Explicit equations for designing surrogate gasoline formulations containing ethanol, isopentane, n-heptane, isooctane and toluene

It is useful for research purposes to define simple surrogate gasoline compositions that can replicate the chemical and physical properties of more complex mixtures. Ethanol is used in commercially available gasolines around the world as part of the pathway to the decarbonization of the transportation sector. In this study equations were developed to predict the Research Octane Number (RON), Motor Octane Number (MON) and Dry Vapour Pressure Equivalent (DVPE) of gasoline surrogates containing ethanol (10-25 vol%), isopentane, n-heptane, isooctane and toluene. The non-linear blending behaviour associated with ethanol is found to necessitate coefficients in the equations developed for MON that are a function of ethanol content, whereas surprisingly the equations for RON and DVPE do not need this added level of complexity. Using the equations developed the RON and DVPE of the ethanol-containing surrogates can be calculated using one set of coefficients for any ethanol concentration between 10 and 25 vol%. Calculating the MON of such surrogates requires different sets of coefficients for different ethanol concentrations.