A numerical investigation of the effect of surface wettability on the boiling curve

<div><p>Surface wettability is recognized as playing an important role in pool boiling and the corresponding heat transfer curve. In this work, a systematic study of pool boiling heat transfer on smooth surfaces of varying wettability (contact angle range of 5° − 180°) has been conducted and reported. Based on numerical simulations, boiling curves are calculated and boiling dynamics in each regime are studied using a volume-of-fluid method with contact angle model. The calculated trends in critical heat flux and Leidenfrost point as functions of surface wettability are obtained and compared with prior experimental and theoretical predictions, giving good agreement. For the first time, the effect of contact angle on the complete boiling curve is shown. It is demonstrated that the simulation methodology can be used for studying pool boiling and related dynamics and providing more physical insights.</p></div

Bubble growth and departure for hydrophilic surface using (a) volume of fluid method and (b) lattice Boltzman method [16].

<p>Bubble growth and departure for hydrophilic surface using (a) volume of fluid method and (b) lattice Boltzman method [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0187175#pone.0187175.ref016" target="_blank">16</a>].</p

Maximum (critical) and minimum heat flux vs. contact angle.

<p>Maximum (critical) and minimum heat flux vs. contact angle.</p

Three dimensional cylindrical simulation of boiling curve for contact angle = (a)10°, (b)60°, (c)120°, and(d)160°.

<p>Vertical bars indicate the range of temporal fluctuations in heat flux.</p

Boiling curves for (a) hydrophilic surfaces and (b) hydrophobic surfaces.

<p>Boiling curves for (a) hydrophilic surfaces and (b) hydrophobic surfaces.</p

Temperature fields at contact angle = 120° for (a)nucleate boiling, (b)CHF, (c)transient boiling, (d)LFP, and (e)LBM results of pool boiling process on a hydrophobic surface [16].

<p>Temperature fields at contact angle = 120° for (a)nucleate boiling, (b)CHF, (c)transient boiling, (d)LFP, and (e)LBM results of pool boiling process on a hydrophobic surface [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0187175#pone.0187175.ref016" target="_blank">16</a>].</p

A numerical investigation of the effect of surface wettability on the boiling curve - Fig 6

<p>Two dimensional planar vapor dynamics at (a) contact angle = 10° (1)Nucleate boiling: vapor bubble growth at ΔT = 25K (2)Critical heat flux: vapor bubble dynamics at ΔT = 45K (3)Transient boiling: vapor bubble dynamics at ΔT = 55K (4)LFP: vapor bubble dynamics at ΔT = 60K; (b)contact angle = 60° (1)Nucleate boiling: vapor bubble growth at ΔT = 30K (2)Critical heat flux: vapor bubble dynamics at ΔT = 50K (3)Transient boiling: vapor bubble dynamics at ΔT = 55K (4)LFP: vapor bubble dynamics at ΔT = 60K; (c)contact angle = 120° (1)Nucleate boiling: vapor bubble growth at ΔT = 20K (2)Critical heat flux: vapor bubble dynamics at ΔT = 25K (3)Transient boiling: vapor bubble dynamics at ΔT = 30K (4)LFP: vapor bubble dynamics at ΔT = 40K; (d)contact angle = 160° (1)Nucleate boiling: vapor bubble growth at ΔT = 2K (2)Critical heat flux: vapor bubble dynamics at ΔT = 5K (3)LFP: vapor bubble dynamics at ΔT = 10K (4)LFP: vapor bubble dynamics at ΔT = 15K.</p

Properties of the fluid used in simulation.

<p>Properties of the fluid used in simulation.</p

Critical heat flux normalized by the corresponding maximum value of CHF in simulation, model, and experimental data.

<p>Qualitative trends in CHF vs. contact angle in data from simulations, models, and experiments are compared.</p

Properties of water.

<p>Properties of water.</p