Cleaning of a model food soil from horizontal plates by a moving vertical water jet

Abstract

The removal of layers of a model food soil (dried Xanthan gum containing fluorescent ZnS particles) by a vertical water jet impinging normally on to the plate, generated by a solid stream nozzle which moves across the plate was reported by Köhler et al. (2014). Their experiments investigated nozzle pressures from 0.5 to 2.0barg; nozzle diameters from 0.84–2.66mm, nozzle-layer separation of 20mm, and nozzle traverse speeds of 2.1–126mms−1. The flow parameters and separation are smaller than those typical of industrial jet cleaning operations. The model developed by Wilson et al. (2014) [Chem. Eng. Sci. 109, 183–196] for cleaning of similar layers by a stationary impinging jet was modified to describe the case of moving nozzle. This new model predicted the trends observed in the experiments, and analysis of the data yielded a similar cleaning rate constant to that obtained previously for cleaning of similar layers by stationary jets. The model predicted a non-circular cleaning front which matched that extracted from new experiments in which the flow was interrupted in order to capture this feature. The model allowed the cleaning performance indicators suggested by Köhler et al. (2014) to be expressed quantitatively: these indicated that higher nozzle traverse speeds give increased cleaning time, energy and liquid consumption performance.