Showing papers on "Volumetric flow rate published in 1986"

Performance of capillary restrictors in supercritical fluid chromatography

Abstract: The operating characteristics of capillary flow restrictors to control linear velocity and for transport analytes to gas phase analysis devices have been investigated for use in supercritical fluid chromatography (SFC). Expansion of the fluid from too low a temperature can result in formation of a condensed solvent phase and problems in flow regulation. Fluid flow rates for expansions that avoid two-phase regions can be estimated to within approx.30%. The expansion process has been directly observed and solvent droplet size was found to be strongly dependent on fluid temperature, with average droplet size decreasing to under 0.2 ..mu..m above the critical temperature and being negligible for reduced temperatures >1.3. The source of detector noise with flame ionization detectors (FID) and the loss of less volatile compounds in SFC results from precipitation and collection of the analyte on the restrictor during expansion of the fluid. The transport of low volatility analytes is facilitated by heating the fluid prior to the restrictor or, less effectively, by heating in the restrictor. The successful transport and detection of nonvolatile compounds in FID with SFC are demonstrated.

The hydrodynamics of trickling flow in packed beds. Part II: Experimental observations

Abstract: The liquid holdup and the pressure drop for two-phase trickling flow in a packed bed were measured experimentally. Different values of those parameters were obtained as the liquid flow rate was increased and then decreased, indicating a multiplicity in hydrodynamic states. This behavior was observed even when the gas flow rate was zero in the bed. It was determined that the hysteresis exhibited by the process is due to imperfect wetting of the packing and to the difference between advancing and receding contact angles at the gas-liquid-solid contact lines. The reduced wetting conditions are also the cause of the increase in liquid holdup observed when the surface tension of the liquid is decreased. In this case, the amount of liquid retained in the bed is controlled by the extension of the wetted regions due to the more favorable contact angles as the surface tension decreases. The transition from the trickling to the pulsing flow regime was also dependent on the history of the process. A new correlation for predicting liquid holdups and pressure drops for trickling flow in packed beds is proposed for the decreasing liquid flow rate operating mode. This correlation is based on the experimental determination of the liquid phase relative permeability as a function of the the liquid phase reduced saturation and the determination of the gas phase relative permeability as a function of the gas phase saturation and the gas phase Reynolds number. The new data are analyzed in the light of the theory developed in the first part of this paper.

Annular oil damper arrangement

Abstract: A fluid damper for controlling transverse orbital movement (14) of a non-rotating cylindrical body (12) is provided with a sealed, fluid filled reservoir (30) in fluid communication with a vent opening (24) disposed in a surrounding support member (10). A sized orifice (34) controls the volumetric flow rate of the damping fluid, maintaining an elevated average static fluid pressure in the annular volume (16) and resisting surge flow into the reservoir (30) through the vent (24) during the periodic occurrence of high fluid pressure in the annular volume (16) adjacent the vent opening (24).

Studies of a Water Treatment Device That Uses Magnetic Fields

Abstract: It is experimentally shown that voltages and currents are produced when conducting solutions are made to flow through a water treatment device that uses magnetic fields. The magnitude of this voltage is found to vary with the solution flow rate in accordance with well-known laws of physics governing the motion of charged particles under the influence of a magnetic field. Current vs flow rate plots and surface pH measurements yield results that are in accord with the presence of enhanced corrosion of the metal housing of the device. It is postulated that the current generated magnetohydrodynamically produces a precipitation initiator that favors the precipitation of scaling salts in the bulk of the solution rather than on the walls of the plumbing.

High-performance phase-change thermal energy storage using spherical capsules

Abstract: A theoretical and experimental investigation of the transient thermal characteristics of a phase-change thermal energy storage (TES) unit using spherical capsules is presented. A simulation program that considers rigorously transient aspects of both the surrounding heat transfer fluid and the phase change material (PCM) packed inside the spherical capsule is developed. The overall thermal response of this TES unit is described with variation of the capsule diameter, the flow rate, and the kind of PCMs, etc. The simulation results are then compared with experimental observations. Furthermore, a unique device employing a heat pump is presented to overcome the supercooling problem which has been one of the most serious problems (especially for inorganic hydrates) in the phase-change thermal energy storage.

