| dc.description.abstract | This Part-II of the manuscript reports on the unsteady two-dimensional numerical
investigations of melting oJ'a para/fin wax (phase change mqterial, PCM) which melts over a
temperature range of 8.7'C. The PCM is placed inside a circular concentric horizontal-finned
annulus ./br the storage of'thermal energy. The inner tube is fitted with three longitudinal fins
which are placed strategically near the bottom part of the annulus to accelerate lhe melting
process. The non-dimensional conservation equations for mass, momentum, and energy are
solved employing a staggered control-yolume based .finite difference method trsing the
previously verified in-house CFD code. (lnder identical geometrical configuration and
operating conditions, the melting characteristics of the finned annulus are compared with the
anrutlus without Jins presented in Ref. [1J. The numerical results show thatthe average
Nusselt number over the inner tube surface, the total melt fraction, the total stored energy
all increased at evety time instant in the internally finned annulus compared to the annulus
**ithotn./ins. This is due to thefact that in thefinned annulus, thefins at the lower part of the
annulus promotes buoyancy-driven convection as opposed to the slow conduction melting that
prevails at the bottom pqrt oJ'the plain annulus. Fins with two different heights have been
considered. It is found that by extending the height oJ' the fin to 50% o.f the anntilar gap
about 33.05o% more energy could be stored compared to the bare annulus at the melting time
of 82.37 min.for the identical operating conditions. The el/bcts of.fins with dilferent heights on
the temperature distribution are Jbund to be dffirent. The present study can provide some
useful guidelines for achieving a better energ)) storage system and also can aid in the
design/optimization of the shell-and-tube LHTES devi ces. | en_US |
