Showing papers on "Thermal mass flow meter published in 1999"

Wide range gas flow system with real time flow measurement and correction

Abstract: A gas delivery system accurately measures and optionally regulates mass flow rate in real time. A fluid conduit connects an inlet valve, calibration volume, flow restrictor, and outlet valve in series. Pressure and temperature sensors are coupled to the calibration volume. One or more pressure sensors may be attached across the flow restrictor. Alternatively, an absolute pressure sensor may be attached upstream of the flow restrictor. One embodiment of differential pressure sensors comprises a floating reference differential pressure sensor, including a first transducer attached to the fluid conduit upstream of the flow restrictor and a second transducer attached to the conduit downstream of the flow restrictor. In this embodiment, each transducer receives a reference pressure from a reference source, and optionally, after the calibration volume is charged, the floating reference differential pressure transducers are calibrated. When gas flow is initiated, differential and/or absolute pressure measurements are repeatedly taken, and a measured mass flow rate calculated thereon. Gas flow is adjusted until the measured mass flow rate reaches a target mass flow. Using the temperature/pressure sensors at the calibration volume, repeated calculations of actual flow rate are made to uncover any discrepancy between actual and measured mass flow rates. Whenever a discrepancy is found, the manner of calculating measured mass flow is conditioned to account for the discrepancy; thus, the measured mass flow rate more accurately represents the actual mass flow rate thereby providing an actual mass flow rate more accurately achieving the target mass flow rate.

Coriolis mass/flow density meter

Abstract: The present Coriolis mass/flow density meter and method for measuring a mass flow rate of a medium flowing through a flow tube of a Coriolis mass flow meter provide measurement results which are independent of the current velocity field of the medium to be measured. At least one measuring tube is provided, through which the medium flows, which oscillates during operation. A means for measuring the oscillations is arranged at an inlet end of the measuring tube and provides a measurement signal. A second means for measuring the oscillations is arranged at the outlet of the measuring tube and provides a second measurement signal. A third measuring means provides a third measurement signal which represents the current Reynolds number of the flowing medium, Evaluation electronics generate a measurement value representing the mass through-flow. The evaluation electronics also generate a measurement value representing the current density of the medium.

Variable flow hydraulic system

Abstract: A variable flow hydraulic system including a fixed displacement pump and a variable displacement pump for supplying pressurized hydraulic fluid in a machine is disclosed herein. Along with the dual pumps, the system includes a reservoir, a flow sensitive unloading valve, and a conduit system for distributing fluid flow between the system components. The reservoir stores fluid for use in a work circuit with an actuator for performing work in response to applied fluid flow. The fixed and variable displacement pumps are driven by a power source (e.g., an engine) to provide a fixed and a variable fluid flow, respectively. The variable flow is applied to the work circuit. As for the fixed flow, the unloading valve switches the fixed flow to either bypass or be applied to the work circuit in response to a flow signal, which depends upon the fluid flow being applied to the work circuit. The flow signal can be a differential pressure signal generated as the flow applied to the work circuit passes through a restriction in the conduit which supplies fluid flow to the work circuit. As the fixed flow is switched to and bypassed from the work circuit, the inherent flow compensation characteristics of the variable displacement pump provide for smooth, accurate, responsive and efficient machine operation.

Fluid dynamic characterization of operating conditions for continuous flow blood pumps.

Abstract: As continuous flow pumps become more prominent as long-term ventricular assist devices, the wide range of conditions under which they must be operated has become evident. Designed to operate at a single, best-efficiency, operating point, continuous flow pumps are required to perform at off-design conditions quite frequently. The present study investigated the internal fluid dynamics within two representative rotary fluid pumps to characterize the quality of the flow field over a full range of operating conditions. A Nimbus/UoP axial flow blood pump and a small centrifugal pump were used as the study models. Full field visualization of flow features in the two pumps was conducted using a laser based fluorescent particle imaging technique. Experiments were performed under steady flow conditions. Flow patterns at inlet and outlet sections were visualized over a series of operating points. Flow features specific to each pump design were observed to exist under all operating conditions. At off-design conditions, an annular region of reverse flow was commonly observed within the inlet of the axial pump, while a small annulus of backflow in the inlet duct and a strong disturbed flow at the outlet tongue were observed for the centrifugal pump. These observations were correlated to a critical nondimensional flow coefficient. The creation of a "map" of flow behavior provides an additional, important criterion for determining favorable operating speed for rotary blood pumps. Many unfavorable flow features may be avoided by maintaining the flow coefficient above a characteristic critical coefficient for a particular pump, whereas the intrinsic deleterious flow features can only be minimized by design improvement. Broadening the operating range by raising the band between the critical flow coefficient and the designed flow coefficient, is also a worthy goal for design improvement.

