c ) Plo t Fil e Outpu t

3 0 D ) Progra

m Generatio n an d Modificatio n 3 0 1 ) Progra mGeneratio n 3 1 2 ) Progra mModificatio n 3 1 IV Reference s 3 3 V Appendice s 3 4 A ) Distributio n Dis k Contents an d Model Installatio n 3 4 1 ) Distribution Disk

Content s 3 4 2 ) Mode l Installation 3 5 B ) Refueling/Exces s Evaporativ e Emission s Worksho p Dat a 3 8 1 ) Introduction 3 8 2 ) Inpu t Dat a3 8 a ) Scala r Dat a3 8 b ) Tabula r Dat a3 8 c ) EventData3 9 C ) Sampl e Run s 4 0 1 ) Descriptio

n 4 0 2 ) Test l Sampl e Ru n Dat a4 0 3 ) Test 2 Sampl e Ru n Dat a47 D ) Vapo r Generatio n an d Temperature Profil e Dat a 5 2 1 ) Emission s Modellin

g 5 2 2 ) Diurna l Uncontrolled Emission s 5 2 3 ) Hotsoa k Uncontrolled Emission s 5 2 4 ) Vapo r Generatio n 5 3P.1 3

I Introductio n Th e PT mode l i s ase t

o f compute r algorithm s and associate d dat atha t ca n b e use d to simulat e th e behavior

and performanc e o

f evaporativ e emission s contro l systems . The model i s base d o n a

n accountin g syste

mtha t include s source s o

f hydrocarbo n vapor s i n a vehicle , suc

h a s th e fue

l tank , vapo r

storag e devices , such a s th e charcoa l canister , and finally , vapo r

sinks , such a s th e engine/purg e contro l system . Durin g simulatio n o f variou s evaporativ e emission s events , th e behavio r o f thes e vehicl e component s i s predicted , an

d acontinuou s histor

y i s maintaine d o

f th e carbon caniste

r storag e device
. A ke y featur e o f th e model i s tha

t i t make s us e o

f instantaneou s drivin g schedul e velocitie s an d accelerations , i n contras t t o averag e values , s o tha t interaction s between drivin g patterns , purg e control , fue

l tan k vapo r generation an

d charcoa l adsorptio n characteristic s ca n b e realisticall

y simulated
. The PT model i s intende d to serv e thre e purposes . Th e firs t i s to estimat

e evaporativ e an

d runnin g los s emission s fro

masingle vehicl e in respons e t o aspecifie d set

o f events , fue

l tan k and caniste

r characteristics , and purg e contro l strategy . Th e second i s t o serv e a s a desig n too l to evaluat

e variou s vehicl e emission s tes t procedure s and to determine caniste r size s and purg e rate s neede d to pas s give n procedures
. Finally , th e mode l i s intende d t o provid e estimate s o

f instantaneou s engin e fue l requirement s an d o f

unmetere d fue

l provide d durin g caniste r

purge . Thes e value s ca

n assis t in estimatin g th e impac t

o f evaporativ e emission s contro l systems o n exhaus t pollutants
. Becaus e the model wa s constructe d primaril y as atoo l t

o evaluat e evaporativ e emission s tes t procedures , severa

l aspect s o f evaporative emission s hav e not bee n explicitl y modelled
. The firs t o f thes e i s th e respons e o f

fue l syste mtemperature s t

o ambien t temperatur

e and vehicl e operatin g mode
. Temperatur e effects , however , ar

e implicitl y accounted fo

r in thi s mode l throug h appropriat

e specificatio n o

f ho t soa k and diurna

l emissions , a s wel l a s running los s vapo

r generation
. A secon

d aspect o f evaporativ e emission s tha

t ha s no t bee n explicitly modelle d i s fue

l syste mpressure . Fue l syste

mpressure s ar

e assumed to remai n a t aconstan t valu e durin g all phase s o

f simulation an

d th e corresponding vehicl e operatin g events . A s wit

h fue l systemtemperature , th e influenc e o f pressur e o n evaporativ e emission s ca

n b e implicitl

y accounted fo

r throug h appropriat

e specificatio

n o f hydrocarbon vapor generation values
. There ar e tw o additional consequence s o f th e mode l havin g bee n develope d a s a n evaluatio n tool
. The firs t

o f thes e i s tha

t the mode l ha s bee n subject t o numerou s revision s an d enhancements , includin g severa l significanl one s sinc e th e Jun e 30 , 198 8 publi c workshop[2 ] a

t whic h th e model wa s firs t

presented.
. Thi s repor

t describe s th e mode l in it s stat e o f developmen

t a s o f September , 1988
. I t

i s likely tha

t furthe r modification s wil l b e mad e in in the future
. The second o f thes e consequence s i s tha

t emphasi s ha s bee

n place d on functionalit

y rathe r tha n appearance . I

n th e mode

l itself , fo r example , basi c error checking ha s bee

n included , but

exhaustiv e verification o

f al l inpu t dat aha s not . Althoug

h graphica l displa y o f certai n model output s i s useful , onl y tabula r output o f thes e dat ai s generate d b y th e model
. User s ma y incorporat

e thes e datainto thei

r preferre d graphic s packag e i n orde

r to generat e an y desire d plots
. I

n th e report , the functio

n and forma

t o f al l inpu t dat ai s described , but

specificatio n o

f method s fo

r generatin g specifi c numerica l value s ar e omitted in som

e instances
. I

n thes e cases , the needed datama y b e obtained fro

m source s rangin g fro

mlaborator

y dat at o compute r simulations , accordin g t

o th e resource s availabl e t o th e user . Finally , i n man y instances , "in-us e average " value s fo r inpu t variable s ar

e not provided , sinc e th

e mode l will ofte n b e use d t

o simulat e vehicle s an

d tes t procedure s fo

r whic h suc h dat aar e no t available
.P.1 4

Thi s documen

t i s divide d int

o tw o majo

r sections
. I

n Section II , Mode

l Descriptio n the datarequire d by the model i s discussed , alon g wit h structur e an d operatio n o

f th e model I n Sectio n UI , "User

s Guide, " specific detail s o f ho w the model ca

n b e used ar

e provided[.including preparatio n o f dat afiles , running th e mode

l itself , error determination , an d interpretation o

f output .P.1 5

I I Mode l Descriptio n Thi s sectio n provide s description s o f th e P T model , input

dat arequire d b y it , an

d how thes e dat aar

e use d durin g simulations
. Sectio n A , "Introduction, " give s agenera l overvie w o f th e model an

d it s operation
. Section B , "Inpu tData, " discusse s in detai l th e variou s dat aitem s and table s tha t mus t b e supplie d t

o th e model
. Finally , Sectio n C , "Mode l Operatio n and Structure, " describe s th e detaile d calculatio n step s carrie d ou t b y th e model , an

d th e structur e an d algorithm s used b

y it
. A ) Introductio n I n the mos t genera l sense , th e P

T mode l consist s o

f ase t o f computationa

l algorithms , an

d anumbe r o f dat aset s upo n whic h thes e algorithm s operate . I n practical terms , th e computationa

l algorithm s ar

e embodie d in acompute

r program , an d th e set s o

f dat aare store d a s number s and text

i n compute r dat afiles
. The model carrie s out simulation s b y firs t readin g datafile s tha

t describ e th e vehicl e to b e simulate d an d it s initia l condition , th e behavior o f vehicl e component s associate d wit h evaporativ e emissions
. Next , th e model reads , i n asequentia

l fashion , aserie s o

f event s tha t asimulate d vehicl e i s t o experience
. Durin g simulatio n o

f each event , the mode

l calculate s th e quantit

y o f hydrocarbo n vapor s generated , how much o f

thes e ar e loade d to or

purge d fro mth e charcoa

l canister , an d th e quantit y o f vapor s burned b

y th e engine
. A

t th e end o f eac h simulated event , summarie s o f simulation result s fro

mthe even

t an d th e curren t stat e o f th e simulated vehicl e ar

e generated and displayed
. B ) InputDat

a Thi s sectio n describe s th e variou s dat aitem s tha t ar e require d b

y th e P T model , th e expected dataformat , i

f any , an d th e sourc e o f datafo r eac h ite mor table
. Mode

l inpu t dat a ca n b e divide d int o thre e types : scalar , tabular , an d event . Scala

r data , describe d belo w in sectio n 1 , "Scala

r Data, " i s generall

y vehicle-specific , whil e tabula r data , describe d i n sectio n 2 , "Tabula

r Data, " i s eithe

r mostl y or totally vehicl e independent
. Event data , describe d belo w in section 3 , "Even tData, " i s vehicl e dependent , but wil l var y slightly i n respons e to fue

l vapo r pressure . 1 ) Scala r Dat

a Scala r dataitem s consis t

o f asingle value o r

asmal l but fixe d numbe r o f dat aitems
. Thes e dat avalue s generall

y describ e vehicl e components , thei r behavior , or

thei r conditio n a

t th e star t o f asimulation
. Som

e value s ar e dependen

t onl y o n the vehicl e t

o b e simulate d (fue

l tan k size , fo r example) , whil e other s depend o n fue l characteristic s a s wel l (diurna l an d hotsoa k canister loads)
. Fuel-dependen

t dat avalue s ca

n b e obtaine d fro

mexperimenta

l data , o r fro mmodellin g results
. Car

e mus t b e exercised , however , tha t suc h dat ab e obtaine d o n aconsistent

basi s wit h th e vehicl e to b e simulate d b y th e P T model
. Each scala r dat aite mrequire d b

y th e P T mode l i s described below
. a ) Tan k Siz e Thi s dataite

mspecifie s the nomina

l usable liqui d volume , i

n gallons , o

f th e fue l tan k i n the vehicl e t o b e modelled
. Th e value specified mus t li e within the rang e o

f 0.0<(Tan k Size ) <100.0
. Neithe

r th e fre e headspac e no

r the fil l leve l i s explicitly specifie d in the model
. Bot h o f thes e value s ar

e implicitly accounte d fo

r i n th e value s specifie d fo

r diurna l an dP.1 6

hotsoa k canister load s and fo

r value s containe d in th e vapor generatio n table
. Furthe

r description s o

f thes e latte r value s ca n b e foun d below
. b ) Caniste r Siz e Thi s dat aitemspecifie s th e carbon caniste r size , i n liter s o

f charcoal , o

f th e caniste

r in the vehicl e to b e modelled
. Th e valu e specified mus t li e withi n th e rang e o

f 0.0<(Caniste

r Size)<50.01
. The typ e an

d load/purg e characteristic s o f th e charcoa

l i s implicitl

y specifie d throug h di e caniste

r purg e table , described below
. c ) Initia l Caniste r Loa d Thi s dat aitemspecifie s the initia l loadin g a

t the star t o f simulation , i n percent

o f tota l capacity , o f th e caniste r i n th e vehicl e t o b e modelled
. Th

e value specified mus t

li e withi n th e rang e o

f 0.0<(lnitial Load)<=100.0
. A valu e o f 0. 0 correspond s to afull

y purge d canister , whil e avalu e o

f 100. 0 correspond s t o afull y loade d canister
. Normally , a n initia l caniste r loadin g slightl

y les s tha n 100. 0 percen

t (99.0 , fo r example ) i s specifie

d to avoi d anomalou s prediction s o f uncontrolle d hydrocarbo n ventin g durin g the firs t fe w second s o f adriv e tha

t begin s wit h afull y loaded canister
. d ) Maximu

m Purg e Rat

e Thi s dataite

mspecifie s th e maximu

mcaniste r purg e rate , in standar

d cubi c fee t pe r minute , characteristi c o

f th e vehicl e to b e modelled
. Th e valu e specified mus t

b e greate r tha n zero . During simulation , th e actua l caniste r purg e rate wil l b e calculate d a s som e fractio n o f thi s maximumrat e i n respons e to vehicl e spee d and acceleration
. Further discussion s o f caniste r purg e rat e calculation s ca

n b e foun d i n Section II-C-l-c , "Getpurge. " e ) Diurna

l Caniste r Load Thi s dat aite mspecifie s the quantit

y o f hydrocarbon s generated during adiurna l hea t build , i n gram s pe

r gallo n o f usabl e liqui d fue

l tan k capacity , t o b e use d durin g simulation
. Thi s valu e represent s uncontrolle d diurna l vapor generatio n i n th e fue

l tank , i n contras t

t o th e quantit y o f hydrocarbon s vented fro

macaniste

r during adiurna

l emission s test . The valu e specified mus t

b e greate r tha n zero . Diurna

l caniste r loa d i s specified fo

r areferenc e hea

t build , usuall

y di e standar

d FT P rang e o f 60-8 4 °F , an

d fo r aparticula

r fue l vapor pressure . Durin g simulation , th e actua l diurna l caniste r loa d i s calculate d by adjusting di e specified loa d fo r fue l tan k siz e and fo

r difference s i n temperatur

e betwee n di e simulate d diurna

l fro mthe referenc e diurnal
. Adjustment s fo r fue l tan k siz e ar e mad e b y multiplyin g di e specified diurna

l loa d b y di e specified fue

l tan k size , while the temperatur

e adjustmen

t i s mad e b y multiplyin g di e specified loa d b y th e diurna l even t multiplie r read fro mthe even

t file fo r adiurna l event . Furthe

r detail s o f thi s temperatur

e correctio n and o

f the diurna

l event multiplier

ca n b e foun d i n Sectio n II-B-3-a , "Diurna l Events, " and i n Sectio n n-C-3-a , "Ptdihs. " Th e diurna

l canister loa d valu e i s partiall y vehicle-independent , a s i t i s specifie d on a specifi c rather

tha n a n absolut e basis , bu t i t i s implicid

y dependen

t o n the fre e headspac e volum e o f th e vehicl e t o b e modelled
. Whil e thi s headspac e volume , a s apercentag e o f useabl e liqui d volume , ma

y b e simila

r acros s abroa

d spectru mo f th e in-us e vehicl e fleet , th e correspondin g volum

e o f aspecifi c vehicl e ma

y deviate markedl y fro

mth e flee

t average . Car

e mus t b e take n whe n specifyin

g the diurna

l caniste r load fo r suc h vehicle s tiiat the appropriat

e value i s used
.P.1 7

f ) Hotsoa k Caniste r Loa d Thi s dat aitemspecifie s di e quantit y o f hydrocarbon s generate d durin g ahotsoa k event , in grams/gallon o

f usabl e liqui d fue

l tan k capacity , to b e used durin g simulation
. Thi s valu e represent s uncontrolle d hotsoa k vapo r generation i

n di e fue l tank , i n contras t

t o th e quantit y o f hydrocarbon s vente d fro

macanister

durin g ahotsoa

k emission s test . The valu e specifie d mus t

b e greate r tha n zero . Hotsoa

k caniste r loa d i s specifie d fo

r a n arbitrar y referenc e end-of-dnv e temperatur e an d aparticula

r fue l vapo r pressure . I

n th e cas e o

f a n FTP pre p drive , in which th e initial fue l tan k temperatur

e might b e 72. 0 ° F and th e temperatur e rise during di e driv e migh t b e 15. 0 °F , the end-of-driv e woul d b e 97. 0 °F
. I n th e cas e o f

carburete d vehicles , an d additiona l contributio n mus t

b e adde d fo

r emission s fro mthe carbureto

r bowl
. Durin

g simulation , di e actua

l hotsoa k caniste r loa d i s calculate d b y adjustin g th e specifie d loa d fo r fue l tan k size an d fo r difference s in temperatur

e betwee n th e simulated hotsoa

k fro mth e referenc e hotsoak
. Adjustment s fo r fue l tan k siz e ar e mad e b y multiplyin g di e specifie d loa d b y th e simulate d vehicl e fue l tank size , whil e th e temperatur

e adjustmen

t i s mad e b y multiplyin g di e specifie d load b y th e hotsoa k even t multiplie r rea d fro mdi e even

t fil e fo r ahotsoa k even t Furthe r detail s o f thi s temperatur

e correctio n and o

f di e hotsoa k even t multiplie r ca n b e foun d in Section H-B-3-b , "Hotsoa k Events, " and i n Sectio n II-C-3-a , "Ptdihs. " Comment s made abov e i n sectio n II-B-l-e , "Diurna l Caniste r Loading, " regardin g fue l tan k vapor headspac e assumption s als o appl y t o specificatio n o f

hotsoa k canister loading values
. g ) Purg e Delay Thi s dat aite

mspecifie s the dela

y betwee n th e beginning o

f adriv e even

t and the star

t o f canister purge , in th e unit s o

f the driv e schedul e table
. (Se e Sectio n II-B-2-a , "Driv e Schedul e Table." ) Th e valu e specifie d mus t b e greate r tha n zero . Specifying avalu e greate r tha n the numbe

r o f entrie s i n th e driv e schedul

e table effectivel

y disable s al l caniste

r purge . Thi s i s permitted , bu t awarning messag e i s generate d whe n such asituatio n i s encountered during mode

l operation
. h ) Horsepowe r Correlatio n Parameter s Thes e dat aspecif

y th e empirica

l parameter s use d by th e Geth p module , describe d in Sectio n IT-C-3-e , "Gethp, " to determin e th e horsepowe r require d to prope l avehicl e a t a give n spee d and acceleration
. Suggested value s fo r th e fou r require d parameter s ar

e give n i n th e descriptio n o

f Gethp
. i ) Driv e Schedul e Dat a Fil e Nam e Thi s dat aitemspecifie s the pat h nam e t o b e used whe

n opening di e dat afile containin g di e driv e schedul e table
. Thi s dat atabl e i s describe d in Sectio n 2-a , "Driv e Schedul e Table " below , an d th e forma t o f thi s dat aite min Sectio n III-C , "Inpu tDat a Preparation. " j ) Vapo r Generatio n Dat aFil e Name s Thes e dataitem s specif

y th e pat h name s t o b e used whe

n opening the datafile s containing vapo r generatio n tables
. Thes e dat atable s are describe d i n Sectio n 2-c , "Vapo r Generatio n Table " below , an d th e forma t o f thi s dat aite mi n Sectio n III-C , "Inpu t Dat a Preparation. "P.1 8

k ) Even tDat

a Fil e Name Thi s dat aite mspecifie d di e pad i nam e to b e use d whe

n openin g th e input

file containin g even t data
. Thi s input

file i s describe d i n Section 3 , "Even tData " below , etc . 1 ) Lo g Outpu tFil e Name Thi s dat aitemspecifie s di e pad i nam e to b e use d whe

n openin g th e outpu t

fd e tha t i s to contain adetaile d lo g o

f simulatio n results
. Thi s outpu

t file i s describe d i n Section IH-C-2 , "Outpu tDescription. " Se

e als o the descriptio n o

f th e Plotfla

g keywor d containe d in Sectio n m-B-1 , "Inpu

tDat a Preparation. " m ) Plo tOutputFil e Name Thi s dat aitemspecifie s the pad i nam e to b e use d whe

n openin g th e output

file tha t i s t o contai n canister

load versu s time data
. Thi s outpu t fde i s describe d i n Sectio n IH-C-2 , "Outpu tDescription. " See als o th e descriptio n o f th e Plotfla

g keywor d containe d i n Sectio n III-B-1 , "Inpu

tDat a Preparation. " n ) Purg e Typ e Fla g Thi s dat aite mspecifie s di e purg e contro l strateg y to b e use d durin g simulations
. A s distributed , th e P

