Studies on the spray characteristics of pressure-swirl atomizers for automatic hand sanitizer application

Abstract

Automatic Hand Sanitizer (AHS) is an effective and useful tool to sanitize hands and is used widely in schools, workplace and healthcare settings. However, there are still issues that arise with spray type AHSs as it does not cover all parts of the hand, the volume of the sanitizer is not sufficient or it may miss the hands or be deflected into the air. The purpose of this work is to use numerical modelling techniques to evaluate the spray characteristics of AHS using pressure-swirl atomizer. ANSYS Fluent is used to simulate the spray produced by pressure-swirl atomizer. LISA (Linearized Instability Sheet Atomization) model is used for the primary atomization process while the TAB (Taylor Analogy Breakup) model is used for the secondary breakup of droplets. The parameters that were investigated include the spray angle and the droplet Sauter Mean Diameter (SMD). The simulation was first conducted using water as the atomization fluid to simulate water-based sanitizer spray and validated against experimental data. It was found that the simulation model developed shows good comparisons with experimental data when water was used. In addition, two scenarios were investigated with the validated CFD model: (i) increase in mass flow rate, (ii) ethyl-alcohol atomization for AHS application. Simulation results showed that the increase of flow rate does not affect water atomization but it does affect spray angle and SMD values for Ethyl-alcohol atomization. It is suggested that a higher flow rate can improve the atomization quality and spray coverage of alcohol-based sanitizer liquid for AHS application.