Abstract: The present invention relates to processes for preparing a stable suspension of carbon nanoparticles in a thermal transfer fluid to enhance thermal conductive properties, viscosity, and lubricity. One process is to disperse carbon nanoparticles directly into a thermal transfer fluid and other additives in the present of surfactants with intermittent ultrasonication. The second process is carried out in three stages. First, carbon nanoparticles are dispersed into a volatile solvent. Then, a thermal transfer fluid, surfactants, and other additives are added into this intermediate dispersion and mixed thoroughly. At last, the volatile solvent is removed to produce a uniformly dispersed nanofluid. The third process is to disperse carbon nanoparticles at an elevated temperature into a homogeneous mixture of surfactants and other additives in a thermal transfer fluid with help of a physical agitation.

Abstract: The present invention relates to a process for preparing a stable suspension of carbon nanoparticles in a hydrophilic thermal transfer fluid to enhance thermal conductive properties and other characteristics such as freezing point of an antifreeze coolant. The process involves the step of dispersing carbon nanoparticles directly into a mixture of a thermal transfer fluid and other additives in the present of surfactants with intermittent ultrasonication. The present invention also relates to the composition of a hydrophilic nanofluid, which comprises carbon nanoparticles, particularly carbon nanotubes, a hydrophilic thermal transfer fluid, and at least one surfactant. Addition of surfactants significantly increases the stability of nanoparticle dispersion.