Foam height effects on heat transfer performance of 20 ppi aluminum foams

This paper investigates the heat transfer performance of two 20 PPI (pores per linear inch) aluminum foams with constant porosity (around 0.93) and different foam core height (20 mm and 40 mm). The aluminum foams are cellular structure materials that present a stochastic interconnected pores distribution mostly uniform in size and shape. Most commercially available metal foams are based on aluminum, copper, nickel and metal alloys. Metal foams have considerable applications in multifunctional heat exchangers, cryogenics, combustion chambers, cladding on buildings, strain isolation, petroleum reservoirs, compact heat exchangers for airborne equipment, air cooled condensers and compact heat sinks for power electronics. The experimental measurements of the heat transfer coefficient and pressure drop have been carried out in a test apparatus built at Dipartimento di Fisica Tecnica of the Università di Padova. The foam core height effects on the heat transfer performance have been studied imposing three constant specific heat fluxes at the bottom of the samples: 25.0, 32.5 and 40.0 kW m-2 and varying the frontal air velocity between 2.0 and 5.0 m s-1. The experimental heat transfer coefficients and pressure gradients have been compared against the predictions obtained from two models recently suggested by present authors.