Enhancing the melting of phase change materials via convective flows and container geometry
Year: 2024
Type: article
Abstract: Three strategies for enhancing the melting rate of phase change materials (PCMs) are analyzed numerically: natural convection, thermocapillary convection, and variations in container geometry motivated by the natural shape of the advancing solid/liquid front. An enthalpy-porosity formulation of the Navier-Stokes equations is used to model the melting process, where the organic PCM n-octadecane is considered as a single phase whose physical properties depend on the local temperature. The phase change is driven by subjecting the material to a constant temperature TH=TM+ΔT, where TM is the melting temperature, at one of its lateral boundaries of length lH; the remaining boundaries are assumed adiabatic. Melting dynamics are described for both individual and combined enhancement strategies, using as reference the melting process in a rectangular container purely driven by conduction. The efficacy of each strategy is compared using the time τ required to melt 90% of the given PCM volume V; the inverse ratio of this time to that of the reference case, G=τ0/τ, defines the enhancement factor. Comparisons are made for small and large values of ΔT and lH. Increasing ΔT drives stronger convective flow and increases the associated enhancement factor. The isothermal length lH has opposite effects on each type of convection, favoring the enhancement of natural convection or thermocapillary flows at large and small values, with rates of G∈512 and G∈1233, respectively. The optimal container geometry is characterized by a type of aspect ratio Γ=lc/hc that compares its characteristic length and height. For pure conduction or with natural convection, Γ∼0.5, while with thermocapillary convection, Γ∼2.5−5.
Language: English
Subfield: Mechanical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,400
Awards: G2992956699, G5805502524
OpenAlex ID: W4401598496