Showing papers on "Volumetric flow rate published in 1989"

A dynamical model of lava flows cooling by radiation

Abstract: The behaviour of a lava flow is reproduced by a two-dimensional model of a Bingham liquid flowing down a uniform slope Such a liquid is described by two rheological parameters, yield stress and viscosity, both of which are strongly temperature-dependent Assuming a flow rate and an initial temperature of the liquid at the eruption vent, the temperature decrease due to heat radiation and the consequent change in the rheological parameters are computed along the flow Both full thermal mixing and thermal unmixing are considered The equations of motion are solved analytically in the approximation of a slow downslope change of the flow parameters Flow height and velocity are obtained as functions of the distance from the eruption vent; the time required for a liquid element to reach a certain distance from the vent is also computed The gross features of observed lava flows are reproduced by the model which allows us to estimate the sensitivity of flow dynamics to changes in the initial conditions, ground slope and rheological parameters A pronounced increase in the rate of height increase and velocity decrease is found when the flow enters the Bingham regime The results confirm the observation according to which lava flows show an initial rapid advance, followed by a marked deceleration, while the final length of a flow is such that the Graetz number is in the order of a few hundreds

Electric properties of flowing blood and impedance cardiography

Abstract: An effective resistivity is defined for axisymmetric flow through a circular tube with a uniform electric field in the longitudinal direction. The resistivity of flowing blood is found to be a function of the shear rate profile. Under axisymmetric conditions shear rate profiles are a function of a single parameter: the reduced average velocity, which is the average velocity divided by the radius of the tube. The resistivity of human blood was investigated while the blood was in laminar flow in a circular tube with different constant flow rates. The relative change in resistivity in % is given by: −0.45·H·{1-exp[−0.26·(〈v〉/R)0.39]}; where H is the packed cell volume in % and 〈v〉/R is the reduced average velocity in s−1. In accelerating flow the resistivity change is synchronous with the change in flow rate, but in decelerating flow there is an exponential decay characterized by a relaxation time τ. For packed cell volumes of 36.4% and 47.5% τ was estimated to be 0.21 s, for a packed cell volume of 53.7% τ was estimated to be 0.29 s. The resistivity changes in elastic tubes are influenced by both velocity changes and changes in diameter, but in opposite directions.

Method and device for controlling pressure, volumetric flow rate and temperature during gas insuffication procedures

Abstract: A system for administering gas to a patient during an endoscopic or medical procedure includes elements for regulating the temperature, pressure, and volumetric flow rate of the gas. A gas source operating with a heated pressure regulator and filter provide a smoothly regulated flow of any medically necessary gas, such as CO2, to a main body of the gas delivery system. The main body comprises a primary heater for control of the temperature of the gas administered to the patient, a fine pressure regulator for controlling its pressure in a safe manner, and a flow regulator for controlling its volumetric flow rate. Temperature, pressure, and volumetric flow rate indicators allow the physician continuous monitoring of the quantitative status of each of these important physiologic parameters; this data may also be recorded for documentation purposes. The system allows increased safety in endoscopic or medical procedures in which gas is used, greater operational convenience for the physician, enhanced quantitative observation and documentation capability, while retaining flexibility in using conventional alternate gas sources.

Liquid volume flux in a weak bubble plume

Abstract: A method has been devised for measuring the volume flux in a bubble plume in a homogeneous liquid. Laboratory experiments on weak bubble plumes using the method determined the flux as a function of height and gas flow rate for air flow rates between 0.41 and 6.25 cc/s. It was found that volume flux was proportional to the square-root of air flow and increased linearly with height. From measurement of bubble velocity it is concluded that the individual bubble wakes make an important contribution to the entrainment.

Mathematical structure of compositional reservoir simulation

Abstract: In this paper multicomponent two-phase isothermal fluid flow in petroleum reservoirs is described. The fluid-flow model consists of component conservation equations, Darcy's law for the volumetric flow rates, balance between the fluid volume and the rock void, and the conditions of thermodynamic equilibrium that determine the distribution of the chemical components into phases. Thermodynamic equilibrium is described by means of a mathematical model for the chemical potentials of each component in each phase of the fluid. The flow equations are manipulated to form a pressure equation and a modified component-conservation equation; these form the basis for the sequential method. It is shown that the pressure equation is parabolic under reasonable assumptions on the thermodynamic equilibrium model, and that the component-conservation equations are hyperbolic in the absence of diffusive forces such as capillary pressure and mixing. A numerical method based on the sequential formulation of the flow equations is outlined and used to illustrate the kinds of flow behavior that occur during miscible gas injection.

