Single Droplet Drying at High Temperatures

structures collected from a lab scaled spray dryer.

Structures obtained from the single droplet drying experiments showed high similarities to

The differences in these drying metrics have been related to key material properties.

final particle size, moisture content at locking were collated at different drying conditions.

encountered above boiling. Several drying metrics including relative size at locking, relative

further understand the differences in drying behaviour and morphology evolution route

conditions collected from the single droplet drying rig have been extensively investigated to

deflation, inflation and puffing. Drying kinetics and morphology time-series at different drying

different drying mechanisms, boiling without any inflation/deflation cycles, inflation and

concentrations using a filament single droplet drying rig. The three materials showed three

and drying kinetics have been investigated across a range of air temperatures and initial solid

sucrose, sodium silicate and Hydroxypropyl Methylcellulose (HPMC). The drying behaviour

and morphology evolution. Three skin forming materials were chosen for this study namely,

The aim of this study is to investigate the effects driven by boiling on the drying behaviour

Wael Ebrahim

above boiling point

An experimental investigation of the drying mechanisms of single droplets

The solution of this model is currently underway.

expression for the expansion of a single centralized bubble within a liquid droplet was derived.

transfer on the expansion of a single bubble in an infinite liquid media was conducted and an

to the asymmetric pressure and velocity field. An initial assessment of the influence of mass

An off-centre bubble was also investigated and a self-centering behaviour was observed due

oscillations which decayed with time. The rate of decay increasing with increasing viscosity.

dynamics of a initially over pressured bubble, behaved as anticipated showing bubble

constructed and solved to allow for asymmetry to be investigated. The 2-D model, of the

spherically symmetric 1-D equations were derived and solved and a 2-D model was also

derived from the mass and the momentum balances and the Navier-Stokes equation. Both

The governing equations for the oscillations dynamics of the bubble and the droplet are

within a droplet, which is termed as ‘bubble-droplet system’ in this report, are investigated.

The effects of mass transfer on the oscillation dynamics of a single bubble centrally located

Tien Nguyen

BUBBLE DYNAMICS INSIDE A DROPLET