Influence of liquid film shape on the evaporation performance of the agitated thin film evaporator

Abstract The agitated thin film evaporator (ATFE), known for its high efficiency, compels the material to form a film through the scraping process of a scraper, followed by evaporation and purification. The intricate shape of the liquid film inside the evaporator can significantly influence its ability to evaporate. This study explores how varying shapes of the liquid film affect the evaporation of the material possessing non-Newtonian characteristics, achieved by altering the scraper's structure. Examining the flat liquid film's circumferential temperature, viscosity, and mass transfer distribution indicates rapid evaporation in shear-thinning regions. Various wavy liquid films have been developed using shear-thinning theory, emphasizing the flow condition in the thinning area and the factors contributing to the exceptional evaporation ability. Further exploration was conducted on the spread patterns of the wavy and flat liquid film on the evaporation wall throughout the process. It's noted that breaking the wavy liquid film on the evaporating wall during evaporation is challenging due to its film-forming condition. The fundamental causes for this were demonstrated by acquiring data regarding the flow rate and temperature of the liquid film. The definitive findings of the analysis reveal a significant improvement in the evaporation ability of the wavy liquid film. The enhancement is credited to increased shear-thinning areas and preserving the film's overall form throughout evaporation.