基于放电动力学评估氧化铝纳米颗粒辅助的NaNO3储能潜力

Abstract Sodium nitrate (NaNO 3 ) is a phase change material (PCM) with high melting temperature and latent heat but has a relatively lower thermal conductivity. Alumina (Al 2 O 3 ) nanoparticles were added to NaNO 3 using ball milling to prepare Al 2 O 3 -NaNO 3 nanocomposite. The effect of alumina nanoparticle concentration (up to 2 wt%) on phase change transition characteristics and thermal conductivity was investigated. Experiments on the discharge of stored latent heat were performed for NaNO 3 and Al 2 O 3 -NaNO 3 nanocomposite with well-agitated Therminol-55 and air under forced convection as the two heat transfer fluids. Enhancements in thermal conductivity and specific heat were observed with Al 2 O 3 nanoparticles’ addition. The loss in latent heat was attributed to the solid nanoparticles present in the nanocomposite. The Al 2 O 3 -NaNO 3 nanocomposite containing Al 2 O 3 at the concentration of 1 wt% resulted in a 15 % reduction in solidification time, 11.9 % & 25.1 % enhancements in the PCM side heat transfer coefficient for latent heat recovery using Therminol-55 and air as the coolants, respectively. The corresponding enhancements in the PCM side heat transfer coefficient for solid phase sensible heat recovery using Therminol-55 and air as the coolants were 21.4 % & 198 %, respectively. These results indicate that Al 2 O 3 -NaNO 3 nanocomposite can offer significant improvement in the heat transfer performance for about 500 cycles before the latent heat loss becomes significant.