Effect of metal matrix and foam porosity on thermal performance of latent heat thermal storage for solar thermal power plant

Abstract

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.