Showing papers on "Volumetric flow rate published in 1982"

Supercritical fluid chromatography with small particle diameter packed columns

Abstract: Supercritical fluid chromatography is carried out with 10, 5, and 3 ..mu..m particle diameter packed columns. Reduced plate heights between 2.0 and 3.0 are achieved in the region of the van Deemter minimum. Using polycyclic aromatic hydrocarbons as probe molecules, the relationship of density of supercritical carbon dioxide to log capacity factor was studied between 32 and 100/sup 0/C. The efficiency of the columns appears to improve as the particle diameter becomes smaller. With a UV detector, minimum detectable quantities are in the range of 1 ng mass injected. Resolution per unit time is 5-10 times better than HPLC with the same columns due to more favorable diffusivity in supercritical fluids. Usable regions of temperature, pressure, density, and flow rate are defined. 9 figures.

Gas Flow Patterns in Horizontal Epitaxial Reactor Cells Observed by Interference Holography

Abstract: Interference holography is used to visualize gas flow patterns and temperature profiles in epitaxial systems. It is demonstrated that in water‐cooled horizontal reactor cells the carrier gases and He give dynamically stable laminar flow profiles throughout the reactor. There is no indication of a stagnant or boundary layer for flow velocities up to 80 cm/sec in this type of cell. In air‐cooled cells, and He also give stable laminar flow profiles, but beyond velocities of 40 cm/sec a cold gas finger appears in these flows due to undeveloped flow and temperature profiles. In contrast to the stable flow characteristics of and He, the flows of and Ar always are unstable due to convective motions. Besides this intrinsic instability, these flows are accompanied by severe entrance effects (especially undeveloped flow profiles), which dominate the flows for flow rates higher than 4 cm/sec. This is observed for both air‐ and water‐cooled cells. Another phenomenom which is observed for and Ar is that beyond 4 cm/sec the convective gas breaks up into a thin (8 mm) laminar layer close to the susceptor across which the entire temperature gradient is present and a highly turbulent/convective part above this laminar layer. Analysis shows that for Ar and about eight times longer entrance lengths in the reactor cell are needed to achieve fully developed velocity and temperature profiles as compared with and He. This explains the dominant influence of this effect on the flows of Ar and . When the influence of the entrance effect on the profiles is taken into account, all the observed flow patterns and temperature gradients are in agreement with the theoretical flows which can be predicted on basis of the respective Reynolds and Rayleigh (or Grashof) numbers.

Hydrodynamics of gas stirred melts: Part I. Gas/liquid coupling

Abstract: A hydrodynamic model of submerged gas injection systems and their effects on liquid metal stirring is presented. It is argued that hydrodynamic conditions at the nozzle, tuyere, or plug are not critical to flow recirculation produced in large cylindrical vessels(i.e., furnaces or ladles). An analysis of a buoyancy driven plume generated through gas injection shows that gas voidages are usually quite low (less than 10 pct). By equating the energy supplied by rising bubbles to turbulent energy losses within the bath, it is shown that mean plume velocities can be predicted using the relationship,U p α (Q 1/3 L 1/3)/R1/3 whereU p equals mean plume velocity,Q is gas flow rate (at mean height and temperature),L is depth of liquid, andR is radius of the vessel. Associated rates of liquid turnover as a function of vessel dimensions and gas flow rate can also be predicted and these are similarly presented.

Long wavelength acoustic flowmeter

Abstract: A nonintrusive instrument for measuring the volume flowrate of, and the speed of sound in, an arbitrary fluid in a pipe, tube or duct. The sound speed measured is that of a stationary fluid even though the measurement is made while the fluid may be flowing. These measurements are absolute in that they require no flow calibration, and they are independent of the composition of the fluid and its temperature. For a flowing, approximately perfect gas or gas mixture, given the average molecular weight and ratio of specific heats, the instrument measures the temperature. Also, given an independent measurement of the pressure, it measures the gas density and mass flowrate. The measurement can be made in a high noise level environment even when the temperature varies rapidly over a large range. The instrument uses sound whose wavelength is much longer than the diameter of the pipe, tube or duct. As a result, the temperature and flow measurements are independent of the profiles of those quantities across the pipe profiles.

