Dmitriy Guzei

Measurement of the heat transfer coefficient of a nanofluid based on water and copper oxide particles in a cylindrical channel

The heat transfer coefficient of a nanofluid in a cylindrical channel under constant heat flux density at the walls is measured experimentally. The studied fluid was prepared based on distilled water and CuO nanoparticles with an average size of 55 nm. To stabilize the nanofluid, a biopolymer was used. The volume concentration of nanoparticles was in the range from 0.25 to 2%. It is shown that the nanofluid is Newtonian at the lowest concentration of nanoparticles, and in all other cases, its rheology is described well by the model of a power-law fluid. A correlation of the dependence of the parameters of this model on the concentration of nanoparticles is obtained. It is found that the presence of nanoparticles greatly intensifies the heat transfer.

Numerical modeling of gas-liquid flows in mini- and microchannels

The paper presents the results of testing a methodology for calculating two-phase flows in mini- and microchannels. The numerical methodology is based on the known fluid-in-cell method (VOF method) and the CSF procedure to account for surface tension forces. Solutions of several test problems of two-phase flow in microchannels, including the water-oil emulsion flow and gas-liquid flow in microchannels of the T-type and the stationary slug flow in a circular minichannel, were considered with the aid of this technique. Comparisons of numerical results with experimental data were carried out. A good agreement between the results was obtained.

Experiment-Calculated Investigation of the Forced Convection of Nanofluids Using Single Fluid Approach

An experiment-calculated investigation of forced convection of nanofluids based on Al2O3 nanoparticles was carried out. The hydrodynamic description and a model of homogeneous nanofluids were used. The homogeneous nanofluids model assumes that the hydrodynamics and heat transfer can be described by conventional Navier-Stokes and heat transfer equations with the physical parameters corresponding to nanofluids. The results showed that this model very well described the experimental data in some cases. However, in some other cases, there are discrepancies between experiment and theory that can be explained by the real heterogeneity of nanofluids and the errors in the experimental determination of thermal conductivity and viscosity of nanofluids.

Investigation of forced convection ZrO2 nanofluid in a channel with artificial roughness

The paper presents the results of experimental study of turbulent forced convection of water-based nanofluid with ZrO2 nanoparticles. Volumetric concentration of the nanoparticles in the experiments was equal to 4%. The average particle size was 105nm. The study was carried out for a smooth round tube and round tube with knurling ring. The effect of additives of ZrO2 nanoparticles on the average heat transfer coefficient and the pressure drop in the channel was investigated. Has been shown that the intensification of heat transfer by using nanofluid weakly dependent on the shape of the channel, and determined only by the properties nanofluid.