Enhancement of thermal conductivity of materials using different forms of natural graphite

Abstract

The quest for improvement of thermal conductivity in every area including aerospace structures is gaining momentum as the modern day technology is embedded with electronics which generate considerable amounts of heat energy. In some other applications, the thermal energy must be absorbed or released at a very fast rate. Natural graphite is highly anisotropic and has excellent thermal and electrical conductivity in a-direction hence; it is one of the potential candidates to enhance thermal conductivity. This paper encompasses various preparation routes used to enhance thermal conductivity in materials/composites using graphite flakes in its natural and treated forms along with characterization results of thermal conductivity and/ or electrical resistivity where available. Addition of graphite has shown to improve thermal conductivity in some materials by 30-130 times whereas one method of preparation described here shows composites to have thermal conductivity as high as 750 W/m K.

Experimental and numerical study on the effective thermal conductivity of paraffin/expanded graphite composite

“…Being around 90% volume of EG connected honeycomb holes, this material has a higher porosity for increasing absorbability and a larger specific surface area than that of graphite. EG with these desirable properties hence has attracted researchers paying more attentions in developing high heat performance of TES [12,[16][17][18][19][20][21].…”

Development of the inorganic composite phase change materials for passive thermal management of Li‐ion batteries: material characterization

“…The differences in the impregnation percentage, on one side, can be attributed to lower viscosity of the paraffin wax (Table ). On the other side, as a result of the intercalation process, EG may contain functional acids and OH groups that induce EG affinity to polymers and organic compounds . In the case of inorganic PCM, the same affinity does not exist, which results in a minor volume of the impregnated inorganic PCM.…”

“…(D)). It can be presumed that sulfur is part of functional groups of acids that appear in the EG as a result of the intercalation process …”

“…The resulting EG has a worm‐like structure with the multipores of different diameters. The layered structure of the EG is similar to the one of nanoclays, but EG is much cheaper, with superior electrical, mechanical and thermal properties . Nowadays, the EG flakes are widely available commercially.…”

“…The layered structure of the EG is similar to the one of nanoclays, but EG is much cheaper, with superior electrical, mechanical and thermal properties. 25 Nowadays, the EG flakes are widely available commercially. In this work, the expanded graphite matrix was used to enhance thermal conductivity of the selected PCM.…”