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• Experimental study on buoyancy-induced convection transport in additively manufactured lattice structures presented. • Effect of lattice aspect ratio and symmetric versus asymmetric heating studied for wide range of Rayleigh numbers. • Cubic lattice outperformed the other four investigated topologies, owing to its high permeability. • Cubic lattice enhanced heat transfer by a factor of 6.6 and 8 for symmetric and asymmetric heating configurations, respectively. In this paper, we report the findings of our investigation on achieving enhanced heat dissipation through buoyancy-induced flow between two vertically oriented heated plates by packing additively manufactured porous media between them. Lattice structures comprising five different unit cell topologies: Octet, FD-Cube, FD-Cube paired, TKD, and Cube were selected as the chosen porous media. They were separated from the vertical plates by a finite distance for two values of aspect ratio (plate separation distance-to-height ratio) of ∼0.5 and 2. The vertical walls were subjected to a constant heat flux (symmetric and asymmetric). Among the five topologies explored, the Cube lattice structure provided the highest heat dissipation for a wide range of investigated Rayleigh numbers, under different aspect ratios and heating conditions. This superiority can be attributed to the inherent characteristics of the Cube structure, which exhibited the highest permeability, consequently offering the least resistance to the fluid motion. In contrast, the Octet lattice structure, despite its high surface area-to-volume ratio, had the lowest permeability as compared to other topologies and provided the weakest thermal performance. Thermal performance of the remaining topologies—TKD, FD-Cube paired, and FD-Cube—fell between that of the Cube and the Octet. The results clearly indicate that the resultant thermal performance is a complex interplay between the permeability, surface-area-to-volume ratio, and local fluid dynamics. The insights gained from this investigation can offer guidance for designing efficient thermal management systems across various applications involving buoyancy-induced flows. [ABSTRACT FROM AUTHOR]

• Experimental investigation on additively manufactured lattices with four different topologies, namely, (a) Octet, (b) FD-Cube, (c) Tetrakaidecahedron, and (d) Cube, was conducted to analyze their periodic heat transfer characteristics. • The flow became thermally fully developed after travelling five or six rows of unit cells in the streamwise direction and heat transfer coefficient levels of Octet, FD-Cube, and TKD in this periodic heat transfer zone were similar with values between ∼216 W / m 2 K and 415 W / m 2 K. • Lattices were capable of providing ∼ 10 to 20 times higher heat transfer than the smooth channels and also yielded overall thermal-hydraulic performance value of ∼ 3 at the lowest representative Reynolds number investigated. In the present study, the flow and heat transfer characteristics of lattices with four different unit cell topologies, namely, (a) Octet, (b) FD-Cube, (c) Tetrakaidecahedron (TKD), and (d) Cube were investigated with air as the working fluid. All the samples had the designed porosity of ∼ 0.88 and unit cell size of 10 mm. The distribution of local heat transfer coefficient revealed that depending on the unit cell topology, the flow became thermally developed after travelling over five or six rows of unit cells in streamwise direction. The heat transfer coefficient values in thermally developed zones were similar for Octet, FD-Cube and TKD. Overall heat transfer coefficient provided by Octet, FD-Cube, and TKD was in the range of ∼216 W / m 2 K to 415 W / m 2 K and Cube yielded the lowest heat transfer coefficient values between 167 W / m 2 K and 290 W / m 2 K. Three different characteristic length scales, viz. (a) channel hydraulic diameter, (b) pore-diameter, and (c) fiber-diameter were used to define the Nusselt number. The usage of pore-scale dimensions such as pore-diameter and fiber-diameter provided a very coherent data set for Nusselt number of all the topologies which helped in deriving a single correlation for predicting the thermal performance. The lattices provided heat transfer augmentation of 10-20 times higher than the smooth channel counterparts. Amongst all the investigated topologies, FD-Cube incurred the highest and Cube yielded the lowest pressure drop. It was also observed that convective heat transfer coefficients obtained for different lattices can be conveniently reported in Nusselt number forms with pore diameter and/or fiber diameters as reference length scales, where such Nusselt numbers for different lattice configurations converges to a single trendline when plotted against Reynolds numbers (also based on same reference length scales). We have provided a single correlation for Nusselt numbers as a function of Reynolds numbers which fits all the lattice configurations studied here. Finally, the thermal-hydraulic performance of lattices is reported which had similar magnitude levels for all the investigated topologies and a single correlation has been proposed for THP covering all the configurations of present study. The investigated topologies provided THP of ∼ 3 at the lowest investigated Reynolds number. [ABSTRACT FROM AUTHOR]