Thermohydraulics of a metal foam-filled annulus

•Measurement of the pressure drop and the temperature fields in the air side of a foam-filled annulus.•Thermal entrance length was calculated as a design criterion for compact metal foam heat exchanger.•For a vertical foam annular heat exchanger, the pressure drop is proportional to the foam length.•Airflow rate has more significant effect on the pressure drop than the PPI or the foam length.•Significant amount of heat transfer takes place in the first half of the foam. This paper offers numerical and experimental analysis of forced convection through an annulus filled with aluminium foam. Effects of flow rate and foam pore density on the performance of the heat exchanger were investigated. Specifically, 5 and 20 pore per inch (PPI) aluminium metal foams were tested at three different airflow rates; 20, 85 and 150 standard litre per minute. In parallel, the problem has been simulated numerically. Once validated against experimental data, numerical simulations were conducted to add to the level of details obtained from experiments. The thermal study was done by analysing the temperature field throughout the porous volume and determining the thermal entrance length. This parameter, the thermal entrance length, establishes a reliable design criteria for metal foam-filled heat exchangers, since it marks the length beyond which heat transfer does not significantly increase while the pressure drop keeps growing.