During the vaporization process of a fuel droplet, the composition is constantly changing as the fluid is being distilled. This results in transitioning thermo-physical and chemical properties of the fluid, which must be accounted for to accurately simulate the droplet regression and the combustion of the vapor phase. Typical vaporization models assume constant properties, primarily because of the lack of data available for complex fuels as a function of fluid distilled. One particular property of interest in describing the vaporization of a fluid is the enthalpy of vaporization (Hfg). Assuming an ideal gas, the Clausius-Clapeyron equation can be rewritten to provide an expression for Hfg. Based on this derived expression, Hfg can be determined with the knowledge of the fluid’s vapor liquid equilibrium (VLE) at varying pressures. A variable pressure distillation apparatus is used as an analog for droplet vaporization and is applied in concert with thermodynamic principles to evaluate the evolving enthalpy of vaporization as function of volume distilled. This novel technique is applied to determine the varying Hfg of a diesel fuel and is validated by comparing values determined using a previously published compositional based technique. Initial data has demonstrated the potential of a variable pressure distillation curve approach to determine the enthalpy of vaporization of a fuel as a function of volume distilled.

Derived measurement of the enthalpy of vaporization of complex fuels using a variable pressure distillation curve approach

249th National Meeting (2015)

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