Vortex chamber separator

Abstract: The invention concerns a process for separating and/or precipitating of solid and/or liquid particles (disperse phase) from gaseous and/or liquid media (continuous phase) as well as for separating mixed gases (gas-gas-separation) and/or mixed fluids (fluid-fluid-separation) as well as for screening and/or classifying by means of a vortex chamber separator with suction tube 35. For decrease of flow resistance at generation of moment of momentum the contact zone between main flow and eddy is adjusted to cylinder casing that the tangential initial impulse in laminary bottom flow is increased by means of decrease of laminary bottom flow impulse, secondarily circulating in vortex chamber. For reduction of loss of impulse by means of dissipative drop of pressure in flow of main channel, laminary bottom flow is dynamically balanced with constant or mainly constant average main flow rate. Clean gas flow is passed through suction tubes 35 with increasing cross sections in outlet direction, that flow is affected by only little meridian deviations in zones of extremely high flow speed. The clean gas flow is passed along outside of suction tubes with increasing speed towards inlet sections.

Electromagnetic flowmeter capable of simultaneous measurement of flow rate and conductivity of fluid

Abstract: An electromagnetic flowmeter is disclosed in which one of two electrodes (2a, 2b) mounted on a measuring pipe (1) is impressed with an electrical pulse synchronous with the switching of an excitation current, thereby detecting the voltage drop across the electrical resistance of a fluid, so that both the conductivity and the flow rate of the fluid are measureable at the same time.

Uniformity of Etching in Parallel Plate Plasma Reactors

Abstract: A two‐dimensional transport and reaction model of a high pressure (~1 torr) high frequency (13.56 MHz) single‐wafer parallel plate plasma reactor was developed. The chemical etching uniformity was studied as a function of reactor operating conditions. The ratio of the reactivity of the surrounding electrode surface as compared to that of the wafer surface, , critically affected uniformity. A bullseye clearing pattern was predicted for , and the reverse pattern for , while etching was uniform for . In the case of , and for the parameter range studied, the absolute uniformity was found to improve by surrounding the wafer with a material of similar reactivity, by increasing the flow rate, or by decreasing the reactor pressure or power. However, such actions also served to decrease the etch rate. The oxygen plasma was used as a model experimental system to test the theoretical predictions. An experimental technique based on spatially resolved optical emission spectroscopy in concert with actinometry and the Abel transform was developed to obtain a three‐dimensional mapping of the reactant (O atom) concentration profile in the plasma reactor. When a reactive film was covering part of the substrate electrode, a profound decrease in the reactant concentration was observed over the film. At the same time, large concentration gradients developed, especially at the boundary of the reactive film with the surrounding electrode. Good quantitative agreement was found between the model predictions and the experimental reactant concentration data for the range of pressure, power, flow rate, and reactive film radius examined.

Mass flow controller

Abstract: A mass flow controller including a valve assembly wherein a flow rate-controlling portion of the valve assembly is mirror finished and wherein the maximum flow rate through the flow rate-controlling portion during the time that the flow rate is not being controlled is set so as to be sufficiently large in comparison with the flow rate during control whereby a moisture purging function may be performed without external fluid bypass circuits.

A sputtering method for fabricating thin film

Abstract: A method for sputtering by a glow discharge in gas is disclosed. The sputtering chamber is evacuated by a pump with a high speed, and the flow rate of the gas injected into the chamber is varied periodically between a high flow rate and a low flow rate. During the high flow rate, the discharge is ignited. The glow discharge is sustained during the low flow rate injection period, and when the pressure becomes too low to maintain a stable discharge, the flow rate is again increased to ignite or reinforce the electric discharge. In such a manner, the flow rate of the injection gas is periodically alternated between a high and a low injection rate. The sputtering is mostly done at the lower injection rates, and the evacuation speed is kept always high. Accordingly, contamination otherwise caused by residual gas is prevented, and a high grade sputtered film is obtained. By operating in this manner, the gas consumption is reduced and the life of the cryogenic pump, used for evacuating the sputtering chamber, is prolonged, and hence the on line operation of the sputtering device is improved.

