A two-fluid model of gas-assisted atomization including flow through the nozzle,phase inversion,and spray dispersion

This paper describes a new approach to modelling compressible gas–liquid flows that undergo change of the continuous phase. The presented model includes the system of the ensemble averaged Navier–Stokes equations together with the particle number density equation for each phase. The constitutive equations that depend on the flow regime are obtained from many sub-models that have been developed alongside the main model. Droplet size is allowed to vary in the flow field but is considered constant within a control volume. Bubbles and droplets break-up and coalescence models are adapted to the flow conditions. The proposed model for atomization treats it as a catastrophic phase inversion that takes place over the surface determined by the local values of phase volume fractions. The model is applied to simulate the premixed air-assisted atomization of water in a nozzle-type device. The computational domain includes the nozzle and the surrounding area of the spray dispersion. The model performance has been verified by comparing the predicted and measured liquid flow rates in the spray as well as the pressure values along the nozzle wall. Computational results are analysed, and the main flow features are presented.     

Characterization of Ultra Fine Solids（BS） in Athabasca Bitumen

The ultra fine (＜200 nm) inorganic solids (BS) were separated from bitumen which was washed by toluene and centrifugated at 2000 rpm. The result of PAS FTIR and image of TEM showed that the structure of BS particles was smiliar to that of kaolinite clay. On the surface of BS, both toluene insoluble organic matter and structural OH group are detected at the same time.The surface characteristics imparted a bi-wettable nature to the BS. As a result, the BS is able to stabilize fine water emulsion in the bitumen phase. The organic matter associated with BS is a possible factor of the fouling on catalyst and equipment.