Showing papers on "Volumetric flow rate published in 1995"

Method and apparatus for measuring multiphase flows

Abstract: A device for measuring flow rate of multiphase fluids such as oilwell effluents, containing liquid hydrocarbons, gas, and water includes first and second sections situated at a distance one from the other in the flow direction, each including a passage provided with structure such as venturis for inducing a change of speed therein, and respective means for measuring the resulting pressure differences, the pressure difference signals obtained in the respective sections being suitable for cross-correlation to produce a signal representative of the total volume flow rate.

Underfill flow as viscous flow between parallel plates driven by capillary action

Abstract: Epoxy underfill is often required to enhance the reliability of flip-chip interconnects. This study evaluates the flow of filled epoxy underfill materials between parallel plates driven by capillary action. An exact model was developed to understand the functional relationship between flow distance, flow time, separation distance, surface tension, and viscosity for quasi-steady laminar flow between parallel plates. The model was verified experimentally with a typical underfill material. The measured values of flow distance agreed well with the exact model. A new material parameter, the coefficient of planar penetrance, is introduced. This parameter measures the penetrating power of a liquid between parallel plates driven by capillary action. The effectiveness of gravity and vacuum as flow rate enhancements are explored.

Vapor recovery system for fuel dispenser

Abstract: A system for recovering vapor and liquid emerging from a tank as it is being filled, in which the volumetric flow of a recovery pump that withdraws the vapor through a recovery tube is made equal to the volumetric flow of a fuel delivery pump with a microprocessor. The microprocessor can also modify the volumetric flow of the recovery pump in response to variations in the hydraulic pressure at the inlet side of the recovery pump.

Fluid micropumps based on rotary magnetic actuators

Abstract: A jet-type magnetically driven fluid micropump to drive conductive fluids has been designed, fabricated, and tested The pump actuation is based on a rotary magnetic micromotor with fully integrated stator and coils operating with the rotor immersed in the fluid to be pumped, thereby driving the fluid from a inlet flow reservoir through integrated flow channels to an outlet flow reservoir The micropump has been successfully driven using standard diabetic-prescription insulin in saline buffer (Novo Nordisk, Regular Insulin) as a working fluid, demonstrating the feasibility of a rotary micropump for pumping and injecting fluids in drug delivery or chemical flow systems The attained flow rate varies monotonically with motor speed In the realized micropump, the fluid flow rate achieved is up to 24 p!/min at a rotor speed of 5000 rpm The operating voltage is less than 3 V and the power consbmption is approximately 05 W The differential pressure is expected to be approximately 100 hPa

Electrodeposition of nickel/silicon carbide composite coatings on a rotating disc electrode

Abstract: Composite coatings suitable for protection against wear were prepared by electrodeposition from a nickel Watts solution containing silicon carbide particles maintained in suspension. To obtain a better understanding of hydrodynamic effects on the codeposition process a rotating disc electrode, immersed in a vertical rising flow, was used. The local concentration of embedded SiC along the radius of the disc electrode was studied as a function of suspension concentration, rotation rate and the particle mean diameter. The effect of a rheoactive polymer was also examined. Although it is generally admitted that the particle incorporation rate is governed by a two-step adsorption process, the experimental results show that it is also dependent on the spatial distribution of the wall fluid flow. The normal component of the fluid velocity promotes particle impingement, whereas the parallel component tends to eject the loosely fixed particles. The competition between the forces which tend to maintain particles attached to the surface and the shear force which tends to remove them, depends on several parameters, in particular the surface chemistry and the size of the particles, the flow rate and the current density.

