Property Measurement for Fuel Research - NIST · 2012. 5. 8. · 840 800 820 kg/m 780 3 Jet-A-3638 Jet-A-4658 Je-tA-3638 model Je-tA-4658 model 760 ... LMO WBU DEN FNL APA 3602 3638

Property Measurement for Fuel Research: Th D l t f P t T bl S tThe Development of Property Tunable Surrogate

Mixture Models

Thomas J. BrunoThermophysical Properties Division

National Institute of Standards and Technology

Boulder, CO

Why Surrogates?We all know the reasons‐

• Aviation fuels are made of hundreds of componentscomponents– Must meet general specifications,b t an infinite n mber of ombinations an do sobut an infinite number of combinations can do so


• Aviation fuels are made of hundreds ofAviation fuels are made of hundreds of components– Must meet general specifications– Must meet general specifications,but an infinite number of combinations can do so

For well controlled measurements and modeling, a more defined composition is requiredmore defined composition is required.


• Aviation fuels are made of hundreds ofAviation fuels are made of hundreds of components– Must meet general specifications– Must meet general specifications,but an infinite number of combinations can do so

For well controlled measurements and modeling, a more defined composition is requiredmore defined composition is required.

‐repeatability

tractability‐tractability

“Surrogate”Surrogate means different

things tothings to different people



Operational Surrogates:

kineticskineticsflame characteristicssafety characteristics



Thermophysical propertyproperty

predictive surrogates

Results• For a specific sample (POSF 4658) regressed IBT, full ADC,

density, viscosity, sound speed, thermal conductivity and cetane number to obtain an 8 component surrogate mixturecetane number to obtain an 8 component surrogate mixture capable of representing – the density to within 0.2% at atm. p, – sound speed 3.5%,sound speed 3.5%, – viscosity 3%, – thermal conductivity 4% – cetane number within 1 cetane number.cetane number within 1 cetane number. – The distillation curve is represented to within about 1K.

• For a second sample (POSF 3638) the same procedure wasFor a second sample (POSF 3638) the same procedure was applied and a different 7 component surrogate was obtained, with similar performance.

But,

• POSF 4658 and POSF 3638 are very different:different:

– 4658 was a composite of 5 batches prepared at AFRL– 4658 was a composite of 5 batches, prepared at AFRL– 3638 was an oddball, in spec but with low aromatics

Different how???

Different how???

520

530

500

510

K

480

490

mpe

ratu

re, K

460

470Tem

Jet-A-3638

Jet-A-4658

440

450

Jet-A-3638 model

Jet-A-4658 model

0 0.2 0.4 0.6 0.8 1Volume fraction

Different how???

520

530

500

510

K

ADC Curves 10 – 30 oC apart

480

490

mpe

ratu

re, K

apart

460

470Tem

Jet-A-3638

Jet-A-4658

440

450

Jet-A-3638 model

Jet-A-4658 model

0 0.2 0.4 0.6 0.8 1Volume fraction

Different how???

840

800

820

780

800

kg/m

3

Jet-A-3638

Jet-A-4658

Jet-A-3638 model

Jet-A-4658 model

760

ρ,

Densities

720

740Densities were 1.5 %

apart720

250 270 290 310 330 350 370 390

Temperature, K

Different how??? Viscosities wereViscosities were between 4 and 20 % apart

3000

3500

2000

2500

uPa.

s

Jet-A-3638

1000

1500

Visc

osity

,

Jet-A-4658

Jet-A-3638 model

Jet-A-4658 model

500

1000

0250 270 290 310 330 350 370 390

Temperature, K

A similar problem with RP‐1, RP‐2:A similar problem with RP 1, RP 2:

• Exactly how variable is RPExactly how variable is RP,• And how good is the Refprop model?

B d l l– Based on only one sample


• Exactly how variable is RPExactly how variable is RP,• And how good is the Refprop model?

B d l l– Based on only one sample

Which we regarded as if it were brought

down the mountain by Mel Brooks, I mean,

Moses.


• Exactly how variable is RPExactly how variable is RP,• And how good is the Refprop model for it?

