Cooling effectiveness of droplets at low Weber numbers: Effect of temperature

The impact of water droplets onto a heated non-isothermal surface is studied numerically using the VOF methodology and assuming a 2D-axisymmetric computational domain. An adaptive grid refinement technique in both the fluid and the solid phases is used to solve the conjugate problem of fluid flow an...

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Bibliographic Details
Published in:International journal of thermal sciences 2013-10, Vol.72, p.60-72
Main Authors: Strotos, George, Nikolopoulos, Nikos, Nikas, Konstantinos-Stephen, Moustris, Kostas
Format: Article
Language:English
Subjects:
Applied sciences
Computational fluid dynamics
Droplet
Droplets
Energy
Energy. Thermal use of fuels
Evolution
Exact sciences and technology
Fluid flow
Fluids
Heat transfer
Heated wall
Mathematical analysis
Mathematical models
Spreading
Theoretical studies. Data and constants. Metering
Transient conduction
VOF
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Summary:The impact of water droplets onto a heated non-isothermal surface is studied numerically using the VOF methodology and assuming a 2D-axisymmetric computational domain. An adaptive grid refinement technique in both the fluid and the solid phases is used to solve the conjugate problem of fluid flow and heat transfer. Parametric studies examine the effect of initial solid surface temperature and initial droplet temperature, while all the other parameters which affect the temporal evolution of the phenomenon are kept constant; the wall temperatures examined are low enough to prevent the onset of nucleate boiling. It is proved that the variables describing the temporal evolution of the phenomenon evolve with the same way when they are non-dimensionalised with expressions arising from the transient heat conduction theory. Additionally, a formula for the maximum droplet spreading which accounts for the droplet heating during spreading is proposed, as also semi-analytical expressions which describe the thermal behaviour of the droplet •Conjugate solution of energy equation for an impacting droplet onto a heated wall.•VOF methodology coupled with an adaptive local grid refinement technique.•Detailed examination of the effect of temperature on the cooling effectiveness of droplets.•Useful relationships are provided which describe the thermal behaviour of the droplet.
ISSN:1290-0729
1778-4166
DOI:10.1016/j.ijthermalsci.2013.05.008