Toggle Main Menu Toggle Search

Open Access padlockePrints

Numerical analysis of in-flight freezing droplets: Application to novel particle engineering technology

Lookup NU author(s): Andrew Tait, Dr Jonathan LeeORCiD, Professor Gary Montague



This is the authors' accepted manuscript of an article that has been published in its final definitive form by Institution of Chemical Engineers, 2019.

For re-use rights please refer to the publisher's terms and conditions.


© 2019 Institution of Chemical Engineers The freezing of a stream of free-falling monodispersed droplets was simulated through the development of numerical models in this work. Prediction of the freezing time and temperature transition of a single droplet is beneficial for optimisation of novel continuous spray freeze drying (cSFD) processes. Estimations of the vertical free-falling distance of the droplets in a slip stream and predictions of the chances of droplet coalescence greatly enhance process understanding and can be leveraged to direct equipment design and process development. A design space of droplet diameters in the range from 100 μm to 400 μm and ambient temperatures from −120 °C to −40 °C was explored. The rate of supercooling within the design space was predicted to range from 48 to 830 °C s −1 depending on the ambient temperature and droplet size. A comparison of the vertical free-falling distances of solitary droplets and streams of droplets at different temperatures showed that the terminal velocity of a vertically falling stream of droplets is always in excess of the terminal velocity of a solitary droplet of the same size. A difference of 1.35 m was predicted for the free-falling distance of a 400 μm droplet compared to a stream of droplets at −42 °C. A comparison between flow rates for consecutively generated 100 μm droplets showed that droplet coalescence was predicted at 0.05 Lh −1 , whilst at 0.02 Lh −1 a separation distance of 23 μm was maintained thus preventing coalescence.

Publication metadata

Author(s): Tait A, Lee JGM, Williams BR, Montague GA

Publication type: Article

Publication status: Published

Journal: Food and Bioproducts Processing

Year: 2019

Volume: 116

Pages: 30-40

Print publication date: 01/07/2019

Online publication date: 27/04/2019

Acceptance date: 22/04/2019

Date deposited: 04/07/2019

ISSN (electronic): 0960-3085

Publisher: Institution of Chemical Engineers


DOI: 10.1016/j.fbp.2019.04.009


Altmetrics provided by Altmetric


Funder referenceFunder name
EP/G037620/1Alcyomics Ltd
EP/G037620/1BOC Group Limited