Enhancing the Heat Storage Performance of a Na₂HPO₄·12H₂O System via Introducing Multiwalled Carbon Nanotubes

Abstract

The hydrated salt disodium hydrogen phosphate dodecahydrate (DHPD, Na 2 HPO 4 •12H 2 O) has a suitable phase transition temperature and high latent heat of phase transition. Still there are problems such as supercooling, phase separation, and low thermal conductivity. In this paper, DHPD, sodium carboxymethyl cellulose (CMC), aluminum oxide (Al 2 O 3 ), and poly-(vinylpyrrolidone) (PVP) are used to configure DHPD-CAP to suppress supercooling and phase separation successfully. Multiwalled carbon nanotubes (MWCNTs) are used to stabilize DHPD-CAP phase-change materials and improve the thermal conductivity of pure DHPD. Further studies show only a physical interaction between MWCNTs and DHPD, and no new phases are generated. The addition of MWCNTs can also promote the nucleation of the DHPD-CAP composite, and the corresponding latent heat of phase change shows a trend of increasing and then decreasing with the increase of MWCNT content. Compared with DHPD after one cycle, the latent heat of DHPD-CAP/MWCNT 4 increases by 36.19%. With the addition of MWCNTs, the thermal stability of the composites is improved compared to pure DHPD. The DHPD-CAP/MWCNT 4 composite has good stability after many cycles.

Carbon-Enhanced Hydrated Salt Phase Change Materials for Thermal Management Applications

“…Jia's group [80] developed a CVD method and successfully synthesized aligned CNTs (a-CNTs) by using propylene as the carbon source (Figure 5c), which decomposed on vermiculite-supported catalysts in a fluidized bed reactor. Compared with randomly In addition to the enhancement of thermal conductivity, Ding et al [83] reported that MWCNTs together with SCMC altered the phase change temperature and the fusion enthalpy of DHPD. In contrast to pure DHPD, which exhibited two melting peaks at 33.42 • C and 45.85 • C, the DHPD-SCMC-MWCNT composites effectively suppressed the phase separation of DHPD and the formation of low-grade salt Na 2 HPO 4 •7H 2 O, showed a single melting peak, and increased the latent heat enthalpy by 36.19%.…”

Hybrid Polymer Salogels for Reversible Entrapment of Salt-Hydrate-Based Thermal Energy Storage Materials

“…Moreover, polymer thickeners do not provide shape stabilization or prevent leakage of molten PCMs (Figure S1). − In contrast, covalently crosslinked polymer gels, which also often require large polymer amounts (5%–60% by weight), provide shape stabilization (Figure S1). − However, the permanent nature of the crosslinks renders these materials irreversible, making filling and removal from thermal energy storage modules impossible.…”