In situ water motion and nutrient uptake by the giant kelp Macrocystis pyrifera

Abstract: Rates of NO 3 - uptake by individual blades of Macrocystis pyrifera (L.) C. Agardh were measured at different flow rates in the laboratory. Dissolution rates of hemispherical, plaster buttons attached to the blade surface provided a relative measure of flow rates over blades used in uptake experiments and also over intact blades of adult kelp plants in situ (Laguna Beach, California, USA; 1981). Laboratory results indicated that uptake was saturated at a flow rate equivalent to 2.5 cm s-1 current velocity. Flow rates over intact blades in situ always exceeded this uptake saturation level. Wave surge and movement of plant surfaces relative to the surrounding water provided sufficient flow to saturate uptake, even in a dense kelp canopy during low-current and calm sea-state conditions.

Resin Flow During the Cure of Fiber Reinforced Composites

Abstract: Experiments were performed studying resin flow during the cure of fiber reinforced, organic matrix composites using a system in which the resin was simulated by viscous liquids and the fibers either by layers of thin rods or by layers of porous plates. The flow pattern was observed and the flow rate was measured for different applied pressures. The data were compared to the results of the Springer-Loos model and excellent agreement was found bet ween the data and the model.

Two-phase flow measurements with sharp-edged orifices

Abstract: This paper contains the results of a set of two-phase flow measurements of 4 different ratios of vapor to liquid density (up to 0.328) across a sharp-edged circular orifice. Test fluid was R-I13. Tests were carried .out upon 3 orifices whose diameter ratios were 0.312, 0.439 and 0.625. The test quality ranged from 0--100%, while the mass velocity from 917-1477 kg/m2.s. On the basis of a modified separated flow model, a relationship is developed for the flow rate and quality and is compared with experimental data and 5 proposed correlations. Comparison shows this method can be used to calculate the flow rate or the quality of vapor liquid (or steam water) mixture in the range 0.00455 to 0.328 of the density ratio, and in pipe size ranging from 8 to 75 mm (/~ = 0.25-0.75). The RMS error of this method is about 12% when the quality, x, ranges from 2% to 100%. Measurements of flow rate and quality of vapor liquid mixture are of interest in many fields of engineering such as power cycles, chemical, geothermal, petroleum and control. An orifice is a convenient and reliable device and has sufficient accuracy for these measurements, it has been receiving increasing attention in the recent two decades, and a considerable number of papers on this topic have been published. For instance, the use of orifices for quality and flow rate metering is described by Hoopes (1957), Ragolin (1958), Murdock (1962), James (1965), Bizon (1965), Chisholm (1967, 1974), Heckle (1970), Collins & Gacesa (1971), Smith & Leang (1975), Lorenzi & Muzzio (1976) and Smith & Murdock (1977). However, in previous studies, all experiments were conducted with a low ratio of gas (or steam) density Po to liquid density PL, PCJPL. The highest tested ratio was PC,/PL = 0.107 and the largest tested ratio of the operating pressure to the critical pressure was PIPc = 0.535 (table 1). Apparently, these cannot satisfy the requirements of various practical engineering problems. In addition, the effective ranges of these proposed correlations are in narrow limit, and there is a lack of generality in them. This paper contains the results of a set of two-phase flow measurements of high PC~PL (up to 0.328) and high P/Pc (up to 0.8319) across a sharp edged circular orifice. On the basis of a modified separated flow model, a simple and rational relationship is developed for the flow rate and quality by the introduction of a corrective coefficient 0, to be determined empirically. 0 is a function of pcJpx, and is derived from the experimental data of high PJPL presented in this paper as well as that of lower PC,/PL ratio obtained by other authors. Our experimental work was accomplished in collaboration with engineerst of the Shanghai Boiler Institute of China and the author. The test fluid was R-113 vapor liquid mixture. The relationship is compared with other experimental data and 5 proposed correlations. 2. THEORETICAL CONSIDERATIONS Reported correlations for two-phase flowmeters were mainly derived from two flow models: The homogeneous flow model and the separated flow model. However, in reality, experiments showed that the flow at the throat of a two-phase flowmeter was not homogeneous. Even the flow pattern upstream of the throat was bubbly flow which is usually considered as a homogeneous flow. Three-dimensional suction effects gave rise to an appreciable transverse

