Separating a fuel on-board a vehicle

A method comprising:

• in a mixer, mixing a fuel stream with a solvent to form a mixed stream, the solvent having a higher affinity for a second component of the fuel stream than for a first component of the fuel stream;
• in a first separator downstream from the mixer, separating the mixed stream into a first fuel fraction including the first component of the fuel stream and a mixed fraction including the second component of the fuel stream based on a difference in volatility of the first fuel fraction and the mixed fraction;
• in a second separator downstream from the first separator and in fluid communication with the mixer, separating the mixed fraction into a second fuel fraction including the second component of the fuel stream and a solvent fraction;
• in a heat exchanger, transferring heat from the second fuel fraction to the mixed fraction, thereby condensing the second fuel fraction and pre-heating the mixed fraction upstream of the second separator;
• and
• recycling the solvent fraction from the second separator to the mixer to mix with the fuel stream to form the mixed stream.