The entrainment of high-viscosity magma into low-viscosity magma in eruption conduits

Abstract: We report experiments on the flow of two fluids of contrasting viscosity through a pipe in which low-viscosity fluid occupies the center of the pipe. The volume flux of the low-viscosity fluid in the pipe increased during an experiment but did not reach 100% in most cases. The transition from high- to low-viscosity-dominated outflow involved a drop in pressure gradient and an increase in flow rate due to reduced viscous resistance in the pipe. Initially, the central flow was thin and parallel-sided, but as its diameter increased the flow became unstable. A sequence of instabilities was observed during the course of each experiment, both in time and as a function of height in the pipe. In the most commonly observed instability the central flow adopted a helical geometry. The transition from parallel-sided to unstable flow first appeared at the top of the pipe and propagated downwards against the flow. Axisymmetric instabilities originating at the pipe entrance were also observed. All forms of instability exhibited entrainment of viscous fluid into the faster moving central flow. Entrainment was extensive early in the existence of the central flow, but later on the volume flux of lower-viscosity fluid in the central flow rose more rapidly than the rate of entrainment and the proportion of lower-viscosity fluid increased with time. These compositional changes determined the viscosity of the central flow which was found to control its diameter and velocity. In banded pumice deposits, silicic pumice without mafic component is commonly erupted alongside banded pumice blocks. We infer that banded pumice may correspond to the central flow in our experiments, i. e., that viscous magma has been incorporated into less viscous melt, and that pure acid pumice is derived from the outer flow. Changes in eruption style may be caused by variations in pressure gradient and flow rate due to changes in the viscosity of the melt in the conduit. Varied mafic/silicic proportions and degree of mixing in magmatic associations are controlled by the bulk volume erupted, discharge rate, initial temperature difference and aspect ratio of the conduit.

Thermal mass flowmeter and controller

Abstract: A mass flowmeter and controller measures the mass flow rate of liquid or gaseous fluids and controls the flow rate of the fluids being utilized in a processing operation. A series of flow channels and blocked channels are micro-etched from a silicon substrate leaving an integral membrane suspended across the channels. A heater-sensor thin film resistor, diode or transistor is formed on the membranes and the substrate during manufacture to sense the temperature at particular locations. A cover housing matching channels and grooves forms flow and stagnant blocked conduits in the structure. Through a bridge circuit a signal indicative of mass flow is produced. This signal is passed to a control valve armature coil in an in-line flow control valve. The controller includes a sensor module containing monitored flow and blocked channels and passive by-pass channels as required for additional flow capacity, a control valve cartridge, an overall housing and the magnetic armature coil which controls the flow of fluid through the valve and the sensor module.

Measurement of vapor-liquid equilibria at elevated temperatures and pressures using a flow type apparatus.

Abstract: A new flow-type apparatus was developed using an overflow-type liquid level self-control system and a back pressure regulator The present apparatus makes possible vapor-liquid equilibrium measurements at high temperatures by minimizing the residence time of heat-sensitive substances It was shown that the resulting vapor-and liquid-phase compositions were independent of the sample flow rate within the range of flow rates employed Vapor-liquid equilibrium data were measured with this apparatus for the systems CO2-n-heptane, CO2-n-decane, CO2-teans-decalin, CO2-tetralin, CO2-quinoline, benzene-tetralin and benzene-quinoline in the temperature range from 340 to 710 K at several pressures up to 23 MPa

Fluid injection control system

Abstract: Disclosed herein is a method and related system for controlling the injection of fluid into a plurality of spaced wellbores using a fluid distribution system to direct fluid from a fluid source to each of the spaced wellbores In the method, high/low fluid flow rate limits and high/low fluid pressure limits for each wellbore are determined and inputted into an RTU The fluid flow rate and fluid pressure for each wellbore are measured at the fluid distribution system and the measured fluid flow rate and the fluid pressure for each wellbore are compared to the determined limits Thereafter, the flow of fluid to each wellbore is adjusted at the fluid distribution system for those wellbores that have a measured fluid flow rate and/or fluid pressure outside of the determined limits and the adjustment is continued until the measured flow rate and fluid pressure are within the determined limits

High rate photoresist stripping in an oxygen afterglow

Abstract: Photoresist stripping in the afterglow of a microwave discharge in has been performed at rates compatible with high productivity single wafer processing. By design of the reactor and optimization of the process parameters, rates of up to 3 μ/m were attained. An activation energy of 11.0 kcal/mol was measured. Moderate heating and high gas flow rates are required to achieve high rates. Under these conditions, the process exhibits essentially infinite selectivity toward and Si. Separation of the discharge zone from the reaction chamber ensures that ion bombardment of the wafer does not occur.

Model study of mixing and mass transfer rates of slag-metal in top and bottom blown converters

Abstract: Water model experiments have been conducted to clarify mixing rates of molten steel and mass transfer rates between slag and metal in LD and Q-BOP furnaces using six different circular tuyere arrangements. Splashing and ‘spitting’ were also examined with a view to finding a quiet bath with minimum mixing time and maximum mass transfer rate. Froude’s similarity criterion was fulfilled to determine gas flow rate and bath depth. Complete mixing time of water determined by tracer technique had been 0.9 second to 1.8 seconds for Q-BOP as compared to 6 seconds to 13 seconds for LD. This shows that the stirring intensity in Q-BOP is remarkably larger than that of LD. A simple relationship τ = 5.9(Q/N) −0.49 was obtained with gas flow rateQ and number of tuyereN. This indicates that flow rate of gas per tuyere should be intensified to realize better mixing. Mass transfer coefficient KBa for bottom blowing was found to be almost double that for top blowing. Of all the tuyere configurations studied for Q-BOP’s, a half circular tuyere arrangement was found to be the best considering all aspects of mixing, mass transfer, and bath agitation.

