Experimental study on the interaction of falling films and sprays during cleaning

In hygiene-critical industries such as the food industry, there is great interest in designing needs-based cleaning processes with optimized parameters. Simulations of the cleaning processes can support optimization, but often take too long, especially regarding the spray cleaning of large containers. Simplified and semi-empirical prediction models can improve the situation but require a solid experimental basis. The present study addresses an important knowledge gap by investigating the cleaning of a swellable, food-related model soil with water by a spray that is superimposed with a falling film. The variation of the impact angle of the spray (30° … 90°), the pre-wetting time (0 s … 120 s) and the nozzle pressure (1 barg … 5 barg) reveals a wide range of possible effects. Compared to spray cleaning only, both an increase in the cleaning rate of almost 50 % as well as a decrease in the cleaned area of about 80 % were observed, depending on the parameter selection and focus of the analysis. • Influence of fluid films on cleaning by stationary sprays. • Impact of important processes: swelling and damping. • Benefit of explicit pre-wetting when spray cleaning food based model soil.