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A. Bhattacharya
significantly higher thermal conductivity of copper. The density of copper is about
3 times as that of aluminum and thus the mass of copper is higher for the same
overall porosity. However, copper has significantly lower specific heat as compared
to aluminum. Thus the overall sensible heat absorption in copper is not markedly
higher. The main difference in the system comes from the faster heat transfer to the
PCM with use of copper foam which results in faster melting of PCM. This is evident
from the liquid fraction contours for the two systems shown in Fig. 11.4.
The variation of total energy absorption and latent heat absorption with time is
compared in Fig. 11.5a. It can be observed that use of Cu foam results in increase
of approximately 20% in total heat absorption and approximately 23% in latent heat
absorption for the given configuration. The variation of overall liquid fraction with
time, as shown in Fig. 11.5b, confirms the higher melting rate of PCM with embedded
Cu foam.
Fig. 11.4 Liquid fraction at the mid-section. a Aluminum foam at t = 500 s. b Aluminum foam at
t = 1000 s. c Copper foam at t = 500 s. d Copper foam at t = 1000 s