Local Momentum Transfer Process in a Wall Region of an Agitated Vessel Equipped with an Eccentric Impeller

Abstract

The results of the experimental studies of local momentum transfer process in the region of the cylindrical wall of an agitated vessel equipped with an eccentric axial flow impeller are presented. The data for eccentrically located impellers both, propeller and HE 3 impeller, differing in the operating liquid pumping mode were compared. In total, 5120 experimental points for both impellers were obtained on the basis of the electrochemical experiments for each of the tested impeller. Axial and angular distributions of the shear rate and friction coefficient in the agitated vessel without baffles were found within the turbulent regime of the Newtonian liquid flow. Local shear stress, dynamic velocity and energy dissipated were also identified in this region of the wall. The results of the study show that the profiles of the transport coefficients depend strongly on the eccentricity e/R, axial and angular coordinates, liquid circulation imposed by axial flow impeller, and liquid turbulence in the agitated vessel. The distributions of the quantities which describe momentum transfer process in the region of the cylindrical wall of the agitated vessel as the function of the e/R, z/H, j/2π, and Re number were approximated mathematically for both impellers by means of eqs 6-9. Averaged values of the local quantities, obtained as a result of the numerical integration, were described by means eqs 12-17. The eqs 6-9 and 12-17 have no equivalent in the open literature concerning this subject.

Local Heat Transfer Process for a Gas–Liquid System in a Wall Region of an Agitated Vessel Equipped with the System of CD6-RT Impellers

“…Diffusion current I d representative for a given measuring point was calculated automatically based of the averaged value from the sampling. This experimental method was described in detail in refs , , and .…”

Experimental Modelling of Local Heat Transfer Process for a Gas-liquid System in an Agitated Vessel with the System of A 315 – RT ImpellersExperimental Modelling of Local Heat Transfer Process for a Gas-liquid System in an Agitated Vessel with the System of A 315 – RT Impellers

“…Electrochemical measurements of the local heat transfer coefficient a were carried out by means of the computer-aided method. This method was described in detail in papers 22,26,27,54 . In an electrochemical method, diffusion current I d , proportional to the local mass transfer coefficient k A , is measured and an analogy between mass and heat transfer processes is assumed, i.e.,…”