Porosity effect of metal foam used in a multi-tube heat exchanger latent thermal energy storage system

Abstract

Since metal foams play an important role in enhancing the performance of performance of phase change materials (PCMs) in latent heat thermal energy storage (LHTES) systems, the effect of different porosity values was analyzed. Two geometries, circular and hexagonal for shells, and circular and elliptical for tubes, were studied in conventional multi-tube heat exchangers. The Darcy-Brinkman-Forchheimer model governed the equations, and enthalpy-porosity approximation was applied during melting. The PCM used was organic RT35HC, combined with aluminum foam with different porosity (ε = 0.85, 0.90, and 0.95 with pore density ω = 20 PPI). Hybrid nano PCM (HyNPCM) with φ = 6.0% volume concentration was formed by mixing graphene oxide and MXene nanoparticles into the PCM. Results indicated that the 0.85 porosity value had the shortest melting time with H-Elliptical model which is 1/5 time of 0.95 porosity. The H-Elliptical reached complete melting 30 seconds earlier than the C-Circle, storing approximately 0.7% more energy.