System for validating calibration of a coriolis flowmeter

Abstract: A System for validating a flow calibration factor for a Coriolis flowmeter. In accordance with the present invention, the period of oscillation of a flow tube is measured as a material of a known density flow through the flow tube. The period of oscillation is used in an equation derived from an equation used to calculate the density of material flowing through the flow tube to find a result. The result is then compared to a result derived from the known density of the material to detect a possible error condition in the flow tube. If an error condition exists an error signal is generated that indicates the Coriolis flowmeter should be inspected.

Development of Electrical Capacitance Tomography for Solids Mass Flow Measurement and Control of Pneumatic Conveying Systems

Abstract: This paper describes a novel development of a solid mass flow meter incorporating a combination of a twin-plane Electrical Capacitance Tomography (ECT) System and a DSP-based multi-channel direct cross correlator. In addition to flow imaging, the ECT system is able to measure the concentration and velocity of the solids moving in the conveying pipe. By using inferential measurement, it is possible to get the mass flow rate by combining the concentration and velocity measurements. Industrial evaluation of the measuring system was undertaken and results and challenges are presented.

Density and viscosity monitoring systems using Coriolis flow meters

Abstract: Multivariable industrial transducers are becoming commonplace. The Coriolis effect-based flow meter measures mass flow, density and temperature, and thus provides volumetric flow information as well, with one single transducer. By using an additional simple device, the differential pressure transmitter, an additional process parameter, the fluid viscosity can be measured and used to monitor or control the process. The density signal makes it possible to perform measurements either in terms of absolute or kinematic viscosity units. The laws of physics limit the application of a tube viscometer to laminar flow of Newtonian fluids. Using various computing means and characterizations, a suitable physical layout and control, it is in addition possible to measure non-Newtonian fluids with the capillary viscometer. The paper discusses the use of direct mass flow meters which accomplish high precision density and viscosity measurements for a wide range of industrial processes.

Thermal mass flow sensor with improved sensitivity and response time

Abstract: A thermal mass flow sensor having superior sensitivity and response time includes a flow sensor tube defining an interior channel for fluid flow between input and output ends, a heating element in thermal communication with a portion of the flow sensor tube for heating a fluid flowing through the tube, a pair of spatially compact thermal sensors located at the upstream and downstream ends of the heating element for sensing the temperature of the fluid flowing through the tube at their respective locations and providing a signal representative of the fluid temperature at those locations, and a pair of thermal grounding members on the flow sensor tube, yet positioned at specified locations substantially beyond the heated portion of the tube, for establishing reference temperatures for the fluid flowing therethrough at those locations.

Single meter blending fuel dispensing system

Abstract: A single meter blending fuel dispensing system utilizing a pair of proportional flow control valves each having a pressure transducer positioned aft of the valve flow control mechanism. A computer controller is used to program a desired fuel mixture by varying the pressure for each flow control valve. A pressure decrease in one valve produces a corresponding pressure increase in the other valve. A third pressure transducer can be situated downstream of the valves and is set such that the pressure it receives cannot exceed that of the two valve pressures. Flow meters can be substituted for the pressure sensors. A calibration method for calibrating the positive displacement meter is also disclosed. At installation the positive displacement meter is at its most accurate and is synchronized with the less accurate pressure sensors or flow meters. As time passes and the positive displacement meter wears it can be re-calibrated using the baseline data and the pressure sensors or flow meters which are not subject to mechanical wear.

Process mass flow apparatus and method for measuring the mass flow of powdered and granulated solids as well as the accumulated weight of material passed during a specified time

Abstract: A process mass flow apparatus for measuring the mass flow rate of a powdered, granulated or otherwise substantially divided process solid, seeds, grains, or similar particulate materials includes a process material inlet, a process material outlet, a measuring chamber connecting the process material inlet and the process material outlet, comprising a movable element with a fixed axis of rotation located in the flow path of the process material and having attached to the axis of rotation a material flow sensor which provides a raw output signal corresponding to an unknown mass flow rate and a processor which contains an empirically derived calibration function for converting the raw output signal to an adjusted signal indicating the mass flow rate of the process fluid. A method is also disclosed for determining an unknown mass flow using an empirically derived conversion function, the function being derived by correlating the output signals of a mass flow instrument sensing the flow of a calibration material with the output signals of the mass flow instrument sensing the flow of the process material, as is a method for calculating the accumulated weight of material having passed through the measuring chamber during a period of time specified by the user.

