Approaches for describing processes of fuel droplet heating and evaporation in combustion engines

Fuel consumption and energy efficiency are still of great interest in combustion engineering and science. This state-of-the-art review revisits the fuel droplet heating and evaporation in combustion engines by accessing the nano/microscopic, mesoscopic and macroscopic fluid elements. Both fluid flow and heat transfer have been intensively recovered when a fuel droplet (dodecane) is heating and evaporated into a background gas (nitrogen) crossing the liquid–vapour interface, kinetic region and the bulk regions of liquid and gas in terms of molecular dynamics simulations, kinetic theory modelling and conventional hydrodynamic approach at each scale. Moreover, the introduction of inelastic collisions between fuel molecules helps fully unfold the underlying physics of droplet heating and evaporation and resolve the ignition delay and combustion phasing in engines. The proposed multi-scale modelling of fuel droplet heating and evaporation will make significant input into a cleaner engine targeting the low-carbon emissions and enhance the energy efficiency towards net zero.