Multiple-function fluid measuring and transmitting apparatus

Abstract: A measuring and controlling system is provided which has a control function as well as a measurement function to perform the measurement and control of fluid amounts such as the flow rate, pressure, liquid level, weight and so on by itself in the same field. A pressure receiving unit is directly mounted on a pipe or a container, in which a fluid under measurement exists, in order to detect the temperature, differential pressure and static pressure of the fluid under measurement independently of each other. Means for storing the characteristic of fluids under measurement is provided such that the mass flow rate, weight and liquid level can be calculated. By providing the transmitter with the measurement and control functions, the measurement and control of fluid amounts such as flow rate, pressure, liquid level, weight and so on can be performed in a closed form, thereby making it possible to simplify a correction procedure for the static pressure and temperature, improve the responsibility, and enhance the control performance of the whole plant. Also, a measuring and controlling system can be realized which reduces a wiring amount for connecting with an upper level control unit.

Experimental velocity profiles and volumetric flow via two-dimensional speckle tracking

Abstract: The performance of a two-dimensional speckle tracking system in measuring in vitro laminar flow is evaluated. The system uses a pattern matching algorithm to track subresolution-sized speckle regions between successive ultrasonic 2D pulse-echo acquisitions in order to determine both the axial and the lateral components of velocity. In this study, multiple 2D vector velocity maps were acquired in real time using a calibrated laminar flow phantom, and then statistically analyzed off-line. At a 90° transducer angle, volumetric flow rates computed from measured velocity profiles exhibited excellent linearity ( R 2 > 0.99), with a mean error of −6.1%, over the range 5–30 mL/s. At 105° and 120°, experimental volume flow rates also agreed well with actual rates, although measured velocity profiles appeared more irregular with decreasing Doppler angles. Velocity profiles estimated using sampled radio-frequency data rather than envelope-detected data were inconsistent due to an insufficient sampling rate and the quantization of the velocity grid. Results indicate that excellent flow velocity and volume rate estimates can be obtained from vector velocity measurements along a single line of sight, without a priori knowledge of the flow direction, at transducer angles near 90° where Doppler instruments are prone to large errors.

Generalized Relative Permeability Coefficients during Steady-State Two-Phase Flow in Porous Media, and Correlation with the Flow Mechanisms

Abstract: A parametric experimental investigation of the coupling effects during steady-state two-phase flow in porous media was carried out using a large model pore network of the chamber-and-throat type, etched in glass. The wetting phase saturation, S 1, the capillary number, Ca, and the viscosity ratio, κ, were changed systematically, whereas the wettability (contact angle θ e ), the coalescence factor Co, and the geometrical and topological parameters were kept constant. The fluid flow rate and the pressure drop were measured independently for each fluid. During each experiment, the pore-scale flow mechanisms were observed and videorecorded, and the mean water saturation was determined with image analysis. Conventional relative permeability, as well as generalized relative permeability coefficients (with the viscous coupling terms taken explicitly into account) were determined with a new method that is based on a B-spline functional representation combined with standard constrained optimization techniques. A simple relationship between the conventional relative permeabilities and the generalized relative permeability coefficients is established based on several experimental sets. The viscous coupling (off-diagonal) coefficients are found to be comparable in magnitude to the direct (diagonal) coefficients over board ranges of the flow parameter values. The off-diagonal coefficients (k rij /μ j ) are found to be unequal, and this is explained by the fact that, in the class of flows under consideration, microscopic reversibility does not hold and thus the Onsager—Casimir reciprocal relation does not apply. The coupling indices are introduced here; they are defined so that the magnitude of each coupling index is the measure of the contribution of the coupling effects to the flow rate of the corresponding fluid. A correlation of the coupling indices with the underlying flow mechanisms and the pertinent flow parameters is established.

Analytical chemistry in a liquid film/droplet

Abstract: The measurement of nitrogen dioxide at the parts-perbillion level is described. The experimental arrangement consists of two optical fibers placed on opposite sides of and in contact with a liquid film (14-57 μL in volume) supported on a U-shaped wire guide and two tubular conduits (one of which constitutes the means for the delivery of the liquid). Light from a green (555 nm) light-emitting diode enters the liquid film, composed of Griess-Saltzman reagent The transmitted light is measured by a referenced photodetection arrangement Sample gas flows past the droplet at a low flow rate (typically 0.10-0.25 L/min). The response is proportional to the sampling period and the analyte concentration. The limit of detection for this nonoptimized arrangement is estimated to be <10 ppb by volume for a 5 min sample. Some unusual characteristics are observed. The initial absorbance, when most of the analyte/reaction product is still near the surface, is higher than that when the content of the droplet is fully mixed. The signal depends on the sample flow rate in a nonmonotonic fashion, first increasing and then decreasing with increasing sampling rate ; the specific chemistry involved in the collection and determination of NO 2 may be responsible.