Steel dissolution in quiescent and gas stirred Fe/C melts

Abstract: The dissolution rates of commercial black iron rods in iron/carbon melts under isothermal conditions were measured. The effect of melt carbon content, temperature, natural convection, and gas stirred forced convection conditions were investigated. The experimental data under natural convection conditions (no external stirring) were fitted with a dimensionless correlation for vertical cylinders: Sh = 0.13(Gr . Sc)0.34, representing mass transport control dominated by turbulent natural convection. Under bottom injection gas stirring conditions, it was found that the kinetic power input had little effect on the rod dissolution rates which were controlled by the total gas flow rate. Derived mass transport coefficients under gas stirring conditions were found to have the following dependence on the gas injection rates:k m ∝Q 0.21, wherek m = mass transport coefficient andQ = gas flow rate. A comparison of the experimental results with previously measured mass transfer coefficients under forced convection conditions gave a plume velocity flow rate dependence ofU ∝Q 0.3. A general discussion of gas stirring fluid dynamics and resulting mass transport effects is presented.

Acoustic wave microsensors for measuring fluid flow

Abstract: The use of a surface acoustic wave (SAW) device to measure rate of fluid flow. A SAW oscillator heated to a suitable temperature above ambient is placed in the path of the flowing fluid. Convective cooling caused by fluid flow results in a change in the oscillator frequency. A 73 MHz oscillator fabricated on 128° rotated Y-cut lithium niobate substrate and heated to 55° C. above ambient shows a frequency variation greater than 142 kHz for flow rate variation from 0 to 1000 cm3 /min.

Particulate flow control

Abstract: A continuous flow of particulate solids to a reactor is accomplished by first forming a heavy slurry in a storage tank, then transferring the heavy slurry to a mixing tank, where the heavy slurry is diluted to form a dilute slurry of desired density which can be continuously pumped to the reactor. Control of the particulate solids flow to the reactor is accomplished by calculating the flow rate of solid particles contained in the dilute slurry in an on-line computer, and comparing the calculated value to a desired value. The on-line calculation of particulate flow is based on the measured density and flow rate of the dilute slurry, and the predetermined densities of the dry particulate solids and the liquid diluent consituting the dilute slurry. The flow rate of the dilute slurry is continuously manipulated so as to maintain a desired flow rate of solid particles contained in the dilute slurry.

Net oil computer

Abstract: Apparatus and accompanying methods for implementing both an accurate densimeter and a net oil computer utilizing a common Coriolis meter assembly is described. In essence, this apparatus measures density of an unknown fluid by first determining the period at which both flow tubes contained within a dual tube Coriolis meter oscillate while the unknown fluid passes therethrough. This apparatus then squares the result. Thereafter, the density of the unknown fluid is determined as a linear function that relates the squared tube period measurement for the unknown fluid, and squared tube period measurements and known density values for two known fluids, such as air and water, that have previously and successively passed through the meter during calibration. When used as a net oil computer, the inventive system obtains mass flow and temperature measurements from the same flow tubes. By using measured density and mass flow values of an oil-water emulsion that flows through the same Coriolis meter, the inventive system can advantageously provide both volumetric and mass based measurements of the flow rate and totalized flow of the entire emulsion and of the individual water and oil components present therein.

Gas absorption in a hollow fiber device

Abstract: The absorption of S02 and NH3 from air and air/CO 2 streams was studied for the first time in a certain novel hollow fiber mass transfer device, for various inlet gas compositions, liquid compositions, gas flow rates, and liquid flow rates. The gas and liquid flows were countercurrent. Analyses of the amounts of S02and NH3 absorbed demonstrate that the hollow fiber unit has a relatively small membrane resistance and is an effective gas scrubbing device. Additionally, it offers a large interfacial area per unit volume, and avoids flooding problems entirely

Gas velocity measurements from a close-coupled spray deposition atomizer

Abstract: Gas-atomized melt spraying is used for the manufacture of metallic particulate and spray-deposited preforms. The flow behaviour of the gas in the spray is a critical component of the spraying process. Knowledge of the gas flow field generated by the atomizer is a prerequisite for characterizing the transport phenomena controlling droplet dynamics and heat transfer during droplet flight. Flow visualization, Pitot tube measurements and laser Doppler anemometry have been used in the present study to investigate the steady state gas flow field generated by a close-coupled spray deposition gas atomizer for gas flow rates of 2.0 and 2.7 l s −1 and atomizer-to-substrate distances of 180 and 360 mm. Maximum gas velocities of up to 119 m s −1 have been measured along the axis of the conical flow field generated by the atomizer. The variation in axial gas velocity perpendicular to the axis of the flow follows the form of a gaussian distribution. A mathematical model of the flow field generated by the gas atomizer has also been developed, and the predictions of the model are compared with the gas flow measurements.

