03-12-02IASFPWG – Seattle, WA Jet-A Vaporization Computer Model A Fortran Code Written by Prof. Polymeropolous of Rutgers University International Aircraft

03-12-02IASFPWG – Seattle, WA

Jet-A Vaporization Computer Model

A Fortran Code Written by Prof. Polymeropolous of Rutgers University

International Aircraft Systems Fire Protection Working GroupSeattle, WAMarch 12 – 13, 2002

Steve SummerProject EngineerFederal Aviation AdministrationFire Safety Section, AAR-422


Acknowledgements

Professor C. E. Polymeropolous of Rutgers University

David Adkins of the Boeing Company


Introduction

Original code was written as a means of modeling some flammability experiments being conducted at the Tech Center (Summer, 1999)

Hot Air In

2 HC Ports

5 Gas Thermocouples1 Liquid Thermocouple

Fuel Pan

Air Out

0.93 m

2.2 m

1.2 m

5 Wall and Ceiling

Thermocouples


Introduction

This model proved a good method of predicting the evolution of hydrocarbons (i.e. it matched the experimental data).• Results were presented by Prof. Polymeropolous

(10/01 Fire Safety Conference)

Could prove to be a key tool in performing fleet flammability studies.

Fortran code has been converted to a user-friendly Excel spreadsheet by David Adkins of Boeing.


Previous Work

Numerous previous investigations of free convection heat transfer within enclosures• Review papers: Catton (1978), Hoogendoon (1986), Ostrach

(1988), etc.• Enclosure correlations

Few studies of heat and mass transfer within enclosures• Single component fuel evaporation in a fuel tank, Kosvic et al.

(1971)• Computation of single component liquid evaporation within

cylindrical enclosures, Bunama, Karim et al. (1997, 1999) Computational and experimental study of Jet A

vaporization in a test tank (Summer and Polymeropoulos, 2000)


Physical Considerations

3D natural convection heat and mass transfer within tank• Fuel vaporization from the

tank floor which is completely covered with liquid

• Vapor condensation/vaporization from the tank walls and ceiling

Multi-component vaporization and condensation

Initial conditions are for an equilibrium mixture at a given initial temperature

Gas, Tg

Liquid, Tl

Walls and Ceiling, Ts


Major Assumptions

Well mixed gas and liquid phases within the tank • Uniform temperature and species concentrations in

the gas and within the evaporating and condensing liquid

• Rag ≈109, Ral ≈ 105-106

Externally supplied uniform liquid and wall temperatures. Gas temperature was then computed from an energy balance

Condensate layer was thin and its temperature equaled the wall temperature.


Major Assumptions (cont’d)

Mass transport at the liquid–gas interfaces was estimated using heat transfer correlations and the analogy between heat and mass transfer for estimating film mass transfer coefficients

Low evaporating species concentrations Liquid Jet A composition was based on

previous published data and and adjusted to reflect equilibrium vapor data (Polymeropoulos, 2000)


Assumed Jet A Composition

Based on data by Clewell, 1983, and adjusted to reflect for the presence of lower than C8 components

Compound Volume,% Molecular Boiling Density,Weight Point, °C kg/m3

C5 parafins 0.01 72 309 630C6 paraffins 0.15 86 341 664C7 paraffins 0.5 100 371 690C8 parrafins 0.5 114.2 391 700C8 cycloparaffins 0.5 112.2 397 780C8 aromatics 0.54 106.2 412 870C9 paraffins 2.333 128.3 415 720C9 cycloparaffins 1.433 126.2 427 800C9 aromatics 0.933 120.2 438 880c10 paraffins 5.533 142.3 433 720c10 cycloparaffins 3.433 140.3 444 800c10 aromatics 2.233 134.2 450 860c11 paraffins 8.633 156.3 469 740c11 cycloparaffins 3.233 154.3 469 800dicycloparaffins 3.033 152.3 474 890c11 aromatic 3.533 148.2 478 860c12 paraffins 10.733 170.3 489 750c12 cycloparaffins 7.933 166.3 494 880c12 aromatics 4.533 162.3 489 860c13 paraffins 11.433 184.4 508 760c13 cycloparaffins 8.433 182.4 498 800c13 aromatics 4.833 176.3 507 870c14 paraffins 5.833 198.4 527 760c14 cycloparaffins 4.333 192.4 563 940c14 aromatics 2.433 186.3 568 1030c15 parafins 1.333 212.4 544 770c15 cycloparaffins 0.933 206.4 573 900c15 aromatics 0.533 200.4 578 950c16 hydrocarbons 0.133 226.4 560 770


Assumed Jet A Composition

0

5

10

15

20

25

5 6 7 8 9 10 11 12 13 14 15 16

Number of Carbon Atoms

MW: 164

% b

y V

olu

me


PRINCIPAL MASS CONSERVATION AND PHYSICAL PROPERTY RELATIONS

tsCoefficien Diffusion Species Gasfor Method sFuller'

Mixture c)(p PressureConstant Gas, Ideal

:Balance Energy Gas

:Balance Mass Species Gas

:Equation AntoineModified

:Law sHenry'

dt

d :Balance Mass Liquid

apgoapgospgclpve

wgwglllgpgg

airogiocieigi

bi

li

ilifi

gifiiil

li

TcmorTcmTcmTcm

TThTTAhdt

Tcmd

ymorymmmdt

dm

T

Tp

p

pxx

yyL

DShAm

3.6215.385

289953.20exp


Heat/Mass Transfer Coefficients

HHTTg

D

HhSh

k

hHNu

LgGr

GrScD

LhSh

Grk

hLNu

sg

Sc

i

ii

p

gs

ii

ii

i

r

5.0

5.0

5.0

2

3

3/1

3/1

Rewith

Re664.0

Plate) (VerticalRe664.0

055.0

Pr055.0

3/1

3/1

:Transfer Mass

:TransferHeat

Surfaces Vertical

with

:Transfer Mass

1975) al.et (Hollands :TransferHeat

Surfaces Tank Horizontal


User Inputs

Equilibrium TemperatureFinal Wall and Liquid TemperaturesTime ConstantsMass LoadingTank Dimensions


Program Outputs

Equilibrium gas & liquid concentrations/species fractionation

Species fractionation as a function of timeUllage, wall and liquid temperatures as a

function of timeUllage gas concentrations as a function of

time• FAR, ppm, ppmC3H8


Fortran Program Demonstration


Excel Version Demonstration


Sample Results


Future Work

Provide the ability to vary liquid fuel distribution throughout the tank.

Provide the ability to input temperature profiles for each tank surface.

Provide the ability to track pressure changes Experimental validation tests will be conducted in

the near future at the tech center.

Documents

03-12-02IASFPWG – Seattle, WA Jet-A Vaporization Computer Model A Fortran Code Written by Prof. Polymeropolous of Rutgers University International Aircraft