Response surface method optimization of innovative fin structure for expediting discharging process in latent heat thermal energy storage system containing nano-enhanced phase change material

Abstract

Performance enhancement of Latent Heat Thermal Energy Storage Systems (LHTESS) containing Phase Change Material (PCM) during discharging process has been discussed in present study. Storage and retrieval of thermal energy in LHTESS occur during solid-liquid phase change. This system is used to establish balance between energy supply and demand, but the main restriction for this system is the weakness of thermal conductivity of PCM. Several enhancement techniques are employed in order to overcome this problem. In the present study, the method of nanoparticles dispersion in the pure PCM to make Nano-Enhanced Phase Change Material (NEPCM) and adding fins with innovative structure are applied to expedite solidification process. The abovementioned techniques are analyzed separately. First the effect of geometry parameters of the fin on the system performance is investigated and after that, Response Surface Method optimization is employed in order to find the best fin array. Then the effect of volume fraction on solidification rate is studied and comparison between nanoparticle dispersion and adding fin is carried out. The numerical approach in this paper is Standard Galerkin Finite Element Method. In this work, the innovative fin configuration is inspired from snowflake crystal structure and the efficiency of nanoparticles dispersion in PCM and adding fin with different structures on LHTESS performance have been examined from the viewpoint of either discharging expedition or maximum energy storage capacity, which are proposed as the novelties here. Results indicate that employing fin of any structure, is a more efficient enhancement technique for discharging process of LHTESS in comparison with nanoparticle dispersion from the viewpoint of both maximum energy storage capacity and solidification rate. Also it is found that immersing optimized Snowflake shaped fin into the PCM enhances significantly the solidification rate in comparison with LHTESS with common fin arrays.