The ongoing movement to replace the NATO military aircraft fuel, F34 (JP-4) with F40 (JP-8), a kerosene-type fuel almost identical to JET A1, has prompted new research on the effects of fuel properties. The physics and the chemistry occurring during the vaporization and burning process is complex, making it necessary to split the problem into distinct phenomenological models such as the prediction of the rate of vaporization from real fuel blends. The objective of this study was to develop an algorithm for multi-component droplet vaporization and to incorporate it into a complete spray combustion analysis for engineering applications. The work described relates the rate of evaporation and the history of the multi-component fuel droplets, JP-4 and JET A1, in an infinite surrounding medium of air moving at low velocity so that the flow is considered laminar. Computational Fluid Dynamics codes (CFD) are currently used to define appropriate design strategies for combustion chamber modelling. The integration of the new multi-component fuel evaporation model that accounts for fuel specification evolution during the evaporation process into existing CFD codes leads to improved predictions of droplet evaporation. This is shown to be particularly important in calculations made under cold-starting conditions in gas-turbine engines.