Single droplet drying of detergents: Experimentation and modelling

This study evaluates the single droplet drying (SDD) of detergents. Experimental data are used to validate a theoretical multistage model. The experiments are carried out in an acoustic levitator analysing six different detergent formulations at 393 K. The work is completed by developing a model based on conservation equations. The model is composed of the three stages observed in the drying curve. In the first stage, an external surface drying stage occurs until the surface is saturated and the crust is formed. In the next stage, the drying rate is governed by diffusion through the pores. At the same time, the particle heats up until boiling conditions are achieved in the core of the particle. At this point, the third stage begins. In the final stage, the droplet core is in boiling conditions which are governed by the pressure drop through the crust and the concentration of salts. This model has been evaluated for the different formulations being flexible to predict the drying of different mixtures with good accuracy