Modelling of fuel droplet heating and evaporation: Recent results and unsolved problems

Models for automotive fuel droplets heating and evaporation

“…biodiesel fuels), DCM approach (described in [2,10,13,17]) is easily implemented, where the number of components (up to 14 components) are relatively small. In the DCM analyses, we assume that droplets are spherically symmetric but temperature gradients and species diffusions in the liquid phase and the effect of internal recirculation due to relative velocity between ambient gas and droplets are all accounted for, using the Effective Thermal Conductivity and Effective Diffusivity (ETC/ED) models.…”

“…Based on recent research findings (e.g. [3,[10][11][12][13]), the drawbacks in modelling fuel droplets heating and evaporation processes (computationally expensive models, ignoring temperature gradient and transient species diffusion) are partially addressed using the MDQD model. This paper summarises some comparisons between the results, referring to fuel droplet evaporation times and time evolution of droplet surface temperatures and radii, predicted by the previously suggested simplified models, the recently developed version of the DCM and the multidimensional quasi-discrete model (MDQDM) [14][15][16].…”

Ignition of liquid droplets fuels under conditions of radiation-conductive heating in air

“…The regularities of the droplet combustion of such fuels have been studied for a long time [7,8] and intensively [9]. However, interest in the combustion of liquid droplets is not reduced to the present time [10,11] due to the complex mechanisms of processes of heat and mass transfer and physicochemical transformations occurring in the drop, on its surface and in the near-surface (or adjacent) layer of the vapor-gas mixture. In particular, up to the present time, the temperature field of droplets is often assumed to be uniform when analyzing the conditions and characteristics of the combustion processes of condensed substances [12].…”

“…In particular, up to the present time, the temperature field of droplets is often assumed to be uniform when analyzing the conditions and characteristics of the combustion processes of condensed substances [12]. The rate of vaporization of a flammable liquid is generally assumed to depend only on the intensity of the vapor mass transfer process in a thin layer of the external environment adjacent to the surface of the droplet [11]. At the same time the experimental data on the conditions and characteristics of the processes of ignition of fuel droplets and flammable liquids in the medium of high-temperature gases published relatively little.…”

“…At the same time the experimental data on the conditions and characteristics of the processes of ignition of fuel droplets and flammable liquids in the medium of high-temperature gases published relatively little. From the review [11] it can be concluded that there are no mathematical models describing the processes of ignition of condensed substance droplets in the oxidizer medium, as well as in the real possible ranges of changes in the main significant factors (ambient temperature, heat exchange intensity, droplet configuration and conditions of its movement, thermal properties of the flammable liquid, etc.). The base in the description of the combustion of drops of liquid is the model of Warsaw formulated many years ago.…”