Phase change nanocomposites with tunable melting temperature and thermal energy storage density

Abstract

Size-dependent melting decouples melting temperature from chemical composition and provides a new design variable for phase change material applications. To demonstrate this potential, we create nanocomposites that exhibit stable and tunable melting temperatures through numerous melt-freeze cycles. These composites consist of a monodisperse ensemble of Bi nanoparticles (NPs) embedded in a polyimide (PI) resin matrix. The Bi NPs operate as the phase change component whereas the PI resin matrix prevents nanoparticle coalescence during melt-freeze cycles. We tune melting temperature and enthalpy of fusion in these composites by varying the NP diameter. Adjusting the NP volume fraction also controls the composite's thermal energy storage density. Hence it is possible to leverage size effects to tune phase change temperature and energy density in phase change materials.

Metal Matrix–Metal Nanoparticle Composites with Tunable Melting Temperature and High Thermal Conductivity for Phase-Change Thermal Storage

“…Our prior work on Bi nanoparticles in polymer matrices showed different ranges of melting temperature and enthalpy of fusion in similarly-sized nanoparticles (218 -240°C and 12.9 -42.1 J/g Bi ). 45 This indicates that the melting temperature and enthalpy of fusion of nanoparticles is a function of both size and surrounding environment. Past observations of size-dependent enthalpy of fusion required the use of sophisticated nanocalorimetry techniques.…”

Preparation and performance of novel form-stable composite phase change materials based on polyethylene glycol/White Carbon Black assisted by super-ultrasound-assisted

“…It is imperative to closely monitor phase change materials (PCMs) used for storing thermal energy [4]. In recent years, PCMs have become extremely important in the fields of solar engineering, solar heating systems, building energy conservation, heat pumps, air-conditioning systems, thermal insulation and regulation, and waste heat recovery [5][6][7], because of their advantages such as isothermal behavior, small temperature differences between heat storage and release, and high storage density [8][9][10][11][12][13].…”

The melting and solidification of nanowires

“…This term occurs due to an assumption that latent heat is released at the bulk melt temperature. Obviously this is incorrect (see the experimental results in Liu and Wang (2013), for example); so we prefer the corrected form derived in Myers (2016) which involves latent heat release at the actual phase change temperature.…”