Improved thermal conductivity of PEG-based fluids using hydrogen bonding and long chain of nanoparticle

An investigation was conducted to examine the extent to which the thermal conductivity of materials in polyethylene glycol (PEG) fluids could be improved using the concept of hydrogen bonding and long chains. Boron nitride (BN), hydroxyl functionalized multiwall nanotube (MWNT-OH), and carbon nanofibers (CNFs) were mixed and exfoliated to form hydrogen bonds between the particles and the PEG fluids. Following this bonding process, clear enhancements in the thermal conductivity were observed. In addition, the long chain boron nitride nanotubes (BNNTs) and carbon nanofibers were shown to significantly enhance the thermal conductivity, due to the resulting increase in the contact and interfacial surface areas. The results of this experimental investigation indicated that PEG400 with a loading of 7.5 wt% MWNT-OH yielded a thermal conductivity increase as high as 89.7% over the base fluid. PEG400 loaded with a combination of 2 wt% CNF and 2 wt% BNNT resulted in a thermal conductivity increase of 73.1%. These results are significantly higher than the best results previously reported in the literature and may in part be attributed to the use of a three roll milling technique to enhance contact. The results presented here will open the way for further exploration of the use of novel phase change materials for thermal energy storage applications.