Showing papers on "Volumetric flow rate published in 1978"

Liquid‐solid mass transfer in packed beds with downward concurrent gas‐liquid flow

Abstract: Mass transfer coefficients were determined by measuring the rate of solution of cylindrical 3 or 6 mm benzoic acid tablets into water in the presence of flowing nitrogen, helium, or argon. Gas flow rates varied from 0 to 1.6 kg/(m2·s) and liquid flow rates from 0.5 to 25 kg/(m2·s), resulting in hydrodynamic flow patterns varying from trickle to turbulent pulse types of flow. In the pulse regime, the mass transfer coefficient was markedly affected by gas flow rate but did not depend on gas density explicitly if correlated in terms of an energy dissipation function.

Transient gas-liquid flow in horizontal pipes: Modeling the flow pattern transitions

Abstract: The theory for predicting flow pattern transition under transient flow conditions is developed and compared with experiment. This work represents an extension of the methods presented by Taitel and Dukler (1976) for steady state flows. Under transient conditions, flow pattern transitions can take place at flow rates substantially different than would occur under steady flow conditions. In addition, flow patterns can appear which would not be expected for a slow change in flow rates along that same path. Methods are presented for predicting the flow rates at which flow pattern transitions will take place during flow transients. The method also reveals when spurious flow patterns will appear.

Studies on wire coating extrusion. II. The rheology of wire coating coextrusion

Abstract: An experimental and theoretical study of wire coating coextrusion through a pressure-type die was carried out. For the experimental study, the wire coating apparatus employed was the same as that described in Part I of this series (14), except for the newly constructed coextrusion die. The die was provided with three melt pressure transducers along the axial direction, which permitted us to determine the pressure gradient in the die. It was found that a reduction in pressure gradient was realized when a lower viscosity polymer was coextruded with a high viscosity polymer. The materials used for the coextrusion were combinations of low-density polyethylene, high-density polyethylene, polystyrene, and two different commercially available thermoplastic rubbers (UniRoyal TPR-1900 and Shell Kraton G 2701). The use of a high shrinking (crystalline) polymer inside a low shrinking (amorphous) polymer was found to give rise to distorted coatings (non-circular cross section of the coated wire). The interface between the coextruded layers was examined under a magnifying lens, and it was found that under certain processing conditions, the interface was highly irregular. Experimental correlations were obtained to explain the onset of an unstable interface in terms of the rheological properties of the individual components being coextruded, and of the processing variables. It was found that interfacial instability occurs when the shear stress and the viscosity ratio (also elasticity ratio) of the two components at the interface exceed certain critical values. For the theoretical study, using a power-law model, the equations of motion were solved numerically to predict the volumetric flow rate as functions of the pressure gradient in the die and the rheological properties of the polymers being coextruded. Solution of the system of equations permitted us to predict the velocity profile and shear stress distributions of two molten polymers inside a pressure-type wire coating coextrusion die. Comparisons were made between the experimental and theoretically predicted volumetric flow rates. The comparison was found to be reasonably good with certain systems. The discrepancy between the experimentally obtained and the theoretically predicted volumetric flow rates was attributed to interface migration and interfacial instability.

Flow rate effects in plasma etching

Abstract: Experimental data concerning the dependence of plasma etching rates on the flow rate of the etching gas have been analyzed in terms of the consumption of the gas, and a simple model is proposed to explain the observed dependence. The decrease in etch rates at low flow rates is shown to be due to an inadequate supply of the etching gas; at high flow rates, etching is retarded because active species are pumped away.