T model contain s asingl e purg e contro l strateg y model , a s describe d i n Sectio n II-C-3-c , "Getpurge, " which i s selecte d by specifying avalu e o f zero fo r th e purg e typ e fla

g dat aitem
. I

f additional , user-supplie d purg e contro l model s ar e added , a s describe d i

n Sectio n III-D , "Progra

m Generatio n an d Modification, " tiiey ma y b e selecte d by specifyin

g value s o f -1 , -2 , etc . fo

r thi s dataitem
. Furthe

r detail s ca n b e foun d i n Section III-D
. 2 ) Tabula r Dat

a Tabula r dataitem s consis t

o f table s o f dat atha t describ e adrivin g schedul e or behavio r o f vehicl e components . Th e dire e type s o f table s neede d b

y th e P T mode l include adriv e schedule , acaniste

r purg e curv e table , an

d on e o r mor e vapo r generatio n tables
. Th

e firs t tw o o f thes e ar e independen

t o f vehicl e an

d fue l characteristics , whil e th e latter dat afil e depend s o n fue

l characteristic s an

d t o asmal l exten t o n vehicle characteristics
. Eac h tabula r datatable needed b

y th e PT mode l i s described below
. a ) Driv e Schedul e Tabl e Thi s dat atabl e describe s di e velocitie s in MPH , and accelerations , i n MP H per second , a t each uni t time interva

l o f the driv e schedule t

o b e simulate d b

y the PT model
. Th

e tabl e consist s o f dire e columns , one eac

h fo r time , velocity , an

d acceleration
. Thes e dat ashould b e availabl e fo

r th e desire d drivin g schedule on asecond-by-second basis , witii eac h tabl e ro w consistin g o

f asingl e se

t o f observations
. Th e numbe r o f dat arow s i

n th e table , therefore , should b e equa

l to the driving schedule lengtii i n seconds
. b ) Caniste r Purg e Tabl e Thi s dat atabl e describe s purg e behavior o f th e carbo n canister

^ t o b e simulated , and contain s dat ao n di e quantit y o f hydrocarbon s removed fro

macaniste

r initiall y loaded t o breakdiroug h versu s volum e o f purg e air
. Th e tabl e consist s o f tw o columns , on e fo

r volume o f purg e air , in standar

d cubi c feet , and one fo

r th e cumulativ e quantit

y o fP.1 9

hydrocarbon s purged , in grams . I t i s assume d tiiat

di e caniste

r purg e tabl e contain s dat a normalized t

o describ e a1.0 1 canister
. c ) Vapo r Generatio n Tabl e Thi s datatabl e describe s th e vapor generation characteristic s o f afue l tan k durin g vehicl e operation , an d contain s dat adescribin g the cumulativ e mas s o f hydrocarbon s generate d durin g adrive , and o n instantaneou s volumetri c flo w rate a t which vapor s ar

e generated
. Th e tabl e consist s o

f dire e columns , on

e fo r time sinc e di e star

t o f adriv e i n minutes , one fo r cumulativ e mas s o

f hydrocarbon s generated sinc e di e star t o f adrive , i n grams , an

d one fo r vapor generatio n rate , in standar d cubi c fee

t pe r minute
. Dat ai n tiiis tabl e mus t b e normalized t o abasi s o

f a1. 0 gallo n fue l tan k wid i a n appropriatel

y scaled vapo

r headspac e volume
. Car

e mus t b e take n tha t the headspac e volum

e a s apercen

t o f liqui d capacit

y i s th e sam e in vapo r generation table s as in di e vehicl e to b e simulated
. A vapo r generation tabl e depend s on bod i fue l volatilit y an d on the time/temperatur

e profile o f th e driv e t o b e simulated
. Simulation o f mos t tes t procedure s require s vapor

generation table s fo r tw o temperatur

e range s pe

r fue l RVP , and simulation o

f in-us e drivin g pattern s ma y require thre e such tables , th e maximu mnumbe r currend y provide d fo

r b y th e PT model
. 3 ) EventData Event dat ai s use d a s asourc e o f input by di e model t o determin e di e sequenc e an d characteristic s o

f event s tha

t asimulate d vehicl e wil l experience
. Event s tha t ca n b e simulate d includ e diurna

l hea t builds , hotsoaks , and drivin g sequences . I n di e event file , event s ar e specifie d by akeywor

d tha t identifie s the desire s event , and one o r mor e optiona l parameter s ma

t specif y or modif y even t characteristics
. Parameter s associated wid i diurna l and hotsoa k event s adjust

simulated emission s to simulat e an y desire d diurna

l temperatur

e rang e an d hotsoa k temperature . Althoug

h onl y asingle driving schedul e i s supported , dii s driv e ma y b e simulate d fo

r u p to thre e ambien

t temperature/initia

l fue l temperatures , and parameter s associate d wid

i driv e even

t specificatio

n allo w an y portio n o f di e driv e schedule to b e simulated
. Thi s sectio n describe s ho w eac h o f thes e event s i s describe d i n di e even t file
. a ) Diurnal Event s Diurna l event s ar

e specifie d by di e "diurnal " keyword
. A singl e optiona l parameter

i s allowe d t o permi t

simulatio n o

f diurnal event s a

t temperature s differin g fro mthos e associate d wit

h di e bas e diurna

l caniste r loa d a s describe d i n Section n-B-l-e , "Diurna l Caniste r Load. " I

f thi s paramete

r i s omitted , o r

avalu e o f -1. 0 i s specified , di e diurna l canister load use d to simulate d th e diurna l i s exacd y a s specifie d b

y th e bas e diurna

l caniste r load dat aitem
. I

f apositive , non-zer

o paramete

r i s given , di e diurna

l loa d use d fo r simulatio n i s di e bas e diurna l caniste r loa d multiplie d b

y the valu e o

f th e parameter . Not e tha t th e bas e diurna

l caniste r loa d i s alway s scaled to th e simulate d vehicl e fue l tan k size , a s described in Sectio

n H-B-l-e , i

n additio n t o an y scalin g specifie d b y adiurna l even t parameter . I n equation form, thi s ca n b e expressed as : Actua l Diurna l Caniste r Loa d = Bas e Diurna

l Caniste r Loa d * Fue l Tan

k Siz e * Diurna l Even t Paramete rP.2 0

Example s o

f diurna l event s in a

n even t file ar e show n below
. diurna l - 1 diurna l 2.7 7 b ) Hotsoa k Event s Hotsoa k event s ar e specifie d by th e "hotsoak " keyword
. A singl e optiona l paramete r i s allowe d to permi t

simulatio n o

f hotsoa k event s a t temperature s differin g fro mthos e associate d wit

h di e bas e hotsoa

k caniste r loa d a s describe d i n Section H-B-l-f , "Hotsoa k Caniste r Load. " I

f dii s paramete

r i s omitted , or

avalu e o f -1. 0 i s specified , th e hotsoa k canister load use d t o simulate d di e hotsoa k i s exactly a s specifie d by th e bas e hotsoa k caniste r loa d dat aitem
. I

f apositive , non-zer

o paramete r i s given , th e hotsoa

k loa d use d fo r simulatio n i s di e bas e hotsoa k caniste r loa d multiplie d b

y di e valu e o

f the parameter . Not e tiiat di e bas e hotsoa

k caniste r loa d i s alway s scaled to the simulate d vehicl e fue l tan k size , a s describe d in Sectio n II-B-l-f , in additio n to an

y scalin g specifie d b y ahotsoa k even t parameter . I

n equation form, thi s ca

n b e expressed as : Actua l Hotsoa k Caniste r Loa d = Bas e Hotsoa

k Caniste r Loa d * Fuel Tan

k Size * Hotsoa k Even t Paramete r Example s o

f hotsoa k event s i n a

n even t file ar e show n below
. hotsoa k - 1 hotsoa k 1.4 6 c ) Driv e Event s Driv e event s ar

e specifie d b

y on e o f di e keyword s "drivel, " "drive2, " o r "drive3. " A keywor d o f "drive " i s als o accepted , an d i s processe d a s a"drivel " event . U p t o tw o optiona l parameter s ar

e allowe d to indicat

e dia t onl y aportio n o

f a n entir e drivin g schedule i s to b e simulated , o r

t o star t asimulated driv e wid

i elevate d fue

l temperature . Eac

h o f di e thre e driv e event

keyword s appl

y to th e singl e driv e schedul e specifie d by th e driv e schedul e tabl e describe d in Sectio n H-B-2-a , "Driv e Schedul e Table. " The ambien t temperature/initia

l fue l temperatur

e a t whic h simulation o

f thi s driv e i s to b e performed i s give n by whic h o f di e dire e keyword s i s used
. The "drivel " keywor d i s use d t o simulat

e a driv e whos e fue

l temperatur

e profile , an

d henc e runnin g los s vapor

generatio n profile , i s describe d b y di e vapo r

generatio n tabl e associate d wit h th e vaporfile l dat aitem
. (Se e Sectio n II-B-2-c , "Vapor Generatio n Table, " an d Sectio n HI-C , "Dat a Tabl e Preparation." ) Similarly , di e "drive2 " keywor d i s associate d wit

h di e vaporfile 2 dat a item , an d di e "drive3 " keywor

d i s associated wid

i th e vaporfile 3 dataitem
. U p t o tw o optiona

l parameter s ma

y b e specifie d to allo w simulatio n o f apartial driv e schedule , or

to simulat e drive s startin

g wit h a n initia l fue l temperatur

e above th e initia

l fue l temperatur

e o f th e associate d vapor

generatio n table
. The firs t o f thes e parameter s indicate s di e lengt

h o f th e driv e t

o b e simulated , in time unit s equa l to thos e use d in di e driv e schedule tabl e (usuall

y seconds)
. The secon

d paramete r indicate s the numbe

r o f driv e table entrie s dia

t would have to have bee

n simulate d i n apreviou s driv e while followin g th e curren t vapo r generatio n tabl e temperatur e profil e to reac h th e desire d initia l fue l temperature . Th e driv e star t tim e is , therefore , the point

in tim e a t whic h th e vapo r generatio n tabl e i s entere d a t the star t o f the simulate d drive
. Not

e tha t th e driv e tabl e i s alway s entere d fro

mit s beginning ; i t

i s no t possibl e to begin adriv e simulatio n par t wa y throug h adriv e schedule
.P.2 1

Defaul t value s ma

y b e use d fo

r bod i optiona l parameters . I

f value s fo r neithe r paramete r ar e given , th e default

actio n i s to simulat

e a n entir e driv e usin g atemperatur e profil e correspondin g to di e star

t o f di e associate d vapo

r generatio n table
. Paramete r value s o f -1. 0 ma y als o b e use d to selec t

dies e defaults
. I

f onl y on e paramete r i s given , the defaul

t actio n i s t o simulat e adriv e whos e lengd

i i s equa l t o th e value o f di e give n parameter , usin

g adefaul t temperatur

e profil e a s describe d above
. I f tw o parameter s ar

e given , bot

h th e driv e lengt h an d di e vapor

generatio n tabl e entr

y point ma y b e modified
. Not

e tha t if a non-default

temperature/vapo r

generatio n profil e i s desired , i t i s necessar

y to provide value s fo r bod i parameters ; i

f desired , avalue o

f -1. 0 ma y b e give n fo r di e first paramete r a s aplac e holde

r dia t select s adefaul

t o f simulating afull-lengt

h drive
. Show

n below ar e severa l example s dia

t illustrat e us e o f parameters wid

i drive entrie s i

n a n even t file. Exampl e 1 drive 2 Thi s entr y specifie s adriv e tha

t follow s th e temperatur

e profil e give n by th e vapo r generatio n tabl e associate d wit h di e "vaporfile2 " dat aitem
. Th e entir e driv e describe d by the driv e schedul

e tabl e i s simulated
. Exampl e 2 drive 2 50 5 Thi s entr y specifie s adriv e dia

t follow s th e sam

e temperatur

e profil e a s describe d in Exampl e 1 above
. Th e simulate d drive , however , proceed s onl y throug h di e firs t 50 5 driv e tabl e entries
. I

f di e driv e tabl e contain s entrie s a t time interval s o

f seconds , tins example migh

t b e use d t o simulat e ba g 3 o f a n FT P test . Exampl e 3 drive 2 50 5 153 7 Thi s entr y specifie s adriv e tha

t follow s di e sam

e temperatur

e profil e a s i n th e previou s examples , excep t

tha t th e temperatur

e profile/vapo

r generatio n tabl e i s entere d a t apoint correspondin g to th e fue

l temperatur

e ma t woul d b e observe d afte

r 153 7 second s (mor

e precisely , tim

e unit s o f driv e schedul e tabl e entries ) ha d elapse d in adriv e widi initia l fue l temperatur e equa l t o dia t o f di e first vapo r generation table entry . Th

e lengt h o f th e driv e i s 50 5 seconds
. The temperatur e profile s followe

d b y tiiis hypothetica

l driv e and di e driv e t

o b e simulate d in thi s exampl e ar e illustrate d i n di e following figur e b y th e portio n o

f th e curv e extendin g fro

m99. 0 ° F t o 103. 0 °F :P.2 2

Sampl e Temperatur

e Profil e

80. 0 0. 0 10. 0 20. 0 30. 0 40. 0 Tim e (min. ) 50. 0 60. 0
Exampl e 4 drive 2 - 1 153 7 Thi s entr y i s identica l t o that

i n Exampl e 3 above , excep t diat aful l lengd i driv e i s simulate d instea d o f onl y di e first

50 5 second s o f

di e ful l drive
. C ) Mode l Operatio n an d Structur e Thi s sectio n describe s di e P T mode l fro mbot h a n operationa l an d astructura l viewpoint
. Sectio n 1 , "Mode

l Operation, " discusse s th e calculatio n sequenc e use d b y th e mode l i n genera l an d t o simulat e specifi c evaporativ e emission s event s i n particular
. Sectio n 2 , "Mode l Structure, " present s th e structura l organizatio n o f di e P T model , an d ho w it s constituen t

module s relate t o on e another
. Thi s sectio n i s o f mos t interes t t o thos e wishin g t o modif y progra mcode
. Finally , Sectio n 3 , "Componen tDescription, " contain s detaile d description s o f

individua l progra mmodule s an d thei r specifi c functions
. Onl y module s direcd y related t o evaporativ e emission s aspect s o f th e mode l ar e discussed
. Othe r modules , relate d t o supervisor y contro l an d dat ainpu t functions , ar e not

describe d i n th e interes t o f simplicity , a s knowledg e o f thes e component s i s not

necessar y t o us e o r

modif y th e model
. 1 ) Mode l Operatio n Operatio n o f

th e P T mode l can b e divide d int o thre e ke y phases
. Th e firs t o f thes e i s one tim e initializatio n an d inpu t of bot h scala r an d tabular

data , a s describe d i n Section s n-B- 1 an d H-B-2 , respectively
. Th e secon d phas e i s readin g o f individua l evaporativ e emission s events fro mdi e even t

dat afile , extractin g applicabl e parameters , an d transfe r o f simulatio n contro l t o module s responsibl e fo r modellin g o f

thes e events . Th e final phas e i s even t processin g an d displa y o f outpu t fro mindividua l even t

simulations
. Th e secon d an d tiiird
1 0P.2 3

o f thes e processin g phase s ar e repeate d fo

r eac h entr y i n the even t datafile. Th

e flow o f contro l amon

g thes e event s i s illustrate d i n di e followin

g figure.

