Analysis of natural convection melting from a heated wall with vertically oriented fins

A numerical study is reported of melting from a horizontal heated wall with vertically oriented fins embedded in the phase change material. This work is motivated by the need to improve the heat transfer rates during the charge and discharge cycles in latent heat thermal energy storage systems. A computational methodology based on a fixed-grid enthalpy method is first presented for handling the complex problem of natural convection dominated melting from a finned wall. The model is validated with experimental data and next a parametric study is conducted to examine the effect of the heated wall (top or bottom), of the number of fins and of the Rayleigh number Ra-H on the melting process. Results show that melting is enhanced with a bottom finned heated wall and increasing Rayleigh number. They also indicate that, for a given Rayleigh number, the melting time is minimized for an optimal distance W between the fins. This optimal distance was correlated with W = a Ra-H + b for 2.10 x 10(6) less than or equal to Ra-H less than or equal to 8.57 x 10(6).