Solution adsorption from liquid chromatography

Abstract: The dynamic technique of frontal analysis is applied toward the measurement of binary solution-solid adsorption utilizing a commercial liquid chromatograph. The original mathematical treatment of ideal equilibrium chromatography is reexamined. Careful analysis of the chromatographic adsorption process indicates that the absolute surface excess concentration determined from the dynamic experiment is constrained to be a volumetric reduced adsorption if the assumption of constant volumetric flow rate is made. A macroscopic approach, however, shows that this constraint can be removed if, in addition to the outlet concentration, the outlet flow rate is accurately monitored. The macroscopic approach also reveals that the dynamic technique can be applied in spite of finite mass transfer resistance and adsorption kinetics. New dynamic and static experimental results for the system n-hexane/n-hexanol/silica gel are presented and are shown to agree over the entire composition range. The advantages of the dynamic flow technique are outlined.

Flow rate meter with temperature dependent resistor

Abstract: A flow rate meter for measuring the flow rate of a fluid medium, especially that of the air aspirated by an internal combustion engine A hot wire or film is placed in the air stream and is made part of an electrical circuit powered by the output of a differential amplifier The voltage drop across the resistor is monitored at the input of the differential amplifier where it is compared with fixed or compensated values In order to reduce the effect that airborne particles, which are deposited on the hot wire or film, have on the measuring characteristics of the apparatus, the wire or film are shaped so that their leading edge constitutes an area much smaller than the surfaces which are substantially parallel to the stream lines

Gas flow metering

Abstract: Gas flow metering using a capacitance measurement and comprising a taut elastomeric membrane, preferably tubular in form, which expands or contracts as a function of flow rate past it to an extent determined by Bernouilli's principle. The thus changing distance between this membrane and one or more external electrodes measured by capacitance change or other means is correlatable with the instantaneous flow rate and such measurement can be made essentially without regard to entrained solids or liquids in the gas flow, phase and temperature changes (moderate) within the gas flow or mixture or changing composition therein and with rapid response and low back pressure.

Behavior of a Microwave Cavity Discharge over a Wide Range of Pressures and Flow Rates

Abstract: Experiments are conducted over a wide range of pressures, flow rates, and power levels to demonstrate the versatility of a microwave cavity discharge. The experimental results are justified using a linear, cold plasma theory that accounts for the electron-neutral particle collisional losses in the plasma. The resonant coupling of E. M. energy to a surface wave and the resulting formation of a long, large volume plasma column is demonstrated. The absorbed power characteristics of the microwave cavity discharge are examined for gas pressures up to 500 torr and flow rates up to 2500 cm3/min in the TE011 and TE*111 mode operation of the plasma cavity system. The experimental results show that the absorbed power variation as a function of pressure of this discharge is uniform. The power absorbed by the flowing plasma is shown to increase directly as a function of the flow rate initially and reach a saturation at high flow rates. By simultaneously optimizing the cavity length, discharge pressure, and the gas flow, it is possible to couple as much as 90% of the incident power to the plasma.

Production of epitaxial layers by vapor deposition utilizing dynamically adjusted flow rates and gas phase concentrations

Abstract: Epitaxial layers of single crystals of gallium arsenide and similar compounds are formed by vapor deposition. A carrier gas flow is passed through a liquid halide of a group VB material to obtain a first vapor having a halogen, carrier gas and group VB material. The carrier gas flow is monitored and adjusted to obtain a predetermined mass of halogen and second material in this raw vapor. A final reactor input vapor is obtained with constant concentration and constant flow going into a reactor by monitoring the total volume of carrier gas in the raw vapor as added per unit of time and adjusting the raw vapor by adding a volume of additional carrier gas to a predetermined value to form a final reactor input vapor. The reaction and deposition of the epitaxial layer is then carried out in a reactor. A system is used for obtaining constant flow within the reactor with addition of dopants at desired levels while maintaining a constant dilution to the input flow so as to maintain at a deposition substrate, a predetermined constant flow or concentration of amount of reactants to carrier and diluent gas used.