Method and system for analyzing a two-phase flow

Abstract: A method of analyzing a two phase flow in a conduit comprising: employing sensing means with a conduit having a two-phase flow therein; operating said sensing means to detect a plurality of flow indicator quantities representative of the flow in the conduit; determining, from a number of said flow indicator quantities, at least one of the flow rate and the flow quality.

Device for machining material with a laser

Abstract: The proposed device for machining material has a laser and a machining module for forming a fluid jet (12) and for injecting the laser beam focused by means of a focusing unit into the fluid jet (12). The type of fluid chosen has a sufficiently low radiation absorption coefficient. The flow rate of the fluid in the path as far as the laser-beam injection point, which is situated preferably in the region of the focusing cone apex, is set sufficiently high to ensure that no thermal lens can form in the fluid region between the focusing optics and the focus, since a thermal lens would divert portions of the beam to the nozzle wall and damage it. The rate of removal of the machined material can be substantially increased if an electrically insulating nozzle and fluid is used and the flow rate set at a sufficiently high level to allow the fluid jet to become electrically charged.

Non-Darcian forced convection analysis in an annulus partially filled with a porous material

Abstract: Numerical solutions are presented for fully developed forced convection in concentric annuli partially filled with a porous medium The porous medium is attached at the inner cylinder, which is maintained at uniform heat flux or at uniform wall temperature while the outer cylinder is adiabatic The Brinkman-Forchheimer-extended Darcy model was used to model the flow inside the porous medium The dependence of the fluid flow and heat transfer on several parameters of the problem is thoroughly documented The inertia coefficient at which the inertial effects reduce the flow rate by 5% is determined as a function of the Darcy number for various thicknesses of the porous substrate It is also shown that a critical thickness at which the value of the Nusselt number reaches a minimum does not exist if the effective thermal conductivity of the fluid-saturated porous medium is much higher than the fluid conductivity

Interfacial Heat Transfer Between Steam Bubbles and Subcooled Water in Vertical Upward Flow

Abstract: In two-fluid modeling, accurate prediction of the interfacial transport of mass, momentum, and energy is required. Experiments were carried out to obtain a data base for the development of interfacial transport models, or correlations, for subcooled water-steam bubbly flow in vertical conduits. The experimental data of interest included the interfacial area concentration, interfacial condensation heat transfer, and bubble relative velocity. In the present investigation, bubble condensation in subcooled water-steam flow in a vertical annulus at low flow rate and low pressure is investigated experimentally. A high-speed video system (up to 1000 frame/s) was used to visualize two orthogonal views of the flow simultaneously. A digital image processing technique was used to track and measure the velocity and size of the collapsing bubbles. The axial void fraction distribution was also measured by a single beam gamma densitometer.

Flow Control System

Abstract: A control system for regulating a flow rate of a heat transfer fluid in a heat transfer system, the heat transfer system having a heat transfer fluid flow path, flow control device for creating flow along the path, a fuel source for providing a combustible fuel to the path, an air source for providing combustion air to the path, and an assembly for combusting the fuel and air, the control system comprising a sensor for sensing a measured flow value at the air source, a controller for storing an optimum flow value at the air source and for storing a range of operating control values for the flow control device, the operating control values corresponding to the optimum flow value, a system for calculating a deviation between the measured flow value and the optimum flow value, and a system for varying the operation of the flow control means in accordance with the deviation.

