SIMULATION OF THE INTENSIFICATION OF CONVECTIVE HEAT TRANSFER BY NANOFLUIDS WITH CARBON NANOTUBES

The intensifi acation of convective heat transfer by nanofl uids based on isopropyl alcohol and ethylene glycol with carbon nanotubes in a cylindrical channel with a heat fl ow of constant density at the channel wall was investigated. It was established experimentally that the indicated nanofl uids are pseudoelastic and, therefore, their rheology is well defi ned by the model of a power-law fl uid. It is shown that the velocity of fl ow of such a nanofl uid in the region of the channel wall is increased, and the velocity profi le of this fl ow is fl attened. The indicated eff ect enhances with increase in the concentration of carbon nanotubes in the nanofl uid. It was established that the deformation of the velocity profi le of the nanofl uid leads to an increase in its heat transfer coeffi cient, which is one of the mechanisms of intensifi cation of convective heat transfer by nanofl uids with carbon nanotubes. The increase in the heat transfer coeffi cient of a nanofl uid, as compared to that of its base fl uid, is especially large for the nanofl uids with singlewalled carbon nanotubes. In the case of their concentration 0.25% in a nanofl uid based on isopropyl alcohol, the heat transfer by the nanofl uid is larger by 2.7 times that the heat transfer by its base fl uid, and the coeffi cient of thermohydraulic effi ciency of the nanofl uid fl ow at small Reynolds numbers can reach 3.5.
The intensifi acation of convective heat transfer by nanofl uids based on isopropyl alcohol and ethylene glycol with carbon nanotubes in a cylindrical channel with a heat fl ow of constant density at the channel wall was investigated. It was established experimentally that the indicated nanofl uids are pseudoelastic and, therefore, their rheology is well defi ned by the model of a power-law fl uid. It is shown that the velocity of fl ow of such a nanofl uid in the region of the channel wall is increased, and the velocity profi le of this fl ow is fl attened. The indicated eff ect enhances with increase in the concentration of carbon nanotubes in the nanofl uid. It was established that the deformation of the velocity profi le of the nanofl uid leads to an increase in its heat transfer coeffi cient, which is one of the mechanisms of intensifi cation of convective heat transfer by nanofl uids with carbon nanotubes. The increase in the heat transfer coeffi cient of a nanofl uid, as compared to that of its base fl uid, is especially large for the nanofl uids with singlewalled carbon nanotubes. In the case of their concentration 0.25% in a nanofl uid based on isopropyl alcohol, the heat transfer by the nanofl uid is larger by 2.7 times that the heat transfer by its base fl uid, and the coeffi cient of thermohydraulic effi ciency of the nanofl uid fl ow at small Reynolds numbers can reach 3.5.
Author:  V. Ya. Rudyak, D. V. Guzei, and A. V. Minakov
Keywords:  nanofl uid, thermohydraulic effi ciency, heat transfer, carbon nanotubes
Page:  427