Mass‐Transfer Study of Carbon Felt, Flow‐Through Electrode

Abstract: The mass‐transfer characteristics of a carbon felt, flow‐through electrode that has potential application for the positive electrode in zinc‐bromine batteries were studied. The electrochemical technique of limiting current measurements for the cathodic reduction of bromine in excess supporting electrolytes was used. In an electrochemical cell with perpendicular flow of electrolyte and current, limiting currents that were proportional to the electrolyte velocity, , where , which was dependent on the electrode thickness but independent of the concentration of reactant species, were obtained at low Reynolds numbers. Analysis of the data using a model that relates the conversion efficiency of a porous electrode to a dimensionless group, , which contains experimental parameters such as porosity, pore diameter, flow rate, and diffusion coefficient, showed good agreement.

Some aspects of the relationship between instantaneous volumetric blood flow and continuous wave Doppler ultrasound recordings--I. The effect of ultrasonic beam width on the output of maximum, mean and RMS frequency processors.

Abstract: A theoretical model has been developed to predict the effect of ultrasonic beam width on the output of maximum frequency, mean frequency and rms frequency processors when interrogating blood vessels containing either parabolic or plug flow It is shown that the only way to measure blood flow velocities, and obtain waveforms that are proportional to instantaneous volumetric flow (irrespective of changes in velocity profile) is to use an ultrasonic beam which is uniform over the whole area of the vessel, and to process the Doppler shift signal with a mean frequency detector

Method and apparatus for delivering a controlled flow rate of reactant to a vapour deposition process

Abstract: In a vapour phase deposition reaction, particularly the oxidation of a silicon tetrahalide to silica concomitantly with the oxidation of small quantities of other halides to serve as dopants, there have been problems in providing a controlled rate of flow of vapour to the reaction zone. A flow rate which can be varied in a controlled manner, as required from time to time, is critical for various purposes, particularly the production of optical fibres. The invention is based on the finding that a high degree of accuracy of control can be achieved by metering liquid reactant, evaporating it and feeding the vapour to the reaction zone. Alternatively, if desired the liquid can be fed directly into the reaction zone in a finely dispersed form and allowed to vaporise therein. The flow rate of the liquid reactant is controlled independently of the flow rate of carrier gas. The invention is particularly useful in making optical fibres or silica-based semi-conductor devices. Apparatus preferred for use in the invention includes a flow controller, e.g. comprising a stepper motor (85) connected to a carriage (83) operating a displacement pump or equivalent (81 or 82,) a vaporiser (102), having inlets (92, 91) for reactant liquid and carrier gas, and a manifold (94) where the vapour and carrier gas mix. The mixture is introduced through an outlet (95) from the manifold into a vapour deposition reaction zone (11).

Fluid dynamics of vertical submerged gas jets in liquid metal processing systems

Abstract: High speed cinematography and a pressure trace technique have been used to investigate the fluid dynamics of inert gas jets injected vertically upward into water, molten tin, lead-tin alloy, and iron. Two flow regimes of jet behavior were observed: one in which unstable bubbles were produced at the jet nozzle, and one in which a steady cone of gas emerged from the nozzle and broke up continuously into small bubbles. The transition between bubbling and continuous jet flow was controlled by the mass flow of gas per unit area of the jet and occurred at a flow rate of approximately 40 g/cm2 s in all of the systems studied.

Simultaneous flow measurement of specific heats and thermal expansion coefficients of liquids: Aqueoust-BuOH mixtures and neat alkanols and alkanediols at 25°C

Abstract: A flow method is described for the simultaneous measurement of volumetric specific heat capacities c p v and thermal expansion coefficients α of liquids, using a Picker heat capacity microcalorimeter. the method involves a simple sequence of operations in which the calorimeter unit is used alternately to measure a difference in volumetric specific heats at constant flow rate and temperature, or a flow rate variation resulting from a temperature scan on a flow cell. The precision of the method in α measurements is close to 1% which is comparable to that of current dilatometric methods; the overall time for the combined c p v -α measurement is less than 30 minutes. Typical uses and reliability of the method are illustrated through results for aqueous NaCl solutions, t-BuOH-water mixtures, and α,ω-diols (C2−C5) at 25°C. The α and c p v values in homologous series of normal alkanes, alcohols and diols appear well represented by equations comprising two contributions, one related to the hydrocarbon chain length, the other dependent on the number density of −OH groups. The general trends in these data and comparison with similar results for H2O2 and H2O illustrate the magnitude of the c p v and α ‘anomalies’ in liquid water.

