Design and optimization of multi-component fuel for fuel concentration measurement by using tracer PLIF in SI engine

A method to design a feasible multi-component fuel for fuel concentration measurements by using PLIF was developed based on thermal gravity (TG) analysis and vapor-liquid equilibrium (VLE) calculations. Acetone, toluene, and 1,2,4-trimethylbenzene were respectively chosen as tracers for the light, medium, and heavy components of gasoline. A five-component test fuel was designed for LIF measurement, which contains n -pentane (light), isooctane, n -octane (medium), n -nonane and n -decane (heavy). The TG analysis and VLE calculation were used to ensure that the fuel had volatility similar to real gasoline and that all the tracers had a good coevaporation ratio. The fully optimized results of the six-component fuel and the disadvantages of this case are discussed. The results indicated that optimization based on the six-component fuel, which included C4 compounds such as n -butane, controlled acetone's coevaporation ratio. However, using a C4 alkane as a representative of light components resulted in a low boiling point, and thus the mixture could not be used conveniently. Taking into account the improvement in the coevaporation ratio by using n -pentane, the five-component test fuel was recommended. A validation experiment was carried out in a constant-volume vessel by using the five-component test fuel. Normalized fuel concentration distributions within the available area indicated that the three tracers, light, medium, and heavy, show difference in evaporating.