Employing perforated copper foam to improve the thermal performance of latent thermal energy storage units

Abstract

The performance of latent thermal energy storage units (LTESU) is limited by the low thermal conductivity of phase change materials (PCM). Copper foam can enhance PCM's heat conduction, but its structure inhibits the internal natural convection. Based on this, the perforated copper foam was proposed to enhance the natural convection of PCM. The contrast experiment built three LTESUs (Namely, the LTESU only with the copper tube (LTESU-CT), the LTESU with full copper foam (LTESU-FCF) and the LTESU with perforated copper foam (LTESU-PCF). The melting and solidifying state, temperature distribution, and thermal efficiency were compared in three LTESUs during thermal charging and discharging processes. Results showed using copper foam could enhance the thermal performance of LTESU obviously and the perforated copper foam could generate the convective heat exchange, which had a time-average Nusselt number 34.1 % higher in LTESU-PCF than that in LTESU-FCF. Due to the reduced heat transfer area, LTESU-PCF had the lower thermal efficiency than LTESU-FCF, but its thermal storage capacity and release capacity were 6.4 % and 1.4 % higher than that in LTESU-FCF, respectively. It was confirmed that employing perforated copper foam could s enhance the natural convection and heat transfer of PCM significantly, but the perforation parameter still needs to be further explored to achieve higher thermal performance.