Anodic Behavior of Lithium in Aqueous Electrolytes III . Influence of Flow Velocity, Contact Pressure, and Concentration

Abstract: The influence of electrolyte flow velocity, concentration, and contact pressure on the anodic behavior of lithium at constant temperatures in was studied. The experimental results reveal that, under constant load polarization, a steady‐state curve is obtained consisting of resistance and concentration polarization components. A method to accurately determine the film thickness was devised. It was found that the oxide film at the anode surface is quite thick, ca. 10−2 cm, and its thickness remained constant irrespective of polarization level at constant electrolyte concentration, flow rate, and anode‐cathode contact pressure. The effective diffusion layer at the Li active surface is thin, ca. 10−3 cm. The fraction of active surface area was found to change significantly with concentration (ranging from 0.05 in 4.84M to 0.39 in 2.96M), but it was virtually independent of flow velocity and contact pressure. Likewise, electrolyte concentration has far greater influence on film resistance than flow rate or contact pressure. Electrolyte flow velocity variation is, however, an effective means to alter power output from the cell.

System for monitoring unit and total quantities of a dispenser fluid

Abstract: A flow meter for use in monitoring unit and total quantities of a dispensed fluid, such as draft beer, includes a motion detection switch inside a housing and is coupled to a valve which controls the fluid flow. The switch provides an electrical indication during periods when the valve is open. A totalizer including microprocessor circuitry totalizes the amount of fluid passing through the valve based upon an adjustable, predetermined flow rate setting. An indicator is also coupled to the totalizing circuitry to provide an indication when a unit quantity has passed through the valve at the predetermined flow rate. The totalizer further totalizes the number of occurrences of the unit quantity or any other preselected quantity.

Method and apparatus for measuring particulate matter flow rate

Abstract: A flow rate meter is provided for measuring the flow rate of particulate material being conveyed in a fluid stream along a tubular member. The apparatus includes a throat portion in the tubular member which has a length sufficient to accomplish a pressure drop adequate for accurate particulate material flow rate measurement in the conveying of particulate material in a fluid stream through the throat. The pressure drop is measured across the throat and the measured pressure drop is correlated with the particulate material flow rate. There can be provided converging and diverging tubular sections on opposite sides of the throat to form a venturi. One or more of the flow rate meters can be used in the control of a particulate material blending system. A fluid flow rate measuring means can be used in conjunction with the flow rate meter to provide a signal representative of the difference between the flow rate of particulate material and fluid and the flow rate of the fluid alone, i.e., the flow rate of particulate material alone.

Water injection profiling

Abstract: Water injection profiling of a well by nuclear logging is disclosed. A dual detector sonde with a high energy neutron source and a spinner flowmeter is oriented and positioned above and below perforations in the casing of an injection well to monitor upward and downward flow, respectively, of injection water. The water is irradiated by the neutron source and resulting gamma ray production is sensed as the activated water flows by the spaced detectors. Count rate data is reduced and analyzed in terms of two energy windows to obtain linear flow velocities for water flow behind the casing. Fluid flow within the casing is measured by means of the spinner flowmeter. Volume flow rates are determined for upward and downward flow, and horizontal volume flow into the surrounding formations is calculated.

Method for performing step rate tests on injection wells

Abstract: Method for performing step rate tests on injection wells, including inserting a portable pumping unit to receive the water or other fluid normally injected into the well and controlling its pressure, and then increasing the pressure of the injection fluid to a predetermined pressure by use of the portable pumping unit to determine fluid flow at said predetermined pressure, the fluid at the predetermined pressure being pumped continuously until a stable flow rate is achieved. The procedure is repeated for plural stepwisely increased pressure points at each side of the fracture pressure, whereby the fracture pressure is accurately determined.

Fluid bed furnace and fuel supply system for use therein

Abstract: A fuel supply system for use in a fluid bed furnace or the like of the type which includes a bed comprising a quantity of particles, which bed fluidizes in response to the flow of heated gases upwardly therethrough and a burner for burning a supplied fuel and providing the fluid bed with a sufficient gas mixture flow at an elevated temperature for heating and fluidizing the fluid bed. The fluid supply system includes a source of air, a source of gas fuel, mixing means coupled to the furnace burner for mixing the air and gas fuel together for providing the burner with a fuel mixture, flow rate control means for providing the air and gas fuel to the mixing means in substantially stoichiometric flow rate proportions and fluid bed level detecting means for sensing the level of the fluidizable material within the fluid bed and coupled to the flow rate control means for varying the flow rates of the gas fuel and air provided to the mixing means in direct relation to the level of the fluidizable material within the fluid bed. As a result, excessive agitation of the fluid bed is avoided.

