Horizontal Cylindrical Channel Research Articles

Numerical Investigation of Gas-Liquid Two-Phase Flows in a Cylindrical Channel

Two-phase flows are widely encountered in many natural phenomena and industrial processes. The presence of one or more interfaces between the two phases presents a major difficulty which makes the modeling and the simulation of this type of flow complex. This work consists in performing a three-dimensional numerical simulation of a two-phase Hydrogen-Water flow inside a horizontal cylindrical channel. The results are obtained in the form of velocity contours, enthalpy and pressures.

Model To Predict the Concentration of Ultradispersed Particles Immersed in Viscous Media Flowing through Horizontal Cylindrical Channels

An innovative way to upgrade heavy crude oils is the use of ultradispersed catalysts; however, an adequate mathematical expression that describes the mass transfer on this process is still missing. This paper studies the separation and suspension of ultradispersed particles based on their motion through diverse viscous media enclosed in horizontal cylindrical channels. A time-dependent, three-dimensional convective−dispersive model which simulates the transient deposition and suspension of these particles immersed in viscous media inside a horizontal cylinder was developed and solved. This model was also experimentally validated, and its results unveiled the particle and fluid media properties that are necessary to control particle deposition. The experiments were performed using Fe2O3 particles (average sizes of 198 nm) immersed in water−glycerol mixtures with different densities and viscosities subject to different fluid velocities. The effect of the fluid medium properties, the initial particle concent...

A Model To Predict the Concentration of Submicrometer Solid Particles in Viscous Media Confined inside Horizontal Cylindrical Channels

As light oil reserves dwindle, the extraction and processing of heavy crude oils are becoming increasingly important. The use of ultradispersed catalysts (nanometric catalytic particles dispersed in the oil) is considered to be a promising way to upgrade these materials. To simulate such processes, mass transfer of the ultradispersed particles must be estimated. However, an adequate mathematical expression to describe the motion of these particles through viscous media in a horizontal cylindrical channel is still missing. In this paper, we developed and solved a time-dependent, two-dimensional convective−dispersive model, which simulates the transient deposition and suspension of ultradispersed particles immersed in a viscous medium, inside the cross section of a horizontal cylindrical channel in a stagnant situation. The results of the modeling are compared with a series of experiments that permit knowledge of the concentration of the ultradispersed particles inside a horizontal cylinder. These experiments were performed using particles in the submicrometer range (average sizes of 198 nm) and fluid media with diverse densities and viscosities. The effect of the fluid medium properties and the initial particle concentration in the calculation of the dispersion coefficient was also studied. The conditions needed to maintain the solid particles suspended in the liquid medium, contained in a vessel with cylindrical geometry, are also unveiled by the presented model.

A Model To Predict the Concentration of Dispersed Solid Particles in an Aqueous Medium Confined inside Horizontal Cylindrical Channels

The deposition of solid particles in cylindrical channels has received considerable attention, because of its direct application in industry. However, an adequate mathematical expression that studies the separation and suspension of dispersed particles present in horizontal cylindrical channels is still missing. In this paper, we developed and solved a time-dependent, two-dimensional convective-dispersive model that simulates the deposition and suspension of dispersed particles immersed in a fluid medium inside the cross section of a horizontal cylindrical channel in a stagnant situation. The results of the modeling are compared with a series of experiments that permit one to know the concentration of the particles in different points in the cross section of a horizontal cylinder. These experiments were performed using particles in the micrometer range dispersed in an aqueous medium. The conditions that permit to control the suspension and deposition of the particles inside a liquid medium with cylindrical geometry are unveiled by the presented model.

Some aspects of free-convective heat transfer in eddy flow through a horizontal tube

Experimental investigation of unsteady-state free convection in a horizontal cylindrical channel is carried out for the case of non-uniform distribution of heat flux along a channel at a constant temperature on the wall. The averaged temperature field in a gas was investigated on a Mach-Zender interferometer. Hydrodynamic structures were investigated by the smoke visualization technique. Heat fluxes were calculated on the basis of thermocouple measurements. In the case of non-uniform heat flux on the channel wall, the existence of longitudinal large scale hydrodynamic structures has been noted. Longitudinal and lateral Rayleigh numbers varied from 0 to 4 × 10 9 and from 0.8 × 10 4to 1.2 × 10 5, respectively. Investigations were carried out with air, carbon dioxide and helium flows.

