metal foam in both the inner tube and annular space. The heat flux
on the interface wall was fixed at a constant value and is known at
the beginning of analysis. However, the wall heat flux is actually
determined by coupled heat transfers in the inner and annular
spaces. The analytical solution is carried out separately in two
sides of the double-pipe heat exchanger, and the coupling effects
are neglected, resulting in deviations from the physical process.
T’Joen and Jaeger et al [22] studied design of metal foam filled heat
exchanger in order to reduce pressure loss on airside. The thermohydraulic
performance considering effects of parameters were also
tested. It was concluded that reducing tube spacing or heights of
metal foams potentially enhance overall heat transfer at higher airside
frontal velocities (>4 m/s). Mahjoob and Vafai [23] reviewed
correlations of flow resistance and heat transfers in channels and
tubes filled with open cell metal foam, which provided guidance
for the heat exchanger design.