11 PCM-Metal Foam Composite Systems for Solar Energy Storage
215
foam-PCM systems using the two equation non-equilibrium approach with different
interface heat transfer coefficients (Mesalhy et al. 2005; Srivatsa et al. 2014; Yang
et al. 2018).
Volume averaged models can predict the overall heat transfer characteristics and
melting pattern. However, they cannot capture the localized heat transfer between the
metal foam and PCM accurately. This is particularly problematic for systems which
have similar porosities but different foam structures as the governing equations for
the volume averaged models are functions of porosities. These models also may not
capture the convection pattern accurately as convection in metal foams is dependent
on the foam structure itself.
Pore-scale models. The primary distinguishing feature of pore-scale models (Ren
et al. 2017, 2018; Dinesh and Bhattacharya 2019; Abishek et al. 2018; Deng et al.
2017) is that they resolve the metal foam structure in the model. Metal foam geometry
is modelled by using various geometry creation techniques (Dinesh and Bhattacharya
2019; Boomsma et al. 2003; Wang and Pan 2008; Abishek et al. 2017). It is assumed
that the porous region in the metal foam is filled with PCM. These models can capture
the heat transfer between the metal foam and PCM accurately as the effect of foam
structure is present in the model. Simulations based on these models have shown
that the pore structure plays an important role in determining the energy transfer
characteristics of the system (Ren et al. 2017; Dinesh and Bhattacharya 2019). The
main drawback of pore-scale models is the increased computational effort required
as very fine numerical grid is necessary to capture the foam structure. A typical
pore-scale model (Dinesh and Bhattacharya 2019) has been discussed in details in
Sect. 11.5.1.
11.5 Case-Studies
11.5.1 Numerical Model and Problem Description
In this section, the effects of important design parameters described in Sect. 11.3
are studied by performing pore-scale simulations of melting for a metal foam-PCM
composite energy storage system. Five different comparative studies are performed to
see the effect of different foam material, different PCM, change in porosity, change
in pore size and overall system size. For performing the simulations, the model
described in (Dinesh and Bhattacharya 2019) is used. The main characteristics of the
model are described briefly in the subsequent paragraphs. For more details, one can
refer to Dinesh and Bhattacharya (2019).
Problem description. For the comparative studies, a cuboidal domain with heating
from the bottom is considered. It is assumed that all the other sides are insulated.
The domain is initially held at a certain temperature below the melting temperature
215
foam-PCM systems using the two equation non-equilibrium approach with different
interface heat transfer coefficients (Mesalhy et al. 2005; Srivatsa et al. 2014; Yang
et al. 2018).
Volume averaged models can predict the overall heat transfer characteristics and
melting pattern. However, they cannot capture the localized heat transfer between the
metal foam and PCM accurately. This is particularly problematic for systems which
have similar porosities but different foam structures as the governing equations for
the volume averaged models are functions of porosities. These models also may not
capture the convection pattern accurately as convection in metal foams is dependent
on the foam structure itself.
Pore-scale models. The primary distinguishing feature of pore-scale models (Ren
et al. 2017, 2018; Dinesh and Bhattacharya 2019; Abishek et al. 2018; Deng et al.
2017) is that they resolve the metal foam structure in the model. Metal foam geometry
is modelled by using various geometry creation techniques (Dinesh and Bhattacharya
2019; Boomsma et al. 2003; Wang and Pan 2008; Abishek et al. 2017). It is assumed
that the porous region in the metal foam is filled with PCM. These models can capture
the heat transfer between the metal foam and PCM accurately as the effect of foam
structure is present in the model. Simulations based on these models have shown
that the pore structure plays an important role in determining the energy transfer
characteristics of the system (Ren et al. 2017; Dinesh and Bhattacharya 2019). The
main drawback of pore-scale models is the increased computational effort required
as very fine numerical grid is necessary to capture the foam structure. A typical
pore-scale model (Dinesh and Bhattacharya 2019) has been discussed in details in
Sect. 11.5.1.
11.5 Case-Studies
11.5.1 Numerical Model and Problem Description
In this section, the effects of important design parameters described in Sect. 11.3
are studied by performing pore-scale simulations of melting for a metal foam-PCM
composite energy storage system. Five different comparative studies are performed to
see the effect of different foam material, different PCM, change in porosity, change
in pore size and overall system size. For performing the simulations, the model
described in (Dinesh and Bhattacharya 2019) is used. The main characteristics of the
model are described briefly in the subsequent paragraphs. For more details, one can
refer to Dinesh and Bhattacharya (2019).
Problem description. For the comparative studies, a cuboidal domain with heating
from the bottom is considered. It is assumed that all the other sides are insulated.
The domain is initially held at a certain temperature below the melting temperature