Evaporation of diesel fuel droplets: kinetic versus hydrodynamic models

Abstract

A comparative analysis of hydrodynamic and kinetic approaches to the problem of diesel fuel droplet evaporation is presented. It is pointed out that the kinetic effects on droplet evaporation are always noticeable, despite the fact that this evaporation takes place at high pressures (up to 30 atm and even more). This shows the limitation of applying the hydrodynamic approach to modelling this process. The hydrodynamic approach is universally used in computational fluid dynamics (CFD) codes. Kinetic models predict longer evaporation time and higher droplet temperature compared with the hydrodynamic model. The kinetic effects are shown to be more pronounced for smaller droplets (5 μm) than for larger ones (20 μm). The droplet evaporation time and droplet temperature increase with decreasing evaporation coefficient. It is recommended that kinetic effects are taken into account when modelling the evaporation process of diesel fuel droplets in realistic internal combustion engines.