We study the role of surface topology, surface chemistry, and wall superheat temperature on the onset of boiling, bubble nucleation and growth, and the possible formation of an insulating vapour film by means of a novel setup for large-scale MD simulations. To minimise the effects of the system size on the bubble growth and the formation of the vapour film, we perform simulations in a box larger than those previously considered. The effect of the system pressure on bubble nucleation and growth is isolated by imposing a constant force on a moving piston and mechanically controlling the pressure. The simulations reveal that the presence of a nanostructure determines the nucleation site and facilitates the energy transfer from the hot substrate to the water. The surface chemistry, on the other hand, governs the shape of the formed bubble. A hydrophilic surface accelerates the bubble nucleation, however, decelerates the bubble expansion, thus postponing the formation of the film of vapour. Hence, a hydrophilic surface provides better energy transfer from the hot wall to the water. By analysing the system energy, we show that irrespective of wall topology and chemistry, there is a wall temperature for which the amount of transferred energy from the wall is maximum.

Shahmardi, A., Tammisola, O., Chinappi, M., Brandt, L. (2021). Effects of surface nanostructure and wettability on pool boiling: A molecular dynamics study. INTERNATIONAL JOURNAL OF THERMAL SCIENCES, 167 [10.1016/j.ijthermalsci.2021.106980].

Effects of surface nanostructure and wettability on pool boiling: A molecular dynamics study

Chinappi M.;
2021-01-01

Abstract

We study the role of surface topology, surface chemistry, and wall superheat temperature on the onset of boiling, bubble nucleation and growth, and the possible formation of an insulating vapour film by means of a novel setup for large-scale MD simulations. To minimise the effects of the system size on the bubble growth and the formation of the vapour film, we perform simulations in a box larger than those previously considered. The effect of the system pressure on bubble nucleation and growth is isolated by imposing a constant force on a moving piston and mechanically controlling the pressure. The simulations reveal that the presence of a nanostructure determines the nucleation site and facilitates the energy transfer from the hot substrate to the water. The surface chemistry, on the other hand, governs the shape of the formed bubble. A hydrophilic surface accelerates the bubble nucleation, however, decelerates the bubble expansion, thus postponing the formation of the film of vapour. Hence, a hydrophilic surface provides better energy transfer from the hot wall to the water. By analysing the system energy, we show that irrespective of wall topology and chemistry, there is a wall temperature for which the amount of transferred energy from the wall is maximum.
2021
Pubblicato
Rilevanza internazionale
Articolo
Esperti anonimi
Settore ING-IND/06 - FLUIDODINAMICA
English
Pool boiling
Bubble nucleation
Molecular dynamics
Wetting
Energy transfer
Nano-structured surfaces
Shahmardi, A., Tammisola, O., Chinappi, M., Brandt, L. (2021). Effects of surface nanostructure and wettability on pool boiling: A molecular dynamics study. INTERNATIONAL JOURNAL OF THERMAL SCIENCES, 167 [10.1016/j.ijthermalsci.2021.106980].
Shahmardi, A; Tammisola, O; Chinappi, M; Brandt, L
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2108/297153
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