B d l l– Based on only one sample– 2009 workshop at NIST‐Boulder pointed out need to determine variabilityto determine variability

AFRL EAFB f l t th O th l El– AFRL‐EAFB formulates the Orthogonal Eleven

• 11 separate formulations• 11 separate formulations– Individually mixed from blending stocksAll i– All are in spec

– All are possible deliverables

• Composition, ADC, ρ, µ, ss, etc.d l• Model comparisons

• Experimental part is done:• Lovestead, T.M., Windom, B.C., Rigge, J.R., Nickell, C, Bruno, T.J., Assessment of the

C iti l V i bilit f RP 1 d RP 2 ith th Ad d Di till ti CCompositional Variability of RP‐1 and RP‐2 with the Advanced Distillation Curve Approach, Energy Fuels 2010, 24, 5611–5623

Approach for JP‐8/Jet‐A:Approach for JP 8/Jet A:

• Obtain all JP‐8 and Jet‐A Jet‐A1 we can getObtain all JP 8 and Jet A, Jet A1 we can get– Composition, ADC, ρ, µ, ss, etc.

At the same time,

• Develop a “tunable” Refprop model p p p

Both jobs are about half done!Both jobs are about half done!

For the Measurement Campaign:For the Measurement Campaign:

• We obtained 18 “orthogonal” samples of Jet‐AWe obtained 18 orthogonal samples of Jet A and JP‐8– 5 from local airports– 5 from local airports– 13 from AFRL‐WPAFB (Tim)

210

Vapor Rise Temperature (IBT) Variability of Jet‐A

200.3

204.8

199.0 198 1200

205

210

192.0 190.6

194.7

189.7 191.0 190.5

193.1 193.6

196.5 198.1

190

195

200

, Tk (˚C)

184.2

186.9 187.7

179.6

182.7

180

185

190

emep

ature,

170

175

180Te

165

170

Jet‐A

280LMO WBU DEN FNL

APA 3602 3638 4597

260APA 3602 3638 4597

4598 4599 4600 4658

4877 5237 5245 5677

5916 6407

220

240

ure, T

k (˚C)

5916 6407

200

220

Tempe

ratu

180

1600 10 20 30 40 50 60 70 80 90 1000 10 20 30 40 50 60 70 80 90 100

Distillate Volume Fraction (%)

280LMO WBU DEN FNL

APA 3602 3638 4597

260APA 3602 3638 4597

4598 4599 4600 4658

4877 5237 5245 5677

5916 6407

220

240

ure, T

k (˚C)

5916 6407

200

220

Tempe

ratu

50 oC

180

50 C

1600 10 20 30 40 50 60 70 80 90 100

25 oC

0 10 20 30 40 50 60 70 80 90 100Distillate Volume Fraction (%)

280Average LMO WBUDEN FNL APA

260

DEN FNL APA3602 3638 45974598 4599 46004658 4877 52375245 5677 5916

240

re, T

k (˚C)

5245 5677 59166407

200

220

Tempe

ratur

180

200T

The average

1600 10 20 30 40 50 60 70 80 90 100

The average

0 10 20 30 40 50 60 70 80 90 100Distillate Volume Fraction (%)

280Average LMO WBU

260

DEN FNL APA3602 3638 45974598 4599 46004658 4877 5237

240

e, T

k (˚C)

5245 5677 59166407

200

220

empe

rature

180

200Te

The standard deviation

1600 10 20 30 40 50 60 70 80 90

The standard deviation

0 10 20 30 40 50 60 70 80 90Distillate Volume Fraction (%)

Tunable Model DevelopmentTunable Model Development

• Work was concurrent with the measurementsWork was concurrent with the measurements on Jet‐A, JP‐8



• Efforts were keptindependent



• Only used 4658, 3638 (the model bases) and 3602 ( hi h i ) 3773 ( fli h li JP 8)3602 (a high aromatic), 3773 (a flightline JP‐8)



• Only used 4658, 3638 (the model bases) and 3602 ( hi h i ) 3773 ( fli h li JP 8)3602 (a high aromatic), 3773 (a flight line JP‐8)

• It had to be simple!– Then, we can refine it with the larger data set, g

• How do you “tune” the model to characterize the fuel?the fuel?– Possibilities:

• points on the distillation curve• points on the distillation curve, • heat of combustion, • a single density, g y,• viscosity,• refractive index, • the cetane number???

