Study Of Enhanced Boiling Heat Transfer On Metal Surfaces Modified With Carbon Nanomaterials

With the development of nanotechnology,the integration of electronic components is increasing day by day,resulting in the surface heat flux of electronic components reaching10⁷ W·m^-2 or even higher,which makes the heat dissipation of electronic components extremely challenging.Due to the latent heat of vaporization,boiling heat transfer can achieve a higher heat transfer coefficient at a lower superheat,so it shows great potential in solving the heat dissipation problem of electronic components.In this paper,the molecular dynamics is used to study the boiling heat transfer of liquid nanofilm.Considering the thickness of liquid nanofilm,the influence of nano-rough structure of bottom plate,wettability,simple harmonic vibration and modification of carbon nanomaterials on boiling heat transfer,the boiling heat transfer of liquid nanofilms with different thickness,sinusoidal surfaces,vibrating surfaces,and vertical graphene-modified bottom plates is investigated with constant heat flux applied to the bottom plate.The thickness dependence of boiling heat transfer under constant heat flux shows that with the increase of heat flux,the phase transition mode changes from normal evaporation to explosive boiling.At the same heat flux,the onset time of explosive boiling is delayed with the increase of liquid nanofilm thickness.The larger the thickness of the liquid nanofilm is,the smaller the critical heat flux is.Boiling heat transfer in liquid nanofilm is investigated considering the influence of bottom plate wettability Sinusoidal concave and convex nano-rough structure.The results show that,compared with smooth surface,the onset of explosive boiling is delayed,and the critical heat flux is increased.The more hydrophilic the surface,the longer it takes to trigger the explosive boiling and the greater the critical heat flux.The study of boiling heat transfer in liquid nanofilm on vibrating surface has established a model that simple harmonic vibration and heat flux do not interfere with each other.The results show that simple harmonic vibration not only disturbs the temperature distribution inside the disturbed liquid,but also generates heat through viscous friction inside the liquid nanofilm,which makes water molecules reach the homogeneous nucleation limit of 575 K in advance,leading to explosive boiling in advance.The boiling heat transfer of nanoliquid membranes on graphene-modified surfaces showed that vertical graphene increased the solid-liquid contact area and facilitated the formation of vapor membranes in the bubble cavity.When the height of graphene is small,the increased solid-liquid contact area is negligible,so the explosive boiling occurs earlier.When the height of graphene is larger,the solid-liquid contact area increases significantly,which enhances the heat transfer effect,reduces the temperature distribution heterogeneity inside the liquid nanofilm,and finally shows the explosive boiling occurs later.