Rea d dat a& Perfor m initializatio n Rea d even t data

Proces s diurna

l and hotsoa k event s Calculat e diurna l o r hotsoa k loa d Ad d calculate d loa d to caniste

r Outpu t even t result s 

### PT Mode l Operationa

l Flowchar

t

> / Determine>v__
_ Proces s drive

even t Calculat e tri p lengt h

Calculat e spee d & acceleration T Calculat e purg e rate Calculat e vapo r generation rat

e Fin d ne t load/purg e & updat e caniste r Calculat e fue l rat e & fue l fro mcaniste r Repea

t fo r al l tri p tabl e entrie s

1 1P.2 4

I n th e datainpu

t processin g phase , a

n input datafil e i s read whic

h contain s al l scala

r inpu t data , a s describe d in Sectio n II-B-a , along wid i the name s o

f dat afile containin g tabula

r an d even t data
. Next , check s ar

e mad e o n scala r dat aitem s t o insur

e al l require d value s hav e been specifie d an d tha t they are within reasonabl e ranges . Interna l storag e i s the

n allocate d fo

r dat atables , an

d interna l initializatio n performed
. Finally , information fro m eac h o f di e tabula r dat afiles i s rea

d an d stored internally
. I n th e event

inpu t phase , event

entrie s ar e read , alon g wit

h associate d parameters , a s describe d i n Sectio n II-B-3 , "Even t Data. " Al l driv e event s ar e passe d to th e Ptdriv e modul e fo r processing , whil e diurna

l an d hotsoa k event s ar e passe d t o di e Ptdih s module
. N o checking i s performe

d on even t parameter s a

t thi s stage . Event s continu e t o b e rea d an d simulated until all event s i

n die specifie

d even t dat afil e have bee n processed
. Diurna l and hotsoa

k event s ar e processe d i

n asimila r fashio n b y di e Ptdih s module , wit

h th e primar y differenc e betwee

n the mbeing th e basi c emission rate use d fo r each
. Fo r bot h events , di e appropriat

e emission rate i s obtained , an d correcte d t

o accoun t fo r fue l tan k siz e and fo r th e even t multiplie r containe d in th e even

t dat afile. Th e resultin g uncontrolle d hydrocarbo n emissio n valu e i s the n adde d t o th e canister

throug h us e o

f th e Dopurg e module , thu s updating the caniste r state . Furthe

r detail s ar e containe d i n Section s H-C-3- a and H-C-3-h
. Drive event s ar

e processe d b

y th e Ptdriv e module
. A

t di e star t o f each driv e simulation , di e star t time relative to th e beginnin g o f the specified driv e schedul e and di e driv e lengt h ar e determined fro

mparameter s associated wid i the driv e even

t specification
. Next , eac

h entr y i n th e driv e tabl e include d in th e driv e i s processed
. Fo r each driv e tabl e entry , vehicl e spee d an d acceleratio n i s calculated , alon g wit h canister purg e rate , th e fue

l tan k vapo r generatio n rate , and di e net chang e i n caniste r loa d ove r the interva

l betwee n driv e tabl e entries
. I n addition , value s fo

r di e quantit

y o f fue l require d b y di e engin e and the percen t o f thi s fue l provide d b

y caniste r purg e vapor s ar

e als o calculated
. Afte

r al l driv e tabl e entrie s hav e bee

n processed , atrip summar

y i s displayed
. Furthe

r detail s ar e containe d i n Section H-C-3-b
. 2 ) Model Structur e Thi s sectio n describe s th e overal l structur e o f th e P T model , and how the component s o f di e mode l relat e t o on e another
. Thi s informatio n i s no t strictl y necessar

y to us e o r understand di e model , bu

t i t ma y be usefu l i f die mode l i s t o be expanded or

modified
. Th e figur e belo w illustrate s th e PT mode l structure in term s o f it s highest-leve l components . Th e algoritiim s upo n whic h eac h o f thes e component s are base d are describe d belo w in Sectio n 3 below , "Componen tDescription. "

1 2P.2 5



### Caniste r Mode

l - Progra m Structure PurgeTes t

Thi s diagra mshow s tha t

th e mode l structur e consist s o f fiv e levels
. Th e firs t

o f dies e i s di e modul e labele d PurgeTest , whic h supervise s readin g o f all inpu t dat aan d dat atables , model initialization , dat avalidation , an d displa y o f inpu t data
. Thi s modul e make s us e o f subordinat e module s i n di e secon d level , suc h a s GetFile , Gprdkey , Ptcheck , Ptinit , PtdspO , an d Read_data
. PurgeTes t i s als o responsibl e fo r

startin g th e actua l simulatio n calculation s b y callin g o n Doit , an d fo r displayin g final result s throug h Display_data
. Th e secon d leve l modul e Doi t i s responsibl e fo r

supervisin g th e processin g o f eac h even t

i n th e even t dat afile
. Thes e events , an d thei r associate d parameters , ar e rea d b y th e Rdev t module
. After

eac h even t

i s rea d an d it s typ e determined , Doi t call s upo n on e o f

di e thir d leve l module s Ptdi , Pths , o r Ptdrive , a s appropriate , t o carry ou t th e necessar y calculations. Eac h o f dies e dire e module s mak e us e o f th e fourt h leve l modul e DoPurg e t o carr y out caniste r loadin g an d purgin g calculations 1

. Ptdrive als o makes us e o f severa l fourt

h leve l module s t o perfor mcalculation s associate d wit h determinin g vehicl e spee d an d acceleration , engin e horsepowe r output , purg e flo w rate , an d fue l tan k vapo r flo w rates . Module s use d fo r

thes e purpose s includ e GetSpeed , GetUp , Ge t Purge , an d Getvpr
.
iTh e module(s ) use d t o carr y ou t diurna l an d hotsoa k calculation s ar e referre d t o a s eithe r Ptdihs , o r a s Ptd i an d Pths
. Th e Ptd i an d Pths module

s ar e actuall y entr y point s i n th e Ptdih s module , sinc

e man y o f th e calculations neede

d b y thes e tw o module s ar e identical
. Fro

mafunctiona

l viewpoint , Ptd i an d Pth s ca n b e considere d t o b e separat

e as indicate

d b y th e diagra mabove , eve

n thoug h fro maprogra mstructur e viewpoint , the y ar e reall y subordinat

e component

s o f Ptdihs
. 1 3A numbe r o f othe r module s no t

describe d her

e ar e als o use d b

y th e PT model ; these , however , ar

e associate d wit

h low-leve l datainpu t or progra mcontrol , and ar

e no t described in dii s document
. 3 ) Componen tDescriptio n Thi s sectio n describe s each o f th e computationa

l module s presente d abov e in Sectio n 2) , alon g wid i th e computationa

l algorithm s upo n whic

h the y ar e based
. Module s dia

t ar e describe d here are limite d t o thos e direcd y wit h simulatio n o

f vehicl e component s and operation
. Othe

r modules , suc

h a s thos e associate d wit

h peripheral functions , such a s supervisor y or input/outpu

t tasks , ar e no t documented
. a ) Ptdih s Thi s modul e processe s bot h diurna l an d hotsoa

k events , includin g calculatio n o f uncontrolle d vapor

generatio n an

d change s i

n caniste r loading
. For

diurna l events , th e basi c quantit

y o f hydrocarbon s generate d durin g th e event i s obtaine d fro

mth e Diurna

l scala r inpu t dat aitem , a s describe d i n Sectio n II-B-l-e , "Diurna l Caniste r Load. " Fo r hotsoa k events , di e correspondin g valu e i s obtaine d fro mdi e Hotsoa

k dat aitem
. Thes e value s ar e me n adjusted fo

r fue l tan k size , an d th e fue l tan k an d ambien

t temperature s at whic h di e event

occurs , a s describe d i n Sectio n II-B-3 , "Even tData. " Finally , th e correcte d hydrocarbo n generation valu e i s passe d t o th e Dopurg e module , which perform s th e actua l caniste r loading calculations
. Thes e calculation s include updatin g di e caniste r load , and determinin g di e amount , i f any , o f hydrocarbon s vente d durin g di e event . A summar y o f hydrocarbon s generate d durin g di e event , di e final canister state , and th e hydrocarbon s vented i s displayed a t th e end o f eac h o f dies e even t simulation
. b ) Ptdriv e Thi s modul e processe s driv e events , includin g interaction s betwee n fue l tan k vapo r generation , canister

purge , and driv e characteristics
. Thi s calculatio n procedur e use d t o carr y ou t driv e simulation i s a s follows : 1 ) Determine the star

t an d end times , relativ e t

o th e star t o f th e driv e defined by di e driv e schedul e table , fro

meven t file parameter s a s describe d i n Sectio n H-B-3-c , "Driv e Events. " Initializ e di e curren t simulatio n time to the initial driv e tabl e entr y o f the driv e t o b e simulated
. 2 ) Determin

e th e curren

t vehicl e spee

d an d acceleration throug

h the Getspee d module
. Speed i s returne d in MPH , an d acceleratio n i n MPH/second
. Calculat e tota l mile s travele d in di e driv e b

y integrating velocit

y using Euler' s metho d 3 ) Calculat

e di e horsepowe

r require d by the curren

t vehicl e spee d an d acceleration , using the Geth

p module
. Als o calculat

e the rat e o f fue l consumption , i

n pound s pe

r second , require d b

y thi s powe

r level , using th

e Geth p module
. 4 ) Determin

e th e volumetric flo

w rate , i n SCF/minute , o

f caniste r purg e available fro

m the engin e base d on th e curren t vehicl e spee

d an d acceleration , usin g the Getpurg e module
. I f th e current

simulatio n time i s les s tha n th e specifie d canister

purg e delay , a s describe d i

n Sectio n II-B-l-g , "Purg e Delay, " set thi s purg e rat e t o zero . 5 ) Determin e di e quantity , i n grams , an

d flo w rate , in SCF/minute , o

f hydrocarbo n vapor s generate d i

n the fue l tan k ove r th e uni t time interva

l startin g a t di e curren t 1 4driv e simulatio n time. Thi s valu e i s obtaine d b y di e Getvp r module , usin g th e vapo r generatio n tabl e correspondin g to th e current driv e type . See Sectio n H-B-3-c , "Driv

e Events. " Adjus

t bod i o f dies e quantitie s fo

r th e fue l tan k siz e o f the simulated vehicle
. 6 ) Calculat

e th e net purg e flo w rat e throug h th e caniste

r a s di e differenc e betwee

n the availabl e purg e rat

e foun d i n 4 ) above , an

d di e fue l tan k vapo r flow rat e foun d i n 5 ) above
. Thi s calculatio n assume s tha t di e purg e syste

mi s configure d a s show

n below : I f th e net caniste r purg e i s les s tha

n zero , the n canister

loadin g wil l occur , otherwise , hydrocarbon s wil l b e purge d fro mth e canister
. Caniste

r loadin g i s processe d a s follows : First , fue l tan k hydrocarbon vapor s ar

e apportione d betwee

n the engin e and the caniste

r i n the sam e rati o a s the availabl e purg e rate fro mthe engin e t o th e fue

l tan k vapo r generatio n flow rate . Next , thi s quantit y o f hydrocarbon s are loade d to th e canister by th e Dopurg e module
. Finally , di e amoun t o f hydrocarbons , i

n pounds , available to di e engine a s unmetere d fue l fro m th e fue l tan k i s calculated
. Thi s quantit

y i s foun d fro mth e differenc e betwee

n fue l tan k vapo r generation an

d di e amoun

t o f hydrocarbon s loaded to di e canister
. Fo r caniste r purge , th e followin

g calculation s ar

e performed
. First , th e tota l purg e volum e i s determined b

y multiplying di e net

purg e flo w rate , i n SCF/minute , b y di e interva l widdi , normall

y on e secon d o r 1/6 0 minute
. Then , di e Dopurg e module i s use d to carr

y ou t caniste r purg e calculations
. Finally , th e amoun t o f hydrocarbon s available t o the engin

e a s unmetere

d fue l i s calculated a s di e su

mo f fue l tan k vapor s and vapor s purge d fro

mthe canister
. 7 ) Calculat

e di e percen

t o f engin e fue l requirement s provide d by unmetere d fue l fro m th e caniste r alone , an d fro mdie caniste

r an d fue l tan k combined
. 8 ) Writ e entrie s t o bod

i di e plo t file an d to di e lo g file, if

specified by th e appropriat e Plotfla g dataitem
. 9 ) Continue wit

h 2 ) abov e unti l al l entrie s in the driv e table hav e bee n processed
. A t th e en d o f adriv e simulation , asummar y o f tota l tri p data , vehicl e performance , an d evaporativ e emission s i s displayed
. c ) Getpurg e Thi s modul e determine s th e availabl e purg e flow rat e to the engine
. Purg e rat e ca n b e calculate d fro

ma n internal algorithm , a s describe d below , o r fro mauser-supplie d algorithm , a s describe d in Appendix B
. Usin g th e interna l algorithm , purg e rag e i s proportiona

l t o engin e power , as follows :

1 5P.2 8



# 1

I f spee d < 2. 5 mp

h die n purg e = 0. 0 els e if acceleration > 3. 5 mph/s/

s o r acceleratio n < 0 the n purg e = 0. 0 els e { h p = horsepowe

r a t curren t velocit y an d acceleratio

n maxji p = horsepowe

r a t 60. 0 mp h cruis e min_h p = idl e horsepowe

r k l = max_purge*Oip-min_hp)/(niax_hp-niin_hp ) k 2 = max(1.0-(2./9.)*accel , 0.10 ) purg e = k l * k 2 } Whe n di e vehicl e i s belo w aspecifie d velocit y (2. 5 mph) , or

decelerating , n o purg e occurs . Otherwise , purg e i s proportiona l to horsepower , multiplie d b y a n empirica

l correctio n factor , k2 , dia

t account s fo

r th e reduce d manifold vacuumavailabl e durin g acceleration
. The notatio n show

n abov e fo r th e calculatio n o

f k 2 indicate s th e followin g steps : First , calculat e th e quantit

y 1.0-(2/9)*accel
. Next , compar e thi s valu e t o 0.10 , an

d selec t th e algebraicall

y large r value a s di e resul

t to b e take n a s di e valu e o

f k2
. d ) Getspee d Thi s modul e determine s di e vehicl e spee d an d acceleratio n a

t aspecifie d time durin g a drivin g cycle
. Thes e dat aar e obtaine d b

y tabl e looku

p i n th e driv e tabl e describe d i n sectio n II-B-2-a , "Driv

e Schedul e Table. " Vehicl e speed , i n MPH , i s determine d a s the averag e speed ove

r th e tim e interva l defined b y di e specifie d time and di e time o f di e next sequentia l driv e tabl e entry , i

f any . Acceleration , in MPH/second , i s determine d by di e chang e in velocit

y ove r dii s interva

l divided b y th e interva l width
. e ) Geth p Thi s module determine s th

e horsepowe

r required t o mov e avehicl e a

t aspecifie d spee d an d acceleration
. The followin

g empirica l correlatio n i s use d to obtain di e desire d horsepowe r value : horsepowe

r = k 4 + ki*spee d + k2*speed

^ + k3 * speed * acceleratio n Th e fou r constant s in th e abov e correlatio n ar e selecte d on th e basi s o

f vehicl e weight
. Suggeste d value s ar

e show n below : Vehicl e weigh

t kj ^ k 2 k £ k

4 I 400 0 lbs . 0.01 0 0.005 5 0.48 6 0.75 0 f ) Getfue l Thi s modul e determine s th e rat e o f fue l consumption , in pound s o f fue l per second , o f a vehicl e a t agive n powe r output , as provide d b

y Gethp
. Thi s calculation , show n below , i s asimpl e conversio n tha

t include s th e energ y conten t o f gasolin e (1864 6 BTUAbm) , an d engin e therma l efficienc y (take n a s 28. 0 %)
.