Method for determining volumetric fractions and flow rates of individual phases within a multi-phase flow regime

Abstract: A reference is established indicating the functional relation between differing proportions of one fluid phase within a mixture of a plurality of fluid phases to the dielectric response of that mixture. Measurements are taken within a well wherein the well fluid consists of multiple fluid phases, of the flow rate, density and dielectric response of the well fluid. The dielectric response measurement is related to the established reference to determine the apparent proportion or volumetric fraction of one fluid phase of the well fluid. The density measurement is utilized to determine the volumetric fraction of the same phase of the well fluid. These equivalent volumetric fraction determinations are utilized to adjust the established reference in response to the density-determined volumetric fractions such that subsequent dielectric response measurements within the well fluid may be correlated to such adjusted reference and thus may be translated into appropriate volumetric fraction values with improved accuracy. These volumetric fraction determinations may then be related to the flow rate measurement made within the well to obtain the flow rates of the individual phases of the well fluid at the depths at which the described measurements were made.

Laminar Flow in a Cylindrical Container With a Rotating Cover

Abstract: Unsteady and steady flow in a cylindrical chamber with a rotating cover has been studied for two Reynolds numbers and three aspect ratio values. The structure of the velocity and pressure fields in the apparatus is described. Primary and secondary volumetric flow rates and torque coefficients are also calculated for all six cases solved.

Diffusion of Si atoms and thin film deposition in a silane-argon plasma

Abstract: Time dependences of the Si atom density in a pulsed RF discharge in a mixture of 5% silane and 95% argon have been investigated by absorption spectroscopy. Decay of the Si atom density in afterglow was exponential in a low power and low flow rate limit. The time constant of the decay was proportional to the gas pressure in the measured range of 0.2 to 2 Torr. This relation yields the diffusion coefficient of Si atoms in the mixture to be 1.5*1019 cm-1 s-1 at unit gas density and at 300K. From the diffusion coefficient and the absolute density of Si atoms in the plasma the deposition rate is calculated with the mass density of the deposited film measured by a combination of a multiple beam interferometry and an oscillating quartz microbalance technique. The calculated value is smaller than the measured one by about 30%. The difference is attributed to the deposition of other radicals produced in the plasma.

Apparatus and method for liquid chromatography

Abstract: To stabilize flow rate in a single-stroke, syringe-type high pressure pump to a constant value after turn-on, a control system increases the pump speed until equilibrium conditions are reached and then pumps at the present rate. To quickly reach equilibrium, the outflow of the column is measured under no load conditions at the desired flow rate and when a column is connected, the pumping speed is increased until the same outflow results before reducing the pumping rate. In subsequent runs using the same column, the chromatograph is operated as a constant pressure system, and the speed of a recording chart is adjusted to the pumping speed to provide chromatograph with abscissae of flow rate units.

Mass flow controller apparatus

Abstract: An apparatus capable of selecting and controlling the mass flow rate of a gas to be substantially constant over extended periods of time at very low flow rates and very low gas partial pressures is disclosed.

Pulsating flow of a plastic fluid

Abstract: It has been observed1,2 that when a polymeric solution flows through a circular pipe under a pressure gradient which varies periodically about a non-zero mean, the mean volumetric flow irate increases over that which is due to the mean pressure gradient alone. The magnitude of this flow enhancement depends on the fluid properties and is a function of the mean pressure gradient and the amplitude and the frequency of its varying component. Theoretical work1–6 has indicated that this phenomenon is due to the shear-thinning property of the polymeric fluid. More generally, the flow enhancement arises because of the non-linear relationship between the stress and the strain rate which causes the effective viscosity to decrease. Indeed, we show here that a flow enhancement is possible for a Bingham fluid7.

