Paper presented to the 3rd Southern African Solar Energy Conference, South Africa, 11-13 May, 2015.
In this paper, the thermal performance of latent heat thermal
storage system using metal matrix and foam is investigated for
the medium temperature (~ 200 ⁰C) and medium power (~1
MW) ORC-based solar thermal power plant. The latent heat
storage system using phase change materials (PCMs) is an
effective way of storing thermal energy and has the advantage
of high-energy storage density which makes the storage system
compact. The main drawback of PCMs like molten salts is its
low thermal conductivity (~0.2-0.5 W/m.K) which inhibits heat
transfer to/from PCM. To overcome this, metal matrix and
foam are introduced in PCM as thermal conductivity enhancers
(TCE) to improve the heat transfer rate. The volume averaging
technique for porous medium is adopted to model the metal
foam and matrix embedded in PCM. The fluid flow and phase
change in porous medium is modelled using single domain
enthalpy–porosity technique. A parametric study is performed
to show the effect of porosity of the metal matrix and foam on
the outlet temperature of heat transfer (HTF) during charging/
discharging period. It is found that the TES with 0.7 metal
matrix and foam porosity performs better than TES with PCM
and any other porosity.
The heat transfer properties of phase change materials (PCMs) are of importance for the efficiency assessment on the heat storage and release in solar thermal systems. Previous research results demonstrate that the increase ...