1 6P.2 9

Fuel rat e = horsepower * 2544,98 7 BT U / 3600. 0 sec . /

18464
. BT

U horsepowe r hr
. hou

r lbm
. g ) Getvp r Thi s modul e determine s th e fue l tan k vapo r generation rate a

t th e current

tim e in adrivin g cycle , usin g aspecifie d vapor generatio n table , describe d i n sectio n H-B-2-c , "Vapo r Generatio n Table. " Th e mas s o f hydrocarbo n vapor , in grams , generate d ove r aon e secon d interva l starting a t di e specifie

d tim e i s foun d fro mth e vapo r generation table , alon

g wit h the volumetri c vapo

r flo w rate , in standar

d cubi c fee t pe r minute
. h ) Dopurg e Thi s modul e carrie s out

al l caniste r load/purg e calculations , base d o n dat ai n di e caniste r purg e table , describe d i

n section n-B-2-b , "Caniste r Purge Table. " A semi-empirica l caniste r mode l i s use d tha

t i s base d o n experimental dat atake n under condition s representativ e o

f tiiose typicall

y encountered by evaporativ e emission s systems . Althoug h thes e dat aincorporat

e th e effects o

f caniste r geometr y a s wel l a s charcoa

l characteristics , th e P T mode l assume s tha

t onl y charcoa l typ e difference s ar

e significan

t betwee n canisters , an d dia t canister s o

f differin g siz e bu t identica l adsorben t exhibit performanc e proportiona

l to size
. During canister

loading , th e caniste

r i s assumed t o adsor

b al l vapor s passin g throug h th e adsorben t bed , u p to th e poin

t o f breakthrough
. Afte

r thi s point , an

y additiona

l vapor s fe d t o di e caniste

r ar e assume d t o be entirel y vented
. Mor

e specifically , the adsorptio

n fron t fo r th e adsorbent

be d i s assume d to b e perfectly sharp , wit h n o leadin g o r

trailin g tail
. Calculation s necessar

y t o simulat e caniste r loading , dierefore , ar

e simpl y t o ad d an y portio n o f incomin g vapor s t o the curren

t caniste r loa d u p to di e maximu

mcaniste r capacity , an

d t o ven t an y remainin g inle t

vapor s a s emissions
. Th e maximumcaniste r capacit y i s determine d by the specific caniste r capacit y obtaine d fro

mdi e purg e curve , along wit h th e actua l caniste r volume
. Unlik e di e straight-forwar

d caniste r loadin g calculations , purg e calculation s accoun t fo r th e non-linea r characteristic s o

f di e purg e curve . Th

e calculation sequenc e i s bes t illustrate d b

y example , wid

i the ai d o f di e followin

g figure
. Thi s example demonstrate s determinatio n o f th e fina l canister loadin g startin g fro

maknown initia

l caniste r loa d and aknown purg e volume
. Th

e value s show

n belo w ar e assume d fo r thi s example
. The

y ar e give n o n bot h a specific , o r

pe r lite r o f caniste r volum e basis , an d on atota l basis
. Quantit y Specifi

c Basi s Tota

l Basi s Caniste r size 1.0 1 2.0 1 Working Cap
. 32. 2 g/ 1 64. 4 g A Initia l loa d 12. 2 g

A 24. 4 g Purg e volum

e 17. 8 ft3/l 35. 6 ft3

1 7Sampl e Caniste rPurg e Curv e

H C Purge d 2 0 (gms ) 1 5

1 0 1 5 2 0 2 5 Purg e Volum e (SCF

) 3 0 3 5 4 0
Th e followin g step s ar e carried ou

t t o determin e di e fina l caniste r loading : 1 ) Determine th e amoun

t o f purg e require d t

o reac h the initia

l caniste r load fro mafull y loade d canister
. I

n thi s example , thi s i s di e purg e volum e require d t o reac h aloading o f 12. 2 g/ 1 (24. 4 g total ) fro

ma n initia l loadin g o f

32. 2 g A (64. 4 g total)
. D o thi s by enterin g th e purg e curv e o

n di e y-axi s a

t apoin t corresponding t

o di e valu e (maximu

m loadin g - current

loading ) and read fro

mth e purg e curv e th e correspondin g purg e volume
. Th e entr

y valu e i s a

t 32. 2 - 12. 2 = 2 0 g

A (64.4-24.4=40. 0 g total ) a s show n in Figur e 1
. Not e tha t al l entrie s int

o th e purg e curve ar

e mad e o n aspecific o r

per-lite r basis , s o tha

t di e purg e curv e i s initially entere d a t avalu e o f 20. 0 g/ 1 ratiie

r tha t 4 0 g total
. 2 ) Ad d the availabl e purg e volum e to the purg e volum

e obtained i n 1 ) above
. Thi s valu e i s 2. 2 + 17. 8 = 2 0 fttyl (4. 4 + 35. 6 = 40. 0 ft3 total)
. 3 ) Enter di e purg e curv e fro

mthe x-axi s a

t th e valu e fro

m2 ) above , an d rea d fro

mth e purg e curv e th e corresponding quantit y o f hydrocarbon s purged
. I

n thi s case , th e valu e i s 30. 3 g A (60. 6 g total)
. 4 ) Calculat

e th e final loadin g b

y subtracting th e valu e obtaine d in 3 ) abov e fro mth e tota l caniste r working capacity
. I

n thi s case , the value i s 32. 2 - 30. 3 = 1.9 g A (64. 4 - 60. 6 = 3. 8 g total)
. Thi s example indicate s dia

t th e final caniste

r loadin g i s 1. 9 g A o r atota l loa d o f 3. 8 g . Th e abov e procedure doe s no t account fo r th e influenc e o

f temperature o r

inle t hydrocarbo n vapor

compositio n o

n carbon capacit

y o r performance , no r

doe s i t accoun t fo r non-idea l adsorption characteristic s o f charcoal
.

1 8P.3 1

II I User s Guid e Thi s section provide s instruction s fo r preparation o

f the inpu t dataan d table s neede

d b y \hc PT model , fo

r runnin g th e model , an d fo

r interpretin g outpu

t generate d b y it
. I n addition , guideline s ar

e provide d fo

r making certain progra

mmodification s dia

t ma y b e needed t

o mor e realistically model performanc e o f evaporativ e emission s contro l devices
. Section A give s agenera

l descriptio n o

f di e step s necessar

y to perfor masimulation , whil e Section s B an d C ar e concerne d wit

h dat asource s and preparatio n o f tabula r an d scala

r data , respectively
. Sectio n D describe s di e sequenc e o f step s necessar

y t o ru n th e mode

l onc e datafiles hav e bee

n prepared
. Finally , Section E oudine s how user-prepare d progra mcod e ma y b e incorporated int

o th e model
. A ) Overvie w Us e o f th e PT mode l i s atwo-step procedure , wit h th e first consistin g o

f dat afil e preparation , and th e second , runnin g o f th e model itsel f

an d interpretatio n o

f results
. I n almos t al l cases , dat apreparatio n i s the mos t critica l an d time consuming o

f th e tw o steps . The dat apreparatio n ste

p ca n b e divide d int

o thre e parts , correspondin g t o scala r or input data , tabula

r data , and even

t data , a s describe d i n Sectio n H-B , "Inpu tData. " Generally , adifferen t input dat afile i s neede d fo

r each simulatio n run , aldiough file s fo r aserie s o f run s ar e ofte n simila r in content . A smalle

r numbe r o f event dat afiles ar

e needed , a s th e sam e event s ar e usuall y use d fo r anumbe r o f mode l runs . Th e sam

e i s tru e o f tabula r dat a files, especiall

y di e caniste

r purg e an d drivin g schedule files. Additiona l vapor generatio n files ma y b e needed , dependin

g o n characteristic s o

f fuel s to b e use d fo

r simulation
. Al l dat afile consis t

o f ordinar y tex t an d numbers , s o ma

t diey ca n b e prepare d an d modified wit

h di e ai d o f atext edito r o r wor d processor . It

ma y b e convenien

t t o prepar e tabula r datafiles, suc

h a s vapor generatio n files, wit

h th e ai d o f aspreadsheet
. I

f awor d processo r i s used , a

n appropriate mode shoul d b e selecte d t o avoi d includin g an y formattin g o r

other specia l character s int o dat afiles
. Generally , inpu t dat afile s ar

e frequend y modified , whil e tabula

r and even t dat afiles ar

e seldom , i

f ever , change d onc e the y hav e bee n prepared
. Runnin g th e P T model , a s describe d i n Sectio n III-D , "Progra m Use, " i s straightforwar

d onc e all datafile s ar

e available
. Often , the mode l i s use d a s adesig n tool t

o fin d th e valu e o f som e inpu t variabl e suc

h ma t simulate d vehicl e performanc e meet s certai n criteria
. Thi s desig n proces s involve s selectin g a n initial valu e o

f th e inpu t variable , runnin g the model using thi s value , examinatio n o f output , followe

d by modification o

f di e initia l input value
. Th e mode

l i s die n rerun in a

n iterativ e fashio

n unti l th e desire d model outpu t i s obtained
. A typica

l applicatio n o

f thi s procedur

e i s finding th e canister

siz e needed to provid

e agive n level o f emission s contro l unde

r aspecifie d se t o f conditions
. B ) Dat

a Fil e Preparatio n Thi s section oudine s th e step s necessar y to prepar

e datafile needed by th e PT model
. The structur e o f dies e guideline s follow s tha t o f Sectio n II-B , "Inpu

tData. " I

n Sectio n 1 below , "Inpu

tDat a Preparation, " eac h o

f di e dat aitem s tha

t mus t b e include d i n th e scala r o r inpu t dat afile i s discussed
. Sectio n 2 below , "Tabula r Data Preparation, " describe s preparatio n o

f di e thre e tabula

r dat afile, whil e Sectio n 3 , "Even t Dat a Preparation, " cover s preparatio n o f even t dat afiles. 1 ) Inpu tDat

a Preparatio n 1 9P.3 2

The scala r or inpu t dat afile consist s o

f anumbe r o f entrie s correspondin g t o each o f the dat aitem s describe d in Section n-B-1 , "Inpu tData. " The prototyp e o

f eac h entr y i s as follows : <keyword > <data_count

> <data_list > Th e <keyword

> consist s o

f di e nam e o f a n inpu t dat akeywor d t o whic h anumeric value i s t o b e assigned , an

d <data_count

> i s th e numbe r o f numeric value s tha

t ar e t o b e specified
. <data_list > i s the n di e se t o f one or mor e actua l dat avalues
. The inpu

t datakeyword s used by the P T mode l ar e summarize

d i n di e followin

g Table
. Keywor d titl e tanksiz e maxpurg e diurna l hotsoa k purgedela y cansiz e can s tart pa r a m purgetyp e logfla g Type Coun t Descriptio n Cha r Rea l Rea l Rea l Rea l Intege r Rea l Rea l Rea l 4 Rea l 1 Logica l 2 <8 0 A descriptiv e titl e tha t wil l b e displaye d a

t th e star t o f eac h simulation
. Fue l tan k liqui d capacity , gallon s Maximu mcaniste r purg e rate , SCFM
. Se

e Section H-B-l-d
. Bas e cas e diurna

l caniste r loading
. Se

e Sectio n H.-B-1-e
. Bas e cas e hotsoa

k caniste r loading
. See Sectio n II-B-l-f
. Numbe r o f tim e step s by whic

h th e star t o f purg e i s delaye d afte r th e star t o f adrive
. See Section H-B-l-g
. Caniste r size , liters
. Initial caniste

r loading as percen

t of tota l capacity
. Horsepowe

r correlatio n parameters . Se e Section II-B-l-h
. Purg e strateg

y mode l index
. Normall

y 3
. Se e Section DLI-E
. Lo g fil e an d plo t fil e outpu t contro l flags
. The first

valu e determine s i

f anorma l o r condense d lo g outpu

t fil e shoul d b e generate d (value s .true , an

d .false. , respectively)
. Th e second valu e applie s t o th e plo t outpu t file
. Se e Section III-D-2
. Pathnam e fo r driv e schedule tabula

r dat afile
. Se e Section ITJ-B-2-a
. Pathnam e fo r vapo r generation tabula

r datafiles
. A

t leas t on e o f thes e keyword s mus t

hav e apathnam

e assigned t

o it , a s well a s keyword s corresponding t

o al l driv e even

t keyword s occurrin g in the even t datafile. See Section III-B-2-c
. Pathnam e fo r caniste r load/purg e tabula

r dat afile
. Se e Sectio n IE-B-2-b
. Pathnam e fo r log outpu t file. Se e Sectio n III-D-2
. Pathnam e fo r plo t outpu t file. Se e Section III-D-2
. Pathnam e fo r even t dat ainpu t file. See Sectio

n ITI-B-3
. I n preparin g the input

dat afile, keyword s mus t

appea r exactl y a s i n m e tabl e above , wit

h lowe r cas e letter s use d wher

e indicated
. Uppe

r an d lowe r cas e letter s ar

e no t treate d a s being equivalent
. Th

e meanin g o f th e forma t type s appearing i

n the second colum

n o f the tabl e ar e a s follows : Rea

l value s ar

e number s appearin g in eithe r floating poin t

o r exponentia

l notation ; Intege

r value s ar e number s tha

t d o no t contai n adecima

l poin t o r drivefil e vaporfile l vaporfile 2 vaporfile 3 canfil e logfil e plotfil e eventfil e Cha

r Cha r

Cha r Cha r Cha r Cha r <8 0 <8 0

<8 0 <8 0 <8 0 <8 0

2 0P.3 3

fractiona l point ; Char(acter

) value s ar e alphanumeri c text , al l o f

which mus t

appea r on a singl e dat afile line
. Characte r string s should b e terminate d by adoubl e backslas h ('\\") ; Logical value s ar e eithe r

tru e o r false , a s indicate d b y di e tex t ".true. " or

".false. " respectively
. Fo

r real , intege

r an d logica l dat aitems , the dat

acoun t appearin g wit h di e dat a keywor d indicate s th e numbe

r o f individua l dat aitem s t

o b e specified
. Fo

r characte r dat a items , th e dat acount

refer s to the maximu

mnumbe r o f character s tha

t ma y appea r in th e followin g tex t

string
. Comment s ma

y b e include d a

t an y point i n th e file by placin g a semicolo n (";" ) in di e first

colum n o f di e lin e t o b e mad e acomment . 2 ) Tabula r Dat

a Preparatio n Thi s section describe s source s o f dat afo r eac h o f th e dire e tabula

r inpu t dat afiles described i n Sectio n H-B-2 , "Tabula

r Data, " an

d th e forma

t o f each datafile. Sectio n 1 cover s th e driv e schedul e table , whil e Section s 2 and 3 discus s th e caniste r purg e tabl e an

d m e vapor generation table , respectively
. a ) Driv e Schedul e Tabl e Thi s tabl e consist s o f

vehicl e speed an

d acceleratio n value s a

t equall y space d intervals , usuall y on e second i n width , tha

t describ e aparticula

r driv e schedule
. I

n the cas e o

f light

dut y vehicl e an

d light-dut y truck urba n dynamomete

r (LA-4 ) and heavy-dut

y truck urba n dynamomete

r schedules , th e necessar

y dat aar e availabl e in 4 0 CF

R 86 , Appendi x I , section s a ) an d d) , respectively
. Th

e forma t o f thi s fil e i s as follows : Lin e 1 : Tid

e Lin e 2 : Velocit

y (mph ) Acceleratio

n (mph/sec. ) Lin e n : Velocit

y (mph ) Acceleratio

n (mph/sec. ) b ) Caniste r Purg e Tabl e Thi s tabl e consist s o

f value s describin g caniste

r purg e characteristic s and which relate th e volume o f purg e ai r necessar y to purg e agive

n quantit y o f hydrocarbon s fro

mafull y loade d canister
. Normally , thes e dat aar e obtaine d experimentally , usin g th e followin g procedure : 1 ) Loa d caniste r t o breakthrough
. 2 ) Begi n caniste r purging a t apurg e flow rat

e consisten t wit h die expecte d in-us e rate . Simultaneously , recor

d tota l purg e volum

e an d caniste r weight
. 3 ) Continu e purg e and dat arecordin g unti l th e caniste r i s full y purge d an d astabl e weigh t i s observed
. A t leas t 4 0 to 5 0 datapoint s shoul d be use d t o giv e agoo d representatio n o f th e entir e purg e curve . Th

e forma t o f thi s dat afile i s as follows : Lin e 1 : Tid

e Lin e 2 : Tota

l purg e vol
. (SCF

) Tota

l mas s purge d (gms ) Lin e n : Tota

l purg e vol
. (SCF

) Tota

l mas s purge d (gms ) 2 1P.3 4

Bot h purg e volume an d hydrocarbo n purge d mas s value s shoul d b e i n ascendin g order , an d di e final file lin e shoul d giv e th e caniste r working capacit

y o n aper-liter

basis , along wid i di e tota l purg e volum

e required to full

y purg e aloaded 1.

0 lite r canister
. Th

e tid e lin e consist s o f u p to 8 0 alphanumeri c character s tha t ma y b e use d t

o describ e content s o

f th e file. Al l remainin g dat avalue s ar e al l numeric , format-free , an d shoul d b e separate d b

y blank s or commas . Eac

h pai r o f speed/acceleratio n datashould occupy asingl e lin e i n th e file. c ) Vapo r Generatio n Tabl e , Thi s tabl e consist s o

f value s describin g fue

l tan k vapo r generatio n characteristic s o f a vehicl e durin g operation
. Thes e dataincorporat e the influenc e o

f severa l factor s including th e fue l tan k temperatur

e profil e during vehicl e operation , fue l volatility , fue

l tan k pressure , an d th e rat e a t whic h tan k vapor s ar e generate d i n response t

o change s i

n temperature . Dat

a item s i n thi s fil e include time sinc e di e star t o f adrive , total hydrocarbo n vapor mas s generate d durin g di e drive , an d di e instantaneou s vapo

r generatio n flow rat e a

t each time. The file forma

t i s a s follows : Lin e 1 : Tid

e Lin e 2 : Time(min. ) Tota l H C Mas s (g ) Vapo

r Flo w Rat e (SCFM) Linen : Time(min. ) Tota l H C Mas s (g ) Vapo

r Flow Rat e (SCFM) Th e title lin e consist s o

f u p t o 8 0 alphanumeri c character s tha t ma y b e use d t o describ e content s o f di e file. All remainin g datavalue s ar e al l numeric , format-free , an d shoul d b e separate d b y blank s or

commas . Each set

o f time/mass/flow rate dat ashoul d occupy a single lin e i n di e file
. Dat apoint s i n thi s file nee d not b e equall y space d in time. Th e total lengdi o f time represente d b y th e file should b e a t leas t a s long a s di e longes t

driv e dia t i s t o b e simulated , takin g int o accoun

t sequentia l drive s dia

t hav e initia

l driv e times startin g othe

r tha n a t th e beginning o

f avapo r generation table
. I f available , experimenta

l dat ama y b e used direcd

y i n vapo r generatio n tables
. I

n mos t cases , however , i t

ma y b e necessar

y t o us e simulation s to obtain di e neede d data
. A multi

ste p procedur e wa s use d durin g developmen t o f di e P T model t o obtai n vapor

generatio n dat afiles, a s outline d below
. 1 ) Generat

e atabl e tha

t describe s fue

l tan k vapor generatio n a s afunction o f fue l temperature . Thi s tabl e should hav e entrie s fo r temperature , mas s o

f hydrocarbo n vapor generated , an

d tan k vapo r flo w rate . Th e rang e o

f temperature s shoul d b e representativ e o

f the rang e expecte d fo

r th e vehicl e to b e simulated
. Typically , a rang e o f 25-3 0 ° F i s appropriate
. Hydrocarbon mas s value s shoul d b e in gram s an d indicat e th e cumulativ e vapo r generatio n startin g fro mth e initia l tank temperature . Vapo

r flo w rate s shoul

d be in SCF/minute , an

d indicat e instantaneou s flow rate s a

t eac h temperature . Bod

i hydrocarbo

n mas s an d flow rate value s should b e normalized t

o a1. 0 gallo n tan k size
. 2 ) Generate atabl e o r

functio n tha t relate s time and fue

l tan k temperatur

e durin g vehicl e operation
. Thi s table wil l most likel y b e based o n experimenta

l data , sinc e a realisti c dieoretica

l mode l o f fue l tan k temperature s i s difficul

t to develop i

n di e 2 2P.3 5

absenc e o f experimenta

l data
. Dat

aused t o develo p m e P T mode l i s describe d i

n Appendi x D , "Vapo

r Generatio n and Temperature Profil e Data. " 3 ) Combin

e table s fro mstep s 1 ) an

d 2 ) abov e a s follows
. Select

di e temperatur

e value fro ma n entr y i n th e tabl e for

m1) , an d enter th e tabl e fro

m2 ) a t th e sam e temperatur

e value
. Obtai n th e time , or lengdi o f driv e neede d to reac h tha t temperature , interpolatin g a s necessary . Generat e asingle entr

y in m e final vapo

r generatio n tabl e usin g the time valu e obtaine d fro mth e ste p 2 ) table , and th e hydrocarbon mas s an

d vapo r flo w rat e value s fro

mthe ste p 1 ) table
. 4 ) Repea t ste p 3 ) fo r al l entrie s i n die ste p 1 ) table
. Abbreviate d example s o

f table s correspondin g to thos e describe d i n di e step s 1 ) an

d 2 ) above , an d di e resulting vapo

r generatio n table ar e show n below
. Vapo r Generatio n Tabl e (Ste p 1 ) Temperatur

e H

C Mas s Vapo

r Volum e ( 3 Fahrenheit

) 84. 0 85. 0 85. 5 86. 0 87. 0 87. 5 88. 0 88. 5 89. 0 89. 5 90. 0 90. 5 91. 0 91. 5 92. 0 92. 5 93. 5 94. 0 teams) ISCEgal l

