Experimental study on the cleaning effect of discontinuous sprays

Reproducible cleaning of open geometries and vessels in the food industry is usually ensured by Cleaning-in-Place systems, which spray the cleaning fluid onto the surfaces to be cleaned. The discontinuous operation of nozzles is one possibility to improve the ef-ficiency of these operations. Therefore, the influence of various parameters on the cleaning process is investigated in an experimental study for the simplified configuration of a vertical water spray impinging downwards on a horizontal stainless steel surface at a distance of 150 mm. The industrial full cone and flat fan nozzles used in this research delivered volumetric flow rates of 5.5 and 8.0 l/min, respectively, at an operating pressure of 6 bar. Discontinuous flows were generated by switching a pivoted-armature valve up-stream of the nozzle with frequencies of 5 and 10 Hz. Vanilla pudding and rice pudding were chosen as model food soils to study the cleaning properties of a homogeneous soil layer and a soil layer with protruding particles, respectively. The use of discontinuous sprays increased the cleaning rate because of altered fluid distribution in the spray and, in case of the inhomogeneous soil layer, due to repetitive load maxima.(c) 2022 Institution of Chemical Engineers. Published by Elsevier Ltd. All rights reserved.