International Aircraft Systems Fire Protection Working Group Seattle, WA March 12 – 13, 2002

1. Jet-A Vaporization Computer ModelA Fortran Code Written by Prof. Polymeropolous of Rutgers University Steve Summer Project Engineer Federal Aviation Administration Fire Safety Section, AAR-422 International Aircraft Systems Fire Protection Working Group Seattle, WA March 12 – 13, 2002 IASFPWG – Seattle, WA

2. Acknowledgements • Professor C. E. Polymeropolous of Rutgers University • David Adkins of the Boeing Company IASFPWG – Seattle, WA

3. 1 Liquid 5 Gas Thermocouples Thermocouple 2 HC Ports 5 Wall and Ceiling Thermocouples 1.2 m 0.93 m 2.2 m Air Out Fuel Pan Introduction • Original code was written as a means of modeling some flammability experiments being conducted at the Tech Center (Summer, 1999) Hot Air In IASFPWG – Seattle, WA

4. 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. IASFPWG – Seattle, WA

5. 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) IASFPWG – Seattle, WA

6. Walls and Ceiling, Ts Liquid, Tl 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 IASFPWG – Seattle, WA

7. 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. IASFPWG – Seattle, WA

8. 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) IASFPWG – Seattle, WA

9. Assumed Jet A Composition • Based on data by Clewell, 1983, and adjusted to reflect for the presence of lower than C8 components IASFPWG – Seattle, WA

10. Assumed Jet A Composition 25 20 MW: 164 15 % by Volume 10 5 0 5 6 7 8 9 10 11 12 13 14 15 16 Number of Carbon Atoms IASFPWG – Seattle, WA

11. PRINCIPAL MASS CONSERVATION AND PHYSICAL PROPERTY RELATIONS IASFPWG – Seattle, WA

12. Heat/Mass Transfer Coefficients IASFPWG – Seattle, WA

13. User Inputs • Equilibrium Temperature • Final Wall and Liquid Temperatures • Time Constants • Mass Loading • Tank Dimensions IASFPWG – Seattle, WA

14. Program Outputs • Equilibrium gas & liquid concentrations/species fractionation • Species fractionation as a function of time • Ullage, wall and liquid temperatures as a function of time • Ullage gas concentrations as a function of time • FAR, ppm, ppmC3H8 IASFPWG – Seattle, WA

15. Fortran Program Demonstration IASFPWG – Seattle, WA

16. Excel Version Demonstration IASFPWG – Seattle, WA

17. Sample Results IASFPWG – Seattle, WA

18. 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. IASFPWG – Seattle, WA