Effects Of Liquid Properties Research Articles

Effect of fluid properties on dispersion in flow through packed beds

AbstractAn experimental study is described on the effect of liquid properties on axial dispersion in packed beds. Working with water between 278 and 373 K, the range 57<Sc<1,930 was covered, and this represents a significant fraction of the domain located between what is traditionally considered “gas behavior” (that is, Sc≅1) and “liquid behavior” (typically, Sc>600). A representation of PeL vs. Pem reveals the existence of a very flat minimum (typically 102<Pem<104) for each value of Sc. The value of the minimum is almost insensitive to variations in Sc, for Sc>700, but it increases significantly with a decrease in Sc, for Sc<700. The experimental data used to test available correlations for predicting DL show that they are inaccurate over considerable ranges of the variables.

P-13 超音波霧化を用いた水溶液の濃縮挙動に及ぼす液物性の影響

P-13 超音波霧化を用いた水溶液の濃縮挙動に及ぼす液物性の影響

The dynamic strength of partially saturated powder compacts: the effect of liquid properties

The flow stress of partially saturated pellets was measured at deformation velocities varying from 0.01 to 150 mm/s. The pellets, 20 mm in diameter and 25 mm high, were made with glass ballotini of a surface mean particle size, d p, of 35 μm. Water, glycerol and a series of silicone oils were used as the liquid binder, covering viscosities, μ, and surface tensions, γ, ranging from 0.001 to 60 Pa·s and 0.025 to 0.072 N/m, respectively. It was found that there was a critical strain rate (which was binder dependent) below which the peak flow stress, σ pk, was independent of the strain rate, ε. Above this critical strain rate, the flow stress increased with increasing strain rate. When plotted in terms of two dimensionless groups, the results collapsed onto one curve of the form: Str*=k 1+k 2 Ca n where Str*= σ pk d p/ γcos θ is the dimensionless peak flow stress and Ca= μεd p/ γcos θ is the dimensionless capillary number, the ratio of viscous to capillary forces. θ is the contact angle (assumed zero in this work). The best fit values of the parameters were: k 1=5.3±0.4, k 2=280±40 and n=0.58±0.04. This result suggests that viscous forces are negligible at low strain rates, but become dominant at high strain rates. k 1 is related to the static peak compressive strength of the pellets, k 2 determines the critical Ca at which viscous effects become significant and n gives the power law dependence of viscous forces on the strain rate. This work is significant for granulation research since it highlights the fact that strengths measured under pseudo-static conditions may not be representative, even qualitatively, of how materials behave at the higher strain rates encountered in commercial granulators.

Effects of Liquid Property on Air Entrainment and Oxygen Transfer Rates of a Plunging Jet Reactor.

The effects of liquid property on air entrainment and oxygen transfer characteristics of a plunging jet reactor are investigated in air-corn syrup solution system with changing the viscosity up to 40.5 mPa.s. The effect of liquid property on air entrainment rate is divided into three regions. The transition points of the regions are represented with jet Reynolds number. The change in air entrainment rate with liquid property is discussed in relation to the change in jet surface disturbances. Empirical correlations are also presented to predict the air entrainment rate, gas holdup and oxygen transfer coefficient. The oxygen transfer performance of the reactor is superior to that of the conventional bubble columns and stirred tank reactors over the range of viscosity from about 1 to 40.5 mPa.s. It is concluded that the plunging jet reactor is one of the most promising bioreactor treating a viscous fermentation broth.

415 垂直細管内気液二相流における液体物性の影響 : 第二報, 摩擦損失と界面摩擦力(O.S.4-4 混相流)(O.S.4 : 高度化に向けた流体関連解析と機器開発)

415 垂直細管内気液二相流における液体物性の影響 : 第二報, 摩擦損失と界面摩擦力(O.S.4-4 混相流)(O.S.4 : 高度化に向けた流体関連解析と機器開発)

A highly elevated mass transfer rate process for three-phase, liquid-continuous fluidized beds

Average gas holdup and gas-to-liquid mass transfer in three-phase fluidized beds with non-Newtonian fluids were studied. The effects of liquid property, gas distributor type and magnetic field intensity on mass transfer coefficient and overall gas holdup were examined. The volumetric gas-to-liquid mass transfer coefficient was determined by fitting the oxygen concentration profile data across the bed to the axial dispersion model. The average gas holdup and mass transfer coefficient were all correlated with operating parameters including gas velocity and effective viscosity. Experimental results showed that a three-fold increase in mass transfer coefficient and a two-fold increase in average gas holdup were observed with properly designed liquid property and gas distributor. A modified process was developed to highly elevate the volumetric gas-to-liquid mass transfer rate. The bubble coalescing property of three-phase fluidized beds with small particles is eliminated, and its application to biotechnology and enzyme-catalyzed processes with high gas-to-liquid mass transfer rate could be achieved.

