A quantum chemical study of the processes during the evaporation of real-life Diesel fuel droplets

Modelling of Evaporation of Clusters and Nanodroplets of Organic Molecules Using Quantum Chemical and the Kinetic Gas Theory Methods

“…The following equation for the evaporation rate ( i(i+j) ) [21][22][23][24] was used in the analysis…”

“…where n 0 is the initial number of molecules in a cluster or nanodroplet, i(i+j) is the evaporation rate of the i-th molecule from a cluster (or nanodroplet) i+j, b ij is the collision rate of the i-th molecule with the j-th molecule (cluster/nanodroplet) [23,24], G i+j , G i , and G j are the Gibbs free energies of formation of the molecules (clusters/nanodroplets) from monomers (molecules) at the reference pressure p. If i or j refers to a monomer (in the gas phase) then the corresponding G i or G j is equal t o z e r o . F o r o t h e r c a s e s , G i+j G i G j corresponds to changes in the Gibbs free energy of the system due to attachment of the i-th particle to the j-th particle.…”

“…quantum effects were ignored) [14,15,[18][19][20]. Alternative quantum mechanical approaches used to analyse the droplet evaporation process were recently developed [21][22][23][24][25].…”

“…The electronic effects (enhanced at high temperatures) in intermolecular interactions between evaporated aromatics and organics with polar functionalities, in comparison with alkanes, can result in an increase in the errors in modelling of these systems using MD/FF, especially if the force fields are calibrated for systems under standard conditions. A complex approach based on quantum chemical estimations of the Gibbs free energies of solvation ( G s ) and evaporation ( G ev ) and the kinetic gas theory was applied to analyse evaporation of real-life Diesel fuel clusters and nanodroplets, including a set of alkanes, substituted aromatics and other organics in the C 8 -C 27 range [23,24].…”

“…Detailed analysis of these processes is expected to allow one to develop a better understanding of the underlying physics of the condensation/evaporation processes. The analysis is based on the kinetic gas theory which allows one to apply the model mainly to molecular clusters and nanodroplets [23,24]. Additional theoretical investigations with ab initio, DFT and semiempirical quantum chemical methods are performed to clarify the underlying physics of the evaporation processes of alkanes.…”