Fluid control apparatus and method

Abstract: A fluid control apparatus and method in which a valve unit having a plurality of inlets is respectively connected to multiple fluid sources and an outlet. A unit containing a flowmeter is also provided which cooperates with the valve unit in a manner so that, upon rotation of one of the units relative to the other, the flow of fluid is controlled from the selected fluid source to the valve unit outlet. The flowmeter is adapted to measure variations in the flow rate of the fluid, and the flow of the fluid is controlled in response to one or more related parameters.

Low-cost silicon sensors for mass flow measurement of liquids and gases

Abstract: A low-cost silicon sensor for measuring the mass flow rate of gases and liquids has been developed. Its operation is based on heat transfer from heated resistors to a flowing fluid (electrocaloric principle). The difference between the temperature of the sensors on the chip, the heating power, and the heater temperature can be used to measure the mass flow. It is important to realize that sensors are produced in silicon through the usage of micro-technology. Nitrogen and water are used for testing the sensor. The sensor has a high dynamic response and is suitable for dynamic fluid measurements. The possible measuring flow rates range from 0 to 500 ml/min for gases and 0 to 500 or 0 to 10 ml/min for liquids.

Correction of partial-volume effects in phase-contrast flow measurements.

Abstract: Because of the relatively small size of vessels and limited magnetic resonance (MR) imaging resolution, the accuracy of volume flow rate measurements is limited. A technique that corrects the partial-volume effect in volume flow rate measurements is presented. The technique uses small-phase-shift approximation, with the assumption that blood flow in the voxels at the boundary of the vessel is slow. With the proposed correction technique, the volume flow rate in partially occupied voxels is corrected on a voxel-by-voxel basis and the accuracy of flow measurements increases. Results are shown analytically and for MR phantom data.

General characteristics of two-phase flow distribution in a multipass tube

Abstract: An experimental study has been performed using two different types of multipass tubes, one with four vertical upward passes attached to a horizontal main pipe and the other with five horizontal passes placed to a vertically oriented main pipe. Passes had 6 mm inside diameter, and the inside diameter of main pipes was 20 mm for the vertical type and 6 mm for the horizontal type. Multipass tubes simulated evaporators for air-conditioning systems, and refrigerant R11 was used as the working fluid. Vapor and liquid flow rates at each pass were measured under various conditions of two-phase mixture at the main pipe inlet, that is, inlet flow rate and quality. Results suggested that measured values of flow distribution ratio presented a marked distinction between the vertical and horizontal types. On the other hand, in spite of different pass orientations, the same data trend that the flow distribution is dominated by the main tube inlet flow condition was observed, and the flow division ratio was estimated in terms of both phase flow rates before the junction. Based on these results, a flow split model was suggested and an attempt for the prediction of flow distribution was made.

Spray cooling of power electronics at cryogenic temperatures

Abstract: The operation of power electronics at liquid nitrogen temperature (LNT) is a very attractive possibility. However, a high heat flux (over 1.0 x 10 6 W/m2) cooling technique, like spray cooling, will have to be used to realize all the advantages of low-temperature operation. This study details the results from experiments conducted to study the heat transfer characteristics during spray cooling with liquid nitrogen. Four different nozzles at various pressures were used to study the variation in spray cooling heat transfer at LNT. The effect of nozzle and flow rate on the critical heat flux and overall heat transfer characteristics are presented. Heat fluxes close to 1.7 x 10 6 W/m2 were realized at temperatures below 100 K. The mass flow rate range was from 6.1 x 10 4 kg/h m2 to 3.2 x 10 s kg/h m2. Nomenclature q" = heat flux, W/m2 rsat = saturation temperature, K Tw = surface temperature, K

