Abstract
A numerical model for the complete thermo-fluid-dynamic and phase-change transport processes of two-component hydrocarbon liquid droplets consisting of n-heptane, n-decane and mixture of the two in various compositions is presented and validated against experimental data. The Navier–Stokes equations are solved numerically together with the VOF methodology for tracking the droplet interface, using an adaptive local grid refinement technique. The energy and concentration equations inside the liquid and the gaseous phases for both liquid species and their vapor components are additionally solved, coupled together with a model predicting the local vaporization rate at the cells forming the interface between the liquid and the surrounding gas. The model is validated against experimental data available for droplets suspended on a small diameter pipe in a hot air environment under convective flow conditions; these refer to droplet’s surface temperature and size regression with time. An extended investigation of the flow field is presented along with the temperature and concentration fields. The equilibrium position of droplets is estimated together with the deformation process of the droplet. Finally, extensive parametric studies are presented revealing the nature of multi-component droplet evaporation on the details of the flow, the temperature and concentration fields.
Highlights
Droplet evaporation is an important phenomenon occurring in numerous engineering applications, physical and natural processes
In a number of multi-phase flows with well defined interfaces, the liquid to cell volume fraction denoted by α, can be introduced as an additional scalar property identifying the liquid-gas interface; following the approach described in Volume of Fluid (VOF) methodology, as initially proposed by [38], the volume fraction α is defined as: a= liquid volume total cell volume where α takes the value 0 in the gas phase, 1 in the liquid phase and lies between 0 and 1 in the cells containing the interface area
The temporal evolution of the non-dimensionalised droplet squared diameter for all cases examined is presented in Fig. 4a,b, while in Fig. 4c,d,e the temporal evolution of mean droplet temperature is presented for the cases in which experimental data were available
Summary
Droplet evaporation is an important phenomenon occurring in numerous engineering applications, physical and natural processes. Detailed analysis of the flow field both inside the liquid and the surrounding gas, which was neglected in the previous works, requires the solution of the Navier-Stokes equations Such an approach was presented in [13, 14] who assumed a spherical droplet shape and used empirical correlations for the Nusselt and Sherwood numbers including the effect of Stefan flow. Predictions employing the VOF methodology may account for the liquid-gas interface deformation Such models so far have not been extended in cases which include the evaporation of multi-component liquids. Droplets are held in suspension on a spherical extremity and, compared to previous work, the present model accounts for the effect of the deformation of the droplet interface and gives information for the transient motion of the droplet together with a detailed description of the flow field. The model is first validated against experimental data available in bibliography and parametric studies reveal the effect of the most influential parameters
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
