Özet:

Bio-based Carbon Nanotubes (CNTs) have received significant research attention owing to their comparative advantages of great level stability, simplistic use, low toxicity and overall environmental friendliness. New potentials for improvement in heat transfer applications are presented due to their high aspect ratio, high thermal conductivity, viscosity and special surface area. Phonons have been identified as being responsible for thermal conductivities in carbon nanotubes. Therefore, in order to understand the mechanism of heat conduction in CNTs, investigations relating to the dissimilarity between the varieties of phonon modes must be carried out. Also, knowing the kinds of phonon modes that play the governing role is necessary. In this review, a reference to a different number of studies is made and in addition, the role of phonon relaxation rate primarily controlled by boundary scattering and three-phonon Umklapp scattering process was investigated. Also the roles of shearing time and temperature on viscosity of CNT fluids are discussed. Results show that the phonon modes are sensitive to a number of nanotube conditions such as: diameter, length, temperature, defects and axial strain. At a low temperature (<100K) the thermal conductivity increases with increasing temperature. A small nanotube size causes phonon quantization which is apparent in the thermal conductivity at lesser temperatures. The various viscosity experiments from literature shows that the kinematics viscosity of nanofluids was increased with a corresponding decrease in the temperature and increase of the CNT concentration.

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