Presence Of Swirling Flow Research Articles

Effect of swirl flow on whey protein fouling and cleaning in a straight duct

Whey protein fouling is a complex phenomenon involving several mechanisms. Product, surface properties and process parameters interact simultaneously. This experimental work focuses on the effect of a swirl flow on whey protein fouling and cleaning in a straight tube, independently of any other factors. In a holding section after a heating zone composed of a plate heat exchanger, the dry deposit mass obtained from a straight tube was compared with that obtained in the presence of a swirl flow. For varying conditions, namely two protein concentrations, two processing temperatures and two fouling durations, the dry deposit mass increases despite the wall shear stress increase induced by the swirl device. Nevertheless, the cleaning time was found to be significantly shorter in presence of swirl flow in laminar and turbulent conditions. These results reveal that cleaning efficiency can be improved by such a swirl insert, which is seldom used in the food process industry.

Study of the heat-transfer crisis on heat-release surfaces of annular channels with swirl and transit flows

The results of the experimental study of the heat-transfer crisis on heat-release surfaces of annular channels with swirl and transit flow are presented. The experiments were carried out using electric heated annular channels with one and (or) two heat-release surfaces. For the organization of transit flow on a convex heat-release surface, four longitudinal ribs were installed uniformly at its perimeter. Swirl flow was realized using a capillary wound tightly (without gaps) on the ribs. The ratio between swirl and transit flows in the annular gap was varied by applying longitudinal ribs of different height. The experiments were carried out using a closed-type circulatory system. The experimental data were obtained in a wide range of regime parameters. Both water heated to the temperature less than the saturation temperature and water-steam mixture were fed at the inlet of the channels. For the measurement of the temperature of the heat-release surfaces, chromel-copel thermocouples were used. It was shown that the presence of swirl flow on a convex heatrelease surface led to a significant decrease in critical heat flows (CHF) compared to a smooth surface. To increase CHF, it was proposed to use the interaction of swirl flows of the heat carrier. The second swirl flow was transit flow, i.e., swirl flow with the step equal to infinity. It was shown that CHF values for a channel with swirl and transit flow in all the studied range of regime parameters was higher than CHF values for both a smooth annular channel and a channel with swirl. The empirical ratios describing the dependence of CHF on convex and concave heat-release surfaces of annular channels with swirl and transit flow on the geometrical characteristics of channels and the regime parameters were obtained. The experiments were carried out at the pressure p = 3.0–16.0 MPa and the mass velocity ρw = 250–3000 kg/(m2s).

Numerical investigation of pulverized coal aero mixture combustion at the presence of flow swirling

Numerical investigation results of burning pulverized coal aero mixture in the presence of swirl flow have been presented. The mathematical model has been chosen allowing describing correctly the pulverized coal combustion processes in the furnace with a swirl burner.