“Recipe” for SurrogateRecipe for Surrogate

• Capture volatility• Capture volatility – use IBT (from ADC) to characterize the fuel

• assume ideal solution and apply Raoult’s Law

• you will need an expression for the vapor pressure of each constituent fluid at the IBT of the fuel


use 85% point on distillation curve to capture the variation of the– use 85% point on distillation curve to capture the variation of the distillation curve

• empirical relationship that relies on the fact that for a mixture of n-dodecane n-tetradecane propylcyclohexane and 1 3-dodecane, n tetradecane, propylcyclohexane and 1,3diisopropylbenzene, at 85% it is due almost entirely to the C12 and C14 present

i th T i t f th ADC• requires the T85 point from the ADC


use the cetane number to characterize the fuel– use the cetane number to characterize the fuel• for mixtures, typically a volume fraction average is used

– approximate the volume fraction using molar volumes of the constituent fluids at a fixed temperature (where they all areconstituent fluids at a fixed temperature (where they all are liquid) and assume no change on mixing

• requires molar volume of constituents at a fixed temperature, and the cetane number of the mixture and the constituents


sum of the mole fractions must equal one– sum of the mole fractions must equal one

“Recipe” SummaryRecipe Summary– Now have 4 equations {IBT, T85, cetane, sum mole fractions}, 4

unknowns {x1 x2 x3 x4}unknowns {x1,x2,x3,x4}

– Slate: n-dodecane, n-tetradecane, propylcyclohexane,1,3-diisopropylbenzene

l it!– solve it!

ResultsPOSF 3602(High aromatic)

POSF 3638 POSF 3773(Flightline)

POSF 4658(composite)

d d 0 111 0 282 0 137 0 038n-dodecane 0.111 0.282 0.137 0.038n-tetradecane 0.174 0.046 0.176 0.281propylcyclohexane 0.261 0.353 0.405 0.2991,3-diisopropylbenzene 0.454 0.319 0.282 0.382

ResultsResults• for sample “4658” (the

“composite” sample) 260 0composite sample)– density at 288 K to within

~1% 240.0250.0

260.0

°C

– cetane number within 1– heat of combustion w/in

0.5%210 0

220.0

230.0

mpe

ratu

re, °

– index of refraction w/in 0.3%

– viscosity at 288 K w/in 5% 190.0200.0

210.0

Tem

4658 experimental data4658 new surrogate

– thermal conductivity w/in 10%

– sound speed w/in 3%

180.00 0.2 0.4 0.6 0.8 1

Distillate Volume Fractionp %


“low aromatic” sample) 230low aromatic sample)– density at 288 K to within

~0.5%215220225230

°C


1.5% 200205210215

mpe

ratu

re, °


– viscosity at 288 K w/in 7% 185190195Te

m



– sound speed w/in 3 %

1800 0.2 0.4 0.6 0.8 1



“high aromatic” sample) 250high aromatic sample)– density at 288 K to within

~1.9% 230

240

250

– cetane number within 1 cetane number

– heat of combustion –no data 210

220

atur

e, °C

– index of refraction w/in 0.1%– viscosity at 288 K w/in 6%– thermal conductivity w/in

190

200

Tem

pera


t e a co duct ty /10%

– sound speed w/in 4 %

1800 0.2 0.4 0.6 0.8 1

Distillate Volume Fraction


“flightline” sample)250

flightline sample)– density at 288 K to within

~1% 230

240

e, °C


0.4% 210

220

empe

ratu

re


– viscosity at 288 K –no data190

200Te

3773 experimental data

3773 new surrogate


– sound speed w/in 3%

1800 0.2 0.4 0.6 0.8 1


ResultsResults

• “Full” fitting procedure • Shortie “recipe” procedure• Full fitting procedure– requires full models for VLE,

transport, a distillation algorithm, nonlinear

• Shortie recipe procedure– requires only the 4 equations

along with very limited data (IBT, T85, cetane number), a go , o ea

regression algorithm, etc and appropriate data

– Typically has ~8 components

( , 85, ce a e u be ),and nonlinear fitter

– 4 components– Represents

– Represents• density ~0.2 % (at atm.p)• IBT within ~1 K

di till ti ithi 1K

• density ~ 2 % (at atm. p)• IBT within ~ 5 K• distillation curve within ~7 K

%• distillation curve within ~ 1K• cetane number ~3%• sound speed ~3.5%• viscosity ~3%

• cetane number ~3%• sound speed ~3.5 %• viscosity ~7 %• thermal conductivity ~10 %viscosity 3%

• thermal conductivity 4%• thermal conductivity 10 %

Documents

Property Measurement for Fuel Research - NIST · 2012. 5. 8. · 840 800 820 kg/m 780 3 Jet-A-3638 Jet-A-4658 Je-tA-3638 model Je-tA-4658 model 760 ... LMO WBU DEN FNL APA 3602 3638