Experimental Investigation on the Pressure Drop of Air Flows Through Aluminum and Nickel-Chromium Metallic Foams for HVAC Applications

In this paper, a series of experimental data about the role of the metal foam thickness on the total air flow pressure drop is presented. The tested metallic foams are based on aluminum and nickel-chromium and they are characterized by a considerable value of porosity (>0.92) and by a number of pores per linear inches (PPI) close to 10. The measures were conducted in a range of air velocity values typical for HVAC fan-coils. Under these conditions, the flow regime into the pores is highly turbulent. It was demonstrated that below a threshold value of the ratio between the thickness of the porous medium (H) and the characteristic dimension of the pores (d), the dispersion of the pressure drop values from a sample to another one can be very high. This behavior can limit the industrial use of these materials. In addition, the results presented in this paper confirm that the pressure drop data obtained under highly turbulent conditions can be conveniently used in order to determine the inertia coefficient, C, of the metal foam.