0. 0 1.77e- 3 0.2 0 2.05e- 3 0.3 0 2.10e- 3 0.4 1 2.l5e- 3 0.6 4 2.24e- 3 0.7 6 2.30e- 3 0.8 9 2.35e- 3 1.0 1 2.40e- 3 1.1 5 2.46e- 3 1 2 9 2.52e- 3 1 4 3 2.58e- 3 1.5 8 2.65e- 3 1 7 4 2.72e- 3 1.9 0 2.78e- 3 2.0 7 2.86e- 3 2.2 5 2.93e- 3 2.6 2 3.10e- 3 2.8 3 3.20e- 3

2 3Time/Temperatur e Tabl e (Ste p 2 ) Temperatur

e ( 2 Fahrenheit

) 84. 0 84. 5 85. 0 85. 5 86. 0 86. 5 87. 0 87. 5 88. 0 88. 5 89. 0 89. 5 90. 0 90. 5 91. 0 91. 5 92. 0 92. 5 93. 0 93. 5 94. 0 Tun e

(Min. ) 0. 0 0.5 4 1.1 9 1.8 5 2.5 2 3.2 0 3.8 8 4.5 7 5.2 7 5.9 8 6.7 0 7.4 2 8.1 5 8.9 0 9.6 5 10.4 1 11.8 4 11.9 7 12.7 6 13.5 7 14.3 9 Vapo r Generatio n Table (Step s 3 an

d 4 ) Tim e (Min. ) 0. 0 0.5 4 1.1 9 1.8 5 2.5 2 3.2 0 3.8 8 4.5 7 5.2 7 5.9 8 6.6 9 7.4 2 8.1 5 8.9 0 9.6 5 10.4 1 11.1 8 11.9 7 12.7 6 13.5 7 14.3 9 HCMas s

(prams/pal. ) 0. 0 0.1 0 0.2 0 0.3 0 0.4 1 0.5 2 0.6 4 0.7 6 0.8 9 1.0 1 1.1 5 1.2 9 1.4 3 1.5 8 1.7 4 1.9 0 2.0 7 2.2 5 2.4 3 2.6 2 2.8 3 Vapo r Flo w Rat e fSCFM/min/eal ) 1.77e- 3 1.91e- 3 2.05e- 3 2.10e- 3 2.15e- 3 2.l9e- 3 2.24e- 3 2.30e- 3 2.35e- 3 2.40e- 3 2.46e- 3 2.52e- 3 2.58e- 3 2.65e- 3 2.72e- 3 2.78e- 3 2.86e- 3 2.93e- 3 3.02e- 3 3.10e- 3 3.20e- 3 3 ) Even t

Dat aPreparatio n The even t datafile consist s o

f asequenc e o

f even t entries , on

e pe r file line , eac

h o f whic h consist s o f

akeywor d an d one or mor e parameters . Vali d keyword s an d associate d parameter s ar

e a s follows : 2 4P.3 7

Keywor d Paramete

r drive l drive 2 drive 3 diurna l hotsoa k 

### 1-

2 1- 2 1- 2 

### 1 1 Lowe r cas e tex t mus t b e use d fo r keywords ; uppe

r an d lowe r cas e letter s ar

e not treate d a s bein g equivalent
. Th e definitio n o f even t keywor d parameter s ca

n b e foun d i n Sectio n H-B-3 , "Even

tData. " C ) Program Us e Thi s section describe s us e o f the P T mode l t o carr y out simulation s onc e al l dat

afiles have bee n prepared , a s covere d in Section H- B and H-C
. Basi c command s an d procedure s fo r runnin g di e model on IBM-P C an d compatibl e machine s ar

e foun d i n sectio n 1 , "Runnin

g th e Model," , whil e asummar y o f error message s an

d dieir cause s i s foun

d i n sectio n 2 below , "Error

s an d Messages. " 1 ) Runnin g th e Model Befor e th e model i s run , i t

shoul d b e transferre d fro

mth e distributio n dis k

t o aworkin g floppy disk , o r

installe d on ahar

d disk , a s describe d in Appendix A
. Th e example s ma t follow assum

e ma t th e director

y structur e o f the distributio n dis k

i s preserved , o r

tha t di e mode l i s installe d on ahar d dis k in adirector

y calle d PT
. Th e director

y setu p shoul d therefor e appea r a s show n below
.

2 5P-3 8

PT pt-ke

y pt.ba t rptex e runpt.da t install.ba t DAT A SOURC E pt.fo r ptdihs.fo r
VP R EV

T CA N IN P 7297.vp r 84109.vp r ftp90.ev

t ftplll5.ev t ford.ca

n nissan.ca n sample.da

t testl.dat test2.da t 

### w s 7191a.vp

r 84104a.vp r 96116a.vp r OU T DR

V tes t 1.ou t test2.ou t la4.dr

v nyc.dr v hwfe.dr v Dat afiles containe d i n th e directorie s VPR , EVT , etc. , are liste d i n Appendi x A , "Distributio n Dis k Contents an d Mode l Installation. " Running o f di e P T model i s normall

y accomplishe d throug

h us e o f th e p t batc h file. Thi s techniqu e simplifie s operatio n o f di e model b y automatically locatin g and executin g di e model itself

, an d b y appendin

g the prope

r pat h nam e t o th e scala r inpu t datafile, the nam

e o f which mus t

b e specifie

d whe n th e mode l i s executed
. Inpu

t datafile name s ar

e assumed t o hav e di e forma

t <input_data_file_name>.da

t wher e th e brackete d tex

t represent s auser-specifie

d name . Eac

h o f thes e file i s expected to reside i n the director

y ptNdataMnp

. T o ru n th e model , the workin

g director y should b e se

t to tha t containin g th e pt.ba

t file, i n thi s cas e c^t , an

d the comman

d prototyp e show

n belo w used
. p t <input_data_file_name

> Not e tha t th e extension ".dat " nee

d no t appear , altiioug

h i t ca n appea r i f desired
. 2 6A

t dii s point , di e p t

mode l wil l begin execution , an

d di e inpu t datafile will b e rea d A brie f summar y o f ke y input dat aitem s wil l me

n b e displayed , an

d eac h o f th e tabula r input dat a files wil l b e opened
. Th e nam e o f each file i s displaye d a s i t

i s opened
. A s thes e files ar e me n read , di e numbe

r o f dat aline s i n each file i s displayed , along wit h th e corresponding tide line
. Thi s informatio

n i s usefu l t o verif y tha t th e desired dat

afiles hav e bee

n correcti y specifie d fo r eac h simulation
. Afte

r thes e tabula

r dat afiles hav e bee

n read , di e first

entr y i n di e even t dat afile i s read, an

d simulatio n calculation s begin
. Normally , output

fro mdi e mode

l appear s on di e displa

y screen . Outpu

t ca n b e redirecte d to afile o r device , i f desired , b y using th e followin g comman d prototyp e t o begi

n executio n o f the p t model : p t <input_data_file_name

> <output_fd

> wher e <output_fd

> i s adevic e nam

e (e.g. , lptl:) , o r

th e ful l pat h nam e o f th e desire d output file. Th e redirectio n symbo l "> " i s adde d automatically , s o tha t i t shoul d no t

b e included i n di e <output_fd

> specification
. 3 ) Outpu tDescriptio n The P T mode l generate s diree type s o

f simulatio n output , referred t o a s termina l output , lo g file output , an

d plo t file outpu t

Termina l output , whic

h normall y appear s on the compute

r screen , i s di e primar

y output stream . Thi s strea

mcontain s summarie s o

f bot h input dat a an d simulatio n results
. Lo g fil e outpu t contain s detaile d second-by-secon d outpu t generated durin g driv e events . Becaus e dii s informatio n i s bot h voluminou s and usuall

y o f lesser interes t tha n dia t displaye d a s par

t o f termina l output , i t

doe s no t appea r o n th e compute r screen . Plo t

file output

contain s detaile d second-by-second value s fo r caniste r loading an d percen t o f engine fue l provided b

y caniste r purg e during driv e events . A s wid i lo g file output , thi s strea

mi s directed to adisk

file rathe r tha n b e displaye d on the compute r screen . The following dire e section s describ e each o f dies e output

stream s i n detail , and provid e the file forma

t used fo r recording lo g an

d plo t outpu t data
. a ) Termina

l Output Termina l outpu t i s di e primar

y output strea mfro mth e P T model , containin g inpu t

dat a summaries , summarie s o

f simulatio n results , an d message s describin g an y error s or warning s tha

t are encountere d durin g model operation
. Thi s outpu t strea mi s normally displaye d o n di e compute

r screen , although i t

ma y b e redirecte d to a

n alternate file o r device , a s describe d i n Sectio n III-C-1 , "Runnin g th e Model. " Fo r eac h event simulate d by th e P

T model , severa

l value s ar

e displaye d tha

t identif y th e event

bein g simulated , event

characteristic s or

parameters , and result s fro msimulatio n o

f th e event . Thi s section describe s mi s output , an d ho w eac h dat aite mi s t o b e interpreted
. A t th e star t o f calculation s fo

r eac h simulation event , th

e mode l display s count s o

f di e tota l numbe r o f event s processe d an

d th e tota l numbe r o f event s processe d o f

the sam e typ e a s th e curren t

event . Thi s informatio n i s usefu l to determin e ho w fa

r simulatio n ha s progresse d tiirough th e sequenc e o f event s i n a

n event dat afile. Followin g this , output specifi c to eac h event

i s generated
. Sample s o

f eac h ar e shown below , alon g wit h a description o

f eac h outpu t item
.

2

7P.4 0

Hotsoa k and Diurna

l Events : Lin e 1 : Hotsoa

k even t #2 Cumulativ

e even t #5 Lin e 2 : Even

t type : hotsoa

k Lin e 3 : H C to caniste

r (gms) : 7.4 0 Lin e 4 : H C vente d (gms) : .0 0 Lin e 5 : Fina

l caniste r loa d (%) : 45.7 0 Lin e 6 : Fina

l caniste r ca p (gms) : 20.9 9 Lin e 1 : "Hotsoa

k even t #2 Cumulative even

t #5" Indicate s dia

t th e fifdi even

t i n the even t dat afile i s being processed , and tha t i t i s di e second hotsoa

k even t o f di e simulation t

o b e processed
. Lin e 2 : "Even t type : hotsoak " Indicate s die even t type . Lin e 3 : "H

C to caniste

r (gms)... " Indicate s di e tota l hydrocarbo n vapor

loa d flowin g int o di e caniste

r durin g thi s even t Lin e 4 : "H C vente d (gms)... " Indicate s di e mas s o f hydrocarbon vapor s vente d into di e atmospher e b y th e caniste

r du e to insufficien

t capacit y t o adsor b som e o r al l o f th e vapo r loa d indicated b

y th e value i n Lin e 4
. Lin e 5 : "Fina

l can . loa d (%)... " Indicate s di e exten t o f caniste r loadin g at th e en d o f di e event o n apercentag e basis
. A valu e o f 100.0 0 correspond s t o afull y loade d canister
. Lin e 6 : "Fina

l can . cap . (gms)... " Indicate s th e availabl e caniste r capacit y a t the end o f the even t o n a n absolut e mas s basis
. A valu e o

f 0.0 0 correspond s to afull

y loade d caniste r wit h no available capacity
. Drive Events : Lin e 1 : Drive even

t #2 Cumulativ

e even t #4 Lin e 2 : Processing typ e 2 driv e even t Lin e 3 : Lin e 4 : Lin e 5 : Lin e 6 : Lin e 7 : Lin e 8 : Lin e 9 : Lin e 10 : Lin e 11 : Lin e 12 : Lin e 13 : Lin e 14 : Star

t time Drive lengt

h Endin g time Tota l fue l use d (lbs ) Tota l mile s travele

d Overal l miles/gallo

n Tota l prg . rat e (ft3 ) Tota l H C purged (gms ) Tota l H C vented (gms ) H C pg' d fro

mca n (g ) Fina l can . loa d (% ) Fina l can . cap . (gms ) =

= =

= 2 = = = = = = = = 0 106 1 106 1 1.4 9 5.5 5 23.1 4 19.9 5 42.1 5 0.0 0 25.7 9 26.5 4 28.3 9 Line 1 : "Drive even

t #2 Cumulativ e even

t #4 " Indicate s tha

t the fourt h even t in the even t dat afile i s bein g processed , an d tha t i t i s th e secon d driv e event o f th e simulation to b e processed
. 2 8P.4 1



# 1

Line 2 : "Processin g typ e 2 driv e event " Indicate s adriv e event , an d tha t di e vapo r generation dat

afile specifie

d b y di e vaporfile2 keywor

d i n th e inpu t dat afile wil l be used
. Lin e 3 : "Star

t time..." Indicate s di e startin g time o f di e drive , a s specifie d b

y th e secon d paramete r o f di e drive x keywor d i n di e even t datafile. Lin e 4 : "Driv e length... " Indicate s the lengd i o f th e drive , a s specifie d by th e first paramete r o f th e drive x keywor d i n di e even t dat afile. Lin e 5 : "Endin

g time..." Indicate s di e di e ending time o f th e drive , a s computed fro

m the value s displayed i n line s 3 an d 4 above
. Line 6 : "Amoun

t o f fue l used... " Indicate s th

e calculate d quantit

y o f fue l use d during th e specifie d drive
. Lin e 7 : "Tota

l mile s traveled... " Indicate s th e calculate d distanc e travele d durin g th e specifie d drive
. Lin e 8 : "Overal l miles/gallon... " Indicate d di e calculate d fue l econom y ove r th e specifie d drive
. Line 9 : "Tota

l prg . rate (ft3).,. " Indicate s the tota l volum e o f purg e vapor

enterin g th e engin e ove r the specifie

d drive
. Thi s quantit

y reflect s th e volum

e o f vapor s purge d throug h di e caniste

r a s well a s fue

l tan k vapor s tha t ar e route d direcd

y t o di e engine
. Line 10 : "Tota

l H C purge d (gms)... " Indicate s th e tota l mas s o f purg e hydrocarbon s enterin g the engin e ove

r the specified drive
. Thi s quantit y reflect s hydrocarbon s purge d fro mthe caniste

r a s wel l a s fue l tan k vapor s tha

t ar e route d directly t

o th e engine
. Lin e 11 : "Tota

l H C vente d (gms)... " Indicate s m e mas s o f hydrocarbo n vapor s vente d into di e atmospher

e b y di e caniste

r due t o insufficien

t capacit y t o adsor b som e o r al l o f the fue l tan k vapor s generated during the specifie d drive
. Lin e 12 : "H

