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

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

IASFPWG – Seattle, WA 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 Thermocouples 1 Liquid Thermocouple Fuel Pan Air Out 0.93 m 2.2 m 1.2 m 5 Wall and Ceiling Thermocouples

IASFPWG – Seattle, WA 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 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 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, T g Liquid, T l Walls and Ceiling, T s

IASFPWG – Seattle, WA 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 Ra g ≈ 10 9, Ra l ≈  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 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 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 Assumed Jet A Composition Number of Carbon Atoms MW: 164 % by Volume

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

IASFPWG – Seattle, WA Heat/Mass Transfer Coefficients

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

IASFPWG – Seattle, WA 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, ppm C 3 H 8

IASFPWG – Seattle, WA Fortran Program Demonstration

IASFPWG – Seattle, WA Excel Version Demonstration

IASFPWG – Seattle, WA Sample Results

IASFPWG – Seattle, WA 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.