An investigation of evaporation from single saline water droplets: experimental and theoretical approaches

Sadafi, M. H., Jahn, I., Stilgoe, A. B. and Hooman, K. (2014). An investigation of evaporation from single saline water droplets: experimental and theoretical approaches. In: Harun Chowdhury and Firoz Alam, Proceedings of the 19th Australasian Fluid Mechanics Conference. 19th Australasian Fluid Mechanics Conference, Melbourne, VIC, Australia, (216.1-216.4). 8-11 December 2014.

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Name Description MIMEType Size Downloads
Author Sadafi, M. H.
Jahn, I.
Stilgoe, A. B.
Hooman, K.
Title of paper An investigation of evaporation from single saline water droplets: experimental and theoretical approaches
Conference name 19th Australasian Fluid Mechanics Conference
Conference location Melbourne, VIC, Australia
Conference dates 8-11 December 2014
Proceedings title Proceedings of the 19th Australasian Fluid Mechanics Conference
Place of Publication Melbourne, VIC, Australia
Publisher RMIT University
Publication Year 2014
Sub-type Fully published paper
Open Access Status
ISBN 9780646596952
Editor Harun Chowdhury
Firoz Alam
Start page 216.1
End page 216.4
Total pages 4
Collection year 2015
Language eng
Formatted Abstract/Summary
Heat transfer to and mass transfer from NaCl-water droplets are investigated both numerically and experimentally. A new model is presented and used to simulate saline water droplet evaporation. The model is robust enough to be applied for various initial concentrations and conditions of the droplet, ambient conditions, and dissolved media properties. The model is validated using experimental data obtained in this study on top of those already available in the literature. The experimental apparatus as well as the processing routines to optically measure droplet evaporation at a range of ambient conditions are presented. Data were collected for droplets with an initial radius of 500 µm at three temperatures 25 oC, 35 oC, and 45 oC and three air velocities 0.5m/s, 1.5 m/s, and 2.5 m/s to provide a comprehensive validation dataset. Based on experimental and simulation data, a correlation is presented that captures the start time of solid formation. This time plays an important role in cooling tower design as it shows the time that the outer surface of the droplet dries. Using the validated model, it is shown that for 500 µm radius droplets with 5% initial mass concentration the start time of reaching the final size is 24.9% less than evaporation time of a pure water droplet. Also, the net energy required to evaporate the droplet falls by 12.2%compared to a pure water droplet. Using saline water in spray-cooling has two major effects: the energy extracted from the air per unit droplet volume is reduced (which can be compensated for by increasing the liquid flow rate). Moreover, compared to the time taken for the evaporation of a pure water droplet, the period with wet surface is shorter as a result of crust formation around the saline water droplet. This allows a shorter distance between spray nozzles and heat exchangers.
Q-Index Code E1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Paper 216

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Created: Mon, 02 Feb 2015, 08:48:26 EST by Katie Gollschewski on behalf of School of Mechanical and Mining Engineering