Absolute flow measurements using pulsed Doppler US. Work in progress.

Abstract: Quantitative flow measurements were assessed in both laboratory and canine models using pulsed Doppler ultrasonography (US). A hydrodynamic model consisting of a Harvard pulsatile pump, a water bath, tubing, and a variable resistance reservoir was used to obtain absolute volumetric flow measurements. Parameters including angle of incidence, size of tubing, stroke volume, stroke rate, sample volume, and transducer frequency were changed independently. The effect of varying these parameters on the determination of absolute flow was analyzed. Absolute flow measurements using duplex US were performed in the canine aorta and femoral artery with reference to the electromagnetic flow probe. These data are presented, along with methods to reduce error in flow measurements that can be directly applied to quantitative estimates of blood flow in humans.

Deposition properties of silicon films formed from silane in a vertical‐flow reactor

Abstract: The growth of silicon films by low pressure chemical vapor deposition in an unique vertical‐flow reactor and in a conventional tube reactor is studied, with emphasis on the vertical‐flow reactor. For a hydrogen‐carried silane process in the vertical‐flow reactor, the growth rate depends on both the partial pressure and the flow rate of silane. A growth rate expression incorporating both of these parameters is derived which accounts for a nearly linear dependence on either parameter for small values and saturation at large values. No dependence on hydrogen partial pressure is observed. An Arrhenius‐type dependence of growth rate on temperature is observed for both type of reactors, with an activation energy of 1.5 eV. Thickness uniformity of the films deposited in the vertical‐flow reactor is compared to that found in the conventional reactor. For high temperatures (above 650 °C) depletion effects degrade the thickness uniformity of the deposited films. Such effects are more pronounced in the conventional reactor than in the vertical‐flow reactor. These effects can be attributed to the shorter gas flow path in the vertical‐flow reactor. The vertical‐flow reactor can be operated without a temperature gradient along the deposition chamber so that uniform film properties can be obtained over the entire load.

Method of and apparatus for controlling the flow rate of viscous fluid

Abstract: A method and an apparatus for controlling a flow rate of viscous fluid for feeding the fluid under pressure from a pump through a hose to a spray gun with a control unit. A temperature and a pressure of the viscous fluid in the hose is detected. Based on the detected temperature and a temperature-supplying pressure characteristic data stored in the unit, viscous fluid supplying pressure for obtaining a desired set flow rate is calculated. Based on the detected pressure of the fluid and the calculated supplying pressure, a signal for obtaining a desired supplying pressure is obtained and outputted. The gun is switched on to operate the pump at a constant speed to provide the desired set flow rate. Alternatively, only the pressure is detected and a pressure which is obtained in a previous operation and stored in the unit is used.

Thermal fluid flow sensing method and apparatus for sensing flow over a wide range of flow rates

Abstract: Miniature thermal fluid flow sensors of the airfoil type are made in batch form by forming the thermal fluid flow sensors on a thin sheet of material and bonding the sheet over an array of duct structures and dicing the individual sensors and duct structures apart. In one thermal flow sensor configuration, a flow heater is dispsoed inbetween first and second thermal flow sensors in heat exchanging relation therewith. A third thermal flow sensor is disposed upstream of the others out of heat exchanging relation with the heater for operation of the heater at a certain temperature above that sensed by the third sensor. In the low flow regime, flow is measured by the difference between the outputs of the first and second sensors, whereas in the high flow regime, the power required to maintain the temperature of the heater serves as a measure of the flow.

Volumetric Requirements for Foam and Mist Drilling Operations

Abstract: State-of-the-art foam and mist drilling suggests a need for predictive models for volumetric requirements that properly account for frictional losses caused by the solid phase in solids/foam slurry flow, settling velocities of such solids, and pressure drop across bit nozzles during foam flow. The objective of this paper is to fulfill this need. A model that predicts pressure drop across bit nozzles for foam and mist and minimum volumetric requirements for foam and mist drilling operations is presented. It accounts for the compressibility of foam but assumes negligible pressure losses resulting from friction and change in elevation and for the frictional losses caused by the solid phase, pressure drop across bit nozzles, and particle-settling velocity. This technique offers a high degree of flexibility in the selection of wellhead injection pressures and volumetric injection rates. Field application of this work can be accomplished by two primarily graphical methods that depend on compressor specification: variable-backpressure and constant-backpressure schedules. Charts are presented for 7.875- and 9.00-in. hole sizes, and for 0.500-, 0.75-, and 1.00-in. cutting sizes. Penetration rates range from 30 to 90 ft/hr. Results indicate that volumetric requirements increase with increasing hole size, depth, and particle size. Increases in penetration rate causemore » only minor increases in volumetric requirements. All foam-drilling and well-cleanout operations can be accomplished within the laminar flow region with adherence to 0.55 minimum bottomhole and 0.96 maximum annular foam quality. Annular backpressures greater than atmospheric pressure are needed to maintain a bottomhole foam quality of 0.55 or more while reaching reasonable depths. To maintain constant depth as backpressure increases, however, both wellhead injection pressure and gas injection rate must be increased, and liquid flow rate decreased.« less

