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A model has been developed to predict quantitatively the results of the ASTM D86 fuel distillation procedure. The model uses material and energy balances to treat the procedure as a two stage unsteady-state distillation coupled with an air-filled continuous stirred-tank reactor (CSTR). Heat is removed from the second stage to simulate convection losses from the experimental apparatus. The model requires as inputs the fuel composition and the physical properties of all components (vapor phase heat capacity, vapor pressure, critical properties, density, molecular weight, solubility parameter). Correlations were used to approximate other needed properties. Liquid-phase activity coefficients were calculated with the UNIFAC model. Heat losses were modeled with a correlation from the literature. The model was validated by comparing predictions to experimental measurements on a seven-component model fuel. Agreement was extremely good across the entire range of volume fractions distilled.

To help guide the design of homogeneous charge compression ignition (HCCI) engines, single and multi-zone models of the concept are developed by coupling the first law of thermodynamics with detailed chemistry of hydrocarbon fuel oxidation and NOx formation. These models are used in parametric studies to determine the effect of heat loss, crevice volume, temperature stratification, fuel-air equivalence ratio, engine speed, and boosting on HCCI engine operation. In the single-zone model, the cylinder is assumed to be adiabatic and its contents homogeneous. Start of combustion and bottom dead center temperatures required for ignition to occur at top dead center are reported for methane, n-heptane, isooctane, and a mixture of 87% isooctane and 13% n-heptane by volume (simulated gasoline) for a variety of operating conditions.