C pg d fro mca n (g)... " Indicate s di e mas s o f hydrocarbon s purge d fro

m th e caniste r during di e specifie

d drive
. Lin e 13 : "Fina

l can . loa d (%)... " Indicate s th e exten t o f caniste r loadin g a t th e en d o f th e even t o n apercentag e basis
. A valu e o f 100.00 correspond s t o afull y loade d canister
. Line 14 : "Fina

l can . cap . (gms)... " Indicate s th e available caniste

r capacit y a t th e end o f di e even t o n a n absolut e mas s basis
. A valu e o

f 0.0 0 correspond s to afull

y loade d canister
. b ) Lo g Fil e Outpu t Lo g file output

contain s second-by-second outpu t generate d durin g simulation s o f driv e events . Thes e output

value s provid

e mor e detaile d information about driv e simulation s tha n appear s in termina

l output . Thes e dat aar

e written to a

n output file specifie d by th e logfil e keywor

d in di e scala

r or inpu t dat afile describe d i n Sectio n II-B-1-1 , "Lo g output 2 9P.4 2

file name, " and a s modifie

d b y the lo g file output

fla g describe d in Sectio n ITI-B-1 , "Inpu t Dat a Preparation. " Sampl e output fro mdii s file an

d adescriptio n o

f eac h output

item follows
. Time : 10. 0 Speed : .00 Accel : .00 0 Fuel rate : 2.3030E-0 4 EPrate : .00 0 Canprgvol : -1.0197E-0 2 %fue l a s vapor : .000 0 %fue

l fro mcan. : .00 0 Can
. loa d (%) : 99.027 Can
. ca

p (gms.) : .375 9 Time : Tim

e o f driv e simulation , in tim

e unit s use d in di e driv e schedul e table
. Speed : Vehicl e speed , i n mph
. Accel : Vehicl

e acceleration , i

n mph/sec
. Fue l rate : Liqui d fue

l rat e int o the engine , i

n lbs/sec
. E P rate : Volumetric flo w rat e o f purg e vapor s into the engine , in SCF/min
. Ca n prg . vol : Volumetri c flow rat e o f purg e vapor s ou

t o f th e canister , in SCF/min
. %fue l a s vapor : Percen

t o f tota l fue l required b

y m e engine available fro

mdi e combine d caniste r purg e strea

man d fue l tan k vapo r stream . Thi s valu e ma y b e greate r tha n 100.0%
. %fue l fro mcan : Percen

t o f tota l fue l required b

y di e engine available fro

mth e combine d caniste r purg e stream . Thi s value ma y b e greate r tha n 100.0%
. Can
. loa d (%) : Curren

t caniste r load , a s percen

t o f tota l capacity
. Can
. ca p (gms) : Curren

t available caniste

r capacity , i n grams . c ) Plo tFil e Output Plo t file outpu t

contain s second-by-second output generate d durin g simulation s o f driv e events . Thes e outpu t

value s provid e detaile d informatio n about caniste r loadin g an d percen t o f engine fue l requirements provide d b

y di e caniste

r purg e stream , an

d ca n b e use d t o prepar e plot s o f thes e quantitie s versu s time
. Thes e dat aar e written to a

n output file specifie d by th e plotfil e keywor d in th e scala

r o r inpu t dat afil e describe d i n Sectio n H-B-l-m , "Plot

outpu t file name, " an

d a s modifie

d b y th e plo t file output

fla g describe d in Sectio n III-B-1 , "Inpu

tDat aPreparation. " Sampl e outpu t fromthi s file an d a description o

f each outpu

t ite mfollows
. Colum n 1 Colum

n 2 Colum

n 3 Lin e 1 : Simulatio

n time Caniste

r loa d (% ) %Eng
. fue

l fro mcaniste r Lin e 2 : Lin e 3 : D ) Program Generatio n an d Modificatio n Thi s sectio n contain s abrief guid e t o recompilatio n o f

th e PT model , an d to addin g additional , user-defined purg e contro l strategy models
. Aldioug h neithe r o f thes e step s ar

e necessar y fo r us e o f the model , th

e necessar y instruction s ar

e include d her

e fo r tiiose wishin g to modif

y th e model
. Instruction s ar e brief , and knowledg e o

f FORTRA N i s assumed ; person s wit

h question s no

t answere d in dii s section should contac t di e author
. Th e P T mode l i s writte n in FORTRAN-77 , an d ha s been compile d usin g Microsof t FORTRAN , versio n 4.1
. An y use r modification s to the model wil l requir e tha t thi s o r a 3 0P.4 3

compatibl e compile

r b e available , alon g wid

i asuitabl e tex t

edito r to mak e an y neede d sourc e cod e modifications
. 1 ) Program Generatio n Compilation o

f di e P T model i s normall

y carrie d ou t

diroug h us e o f amak e utility , suc

h a s tha t include d wit

h di e Microsof

t Version 4. 1 FORTRAN-7 7 compiler
. Al l sourc e cod e fo r th e model , alon g wid

i di e dat afiles require d by make , ar e include d i n th e sourc e subdirector

y o f di e mode l distributio n disk
. Tw o dat afiles are use d durin g mode l compilatio n and Unking
. Th e first o f thes e i s th e sourc e code dependenc y file, calle d ptmak , which i s read b

y di e mak e utilit y itself
. Th e secon d datafile, calle d ptlink , i s rea d by th e linke

r t o determin e th e name s o

f al l objec t code files neede d t o buil d di e model
. Sinc e di e mak

e utilit y automaticall

y determine s whic

h sourc e cod

e files mus t

b e compile

d to rebuil d th e P

T model , asingl e comman d i s use d t o d o s o afte r an y sourc e cod e modifications
. Thi s comman d is : mak e ptma k Us e o f thi s command assume s ma t di e curren t working director

y i s set to tha t containin g di e mode l sourc e cod e and di e ptma k an d ptlin k dat afiles
. I

n di e distributio n disk , dii s director y i s calle d source . Sinc e us e o f aFORTRA

N compile r i s syste mdependent , step s necessar y t o acces s th e compde r o n aparticula

r syste mar e not covere d here
. I f additiona l sourc e code module s ar

e added t o th e P

T model , bot

h di e ptma k

an d ptlin k dat afiles mus t

be modifie

d t o reflec t di e addition
. Detail s o

f dii s procedur

e ca n b e foun d i n di e relevan t section s o f th e compile

r documentation
. 2 ) Program Modificatio n Provision s hav e bee

n mad e in di e P T mode l t o accommodat

e user-supplie d addition s tha t allo w simulatio n o

f canister purg e contro l strategie s othe r tha n tha t include d i

n th e distributio n versio n o

f th e model
. T o mak

e such a n addition , th e sourc e cod e fil e containing di e purg e contro l strateg y mode l must b e modified , an

d di e model recompiled a s describe d abov e in Section 1
. I n addition , achang e to di e purgetyp e scala r dat afile dat a ite mmus t b e mad e t o selec t us e o f di e user-supplie d purg e mode l i n plac e o

f th e built-i n model
. Thes e step s ar

e covered in mor

e detail in di e followin

g paragraphs
. Th e purg e contro l strateg y module Getpurg e i s containe d in di e file ptgetprg.for in th e sourc e director

y o f th e distributio n disk
. Withi

n dii s file, comment s indicat e th e portio n o

f the sourc e cod

e reserved fo

r user-supplie d additions
. T o ad d ne w code , di e tw o executabl e line s mus t b e deleted , a s indicate d in di e sourc e cod e comments , an d th e appropriat

e use r code added
. Th e purg e model to b e use d durin g aP T ru n i s specifie d by th e purgetyp e scala r dat afile item , describe d in Section H-B-l-n , "Purg e Typ e Flag. " Durin g executio n o f Getpurge , th e variabl e ptyp e contain s thi s value
. Value s o f ptyp e les s tha

n zer o shoul d b e use d to selec t

user-supplie d models , while avalu e o f zer o shoul d b e use d to selec t

th e distributio n model
. Tw o parameter s ar

e passe d t o th e Getpurg e modul

e whic h ma y b e use d to calculat

e purg e flo w rates . Thes e ar

e a s follows : Variabl e Typ e Descriptio n speed real* 4 Vehicle velocity , i n mph
. acce l real*4 Vehicl e acceleration , i

n mph/sec
. 3 1P.4 4

Th e variabl e max_purge , o

f typ e real*4 , ma

y b e use d in user-supplie d code
. Thi s variabl e contain s th e valu e specifie d fo r th e maxpurg e scala

r dat aitem , describe d i n Sectio n H-B-l-d , "Maximu

m Purg e Rate. " I n addition , di e modul e Gedi p ma y b e calle d by use r cod e t o estimat

e engin e horsepowe

r output a t agive n spee d an d acceleration
. The callin g sequenc e fo

r thi s module i s a s follows : h p = gethp(speed , accel , rvec(hp_base) ) Here , speed an

d acce l ar e m e vehicl e velocit

y an d acceleratio

n a t whic h horsepowe

r i s t o b e calculated
. Th

e diir d parameter , rvec(hp_base) , must appea r exacd y a s shown ; i t

i s used t o pas s horsepowe

r correlatio n parameter s to Gethp
. Detail s o f how thi s thir

d paramete

r i s obtaine d and use d ar

e omitte d fo

r di e sak e o f brevity
. Geth

p wil l retur

n the calculate d horsepowe r valu e a s afunctio

n value , whic

h i s o f typ e real*4
. Afte r auser-supplie d purg e mode l calculate s purg e rat

e i n SCF/min. , i t

should assig n dii s valu e to di e variabl e purge . Th e valu e o f thi s variabl e wil l b e assigne d t o th e function Getpurg e itsel f

upo n retur n fro mdi e function
. A possibl e skeleto n fo r user-supplie d code i s a s follow , wit

h existin g code show

n in bold :

i f (ptyp e .It. 0 ) the n if (ptyp e .eq.-1 ) die

n (calculation s fo

r first adde d model) purg e = purge_value_

l els e i f (ptyp e .eq . -2 ) the

n (calculation s fo

r secon d adde d model) purg e = purge_value_

2 endi f els e i f (ptyp e .eq . 0 ) the n

3 2P.4 5

I V Reference s 1 ) "Summar

y an d Analysi s o

f Comment s o n th e Recommende d Practic e fo r th e Measuremen t

o f Refuelin g Emissions." , March , 1987 , U.S
. EPA/OAR/OMS/ECTD/SDSB
. 2 ) Note s fro

mpubli c worksho

p "Modification s to Evaporativ e and Refuelin g Tes t Procedure s fo

r th e Contro l o f

Exces s Evaporativ e Emissions, " Jun e 30 , 1988 , U.S
. EPA/OAR/OMS/ECTD/SDSB
. Public docke t A-87-11 , documen

t IV-E-58
. 3 ) "Koehl , W.J
. Jr. , "Mathematica l Model s for

Predictio n o f

Fue l Tank

and Carbureto r Evaporation Losses, " SA

E Pape r 690506
. 4 ) Reddy , S.R. , "Evaporativ e Emission s fro mGasoline s and Alcohol-Containin g Gasoline s wid

i Closel y Matche d Volatilities, " SA

E Pape r 861556
. 5 ) AT L Repor t - On-roa d fue l tan k temperatures .

3 3P.4 6



# 1

Appendice s A ) Distributio n Dis k Contents an d Model Installatio n Thi s Appendi

x contain s adetaile d lis t

an d descriptio n o

f al l files include d i n th e PT mode l distributio n disk , an

d instruction s fo

r installing th

e mode l fro mth e distributio n disk
. Thes e topic s ar e covere d in Section s 1 an

d 2 below , respectively. 1 ) Distributio n Dis k Contents Th e director

y structur e o f di e distributio n dis k

i s a s show

n in Sectio n JH-C-1 , "Runnin g th e Model, " o

f the text . Content s o

f eac h director y ar e give n below
. Director y Fil e roo t (pt ) Descriptio n ptba t Batc

h file use d fo r running th e model
. ptke y Dat

afile used internall

y b y di e P T model
. Thi s file mus t

b e i n the curren

t director y a t di e time di e PT mode

l i s run , rptex e Drive

r file use d t o generat e patiiname s needed to star

t the P T model
. Se e Section 2 below , runptda t Dat afile rea d b y rptexe . See Section 2 below , installbat Batc h file fo r installing th

e P T model
. See Section 2 below
. sourc e

dataNvp r ptfo r

Mai

n progra mfo r th e P T model
. ptdihs.for Diurna

l an d hotsoa k modules
. ptgetprg.fo r Purg e contro l module
. ptcan.fo r Caniste

r module
. ptinitfo r Mode

l initialization module
. ptdrive.fo r Driv e simulatio n module
. lintrp.fo r Linea

r interpolatio

n utility
. ptdoit.fo r Even t handle r module
. ptcheckio r

Inpu t dat acheckin g an d verificatio

n module
. ptdspO.fo r Dat adispla y module
. ptinde x Dat

afile require d fo

r compdation
. D o not

modify
. ptgpfi o Dat

afil e require d fo

r compilation
. D o not

modify
. ptdim.in s Dat

afile required fo

r compilation
. D o not

modify
. gpfio.li b Objec

t cod e librar y containin g dat ainpu t utilities
. Sourc e cod e not included
. D o no

t modify , ptma k Dat

afile required b

y mak e durin g compilation , pdin k Dat

arequired fo

r progra mcompilation an

d linking , ptex e P

T mode l executabl e code
. 7297a.vpr Vapo r generation file, curren

t data , 9. 0 #RV

P fuel
. 84109a.vpr

Vapo r generation file, curren

t data , 9. 0 #RV

P fuel
. 96116a.vpr

Vapo r generation file, curren

t data , 9. 0 #RV

P fuel
. 7297c.vpr Vapo r generation file, curren

t data , 11. 5 #RV

P fuel
. 84109c.vpr

Vapo r generation file, curren

t data , 11. 5 #RV

P fuel
. 96116c.vpr

Vapo r generation file, curren

t data , 11. 5 #RV

P fuel
. 3 4

-P.4 7

data\vpr\w s

datatev t 7191a.vp r 84104a.vpr 96116a
. vp r 7191b.vp r 84104b.vpr 96116b
. vp r nprm.ev t ftpws.ev t ftpdi.ev t ftphtdiev t ftpla4.ev t ldir90.evt ldirll7.ev t ldnir90.evt ldnirll7.ev t ldftp90.ev t hdir90.evt hdir l 17.ev t hdnir90.evt hdnirll7.ev t fordxan nissan.ca n sample.da t testl.da t test2.da t la4.dr v hdurb.dr v nyc.dr v 2 ) Mode l Installatio n data^a n
dataMn p

dataNdr v Vapo r generation file, Vapo r generation file, Vapo r generation file, Vapo r generation file, Vapo r generation file, Vapo r generation file,

worksho p data , worksho p data , worksho p data , worksho p data , worksho p data , worksho p data , 9. 0 #RV

P fuel
. 9. 0 #RV P fuel
. 9. 0 #RV P fuel
. 10. 5 #RV P fuel
. 10. 5 #RV P fuel
. 10. 5 #RV P fuel
. NPR M tes t procedure , worksho

p data
. FT P test , worksho

p data
. FT P plu s diurnal , worksho

p data
. FT P plu s high-temp , diurnal , worksho p data
. FT P plu s LA- 4 drive , worksho p data
. Reproposa l TP fo r LD V wit h integrate d on-boar

d refuelin g systems , 9. 0 #RVP fuel , revise d temperatur e profile
. Reproposa l TP fo r LD V wid i integrate d on-boar

d refuelin g systems , 11. 5 #RVP fuel , revise d temperatur e profile
. Reproposa l TP fo r LD V wid i non-integrated refueling systems , 9. 0 #RVP fuel , revise d temperatur e profile
. Reproposa l TP fo r LD V wit h non-integrated refueling systems , 11. 5 #RVP fuel , revise d temperatur e profile
. Curren t FT P TP fo r LD V wit h 9. 0 #RVP fuel , revised temperatur e profile
. Reproposa l TP fo r HD V wid i integrate d on-boar

d refueling systems , 9. 0 #RVP fuel , revise d temperatur e profile
. Reproposa l TP fo r HD V wit h integrate d on-boar

d refuelin g systems , 11. 5 #RV

P fuel , revise d temperatur

e profile
. Reproposa l TP fo r HD V wit h non-integrated refuelin

g systems , 9. 0 #RV

P fuel , revise d temperatur

e profile
. Reproposa l T P fo r HD V wit h non-integrated refuelin

g systems , 11. 5 #RVP fuel , revise d temperatur e profile
. Caniste r purg e table fo

r For d (domestic)-typ e charcoal
. Caniste r purg e tabl e fo

r Nissan-typ e charcoal
. Scala r inpu t dat afile prototyp e template
. Scala r inpu t dat afile fo r sample tes t

run . See Appendi

x C
. Scala r inpu t dat afil e fo r sampl e tes t run . Se e Appendi x C
. LA-4 urba n dynamomete

r driv e schedul

e table Heavy-dut y urba n driv e schedul

e table
. Ne w Yor k cit y drive schedul

e drive table
. T o simplif y installatio n o

f th e P T mode l t o auser' s machine , abatch file i s include d o n di e distributio n dis k

tha t wil l automaticall

y creat e al l necessar

y directories , and copy al l files fro mthe distributio n dis k

to th e appropriat

e targe t directory
. Thi s batc h file i s intende d t o instal l th e model fro

mth e distributio n flopp

y dis k to auser' s fixed dis k

drive , whic h i s 3 5assume d to b e driv e c: . Modification s ma t mus t b e mad e t o m e installatio n batch file t

o plac e m e model on adriv e othe

r ma t driv e c : o r o n aflopp y dis k ar e oudine d a

t th e end o f dii s section
. Th e following installatio n procedure s assum e ma t di e use r i s familia r wit h PC-DOS/MS-DO S commands , tree-structure d directories , an d di e us e o

f flopp y an d har d dis k drives
. I f additiona l guidanc e i s neede d i n dies e areas , user s shoul d consult their compute r hardwar e and operating syste

mmanuals
. The followin

g step s should b e followe

d to perfor mnorma l installatio n fro

mdi e distribution dis k t o afixe d disk : 1 ) Mak e driv e c : (the fixed disk

) di e curren

t disk , an d chang e di e curren

t director y to tha t unde r whic h th e P T mode l i s to b e installed
. The instal l batch file wil l creat e a director y calle d pt , and instal l the model unde r i t a s show n i n Sectio n HI-C-1 , "Runnin g th e Model. " 2 ) Plac e di e distribution dis k indriv e a: , an

d mak e driv e a : di e curren

t disk
. 3 ) Ente r di e comman

d instal l to begin th e installatio n process . 4 ) Afte r installatio n i s complete , amessag e wil l b e displaye d t o mi s effec t A t thi s point , th e curren t

