Journal of Materials Science

, Volume 43, Issue 17, pp 5930–5941 | Cite as

Droplet cooling in atomization sprays

  • Arvind Prasad
  • Hani Henein


Transport between droplets/particles and a gas phase plays an important role in numerous material processing operations. These include rapid solidification operations such as gas atomization and spray forming, as well as chemical systems such as flash furnaces. Chemical reaction rates and solidification are dependent on the rate of gas-particle or gas-droplet transport mechanisms. These gas-based processes are difficult to analyze due to their complexity which include particle and droplet distribution and the flow in a gas field having variations in temperature and velocity both in the jet cross-section and in the axial distance away from the jet source. Thus to study and properly identify the important variables in transport, these gas and droplet variations must be eliminated or controlled. This is done in this work using models based on a single fluid atomization system. Using a heat transport model (referred to as thermal model) validated using single fluid atomization of molten droplets and a microsegregation model, the effect of process variables on heat losses from droplets was examined. In this work, the effect of type of gas, droplet size, gas temperature, gas-droplet relative velocity on the heat transport from AA6061 droplets was examined. It is shown that for a given gas type, the most critical process variable is the gas temperature particularly as affected by two-way thermal coupling and the droplet size. The results are generalized and applied to explain the difference in droplet cooling rate from different atomization processes.


Cool Rate Droplet Size Thermal Model Droplet Temperature Freezing Range 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

List of symbols


Surface area of the droplet


Heat capacity of the droplet


Integral heat capacity


Fraction solid


Modified Fourier number for droplet-gas thermal transport


Total heat transfer coefficient


Convective heat transfer coefficient


Droplet enthalpy


Gas thermal conductivity


Solidification enthalpy

m and (m + 1)

Indices for the numerical calculation


Droplet Nusselt number


Prandltl number


Droplet Reynolds number




Reference time


Solidification time


Liquidus temperature of AA6061


Droplet temperature during solidification


Nucleation temperature for simulation


Solidus temperature of AA6061


User-defined primary undercooled temperature


Gas temperature in the free stream


Volume of the droplet


Droplet density


Gas viscosities at the temperature of the free flow gas


Gas viscosities at the temperature of the droplet


Dimensionless temperature


Dimensionless time



The author wishes to acknowledge funding for this work from the Natural Science and Engineering Research Council of Canada (NSERC) and from the Canada Council for the Arts for award of a Killam Research Fellowship. The contribution of Karine Navell in making the cell spacing measurements presented in Fig. 12 are also acknowledged.


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Copyright information

© Springer Science+Business Media, LLC 2008

Authors and Affiliations

  1. 1.Department of Chemical and Materials EngineeringUniversity of AlbertaEdmontonCanada

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