Heat and mass transfer between two reservoirs through a liquid interface

This paper reports an experimental study of transient natural convection heat and mass transfer between two large cylindrical reservoirs connected through a short horizontal cylindrical channel at half height. The experimental temperature field transient within the hot and cold tank and in the horizontal duct is reported as well the derived heat transfer and flow rate through the duct. The overall heat transfer Nusselt number is presented as a function of the Rayleigh number.

Laws of formation of a plug of liquid heat-transfer agent. In the vapor channel of a thermal diode heat pipe

The authors present results of a theoretical and experimental study of the formation of a “plug” of liquid heat-transfer agent in the horizontal cylindrical channel of a thermal diode heat pipe in a gravity field.

Investigation of the mass transfer across the interface of two concurrent laminal flowing liquids in a horizontal cylindrical channel—I Experimental results

The concentrations of the solute (pyridine) were measured by means of modified liquid scintillation techniques to within 0.66,μm of the interface as well as in the bulk of the organic (toluene) phase during the solute transfer from the toluene to the water phase at different temperatures, flow rates and solute concentrations. These measurements allow the comparison of the mass transfer resistance of the diffusive transfers with the interfacial resistance. In extremely pure systems the interfacial resistance is negligible in comparison with the resistances of the diffusive transfers. In the presence of surface active agents the interfacial resistance strongly increases and exceeds those of the diffusive transfers. The solute transfer from the water to the toluene phase because of the Marangoni instabilities could only be considered qualitatively. The concentrations of the solute (pyridine) to within 0.66 μm of the interface and in the bulk of the organic phase (toluene) during the solute transfer from the organic to water phase in a horizontal cylindrical flow channel with concurrent flow of the phases at different temperatures, flow rates and solute concentrations were measured by means of a modified liquid scintillation technique. These measurements allow the comparison of the mass transfer resistances of the diffusive transfers to and from the interface with the interfacial resistance. In extremely pure systems, the solute concentration at the interface quickly drops to very low values with increasing distance from the channel entrance, which indicates that the mass transfer resistance of the interface is negligible in comparison with the resistances of the diffusive transfers in the laminar flow region. In the presence of surface active agents (LPC) the solute concentration to within 0.66 μm of the interface dramatically increases and exceeds the solute concentration in the bulk of the toluene phase. This indicates a strong increase of the mass transfer interfacial resistance. The high solute concentration at the interface, exceeding its bulk concentration, is caused by the enrichment of the solute in the interface, which was measured by the interfacial tension depression in the presence of the solute. Because the solute transfer from the water to the toluene phase causes interfacial (Marangoni) instabilities, which increase the geometrical interfacial area due to uncontrolled eruptions and formations of microemulsions, the solute concentration could not be measured to within 0.66 μm of the interface in the toluene phase during the water to toluene solute transfer. Only qualitative statements could be made with regard to the area of the interface. Further measurements are necessary in order to determine quantitative relationships with regard to the mass transfer interfacial resistance as a function of different process parameters

Influence of surface tension on damping of the oscillations of a viscous incompressible fluid in a cylindrical channel

A numerical calculation is made of small oscillations of a viscous incompressible fluid that fills half of a horizontal cylindrical channel. The calculation is made with and without allowance for surface tension. The results of the calculation show that allowance for surface tension increases the damping of the oscillations. The general properties of problems of the normal oscillations of a heavy and capillary viscous incompressible fluid were studied in [1–3], in which the possibility of applying the Bubnov-Galerkin method to these problems was pointed out. A method for calculating the oscillations of a viscous incompressible fluid that partly fills an arbitrary vessel at large Reynolds numbers was developed in [3–5].

Velocity profiles of stationary two-phase laminar flow in horizontal, cylindrical channels

The velocity profiles were calculated for stationary two-phase laminar flows in horizontal cylindrical channels by means of solving the Navier-Stokes e

Heating of ions and diffusion at low-frequency instability in plasma with an electron beam: U T Astrelin et al, Zh tekh Fiz, 40 (6), June 1970, 1185–1193 ( in Russian)

Experimental investigation of unsteady-state free convection in a horizontal cylindrical channel is carried out for the case of non-uniform distribution of heat flux along a channel at a constant temperature on the wall. The averaged temperature field in a gas was investigated on a Mach-Zender interferometer. Hydrodynamic structures were investigated by the smoke visualization technique. Heat fluxes were calculated on the basis of thermocouple measurements. In the case of non-uniform heat flux on the channel wall, the existence of longitudinal large scale hydrodynamic structures has been noted. Longitudinal and lateral Rayleigh numbers varied from 0 to 4 × 109 and from 0.8 × 104to 1.2 × 105, respectively. Investigations were carried out with air, carbon dioxide and helium flows.