Method and apparatus for measuring dynamic fluid flow rate

Abstract: A method and apparatus for measuring a dynamic flow rate of a bodily fluid in which the rate of flow is constantly changing includes an inlet to a chamber where flow accumulates. The accumulating fluid is in communication with the base of a sealed vertical column of air. An air pressure transducer in the upper portion of the column of air measures the pressure exerted upon the air by the accumulated fluid. The air pressure corresponds to the volume of accumulated fluid and is manipulated to yield a running indication of the flow rate. The chamber is automatically drained by a drainage conduit when the fluid reaches an upper operating level to reset the apparatus to a lower operating level to be ready to resume taking meaurements.

Control of flow rate in supercritical fluid chromatography

Abstract: Supercritical Fluid Chromatograph was constructed using two pumps and two restrictors. With this system in conjunction with the fused silica column packed with relatively large particles (40 μm), the flow rate was controlled both for isobaric and pressure programmed operations. Application of this system to the determination of molecular weight distribution of polystyrene oligomers was presented.

A highly efficient, compact chemical oxygen-iodine laser

Abstract: The dependence of the laser output power on the flow velocity at a cavity for a compact chemical oxygen–iodine laser is reported. The flow velocity is changed by using two vacuum pumps (3000 and 15 000 l/min). It becomes experimentally clear that the laser output power is proportional to the flow velocity and the extractable O2(1Δ) concentration. Output power in excess of 100 W has been extracted efficiently. The maximum overall reaction efficiency of 16.8% with the chlorine flow rate of 413 mmol/min is obtained.

Fractionating condensation and evaporation in plate-fin devices

Abstract: A model that describes fractionation with condensation and evaporation in a plate-fin device has been formulated. It is capable of evaluating profiles of composition, temperature, and flow rate for both liquid and vapor streams in an extended surface device. The device may be adiabatic or nonadiabatic and the surface may be incompletely wetted. Compared to experimental measurements, the model predictions showed ± 1 number of transfer unit deviation along the length of the device. The predictions of the top and bottom flow rate ratio showed a 5–10% deviation for adiabatic and condensation runs and a 25% deviation for evaporation runs.

Extrusion device for the production of honeycomb structures

Abstract: In the case of this extrusion device, a die part with feed passageways for the plastic material on the inlet side and shaping slots on the outlet side, which are connected to the feed passageways, is supported on a stationary part. The die passageway for the skin of the honeycomb structure is formed by interaction of an adjustable die element with the die part on the outlet side. For this purpose, a disk spring column as die element is arranged around the die part and is supported on a tensioning element which is adjustable in the flow direction of the material. In the feeds of the die passageway is arranged an adjustable means for regulating the flow rate of the plastic material.

Foam Generation in Rotor-Stator Mixers

Abstract: One of the unit operations in foam technology is foam generation in a liquid/gas mixer. The foaming process of an aqueous liquid system with a surface-active agent in a rotor-stator mixer has been studied, and it was found that it could be represented by a mixing characteristic relating the liquid flow rate to the maximum gas flow rate needed to produce a foam without 'blow-by'. Too high a gas flow rate resulted in a short-circuiting flow of gas via the rotor shaft to the outlet. The influence of the number of rotor-stator blades, equipment size and operating pressure on the behaviour of the foam mixer has been investigated.

System and method for controlling secondary spray cooling in continuous casting

Abstract: A system and method is provided for cooling a continuous casting, which includes determining, for each element of steel, the steel residence time in each cooling spray zone of the secondary cooling and determining residence time flow rates as a function of average speed, grade, mold heat removal and section size of the steel strand. The system modifies the residence time flow signal using a feedback error flow signal that is derived in a feedback flow control loop. The feedback error flow signal is derived by comparing the actual measured specific flow GAL/FT 2 , based on the actual measured quantity of specific cooling water that each element of steel has received, with a calculated reference specific flow. The specific flow signal is further used to determine whether the system is to use the modified residence time flow or whether the flow should be shut off when the measured specific flow exceeds a maximum reference specific flow.