Boiling heat transfer modelling: A review and future prospectus

Abstract

This paper reviews the current status of boiling heat transfer modelling, discusses the need for its improvement due to unresolved intriguing experimental findings and emergence of novel technical applications and outlines the directions for an advanced modelling approach. The state-of-the-art of computational boiling heat transfer studies is given for: macro-scale boiling models applied in two-fluid liquid-vapour interpenetrating media approach, micro-, meso-scale boiling computations by interface capturing methods, and nano-scale boiling simulations by molecular dynamics tools. Advantages, limitations and shortcomings of each approach, which originate from its grounding formulations, are discussed and illustrated on results obtained by the boiling model developed in our research group. Based on these issues, we stress the importance of adaptation of a multi-scale approach for development of an advanced boiling predictive methodology. A general road-map is outlined for achieving this challenging goal, which should include: improvement of existing methods for computation of boiling on different scales and development of conceptually new algorithms for linking of individual scale methods. As dramatically different time steps of integration for different boiling scales hinder the application of full multi-scale methodology on boiling problems of practical significance, we emphasise the importance of development of another algorithm for the determination of sub-domains within a macro-scale boiling region, which are relevant for conductance of small-scale simulations.

Molecular Dynamics Study of Bubble Nucleation on an Ideally Smooth Substrate

“…On the basis of these findings, Stefanovićand Novakovićconcluded that the effect of gas entrapment in substrate cavities on bubble nucleation was overestimated by the PEN theory. 1 The experimental results indicate that the bubble nucleation can happen on an ideally smooth surface with homogeneous wettability, coinciding with the present simulation results.…”

“…Stefanović and Novaković ,, used an ideally smooth substrate to exclude the effects of substrate roughness elements, which favored breeding an initial bubble nucleus according to the PEN theory. The ideally smooth substrate was obtained by heating a layer of mercury, which was distilled to eliminate any impurities and air.…”

“…Nucleate boiling is perpetually the focus of studies on enhancing heat dissipation due to its high heat transfer efficiency . The experiment is the conventional method to study the influences of wettability, nanostructure, overheating, and cavity on nucleate boiling, but it cannot eliminate the interference of various factors. − Alternatively, numerical simulation methods are another tool used to study nucleate boiling without the aforementioned drawbacks of the experimental method.…”

Surface Topography Effects on Pool Boiling via Non-equilibrium Molecular Dynamics Simulations

“…Molecular dynamics (MD) has been widely employed in the last few years to provide molecular-scale insights into the complexity of boiling phase change at the nano/micro-scale. ,− Previous attempts at the MD level investigated extensively the role of wettability in heat transfer performances for Lennard–Jones (LJ) liquid argon systems. Tang et al studied the effect of bare and graphene-coated surfaces for atomically smooth solid wall systems and their influence on the critical heat flux (CHF) and transition to film (explosive) boiling for liquid LJ argon.…”

“…Pool boiling is a complex, spatially inhomogenous, nonequilibrium process, dependent on the nature of the solid− liquid interactions that cannot be accounted for by existing meso-and macro-scale models. Molecular-scale investigations, therefore, appear to be a promising approach for pool boiling modeling since the out-of-equilibrium nature of boiling and the effects of molecular interactions are captured at the atomistic scale, 19 without the need for any closure assumptions. More specifically, surface wettability and geometrical details can be built into the model.…”