Executive Summary

This project seeks to develop physically realistic models for spray-drying as used in industry with a focus on high viscosity and non-Newtonian fluid atomization. The goal of this work is to develop understanding and correlations for the accurate pilot-to-production scaleup of spray-drying. We divide the work to focus on two nozzle types: pressure-swirl, and two-fluid.

A testing facility is setup for experiments with swirl nozzle. Various types of pressure swirl nozzle with different scales are selected to be tested with different fluids at relatively high pressure. An imaging system is used to take near-nozzle images to analyze the atomization process. It is also used to measure the droplet size downstream and report number distribution and SMD at various radial positions. An atomization process is proposed by observing near-nozzle images. Physics model is being developed and its predictions will be compared with all the experiment results for further improvements.

Preliminary tests of two-fluid nozzles reveal the similarity to single-droplet breakup, thus detailed experimentation and analysis on single droplet atomization by an air jet was conducted. A working hypothesis that the rate of droplet deformation determines the mode of droplet breakup is being studied, and models for the underlying breakup processes have been compared to the experiments with reasonable agreement. The next phase for this branch of the project will be to apply the developed models for single-droplet breakup to the two-fluid atomization geometry.