Method for recycling a carrier gas from the trapping system to the inlet of a gas chromatographic separation unit

Abstract: During the recycling operation, the carrier gas is subjected to a pre-purification prior to the conventional purification, the flow rate and the pressure of the carrier gas being maintained at strictly constant values at the inlet of the chromatographic unit. The method is primarily applicable to low-pressure gas chromatography and permits finer separations as well as higher productivity than atmospheric-pressure chromatography.

Motion of polymer liquids under unstable conditions and in channel terminals

Abstract: The present paper deals with the motion of elastic and Newtonian polymer liquids in channel terminals when the Reynolds numbersRe ≪ 1, as well as with the low-molecular polyisobutylene motion through capillaries in the unstable flow mode. The investigations were conducted on a set-up, including a constant pressure capillary viscometer and a laser anemometer. The 40 % butyl rubber solution withM w ≈ 3 ⋅ 104 in transformer oil was used as the elastic liquid. As a Newtonian one, the divinylnitrile rubber withM w ≈ 104 has been investigated. The longitudinal velocity distribution measurements were conducted along the channel axis at different cross-sections: in front of the channel inlet, in the inlet portion, in the developed flow region and in the outlet channel portion. It was found that the dimensionless axial velocity distribution along the channel length was invariant for Newtonian fluid with respect to the flow rate. The inlet and outlet portion lengths are approximately equal to half the channel hydraulic radius. It was shown, that for the elastic liquid the character of velocity profile formation in the inlet portion and the reverse process: of profile reconstruction at the channel outlet qualitatively differ from corresponding processes in a Newtonian fluid under conditions in which a substantially nonlinear fluid behaviour is realized. Axial velocity maxima were observed in the channel terminals. The inlet portion lengths were determined, as well as their dependence on the flow mode. It was shown, that in all cases investigated the inlet portion lengths are larger than for a Newtonian fluid under the same flow conditions (Re ≪ 1). Outlet portion length is approximately equal to double hydraulic radius, and does not, practically, depend on the flow mode. The longitudinal velocity distribution over the channel cross-section undergoes considerable changes in the outlet portion. The unstable flow of P-20 low-molecular polyisobutylene (with Flory molecular weight of 2.1 ⋅ 105) was realized in capillaries with different lengths and radii. In the unstable flow mode, a region was discovered in the flow rate vs. pressure relationships, where the flow rate decreases as the pressure drop increases at the capillary end portions. Correlation of velocity fluctuations in the channel central region with disturbances on the exit jet was discovered by the laser anemometry method. Polymer wall slip was discovered and measured. It was found that the radial distribution of the time-averaged longitudinal velocity had an inflection point near the capillary wall.

Chemical analysis sample control

Abstract: A method of controlling spectroscopic analysis in which a sample in liquid concentrate form and containing an element of interest, is nebulized and carried into an analysis zone by pressurized support gas. The invention comprises regulating the flow rate of the support gas to control the density of atoms of the element present in the analysis zone so as to be within a measurable range. The flow of support gas controls sample uptake at the nebulizer, and that uptake is reduced by dividing the gas flow before the nebulizer so that one part by-passes the nebulizer but is nevertheless directed into the analysis zone so that the total gas flow to the analysis zone remains constant. In spectroscopic apparatus for carrying out that method, the gas flow rate through the nebulizer is automatically reduced when an overrange condition is detected, and a correction factor is applied to the apparatus read-out for each reduction in that flow rate so that the read-out at all flow rates is representative of the quantity of the element of interest in the sample.

