Pure edible oils may be used as a diesel fuel. They are nevertheless likely to produce deposits harmful to the engine. The liquid properties have been identified as a major issue but the details of the physical process leading to deposits are not well understood. This paper deals with simulations of a single-cylinder research diesel engine using virtual fuels which show the effects of different liquid properties. The aim is to investigate the impact on the in-cylinder processes of each property change from a conventional alkane to a fatty acid. The critical temperature, which makes fatty acid much less volatile than conventional diesel, has the biggest impact. It strongly delays the release of fuel into the gas phase and extends the combustion time. The effects of droplet break-up, heating and density are marginal. Globally, a longer survival time of droplets tends to spread the combustion and rich mixture zones as well as increase the probability of wall wetting. The swirl motion is likely to expose the droplets to the cooler cylinder walls, which leads to further problems in vaporizing the fuel and completing the combustion process. The findings may be used to explain carbon deposits and lubricating oil contamination.

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