dis k ma y b e change d to driv e c: , an d th e distributio n dis k removed fro

mdriv e a: . 5 ) Chec k tha t all files liste d above i

n Sectio n 1 hav e bee

n copie d fro

mth e distributio n disk , an d ma t die y ar e i n thei r prope r location
. 6 ) Verif y tha t di e mode l i s operatin

g properl y b y runnin g th e tw o sample run s included wit h the mode

l an d describe d i

n Appendi x C , "Sampl

e Runs. " Installatio n o

f di e model to afixed dis k

otiie r tha n driv e c: , or

to afloppy disk , wil l require modificatio

n o f th e installation batc

h file install.bat
. I

n bod i cases , all reference s t

o c : in th e origina l batc h file mus t

b e change d to th e desire d drive
. Fo r alternat e fixed drives , thi s referenc e shoul d b e changed to th e appropriat e driv e letter , whil e fo

r installin g t o afloppy disk , driv e b : shoul d normally b e specified
. Floppy disk s mus t b e formatte d befor

e attemptin g to instal l th e model
. I t i s no t recommended tha

t the P T model b e installe d o n 360 K floppy disks , sinc e littl e spac e wil l b e availabl e fo r output files o r additiona l input dat afiles. I f th e P T mode l i s installe d wit

h adirector

y structur e differin g fro mtha t generate d by th e instal l batc h file, o r

i f differen t dis k drive s ar e t o b e used fo

r the model and fo

r inpu t data files, the n i t ma y b e necessar

y t o modif y di e runptdat

file ma t i s foun d in th e roo t

director y o f th e distributio n disk , and in th e p t director y a s di e model i s installe d b y th e norma l installatio n process . Dat

ai n thi s file ar

e use d t o generat e padiname s during executio n o f th e p t model , an d it s forma t i s a s follows : linel : <Model_code_pathname > / line2 : <Input_data_file_patiiname > Th e content s o

f th e first line contain th

e director y pat h o f the file containin g th

e P T model executabl e code (ptexe) , whil e th e secon d lin e contain s di e director

y padi t o th e director

y 3 6P.4 9

containin g scala

r inpu t datafiles. Not

e tha t di e Model_code_pathnam

e must terminat e i n a file, wherea s di e Input_data_file_padinam e must terminat e i n adirectory
. Durin

g executio n o f th e P T model , the inpu

t datafile t o b e use d i s locate d b

y appending the user-supplie d dat afile nam

e to di e Input_data_file_padiname
. A s distributed , runptda t file appear s a s follows : linel : source\p

t line2 : dataNin

p If , fo r example , scala

r inpu t datafiles ar

e t o b e rea d fro maflopp y dis k i n driv e a : instea

d o f fro mthe director

y pt\data\in

p a s distributed , th e runptda t fil e shoul d b e modified t o appea r as : linel : sourceNp

t line2 : a : Not e tha t modificatio n o

f di e runptda t

file i s no t needed i f th e distributio n dis k

director y structur e i s maintained
.

3 7B ) Refueling/Exces s Evaporativ e Emission s Worksho p Data

1 ) Introductio n Thi s appendix contain s description s an d summarie s o

f datause d to obtai n th e evaporativ e emission s caniste

r size s an d performanc e estimate s presente d a t di e publi c worksho

p titles "Modification s t o Evaporativ e an d Refuelin g Tes t Procedure s fo

r th e Contro l o

f Exces s Evaporativ e Emissions, " hel d o n June 30 , 1988
. Thes e dat aar e presente d a s astartin g point fro mwhic h calculation s upo n which worksho p presentation s were base d ca n b e carrie d out an d verified
. Dat aar e presente d according to th e organizatio n o f Section s I I and I

H o f dii s report . Tha

t is , source s o

f scala r dat aan d diei r sourc e ar e presente d first , followed by tabula r dat aan d even t data
. I n di e cas e o

f scala r data, , dat avalue s an

d diei r source s ar e presented , wherea s fo r tabula r data , reference i s mad

e t o compute r datafiles distribute d wid

i di e model
. 2 ) InputDat

a a ) Scala r Data

1 ) Fue l tan

k size : Al l tank s ar

e 17. 6 gallon s i

n size
. A vapo r

headspac e volum e o f 2. 0 gallon s i s assumed
. 2 ) Caniste r size : Variabl

e 3 ) Initia l Caniste r Load : 99.0 % o

f tota l caniste r capacity , except

for som e ver y larg e canister s (greate

r tha n 20. 0 1) , in which cas e avalu e o f 98.5 % wa s used
. Thes e valu e ar

e use d to simulat

e afull y loade d canister

instead o f 100.0 % to avoi d amode l quir k tha t allow s asmal l amoun

t o f vapo r breakthrough fro

mfue l tan k vapor s durin g simulatio n o f th e first entr y i n the driv e schedule table
. 4 ) Maximu

mPurg e Rate : For

purg e rate s o

f 8. 0 l/LA-4 , avalu e o

f 1.7 3 i s used , an d fo r purg e rate s o

f 20.01/LA4 , avalu e o

f 4.?? ? i s used
. 5 ) Diurna l Caniste r Load : Value s o

f 25. 0 an d 40. 0 g/even

t ar e use d fo r FTP an d in-us e diurnals , respectively. 6 ) Hotsoa k Caniste r Load : Value s o

f 6. 0 and 20. 0 g/even

t ar e use d fo r FTP and in-us e diurnals , respectively
. 7 ) Purg e Delay : A value o

f zer o i s use d fo r al l simulations
. 8 ) Horsepowe

r Correlatio n Parameters : Value s presente d i n Sectio n n-B-l- h ar e use d fo r al l simulations
. b ) Tabula r Dat

a 1 ) Drive Schedul

e Table : Th e driv e schedul e in the file la4.dr v i s use d fo

r al l simulations
. 2 ) Caniste

r Purge Table : Datai n th e caniste r purg e file s ford.ca

n an d nissan.ca n ar e used , a s appropriate
.

3 8P.5 1

3 ) Vapo r Generatio n Tables : Th

e followin g table s ar e used : Initia l Fuel Temperatur

e Fue

l Volatilit y Dat

aFil e 71. 0 ° F 84. 0 ° F 96. 0 O F 71. 0 ° F 84. 0 O F 96. 0 O F 9. 0 #RVP 9. 0 #RVP 9. 0 #RVP 10. 5 #RVP 10. 5 #RVP 10. 5 #RV P 7191a.vpr

84104a.vp r 96116a
. vp r 7191b.vpr l 84104b.vpr 96116b.vpr c ) EventDat

a 1 ) Th e followin g even t dat afile s ar c used : Even t Descriptio n Even t Dat aFile Augus t 198 7 NPR M tes t procedur e fo r nprm.evt load-to-breakdiroug

h an d caniste r pre conditioning
. FT P ftp.ev t FT P followe d by asingle diurna

l ftpdi.ev

t FT P followe d by a n LA- 4 driv e ftpla4.ev t FT P followe d b y ahigh-temperatur

e ftphtdi.ev

t in-us e diurna

l

3 9P.5 2

C ) Sampl e Run s Thi s Appendi x describe s tw o sampl e run s tha t are distribute d wit

h th e P T model to illustrat e dat aformats , ho

w m e model ca n b e use d to simulat

e variou s tes t

procedure s an

d type s o f vehicl e operation , and a s areferenc e t o verif y prope r operatio n o

f the model
. Sectio n 1 belo w give s abrief descriptio n o

f th e tw o tes t

cases , whil e Section s 2 and 3 contai n inpu t datafiles an

d mode l outpu t 1 ) Descriptio n Inpu t dat aan d model outpu

t fro mtw o sample simulation s ar e include d on th e distributio n disk , and reproduce d imprinte d for ma t th e en d o f dii s section
. Thes e example s ma y b e use d t o verif

y tha t di e model ha s bee

n installe d an

d i s operatin g correcdy , a s example s o f typica l inpu t datafile formats , an

d t o illustrat e technique s availabl e to simulat e effects o f fue l tan k temperature s o n evaporative emissions
. Sample datafiles ar e a s follows : Inpu t dat afile: Description : test l .da t Simulatio

n o f th e FTP+LA- 4 tes t

procedure , a s presente d during the Jun

e 30,198 8 workshop
. Fue l temperature s during al l drive s ar e assume d t o b e identical
. Diurna

l an d hot-soa k loading s ar

e take n to b e 25. 0 and 6. 0 grams , respectively.
. test2.da t Simulation o

f di e FTP+LA- 4 tes t

procedure
. Fuel temperature s ar

e continuou s fro

mone tes t procedur e even t to anodier
. Diurna

l an d hot-soa k loading s reflect

updated vapo r generatio n modelling , an

d hotsoa k loading s reflect end-of-drive fue

l tan k temperatures . Bot h inpu t dat afiles ar

e locate d in th e data\in

p directory , and outpu t

fromthes e tw o example s ca

n b e foun d i n dataNautVestl.ou

t an d data\ouf\test2.out , respectively
. Assumin g tha t di e model ha s bee

n installe d a s describe d i

n Appendi x A , dia t the curren t driv e i s tha

t onto which th e model ha s bee n installed , an

d ma t di e curren t director y correspond s t o th e roo t director y o f di e distributio n disk , th e followin g comman d ma y b e use d to run di e first o f the tw o sample runs : p t testl Thi s comman

d wil l caus e simulation outpu t to appea r on the displa

y screen . T o verif

y tha t th e mode l i s operatin g correctly , result s ca n b e compare d t o th e content s o f th e file data\oufStestl.ou

t I f desired , th e comman d p t testl lptl : ca n b e use d t o obtai n aprinte d cop y o f th e sample run output . For furthe r details , se e Sectio n HI-C-1 , "Runnin g th e Model. " Th e second sampl e run ca n b e execute d by substituting "test2 " fo

r "testl " i n ethe r o f th e tw o prototype s above
. 2 ) Test l Sampl e Ru

n Dat a Inpu t Dat aFil e (testl.dat ) 4 0titl e 7 0

P T tes t file , integr . system , ftp+la 4 drive , w s temps. , 9. 0 # fuel\ \ Th e TANKSIZ E keywor d specifie s th e nomina l liqui d capacit y o f th e fue l tank , i n gallons . tanksiz e 1 17. 6 Th e MAXPURG E keywor d specifie s th e maximu minstantaneou s purg e rat e i n cfm/min . maxpurg e 1 4.3 0 Th e DIURNA

L keywor d specifie s th e defaul t diurna l h e generation , i n grams . diurna l 1 1.42 0 Th e HOTSOA

K keywor d specifie s th e defaul t hotsoa k h e generation , i n grams . hotsoa k 1 .0.34 1 Th e DELA

Y keywor d specifie s a dela y i n th e star t o f caniste r purg e afte r th e star t o f simulation . purgedela

y 1 0 Th e CANSIZ E keywor d specifie s th e siz e o f al l canisters , i n liters . cansiz e 1 4. 1 Th e CANSTAR T keywor d specifie s th e initia l loading , i n percent , o f eac h o f eac h canister . canstar t 1 99. 0 Th e PARA

M keywor d specifie s th e horsepowe r correlatio n parameters . para m4 .00 7 .003 8 .33 4 0.8 5 Th e PURGETYP E keywor d specifie s th e purg e strateg y index . purgetyp e 1 0 Th e LOGFLA

G keywor d specifie s i f th e entir e lo g an d plo t file s shoul d b e written . Th e firs t entr y control s lo g files , whil e th e secon

d entr y control s plo t files .



### 4 1P.5 4

logfla g 2 .false , .false , drivefil e 2 5 data\drv\la4.drv\ \ vaporfile l 3 5 data\vpr\ws\7191a.vpr\ \ vaporfile 2 3 5 data\vpr\ws\84104a.vpr\ \ vaporfile 3 3 5 data\vpr\ws\96116a.vpr\ \ canfil e 2 5 data\can\ford.can\ \ logfil e 2 5 data\out\pttestl.log\ \ plotfil e 2 5 data\out\pttestl.plt\ \ eventfil e 2 5 data\evt\ftpla4.evt\ \



### 4 2P.5 5

Even t Dat aFU e fo r sampl e ru n test l (ftpla4.evt) drive 2 - 1 hotsoa k - 1 diurna l - 1 drive 2 - 1 hotsoa k 0. 5 drive 2 50 5 hotsoa k - 1 drive 2 - 1 hotsoa k - 1

4 3P.5 6

Outpu t fro msample ru

n test l (testl.out ) P T tes t file , integr . system , ftp+la 4 drive , w s temps. , 9. 0 # fue l Calculation s begin : 10/11/198 8 14:40:1 5 Fue l tan k siz e (ga l Maximu mpurg e rat e Fo r caniste r 1 siz e Purg e mode l inde x = Driv e schedul e fil e Purg e curv e table : Vapo r gen . fil e # 1 Vapo r gen . fil e # 2 Vapo r gen . fil e # 3 Lo g outpu t file : Plo t outpu t file : Even t file : ) - CF M (1 ) 0 17.6 0 ) = 4.3 0 4.1 0 data\drv\la4.dr v data\can\ford.ca n data\vpr\ws\7191a . vp r data\vpr\ws\84104a.vp r data\vpr\ws\96116a.vp r data\out\pttestl.lo g data\out\pttestl.pi t data\evt\ftpla4.ev t 137 0 entrie s rea d fo r driv e table . Titl e is : D * Th e LA 4 dat a cam e fro mMT S fil e 1402D-S0100 T (las t mo d 11-04-87 ) 12 9 entrie s rea d fo r purg e curv e table . Tim e For d Titl e is :
4 1 entrie s rea d fo r vapo r generatio n tabl e 1 . Titl e is : 71-91 F Runnin g los s vapo r gen . - 9. 0 RV P fuel , AT L on-roa d temp , profil e 4 1 entrie s rea d fo r vapo r generatio n tabl e 2 . Titl e is : 84-104 F Runnin g los s vapo r gen . - 9. 0 RV P fuel , AT L on-roa d temp , profil e 4 1 entrie s rea d fo r vapo r generatio n tabl e 3 . Titl e is : 96-116 F Runnin g los s vapo r gen . - 9. 0 RV P fuel , AT L on-roa d temp , profil e

Driv e event # 1 Cumulativ e even t # 1 Processin g typ e Star t tim e = Driv e lengt h = Endin g tim e =

> 2 driv e event . 0 137 0 137 0
Tota l fue l use d (lbs ) = 1.8 9 Tota l mile s travelle d = 7.4 5 Overal l miles/gallo n = 24.4 5 Tota l prg . rat e (ft3 ) = 20.0 3 Tota l H C purge d (gms ) = 1 0 3.2 7 Tota l H C vente d (gms ) = .0 0 H C pg' d fro mca n (g ) = 9 4.9 3 Fina l can . loa d (% ) = 34.6 7 Fina l can . cap . (gms ) = 8 6.2 5
Hotsoa k even t # 1 Cumulativ e even t # 2 

### 4 4P.5 7

Even t type : hotsoa k H C t o caniste r (gms) : 6.0 0 H C vente d (gms) : .0 0 Fina l caniste r loa d (%) : 39. 2 Fina l caniste r ca p (gms) : 80.2 5
Diurna l even t # 1 Cumulativ e even t # 3 Even t type : diurna l H C t o caniste r (gms) : 24.9 9 H C vente d (gms) : .0 0 Fina l caniste r loa d (%) : 58. 1 Fina l caniste r ca p (gms) : 55.2 6 Driv e even t # 2 Cumulativ e even t # 4 Processin g typ e 2 driv e event . Star t tim e = 0 Driv e lengt h = 137 0 Endin g tim e = 137 0
Tota l fue l use d (lbs ) = 1.8 9 Tota l mile s travelle d = 7.4 5 Overal l miles/gallo n = 24.4 5 Tota l prg . rat e (ft3 ) = 20.0 3 Tota l H C purge d (gms ) = 53.2 3 Tota l H C vente d (gms ) = .0 0 H C pg' d fro mca n (g ) = 34.9 0 Fina l can . loa d (% ) = 31.7 1 Fina l can . cap . (gms ) = 90.1 6
Hotsoa k even t # 2 Cumulativ e even t # 5 Even t type : hotsoa k H C t o caniste r (gms) : 3.0 0 H C vente d (gms) : .0 0 Fina l caniste r loa d (%) : 34. 0 Fina l caniste r ca p (gms) : 87.1 6 Driv e event # 3 Cumulativ e even t # 6 Processin g typ e 2 driv e event . Star t tim e = 0 Driv e lengt h = 50 5 Endin g tim e = 50 5
Tota l fue l use d (lbs ) = .9 5 Tota l mile s travelle d = 3.5 9 Overal l miles/gallo n = 2 3.4 4 Tota l prg . rat e (ft3 ) = 10.3 4 Tota l H C purge d (gms ) = 13.7 3 4 5P.5 8

Tota l H C vente d (gms ) = .0 0 H C pg' d fromca n (g ) = 7.6 4 Fina l can . loa d (% ) - 28.2 0 Fina l can . cap . (gms ) = 94.7 9
Hotsoa k even t # 3 Cumulativ e even t # 7 Even t type : hotsoa k H C t o caniste r (gms) : 6.0 0 H C vente d (gms) : .0 0 Fina l caniste r loa d (%) : 32. 7 Fina l caniste r ca

p (gms) : 88.7 9 Driv e even t # 4 Cumulativ e even t # 8 Processin g typ e 2 driv e event . Star t tim e = 0 Driv e lengt h = 137 0 Endin g tim e = 137 0
Tota l fue l use d (lbs) . = 1.8 9 Tota l mile s travelle d = 7.4 5 Overal l miles/gallo n = 24.4 5 Tota l prg . rat e (ft3 ) = 20.0 3 Tota l H C purge d (gms ) = 26.2 7 Tota l H C vente d (gms ) = .0 0 H C pg' d fromca n (g ) = 7.9 3 Fina l can . loa d (% ) = 26.7 4 Fina l can . cap . (gms ) = 96.7 2
Hotsoa k even t # 4 Cumulativ e even t # 9 Even t type : hotsoa k H C t o caniste r (gms) : 6.0 0 H C vente d (gms) : .0 0 Fina l caniste r loa d (%) : 31. 3 Fina l caniste r ca

p (gms) : 90.7 2 End o f even t fil e found . 9 event s processed . Tota l h e vente d (gms ) = .0 0 Calculation s terminate d at : 10/11/198 8 14:41:0 5 Norma l termination.. .