The flow of gas–liquid foams in vertical pipes

The flow patterns of pneumatically generated foams flowing in vertical pipes and their associated structure, pressure drop and liquid entrainment characteristics have been investigated. Experimental results have been obtained on the effects of liquid properties, surfactant type and concentration, foam generator, and pipe diameter. At low flowrates, the foam has a dry cellular texture with polyhedral cells and flow occurs entirely by slip near the wall. At high flowrates, a wet foam with spherical bubbles is formed and flow is characterised by strong bubble mobility and intensive bubble recirculation. Flow was characterised by a constant pressure gradient under both flow regimes, and foam rheology was successfully described by a power-law model. Friction factors were determined for all systems studied and the data lied remarkably on a unique line on the friction factor-Reynolds number plot. An explicit relationship for predicting the friction factor in foam flows is presented, based on a wide range of experimental conditions. The model has practical significance in that pressure drop in foam flow can be calculated using a constant friction factor along a pipe of constant cross section, in any flow regime.

Hydrodynamic characteristics of counter-current two-phase flow in vertical and inclined channels: effects of liquid properties

Flow patterns, counter-current flow limitation (flooding), and gas hold-up (void fraction) in counter-current flow in vertical and inclined channels were experimentally investigated. Tests were performed in a 2 m-long channel with 1.9 cm inner diameter, using air, and demineralized water, mineral and paraffinic oils, covering a surface tension range of 0.0128–0.072 N/m, and a liquid viscosity range of 1 × 10 −3−1.85 × 10 −1Ns/m 2. The liquid and gas superficial velocity ranges for the tests with demineralized water were 0 ⩽ U GS ⩽ 54 cm/s and 1 ⩽ U GS ⩽ 299 cm/s, for tests with mineral oil were 0 ⩽ U LS ⩽ 23 cm/s and 1 ⩽ U GS ⩽ 248 cm/s, and for paraffinic oil were 0.15 ⩽ U LS ⩽ 11.6 cm/s and 1 ⩽ U GS ⩽ 224 cm/s, respectively. The examined channel angles of inclination with respect to the vertical line were 0, 30 and 68°. Flooding data were significantly different from pure water results only at very high liquid viscosities. The effect of liquid viscosity on gas hold-up and flow patterns was significant, furthermore, and several existing models and correlations were unable to correctly predict the data trends. With increasing the liquid viscosity the parameter range of the slug flow pattern expanded for all angles of inclination, and froth flow replaced the churn flow pattern in the vertical configuration and it replaced the churn/stratified and semi-stratified patterns in inclined configurations. The churn-stratified flow pattern is predominantly wavy stratified and is interrupted by upward-moving flooding-type waves. Semi-stratified is a periodic pattern where in each period the flow regime is initially wavy stratified while liquid accumulates in the bottom portion of the test section and forms a large liquid slug which subsequently moves upwards in the channel.

Design correlations of an air-lift tube reactor

Air-lift reactors are important gas-liquid contactors for gas separation, purification, fermentation and waste water treatment on account of their simple construction and low energy consumption together with high mass and heat transfer rates. Apart from the improved liquid mixing, air-lift reactors have no moving elements and the power requirement comes only from the air supply. A new air-lift tube (ALT)-type reactor was investigated in laboratory and pilot scale. A study was conducted to measure the effects of liquid properties (such as viscosity and density) on the hydrodynamics of the ALT reactor. The systems used for this study were: air/water, air/sodium hydroxide solution, air/sodium citrate buffer solution and air/glycerine. Pressure drop in the reaction tube, minimum and maximum gas velocities, pressure frequency and recycle liquid velocity in the recycle tube were measured under different experimental conditions using different tube diameters for the recycle and reaction tubes. Design correlations for the above-mentioned parameters were developed by computer program in order to design an ALT reactor for gas-liquid reactions. The correlations are valid in the range 0.1–1400 m 3 h −1 of the gas stream.

Oscillation-Controlled Heat Transport Tube. 1st Report. Effect of Liquid Properties.

In the present report, the effect of liquid properties on the effective thermal diffusivity of the oscillation-controlled heat transport tube (the so-called dream pipe) is investigated. First, a slip flow model is presented to investigate the fundamental mechanism and the governing quantities of this phenomena. Results of the analyses show that cascade heat transport between the stagnant boundary layer and the core liquid, which is caused by phase shift between the radial conduction heat-flux and the oscillation, is the fundamental mechanism of the phenomena. Next, it is found that the effective thermal diffusivity reaches a maximum at a value of the thermal diffusivity of the liquid because the phase shift increases with increasing thermal diffusivity. Finally, it is shown that water is one of the desirable operating liquids of the heat transport tube of this type.

Effect of liquid property on gas entrainment behavior in a plunging liquid jet aeration system using inclined nozzles.

Effects of liquid properties on gas entrainment rate Q g and maximum bubble penetration depth Z in an inclined liquid jet aeration system were investigated. Correlations for predicting Q g and Z were presented

Effect of liquid properties and flow on liquid film mass transfer coefficient in silicone membrane oxygenation

Effect of liquid properties and flow on liquid film mass transfer coefficient in silicone membrane oxygenation

Compound atomization by air action. The effect of liquid properties.

