Jet-A Vaporization Computer Model A Fortran Code Written by Prof. Polymeropolous of Rutgers University

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Jet-A Vaporization Computer ModelA 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
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Acknowledgements

• Professor C. E. Polymeropolous of Rutgers
  University
• David Adkins of the Boeing Company

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Introduction

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

Hot Air In
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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.

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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)

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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
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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.

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Major Assumptions (contd)

• Mass transport at the liquidgas 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)

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Assumed Jet A Composition

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

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Assumed Jet A Composition
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MW 164
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by Volume
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0
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Number of Carbon Atoms
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PRINCIPAL MASS CONSERVATION AND PHYSICAL
PROPERTY RELATIONS
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Heat/Mass Transfer Coefficients
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User Inputs

• Equilibrium Temperature
• Final Wall and Liquid Temperatures
• Time Constants
• Mass Loading
• Tank Dimensions

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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

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Fortran Program Demonstration
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Excel Version Demonstration
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Sample Results
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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.