X-ray fluoroscopic observation of bubble characteristics in a molten iron bath

Abstract: The formation of bubbles at a nozzle and subsequent rising behavior of them in a molten iron bath at 1250°C were observed using a high-voltage X-ray fluoroscope and a high-speed video camera. The frequency of bubble formation at the nozzle exit, the mean bubble diameter and the mean bubble rising velocity were obtained for a side range of injected argon gas flow rate. Empirical correlations of these quantities were proposed and compared with previously published experimental data and empirical correlations.It has been commonly believed that the frequency of bubble formation at a nozzle placed in a molten metal bath depends solely on the gas flow rate and the outer diameter of the nozzle when the gas flow rate is relatively high and the wettability between the nozzle material and the molten metal is bad. The present experimental results, however, revealed that the frequency of bubble formation has a close relationship not with the outer diameter but with the inner diameter of the nozzle for a higher gas flow rate. Furthermore, the bubble frequency depended on the gas flow rate and the physical properties of gas and molten metal. The critical gas flow rate for the initiation of small bubbles due to disintegration of large bubbles coming from the nozzle exit was approximately 60 cm3/s under the present experimental conditions. The bubble behavior near the bath surface also was made clear.

Continuous-Flow Microwave Heating of Orange Juice: Evidence of Nonthermal Effects

Abstract: Microwave heating characteristics oforange juice were evaluated under conditions suitable for continuous-flow heat-holdcool pasteurization process. Orangejuice was pumped through a helical glass coil located inside a domestic microwave oven and exit temperatures were determined as a function of flow rate and initial temperature underfidlpower (700W, 2450MHz) heating conditions. The average residence time of the fluid was computed by dividing the volumetric capacity of the helical tube inside the microwave oven by the volumetric flow rate under the test condition. Fluid temperature rise from the tube inlet to the outlet was found to be non-linear based on the steady state temperature profile of the fluid along the tube length as measured experimentally using a fiber optic temperature probe. The calculated average residence times were converted to equivalent thermal times (or effective heating times) at the exit temperature by numerically integrating the thermal effect ofthe measured temperature profilefrom...

Transport of Soil Bacteria Controlled by Density-Dependent Sorption Kinetics

Abstract: Transport of bacteria in a soil was delayed relative to the mobile pore water by rate-limited rather than instantaneous sorption to soil particles. Desorption rates were found to be faster than adsorption rates, and sorption kinetics were dependent on the density of bacteria and on the flow rate of water. Sorption kinetics were revealed by a combination of model descriptions of the mass balance and sorption kinetics of a groundwater bacterium entering a porous system and laboratory experiments using a stirred flow chamber and a soil column. The flow chamber was designed and operated to (1) distinguish instantaneous equilibrium reactions from time-dependent reactions, (2) estimate sorption rate coefficients at different cell densities and water velocities, and (3) obtain rate coefficients that could be used to predict the breakthrough of bacteria in a soil column under saturated, continuous flow conditions. Sorption rates in the stirred flow chamber were expressed by three rate laws, first order, Langmuir, and second order, and the transport of bacteria through the soil column was described and predicted by a model assuming a mixture of instantaneous and time-dependent sorption reactions and, alternatively, by a kinetic model. The sorption rate was primafly dependent on the density of sorbed bacteria, but the desorption rate was, in addition, influenced by the density of cells in the aqueous phase. Rate coefficients obtained in the flow chamber could be used to accurately predict transport of bacteria in the soil column at the corresponding density and flow rate, but extrapolations are complicated by the nonlinear relationship between density and sorption rate. Timescales for reaching equilibrium estimated from the rate coefficients were in the range from 10–15 hours to several days, longer for low densities and velocities.

Method for determination of flow rate in a fluid

Abstract: Method for measuring the flow rate in a fluid flow (30), particularly a two-phase flow comprising oil, water and gas from a development well offshore. The fluid flow is shut off temporarily and transitorily by means of a valve (33), and the fluid pressure is recorded at a location (37) immediately upstream of the valve (33) from a time when the valve starts closing to a selected moment of time after the valve is fully closed, and opening the valve to reestablish the fluid flow. The fluid mass flux G is determined according to the ratio (I), where ς = fluid density, f = friction factor, d = pipe diameter, t* = a selected moment of time after closure of the valve, Δp*f is friction loss recorded at time t* and Δpa is pressure surge pressure represented by recorded pressure increase at the moment when the valve is fully closed.