The study of the effect of liquid physical properties on atomization is an important subject. In this study, the ethyl alcohol-water solution and the glycerin-water solution are used for changing the properties. The correlation between density, viscosity and surface tension of a liquid is obtained. The relationship between SMD and the liquid physical properties is clarified. How the liquid physical properties affect the atomization is examined in detail with a D7-2-2-type nozzle which was used in the former report. An experimental equation including the liqued physical properties is obtained for SMD near the singular point.

Experimental Study on the Squeezing Flow of Viscoelastic Fluids : 1st Report, The Effect of Liquid Properties on the Flow between a Spherical Surface and a Flat Plate

An experimental study has been made on the flow of viscoelastic liquids in thin films held between a flat plate and a spherical surface of a large radius of curvature. In particular, the case is investigated when a spherical surface begins to roll on a flat plate from stationary and contacting state. Dilute polymer solutions are used as viscoelastic fluids, whose properties are elastic but Newtonian in viscosity. Compared with non-elastic liquids, some effects are shown: The point of cavitation is far from the center of contact where the thickness of the liquid film is minimum. The thickness of the liquid film, generated with rolling movement, is larger than that of non-elastic liquids.

Liquid-phase mixing in bubble columns: Effect of liquid properties

Experimental data on the liquid-phase mixing in bubble columns were obtained with air and various liquids by using a transient-state measurement technique. The effect of the liquid physical properties on the liquid-phase longitudinal dispersion coefficient was studied. The liquid-phase dispersion coefficient was found to vary with the viscosity of the liquid, the superficial gas velocity and the column diameter. A new correlation for the liquid-phase dispersion coefficient is presented and shown to correlate the experimental data with an average deviation of 3.07%.

Gas Holdup and Volumetric Mass Transfer Coefficient in Bubble Columns. Effects of Liquid Properties

Gas Holdup and Volumetric Mass Transfer Coefficient in Bubble Columns. Effects of Liquid Properties

Cavitation Erosion in a Thin Film as Affected by the Liquid Properties

The effect of liquid properties and the atmospheric environment on cavitation erosion was investigated in a thin film cavitation apparatus which consists of an ultrasonic horn with a flat tip vibrating against a stationary 1/2 in. ball at a frequency of 20 KC. The experimental results show that cavitation erosion is less severe for liquids of higher gas solubility or at vapor pressures greater than 100 torr. It is therefore possible to reduce the damage by blending a light component in lubricants or liquids and/or by environmental control. The effect of ambient pressure was also observed by tests in vacuum and under various reduced pressures up to one atmosphere. The damage increases with the increase of pressure. These results indicate that the most important factor in cavitation erosion is the differential pressure inside and outside the cavities, with the dissolved gases and/or vapor serving to control this pressure differential. The investigation of cavitation erosion with liquids of various properties also provides information for the understanding of the erosion mechanism. Evidence was obtained which supports the theory that the damage is caused by fatigue failure attributable to the impingement of liquid jets during bubble collapse. The liquid properties may control the jets velocity and thus affect the applied stress on surface boundaries.

Investigation of injectant properties on jet penetration in a supersonic stream

The effect of liquid properties on secondary injection from a single small-diameter nozzle in a supersonic stream was investigated experimentally. Normal penetration of liquid jets was inferred from scattered-light and schlieren photographs. Primary flows of Mro = 2.8 and 4.0 were produced in a 4 X 4-in. blowdown wind tunnel. Data on normal penetration of roomtemperature water were used to extend published correlations to lower injection pressure ratios. The effect of vapor pressure on penetration was investigated by injecting superheated water and acetone. Penetration height was correlated with injection pressure ratio for superheated liquid injection; these data were compared with roomtemperature results. Vapor pressure breakup outside of the spray nozzle had little effect on the penetration height. Liquid viscosity and surface tension were varied over a wide range of conditions; neither property affected the penetration height for flow in the acceleration-wave breakup regime.

Electrical charging of liquid sprays in high-pressure gas flows for electrofluid dynamic processes

To produce charged aerosols for electrofluid dynamic processes, various liquids were sprayed through a metal capillary at very high electric field strengths into high pressure air flows. The current produced as the charged liquid spray ruptures is a function of electrical, gas, and liquid properties. Of these parameters the effects of liquid properties, such as surface tension, electrical conductivity, mass flow rate, and air properties such as pressure and velocity on the current production are experimentally investigated. A semi-empirical relation of the current output with the indicated variables is obtained using dimensional analysis.

Investigation of Annular Liquid Flow With Cocurrent Air Flow in Horizontal Tubes

Abstract Visual observations and flow analysis were made of annular liquid flow with cocurrent air flow in horizontal tubes. The effect of liquid properties and air-stream conditions on the characteristics of the liquid flow were observed. The results are presented in form of shadowgraph pictures of the liquid flow. Analysis of the flow system related the characteristics of the liquid flow to the flow conditions.