Effect of extended surfaces on lauric acid melting process in annular cavities

The objective of the present work is to parametrically analyze the effect of extended surfaces’ proportion and positioning on the lauric acid melting process, in an annular cavity. In total 46 geometric configurations were studied, varying between 5 area ratios, 5 proportions, and 2 positions of the extended surface. Numerical simulations performed with the finite volume method were used to conduct the study. The numerical model, composed of the continuity, momentum conservation, and energy conservation equations, plus the enthalpy-porosity phase change model, was validated with experimental data from the literature. The Grid Convergence Index (GCI) was used to evaluate the computational mesh, resulting in an average index of 0.0026%. The results are presented in terms of liquid fraction vs Fourier, and Nusselt number vs. Fourier. Besides, velocity vectors, and streamlines, liquid fraction, and temperature fields, were presented, comparing different instants and geometric arrangements. For the analysis of the results, the melting time was considered as a performance indicator. The results revealed that: while there is solid PCM in the cavity's upper section, the melting rate in systems with horizontal extensions is 15% higher than systems with vertical extensions; when the extended surface thinness is increased, the overall melting time is reduced by more than 10% in vertical arrangements and less than 1.5% in horizontal arrangements; the total melting time is nearly 45% faster in systems with vertical extensions than in systems with horizontal extensions.