Thermal transport properties at interface of fatty acid esters enhanced with carbon-based nanoadditives

Abstract

There has been growing interest in the development and use of sustainable, bio-based phase change materials (PCMs), as an alternative to conventional paraffinic PCMs. Among possible choices, two fatty acid esters, i.e., methyl palmitate and methyl 9,10-dihydroxystearate, are investigated in this study. The physical properties of these two bio-based PCMs are first characterized using the molecular dynamics method. Upon validating the results with the experimental test data, the reverse non-equilibrium molecular dynamics (RNEMD) method is employed to evaluate the thermal performance of these two PCMs in both pristine and enhanced conditions. The interplay between the molecular structure and thermal properties is then determined using a radial distribution function analysis. To address the issue of low thermal conductivity of these two PCMs, the possibility of enhancing them with carbon-based nanoaddivities, such as graphene, is investigated. The interface between the PCM matrix and the graphene filler is modeled at nanoscale and the interfacial thermal conductance is characterized using the RNEMD simulations. A separate set of vibration power spectra analyses are conducted to shed light on the thermal energy transfer mechanisms across the interface of bio-based PCMs and carbon-based nanoadditives. The outcome of this study is expected to transform the design and implementation of PCMs for sustainable energy storage technologies.