Effect of fumed silica additive on supercooling, thermal reliability and thermal stability of Na2HPO4·12H2O as inorganic PCM

•Novel composite PCM was fabricated by dispersing FS into DHPD.•The supercooling degree of DHPD was reduced effectively by pore structure of FS.•Influence factors of the supercooling degree of DHPD was discussed experimentally.•Excellent thermophysical property was achieved by DHPD with addition of 2 wt% FS.