Experimental evaluation of the effect of perforated spiral fins on the thermal performance of latent heat storage units

Abstract

The spiral fins are widely employed as an innovative fin configuration in latent heat storage units (LHSU) to improve the poor thermal conductivity of Phase Change Material (PCM). Its persistent annulus promotes heat exchange in PCM, but still interferes with buoyancy-driven natural convection. Perforation is a potential solution to facilitate natural convection. Based on this, the thermal properties of the punctured spiral finned LHSU were experimentally studied. An experimental setup was constructed with three spiral finned LHSUs, two of which were installed with perforated spiral fins with 16 mm and 12 mm perforation diameters. The axial and radial temperature distribution, heat transfer characteristics and efficiency were evaluated for three LHSUs. Experimental results showed that the thermal performance of LHSU was improved remarkably by using perforated spiral fins with higher heat benefits achieved at lower heat transfer areas. The thermal efficiency and average heat flux reached 63.4 % and 1370.7 W/m2 respectively, while the average Nusselt number was 44.0 % higher than that of the solid fin. For the same perforation area, fins with higher diameter perforations achieve superior thermal properties and stronger convective heat transfer, while fins with lower diameter perforations continue to limit natural convection.