A Numerical Model of the Non-Isothermal Flow of Carbon Dioxide in Wellbores

Abstract: A numeric model of non-isothermal flow in pure carbon dioxide production or injection wells was developed. The model includes single or 2-phase flow, heat transfer between the well bore and its surroundings, and an accurate representation of the thermophysical properties of carbon dioxide, even near its critical point. Model predictions matched pressures measured during a field production test to within 30 PSI and temperatures to within 3/sup 0/F for flow rates between 4 and 22 MMSCFD. Sensitivities to wellhead conditions and flow rate for a pure carbon dioxide injector were examined with the model. Explanations of behavior of behavior during production and injection should improve the understanding of the use of carbon dioxide in the oil field. 24 references.

Powder flow rate measuring apparatus

Abstract: A novel powder flow rate measuring apparatus having a simple structure is described herein, in which a conveying fluid is injected through a nozzle into an inlet of a single detecting pipe line having an inlet and an outlet, also a powder material within a powder tank is introduced into the same inlet, and a pressure difference between the inlet and outlet of the detecting pipe line at this moment is detected, whereby a flow rate of the powder material flowing through the detecting pipe line can be measured. The thereby obtained measured value is essentially very close to a mass flow rate of the powder material, and moreover the measured value can be obtained continuously.

Method and apparatus for simultaneous determination of fluid mass flow rate, mean velocity and density

Abstract: This invention relates to a new method and new apparatus for determining fluid mass flowrate and density. In one aspect of the invention, the fluid is passed through a straight cantilevered tube in which transient oscillation has been induced, thus generating Coriolis damping forces on the tube. The decay rate and frequency of the resulting damped oscillation are measured, and the fluid mass flowrate and density are determined therefrom. In another aspect of the invention, the fluid is passed through the cantilevered tube while an electrically powered device imparts steady-state harmonic excitation to the tube. This generates Coriolis tube-damping forces which are dependent on the mass flowrate of the fluid. Means are provided to respond to incipient flow-induced changes in the amplitude of vibration by changing the power input to the excitation device as required to sustain the original amplitude of vibration. The fluid mass flowrate and density are determined from the required change in power input. The invention provides stable, rapid, and accurate measurements. It does not require bending of the fluid flow.

Method and device for calibrating a regulated flow spraying apparatus

Abstract: A method and device are disclosed for calibrating a regulated flow spraying apparatus of the type including a source of spraying fluid under pressure, and spray nozzles, the flow rate of the spray nozzles being regulated by varying the pressure of the liquid delivered thereto, the regulation being controlled as a function of at least one external parameter and a calibration parameter Fluid from the source is conveyed to a calibration circuit comprising a flow rate sensor and at least one calibration nozzle The flow rate and the pressure of the fluid are measured in the claibration circuit The calibration parameter is calculated from the measured values of the flow rate and pressure

In situ coal gasification

Abstract: OF THE DISCLOSURE In an injection well for underground gasifica-tion of carbonaceious materials, either liquids or solids, by partial combustion with oxygen-rich gas in the presence of a moderating fluid such as steam, air, CO2 or the like, in which the moderating fluid is introduced through an annular path surrounding the injection tube through which the oxygen-rich gas is injected, back flow of gasification products from the well is prevented by providing a flow restriction in the annular path to increase the linear flow velocity of the moderating fluid while maintaining the designed mass flow rate of said moderating fluid. The flow restriction is so designed that at the predetermined downward flow rate of said moderating fluid the critical velocity of the moderating fluid at the restriction corresponds to the formula: wherein g is the gravity constant, D is the equivalent diameter of the largest opening in the restriction.

Air-conditioning system

Abstract: An improved, energy-efficient method and apparatus for cooling and conditioning the air being supplied to an air-conditioned area in which the volumetric flow rate of the air being directed through a spray chamber is varied in response to changes in the heat load in the air-conditioned area while the volume of water sprayed by the spray chamber is also varied so as to maintain a predetermined ratio between the volumes of spray water and air flow.