Numerical Study of Evaporation Modelling for Different Fuels at High Operating Conditions in a Diesel Engine

A fuel injection system in a diesel engine has different processes that affect the complete burning of the fuel in the combustion chamber. These include the primary and secondary breakups of liquid fuel droplets and evaporation. In the present paper, evaporation of two different diesel fuels has been modelled numerically. Evaporation of n-heptane and n-decane is governed by the conservation equations of mass, energy, momentum, and species transport. Results have been plotted by varying the droplet diameter and temperature. It was observed that droplet size, temperature of droplets, and ambient temperature have notable effect on the evaporation time of diesel fuel droplets in the engine cylinder.

Thermal explosion characteristics of a combustible gas containing fuel droplets

This paper investigated the critical ignition conditions of combustible gas containing liquid fuel droplets. The analysis is done based on the criteria of the thermal explosion theory. It includes analytical and numerical solutions of modeling equations of fuel droplets heating and evaporation by convection and radiation from the surrounding reactive hot gas. The exothermic reaction is usually modeled as a single-step reaction obeying an Arrhenius temperature dependence. The thermal conductivity of the fuel droplet is dependent on temperature. The analytical solution produced relations between the main critical characteristic parameters in all planes of the solution. The results obtained from investigating the effect of the characteristic parameters on the explosion behavior of gas and fuel droplets and the thermal radiation proved that both of them are significant. The study proved that the criticality definitions of the thermal explosion of a single-phase system can be used effectively and efficiently to determine the critical conditions of a multi-phase system. Finally, the application of the numerical solutions of the modeling equations was used to analyze the explosion characteristics of a diesel fuel spray system.