Apparatus for flow rate and energy transfer measurements

Abstract: Temperaature sensors at the inlet and outlet of a heat exchanger are utilized in the disclosed apparatus to measure the temperature of the fluid and to ascertain the the time taken by a localized gradient in heated or cooled fluid to pass through the heat exchanger at the start of a heating or cooling episode in order to obtain the flow rate of fluid through the heat exchanger; a representation of the flow rate is stored; and thereafter, during that heating or cooling episode, the stored flow-rate representation is utilized in deriving flow-rate and energy transfer measurements.

Flow rate measuring apparatus

Abstract: A flow rate measuring apparatus includes a measuring pipe in which a fluid to be measured flows, a flowmeter for measuring a flow rate of the fluid to be measured flowing in the measuring pipe, and a cleaning flow generator for removing an adhesive substance in the measuring pipe by using the fluid to be measured, thereby correctly performing flow rate measurement by the measuring pipe. When the flowmeter is an electromagnetic flowmeter, the cleaning flow generator prevents the adhesive substance from resistively connecting electrodes for induced electromotive force detection. When the flowmeter is an ultrasonic flowmeter, the cleaning flow generator prevents the adhesive substance from interfering with transmission of an ultrasonic wave in the measuring pipe. The cleaning flow generator removes the adhesive substance by performing at least one of injecting the fluid to be measured into the measuring pipe, narrowing a flow path of the fluid to be measured to increase a flow rate of the fluid to be measured in the measuring pipe, inflating a balloon in the measuring pipe, injecting a cleaning agent in the measuring pipe, turning the fluid to be measured, and charging a high-pressure gas into the flow path of the fluid to be measured.

Method and apparatus for proving electronic gas meters

Abstract: A method and apparatus for proving an electronic gas meter and the like that includes counting the number of pulses provided by an encoder associated with a bell prover to define a volume of test fluid which is supplied to the meter under test, enalbing the meter to measure the volumetric fluid flow rate and integrating the volumetric flow rate of test fluid measured by the gas meter during the test, and data representing the actual volume of test fluid supplied to the meter under test to determine the percent proof or accuracy of the meter.

Analysis of the transient compressible vapor flow in heat pipe

Abstract: The transient compressible one-dimensional vapor flow dynamics in a heat pipe is modeled The numerical results are obtained by using the implicit non-iterative Beam-Warming finite difference method The model is tested for simulated heat pipe vapor flow and actual vapor flow in cylindrical heat pipes A good comparison of the present transient results for the simulated heat pipe vapor flow with the previous results of a two-dimensional numerical model is achieved and the steady state results are in agreement with the existing experimental data The transient behavior of the vapor flow under subsonic, sonic, and supersonic speeds and high mass flow rates are successfully predicted The one-dimensional model also describes the vapor flow dynamics in cylindrical heat pipes at high temperatures

Flow rate sensor

Abstract: A flow rate sensor is provided. This sensor includes a flow rate detecting element. The flow rate detecting element is provided within a flow passage so as to expose the flow rate of a medium whether at the center of the passageway or at the inner surfaces of the passage wall. The flow rate detecting element has a plurality of openings for allowing the medium to pass therethrough without pressure loss. Thus, the flow rate sensor may precisely detect the flow rate of a medium flowing within the passage regardless of insecurity in the flow distribution of the medium.

Direct Contact Evaporation Between Two Immiscible Liquids in a Spray Column

Abstract: The present investigation deals with the direct contact evaporation of refrigerant 113 and n-pentane in a stagnant column of distilled water. The operational parameters investigated in the experimental study are the operating column height, the temperature difference, the dispersed phase flow rate, and the diameter and number of orifices in the distributor. The effects of these parameters on volumetric heat transfer coefficient, holdup, and agglomeration are investigated. A modified relation, based on the theoretical analysis of Smith et al. (1982), is also developed for predicting the theoretical volumetric heat transfer coefficient. Comparison with related works available in the literature shows reasonable agreement.

Multiple stream fluid mixing and dispensing apparatus

Abstract: An improved multiple stream, fluid mixing and dispensing apparatus for automatically regulating flow rate and temperature for one or more preset fluid flows for connection to domestic water delivery systems including a plural station, fluid flow rate and temperature control console adapted for cooperating with the standing hydraulic pressure of a dual temperature fluid supply means with a variable effluent flow rate regulator interposed in each of the main supply conduits and associated controller means for presetting the flow rate through each regulator and determining both the degree of mixing and the incidence of fluid flow to be provided from each supply conduit to the exit conduit.