Towards improving charge/discharge rate of latent heat thermal energy storage (LHTES) by embedding metal foams in phase change materials (PCMs)

摘要

PCMs-metal foams composite has been used in LHTES for improving the charge discharge rate of the system. Due to the high exergy efficiency of cold energy storage (CES) systems, cold charging/discharging behaviours of the PCM-metal foams composite in CES was particularly analysed. The product solution method was adopted to synthesize the analytical solutions for multi-dimensional problems. The heat transfer model for the PCM-metal foams composite was established based on the concept of average volume of the composite materials. The internal convection was ignored due to the relatively small thermal resistance caused by the buoyancy force inside the PCM capsule. The case study of paraffin showed that the effective thermal diffusivity and effective thermal conductivity were improved by more than 21 times due to the embedding of Al foams in the PCM. As a result, the temperature of the PCM-metal foams composite became more uniform, while the cold discharge rate was improved by approximately 8 times. The comparative study of different PCMs with/without Al foams indicated the value of effective thermal diffusivity in weighing the charge/discharge rate in LHTES systems. (C) 2016 Elsevier B.V. All rights reserved.