Comparison of an Effervescent Nozzle and a Proposed Air‐Core‐Liquid‐Ring (ACLR) Nozzle for Atomization of Viscous Food Liquids at Low Air Consumption

Recent results regarding the effervescent atomization of viscous food-based liquids reveal that an unfavorable slug flow is formed inside the nozzle for low gas to liquid ratios (GLRs). As a result, a very unsteady spray drop size is formed, which leads the nozzle to be unsuitable for an implementation in spray drying. In this study, we propose a modified nozzle design named ACLR (Air-Core-Liquid-Ring) to establish the favorable annular flow inside the exit orifice. High-speed imaging proved that the desired flow pattern was present in the investigated GLR range of 0.015-0.414 and for liquid viscosities of 0.001-0.308 Pa.s. Comparison with a conventional effervescent nozzle showed similar values of the time averaged Sauter mean diameter of the spray drops. Considering the temporal unsteadiness of the spray drop size, a considerable reduction can be achieved for viscous liquids and low GLRs by the proposed ACLR nozzle.