Experimental investigation of the convective heat transfer coefficient for open-cell porous metal fins at low Reynolds numbers

• Convective heat transfer coefficient of a porous metal was obtained with fin efficiency.
• Nusselt numbers based on equivalent diameter correlate well regardless of the pore density.
• Empirical correlation for the Nusselt number of the porous metal fin was developed.

The heat transfer characteristics and convective heat transfer coefficient of porous metal fin are experimentally investigated. The pore density of the porous metal fin and frontal velocity of the working fluid are varied in the range of 20, 40, and 80 pores per inch, and 0.007–0.17 m/s, respectively. The porous metal fins are fabricated from nickel with different porosities and various pore densities. The geometrical parameters of the test samples are measured using an optical method. In this study, porous metals are considered as a fin and the heat transfer performances are experimentally evaluated. An equivalent diameter based on the permeability and porosity is used as the characteristic length to calculate the Reynolds numbers and Nusselt numbers. When the equivalent diameter is used as the characteristic length, the measured Nusselt numbers converge to a single curve regardless of the pore density. The Nusselt number variation appears to be very similar to previous correlations developed for convective heat transfers of turbulent pipe flows. Consequently, an empirical correlation of the Nusselt number for porous metal fins is proposed in the form of a Dittus–Boelter correlation.