Enhanced thermal conductivity of n-octadecane containing carbon-based nanomaterials

• DOI: 10.1007/s00231-015-1678-0
• Publication Date: 2015-09-24T07:04:35Z
• Authors: Sadegh Motahar; Ali A. Alemrajabi; Rahmatollah Khoda...
• Keywords: Octadecane; Nanomaterials; Carbon fibers

In the present study, carbon-based nanomaterials including multiwalled carbon nanotubes (MWCNTs) and vapor-grown carbon nanofibers (CNFs) were dispersed in n-octadecane as a phase change material (PCM) at various mass fractions of 0.5, 1, 2 and 5 wt% by the two-step method. The transient plane source technique was used to measure thermal conductivity of samples at various temperatures in solid (5–25 °C) and liquid (30–55 °C) phases. The experimental results showed that thermal conductivity of the composites increases with increasing the loading of the MWCNTs and CNFs. A maximum thermal conductivity enhancement of 36 % at 5 wt% MWCNTs and 5 °C as well as 50 % at 2 wt% and 55 °C were experimentally obtained for n-octadecane/MWCNTs samples. Dispersing CNFs into n-octadecane raised the thermal conductivity up to 18 % at 5 wt% and 10 °C and 21 % at 5 wt% and 55 °C. However, the average enhancement of 19 and 21 % for solid and liquid phases of MWCNTs composite as well as 33 and 46 % for solid and liquid phase of CNFs promised a better heat transfer characteristics of MWCNTs in n-octadecane. A comparison between results of the present work and available literature revealed a satisfactory enhancement of thermal conductivity. For the investigated n-octadecane/MWCNTs and n-octadecane/CNFs composites, a new correlation was proposed for predicting the thermal conductivity as a function of temperature and nanomaterials loading.