### 4 6P.5 9

3 ) Test 2 Sampl e Ru n Dat a Inpu t dat afile (test2.dat

) titl e 7 5 P T tes t file , integr . system , ftp+la 4 drive , cont . temps. , 9. 0 # fuel W Th e TANKSIZ E keywor d specifie s th e nomina l liqui d capacit y o f th e fue l tank , i n gallons . tanksiz e 1 17. 6 Th e MAXPURG E keywor d specifie s th e maximu minstantaneou s purg e rat e i n cfm/min . maxpurg e 1 4. 3 Th e DIURNA

L keywor d specifie s th e defaul t diurna l h e generation , i n grams . diurna l 1 1.28 2 Th e HOTSOA

K keywor d specifie s th e defaul t hotsoa k h e generation , i n grams . hotsoa k 1 0.16 3 Th e DELA

Y keywor d specifie s a dela y i n th e star t o f caniste r purg e afte r th e star t o f simulation . purgedela

y 1 Th e CANSIZ E keywor d specifie s th e siz e o f al l canisters , i n liters . cansiz e 1 4. 7 Th e CANSTAR T keywor d specifie s th e initia l loading , i n percent , o f eac h o f eac h canister . canstar t 1 99. 0 Th e PARA

M keywor d specifie s th e horsepowe r correlatio n parameters . para m 4 .00 7 .003 8 .33 4 0.8 5 Th e PURGETYP E keywor d specifie s th e purg e strateg y index . purgetyp e 1 0


### 4 7P.6 0

Th e LOGFLA

G keywor d specifie s i f th e entir e lo g an d plo t file s shoul d b e written . Th e firs t entr y control s lo g files , whil e th e secon

d entr y control s plo t files . logfla g 2 .false , .false , drivefil e 2 5 data\drv\la4.drv\ \ vaporfile l 2 5 data\vpr\7297a.vpr\ \ vaporfile 2 2 5 data\vpr\84109a.vpr\ \ vaporfile 3 2 5 data\vpr\96116a.vpr\ \ canfil e 2 5 data\can\ford.can\\ . logfil e 2 5 data\out\pttest2.log\ \ plotfil e 2 5 data\out\pttest2.plt\ \ eventfil e 2 5 data\evt\ldir90.evt\ \



### 4 8i l 

# 1

Even t dat afile fo r sample ru n test 2 (ldir90.evt

) drive l - 1 hotsoa k - 1 diurna l - 1 drive 2 - 1 hotsoa k 1.14 0 drive 2 50 5 137 0 hotsoa k 3.0 2 drive 2 - 1 153 1 Outpu t fro msample run test l (testl.out ) P T tes t file , integr . system , ftp+la 4 drive , cont . temps. , 9. 0 # fue l Calculation s begin : 10/11/198 8 14:41:2 1 Fue l tan

k siz e (gal. ) = 17.6 0 Maximu mpurg e rat e (CFM ) = 4.3 0 Fo r caniste r 1 siz e (1 ) = 4.7 0 Purg e mode l inde x = 0 Driv e schedul e file : data\drv\la4.drv Purg e curv e table : data\can\ford.ca n Vapo r gen . fil e # 1 data\vpr\7297a.vpr . . Vapo r gen . fil e # 2 data\vpr\84109a.vp r Vapo r gen . fil e # 3 data\vpr\96116a.vp r Lo g outpu t file : data\out\pttest2.lo g Plo t outpu t file : data\out\pttest2.pi t Even t file : data\evt\ldir90.ev t 137 0 entrie s rea d fo r driv e table . Titl e is : D * Th e LA 4 dat a came fro mMT S fil e 1402D-S0100 T (las t mo d 11-04-87 ) 12 9 entrie s rea d fo r purg e curv e table . Titl e is : Time For d 5 1 entrie s rea d fo r vapo r generatio n tabl e 1 . Titl e is : 9.0 # fuel , AT L temps , 72-97F , 1. 0 gal . tan k 5 1 entrie s rea d fo r vapo r generatio n tabl e 2 . Titl e is : 9.0 # fuel , AT L temps , 84-109F , 1. 0 gal . tan k 4 1 entrie s read fo r vapo r generatio n tabl e 3 . Titl e is : 9.0 # fuel , AT L temps , 96-116F , 1. 0 gal . tan k

Driv e even t # 1 Cumulativ e even t # 1 Processin g typ e 1 driv e event . Star t time = 0 Driv e lengt h = 137 0 Endin g tim e = 137 0
Tota l fue l use d (lbs ) = 1. 8 9 4 9Tota l mile s travelle d = 7.4 5

Overal l miles/gallo n = 24.4 5 Tota l prg . rat e (ft3 ) = 20.0 3 Tota l H C purge d (gms ) = 111.7 4 Tota l H C vente d (gms ) = .0 0 H C pg' d fro

mca n (g ) = 101.4 4 Fina l can . loa d (% ) = 31.9 7 Fina l can . cap . (gms ) = 102.9 6
Hotsoa k even t # 1 Cumulativ e even t # 2 Even t type : hotsoa k H C t o caniste r (gms) : 2.8 7 H C vente d (gms) : .0 0 Fina l caniste r load (%) : 33. 9 Fina l caniste r ca

p (gms) : 100.0 9 Diurna l even t # 1 Cumulativ e even t # 3 Even t type : diurna l H C t o caniste r (gms) : 22.5 6 H C vente d (gms) : .0 0 Fina l caniste r loa d (%) : 48. 8 Fina l caniste r ca

p (gms) : 77.5 2 Driv e even t # 2 Cumulativ e even t # 4 Processin g typ e 2 driv e event . Star t time = 0 Driv e lengt h = 137 0 Ending time = 137 0
Tota l fue l use d (lbs ) = 1.8 9 Tota l mile s travelle d = 7.4 5 Overal l miles/gallo n = 24.4 5 Tota l prg . rat e (ft3 ) = 20.0 3 Tota l H C purge d (gms ) = 44.0 5 Tota l H C vente d (gms ) = .0 0 H C pg' d fro

mca n (g ) = 25.6 4 Fina l can . loa d (% ) = 31.8 3 Fina l can . cap . (gms ) = 103.1 7
Hotsoa k even t # 2 Cumulativ e even t # 5 Even t type : hotsoa k H C t o caniste r (gms) : 3.2 7 H C vente d (gms) : .0 0 Fina l caniste r loa d (%) : 34. 0 Fina l caniste r ca

p (gms) : 99.9 0 Driv e even t # 3 Cumulativ e even t # 6


### 5 0P.6 3

Processin g typ e 2 driv e event , Star t tim e - 137 0 Driv e lengt h - 50 5 Endin g tim e =

» 187 5
Tota l fue l use d (lbs ) .9 5 Tota l mile s travelle d = 3.5 9 Overal l miles/gallo n = 23.4 4 Tota l prg . rat e (ft3 ) = 10.3 4 Tota l H C purge d (gms ) = 16.-4 0 Tota l H C vente d (gms ) = .0 0 H C pg' d fro mca n (g ) = 8.2 5 Fina l can . loa d (% ) = 28.5 4 Fina l can . cap . (gms ) = 108.1 4
Hotsoa k even t # 3 Cumulativ e even t # Even t type : hotsoa k H C t o caniste r (gms) : 8.6 6 H C vente d (gms) : .0 0 Fina l caniste r loa d (%) : 34. 3 Fina l caniste r ca p (gms) : 99.4 8 Driv e event # 4 Cumulativ e even t # 8 Processin g typ e 2 driv e event . Star t tim e = 153 1 Driv e lengt h = 137 0 Endin g tim e = 290 1
Tota l fue l use d (lbs ) = 1.8 9 Tota l mile s travelle d = 7.4 5 Overal l miles/gallo n = 24.4 5 Tota l prg . rat e (ft3 ) = 20.0 3 Tota l H C purge d (gms ) = 28.8 2 Tota l H C vente d (gms ) = .0 0 H C pg' d fro mca n (g ) = 8.0 9 Fina l can . loa d (% ) = 28.9 2 Fina l can . cap . (gms ) = 107.5 7 En d o f even t fil e found . 8 event s processed . Tota l h e vente d (gms ) = .0 0 Calculation s terminate d at : 10/11/198 8 14:42:1 2 Norma l termination.. .

5 1P.6 4

D ) Vapo r Generatio n and Temperatur e Profil e Dat a Thi s sectio n describe s method s and dat asource s use d to generat e diurnal and hotsoa

k caniste r loadings , a s wel l a s vapo r generatio n tables
. I n addition , asummar y o f uncontrolle d diurna l an d hotsoa k emissions , generate d afte r th e Jun e 30 , 198 8 workshop(2) , i s included
. 1 ) Emission s Modellin g Value s fo r uncontrolle d emission s fro

mdiurna l an d hotsoa k event s use

d i n connection wid

i th e Jun e 30 , 198 8 evaporativ e emission s worksho p an d presente d i n Appendi x B , "Refueling/Exces s Evaporativ e Emission s Worksho p Data, " wer e selecte d a s approximat

e bu t realisti c estimate s o

f thes e quantities
. Modification s t o an d refinements o

f th e PT mode l sinc e th e worksho p hav e include d additiona l modellin g o f

diurna l an d hotsoa k emissions , a s wel l a s fue

l tan k vapo r generatio n rates . Modellin g o f dies e event s ha s bee n carrie d ou t

wit h apackage , know

n a s th e E E model , currend

y unde r developmen

t a t EPA
. Th e E

E model i s base d o

n individua

l hydrocarbon specie s description s o f fuels , an d i t ca n predic t evaporativ e hydrocarbon vapo r generation.and emission s i n respons e t o change s i n temperatur

e an d pressure tiirough th e us e o f rigorou s thermodynami c and vapor-liqui d equilibriu mprinciples
. Becaus e th e E E model i s stil l under

development , documentation o

f i t i s no t available
. Element s o

f di e mode l applicable t o generation o

f dat a neede d b y di e P T model , however , ar e base d on calculatio n technique s presente d in di e literatur e b y Koehl(3 ) an

d Reddy(4)
. 2 ) Diurna l Uncontrolle d Emission s Simulatio n o

f di e mas s o

f hydrocarbo n vapor s generate d durin g diurna l event s ha s been carrie d ou t fo r tw o diurna

l temperatur

e rang e an d fo r three fue l volatilities
. Result s o

f thes e calculation s ar e presente d below , an d ar e al l base d o n a40 % full tank an d avapo r headspac e volum

e equa l to 15.0 % o

f th e liqui d capacit

y o f th e tank
. Al l value s ar

e o n a basi s o f grams/(gallon tota

l liqui d capacity)/tes t

Diurna l Temperatur

e Rang e Fue l Volatilit y 60-8 4 ° F 72-9 6 ° F 9. 0 #RVP 1.282 g/gal
. 2.23 3 g/gal
. 11. 5 #RV P 2.55 8 g/gal
. 5.40 0 g/gal
. 11. 7 #RV P 2.80 6 g/gal
. 6.18 4 g/gal
. 3 ) Hotsoa k

Uncontrolle d Emission s Uncontrolle d hotsoa

k emission s hav e bee

n estimate d fo

r th e dire e fue

l volatilitie s use d fo

r simulation o

f diurna l emissions , an

d fo r anumbe r o f fue l tan k temperature s corresponding t o end-of-driv e temperature s encountere d durin g driv e simulations
. Unlik e diurnal emissions , EP

A doe s not

hav e arigorous , mechanisti c model o f hotsoa k emission , s o tha

t asemi-empirica

l approach wa s take

n t o obtai n th e needed estimates
. I n thi s approach , i t wa s assume d tha

t hot-soa k emission s originat

e primarily fro

mth e fue l tan k a s in fue l injecte d vehicles , an

d tha t atemperatur

e increas e o

f 0. 6 ° F i s experience d by the content s o f fue l tank s durin g hotsoaks
. Usin g th e sam e fue l tan k fill leve l an d vapo r

spac e assumption s a s wer

e applie d to diurna

l emission s estimates , th e quantit y o f hydrocarbo n vapor s emitte d fro

mafue l tan k during ahotsoa

k wa s calculate d usin g di e E

E model
. Next , 5 2P.6 5

amultiplicativ e facto

r wa s applie d to thes e value s suc h ma t the quantit

y o f emission s fro

m hotsoak s afte

r adriv e wit

h afinal fue

l tan k temperatur

e o f 99. 0 ° F (typica

l afte r a n LA- 4 drivin g cycl e performed o n adynamometer ) an d 9. 0 #RV P fue l wa s 6. 0 g/tes t

A valu e o

f 3.0 9 wa s found fo

r thi s multiplicativ e factor , and i t wa s applie d t o hotsoa

k emission s estimate s fo

r al l thre e fue

l volatilities
. Th e valu e o

f 6. 0 g/tes t wa s selecte d to maintain consistency wid

i earlie r EP A evaporative emission s modelling
. A summar y o f result s fro m hotsoa k emission s modellin g i s show n below , along wid

i di e rati o o

f emission s a

t each indicate d temperatur

e t o bas e emission s a

t 80. 0 oF
. Thes e rati o value s ca n b e use d a s hotsoa k even t parameter s whe

n preparin g event

files, as describe d i n Sectio n III-B-3 , "Even tData Preparation. " Unit s fo r other value s ar e grams/(gallo n total liqui d capacity)/tes t Fuel RVP End-of-Driv e Temperatur

e 84. 0 O F 96. 0 ° F 99. 0 ° F 103. 0 ° F 108. 0 <> F 111. 0 ° F 9. 0 #RV P Basi c Em
. Adj
. Em
. Rati o 0.052 8

0.163 2 1.00 0 0.099 4 0.0307 1 1.88 2 0.119 0

0.367 7 2.25 3 0.156 9

0.484 7 2.97 0 0.234 4

0.724 3 4.43 8 0.282 8

0.874 8 5.36 0 11. 5 #RVP Basi c Em
. Adj
. Em
. Rati o 0.117 6

0.363 4 1.00 0 0.311 8 0.963 5 2.65 1 0.451 1

1.39 4 3.83 6 0.940 5

2.90 6 7.99 7 4.4 0

13.6 0 37.4 1 11. 7 #RV P Basi c Em
. Adj
. Em
. Rati o 0.131 8

.407 3 1.00 0 0.381 4 12.17 9 2.89 5 0.590 2

1.82 4 4.47 8 1.61 7

4.99 5 12.2 6 5.77 3

17.8 4 43.8 0 4 ) Vapo r Generatio n Vapo r generation table s fo

r th e P T mode l wer e constructed a s oudine d i

n Section HI-B-2-c , "Vapo r Generatio n Table. " Th e vapor generatio n tabl e require d by Ste p 1 o f thi s procedur e wa s obtaine d using th

e E E mode l describe d above , while th e time/temperatur e tabl e require d b

y Ste p 2 wa s obtained fro

mexperimentally-obtaine d fue l tan k temperatur

e data
. Thi s section give s abrie f overvie w o f ho w eac h o f thes e datasource s wer

e use d t o obtain di e needed information
. Th e E E model wa s use d t

o predic t vapor generation during vehicl e operatio n by assumin g tha t fue l tan k vapor s ar e produce d in respons e to increase s i n th e temperatur e o f tan k contents . Therefore , atemperature/vapor generatio n tabl e wa s obtaine d b y simulatin g a fuel tank temperatur e ris e coverin g th e rang e expecte d durin g driv e events , wit h intermediat

e output obtained a

t temperatur

e interval s o

f 0. 5 °F
. All suc

h simulation s wer

e carrie d ou t

assumin g 40 % ful

l fue l tanks , aheadspac e volum e o f 15 % o f total liqui d capacity , an

d pressur e equa l to ambien

t atmospheric pressure . Fue l tan k time/temperature dat

awas obtaine

d fro mexperimenta

l on-roa d studie s carried ou

t in connection wit

h EP A vehicl e testing(5)
. Thes e dat agive averag e fue

l tan k temperature s a t severa l point s during extended , continuou s drive s fro maflee t o f 1 6 vehicles
. Eac

h driv e consiste d o

f repeate d execution s o

f on e or mor e drivin g cycles , suc

h a s LA- 4 or

HFE T cycles
. Dat

ause d fo r developmen

t o f th e P T model wer

e fro mdrive s consistin g o f

dire e LA- 4 drivin g cycle s performe d back-to-back , wid i ashor t paus e between eac h cycl e t o 53P.6 6

recor d dataFro

mthes e individua

l time/temperatur

e dat apoints , asecond-orde

r regression Svno S w Calculate d s o tha t th e time needed t

o reach agive

n fue l temperaturexou

W b e obtaine d Dat

agive n b y th e Time/Temperatur

e Table exampl

e in Section HI-B-2- c wer

e generated fro

mdii s polynomial
.

54