Fluid control device

Abstract: PURPOSE:An economical fluid control device provided with a low-cost servo mechanism wherein the flow rate or pressure of the fluid fed to an actuator is controlled through the use of a simple unit manufactured by common art.

Sampling of tangential flow streams

Abstract: The causes and characteristics of tangential flow in industrial stacks are described. Errors induced by tangential flow in the determination of volumetric flow rate and particulate concentration are analyzed. Experiments were conducted at the outlet of a cyclone collector in order to investigate the effect of tangential flow on the determination of emission rates. Straightening vanes were found to be useful in the reduction of error in flow rate measurements.

Method of operating a vapor generating system having integral separators and a constant pressure furnace circuitry

Abstract: A method of operating a vapor generating system for use in a power plant having a turbine control valve means, steam turbine and condenser connected in a main flow circuit in a series flow relationship, in which fluid is passed through a vapor generator furnace section at a predetermined flow rate and a firing rate is established in the furnace section to apply heat to the fluid while controlling the pressure of the fluid as it exits from the furnace section The turbine control valve means are fixed at a predetermined percent open The firing rate is increased to a predetermined percent of full load firing rate until the firing rate approximately corresponds to the percentage of full load flow rate of the fluid The fluid flow rate is then increased together with the firing rate in a manner to increase the throttle pressure of the fluid to the turbine in proportion to load demand on the turbine until the load on the turbine reaches a predetermined percentage of full load

Drag reduction in polymer mixtures

Abstract: Drag reduction was studied in dilute toluene solutions of a mixture of two polymers: polyisobutylene (of three different molecular weights) and 1,4-cis-isoprene rubber in the turbulent region at low (up to 5000) Reynolds numbers. Experiments were carried out with mixed solutions at a concentration equal to optimum concentration of polyisobutylene or higher than it. Drag reduction of the polymer mixtures depending on the ratio of the two polymers showed a positive deviation from the additive straight line at all concentrations investigated. To evaluate the degree of deviation from additivity, the excess drag reduction, was introduced which represents the difference between the actually measured drag reduction and that read from the additive straight line. The excess drag reduction showed almost no dependence on the molecular weight of polyisobutylene in the investigated range of this magnitude. Deviation from additivity depending on the ratio of the two polymers in the mixture growed higher with increasing the flow rate at a given molecular weight of polyisobutylene. The highest excess drag reduction was observed in solutions containing a larger amount of the lower molecular isoprene rubber polymer. The effect of polymer coils on drag reduction in binary polymer solutions was studied. An assumption was made that higher drag reduction in the polymer mixtures as compared to the additive was due to the change of polymer coil dimensions caused by the copresence of the macromolecules of both polymers in the solution. It was further supposed that low shear stresses at which the experiments were carried out caused sufficient orientation and deformation of isoprene rubber enlarged molecules and the contribution of the latter in increasing drag reduction of the mixture was higher.

Area type flow rate measuring device

Abstract: An area type flow rate measuring device comprising an upstream valve and a downstream valve which are disposed in a channel for a fluid, a feedback control mechanism for keeping the pressure difference across the upstream valve constant, the rate of flow of the fluid being measured on the basis of the area of opening of the upstream valve, a pipeline which bypasses the upstream valve, and a mechanism disposed in the bypass pipeline for amplifying the pressure difference by utilizing the flow of the fluid, the arrangement being such that the pressure produced in the mechanism is utilized to drive a valve opening mechanism.

Measuring apparatus for flow rate

Abstract: Flow rate in a fluid passage is measured by making corona discharge in a section of the fluid passage to cause partial ionization of the fluid and measuring a current produced in a DC circuit including a pair of electrodes disposed in the fluid passage downstream of the corona discharge section. Variations in the relationship between the measured current and the flow rate with difference in inherent conductivity among fluids are evadable by measuring a basic current through the DC circuit while the corona discharge is interrupted and regulating a voltage for either ionization or measurement based on the basic current.