Constant-temperature-difference flow sensor, and integrated flow, temperature, and pressure sensor

Abstract: An integrated sensor for automated systems includes a flow sensor, a temperature sensor, a pressure sensor, and a network interface. In a particular embodiment of the invention, the flow sensor includes a temperature sensor ( 26 ) which determines the temperature of the fluid flowing in a flow path ( 12 ). A heater ( 18 ) is coupled to the flow path, and is energized by a controller ( 20 ) with sufficient electrical power to raise the temperature of the heater above the measured fluid temperature by a fixed temperature difference. In order to aid in determining the temperature difference, a sensor ( 24 ) may be associated with the heater ( 18 ). The amount of power required to maintain the temperature difference is a measure of the flow velocity. The volumetric flow rate is the product of the flow velocity multiplied by the area of the flow sensor. The mass flow rate is the product of the volumetric flow rate multiplied by the mass density of the fluid. In a particular embodiment, the pressure sensor is ratiometric.

Multi stage multiple-phase flow meter

Abstract: This invention is related to flow meter instrumentation. More particularly, the invention is related to obstruction flow meters which are used in series in a flow conduit to determine the volume flow rate of liquid and gas phases of fluid flowing within the conduit. Multiple flow meters including at least one obstruction type flow meter are positioned serially within a flow conduit such as a pipe. Mathematical equations are developed for each flow meter based upon measured quantities and phase flow rates within the liquid stream. These equations are then solved simultaneously to obtain the desired phase flow rates. Two flow meters are used to determine the gas and liquid flow rates. Alternately three flow meters are used to determine the flow rates of a gas and two liquid phases.

A Comparative Study of Two Flow Conditioners and Their Efficacy to Reduce Asymmetric Swirling Flow Effects on Orifice Meter Performance

Abstract: The sensitivity of differential-pressure flow meters to the quality of the approaching flow continues to be a cause for concern to flowmeter manufacturers and users. Distortions to the approaching velocity profile generated by pipe fittings and installations located upstream of a flowmeter, can lead to considerable errors in flowmetering. This cannot be ignored because of the likely cost and process efficiency implications. This paper describes the effects of various entrance flow velocity profiles on the performance of an orifice flowmeter with and without flow conditioning. Asymmetric swirling velocity profiles were generated by a ball valve. These caused significant shifts to the meter's calibration. The use of a vaned-plate flow conditioner, consisting of six vanes attached to a 70% porosity plate, greatly improved the performance of the meter. Thus, the device can be used as part of a flowmetering package that will have considerably reduced installation lengths. The less sophisticated NEL plate proved to be a good flow straightener, i.e. a good swirl remover, but was not an efficient flow conditioner.

Sensors and method for measurement of flow rates and cumulative flow in ducts

Abstract: The present invention relates to a sensor for measuring the instantaneous rate of mass flow and the cumulative mass flow in steady or unsteady flows of single-phase liquids or gases in a duct. By measuring the shear stress or the streamwise pressure gradient at the duct wall, and relating it to mass flow through solutions to the Navier Stokes equations of fluid mechanics, information on mass flow through the entire duct cross sectional area is deduced.

System for measuring multiphase flow using multiple pressure differentials

Abstract: An improved method and system for measuring a multi-phase flow in a pressure flow meter. An extended throat venturi is used and pressure of the multi-phase flow is measured at three or more positions in the venturi, which define two or more pressure differentials in the flow conduit. The differential pressures are then used to calculate the mass flow of the gas phase, the total mass flow, and the liquid phase. The system for determining the mass flow of the high void fraction fluid flow and the gas flow includes taking into account a pressure drop experienced by the gas phase due to work performed by the gas phase in accelerating the liquid phase.

Method of setting flow coefficient and flow meter using the same

Abstract: The present invention relates to a method of setting a flow coefficient used in a flow meter for measuring a flow rate of a fluid, and a flow meter having the flow coefficient which is set by the flow coefficient setting method An object of the present invention is to provide a method for efficiently providing an optimal approximate line represented by a low-degree function such that flow coefficients including a number of data sets are within a predetermined error, and to provide a flow meter with a reduced error In order to achieve the object, the present invention includes the steps of: obtaining an optimal approximate line using a number n of consecutive sets of data points (Xi, Yi); increasing or decreasing the number n so that the n sets of data points are all within a predetermined error Er with respect to the optimal approximate line; and setting a region Thus, it is possible to easily and automatically set a flow coefficient using a personal computer, or the like, with high efficiency and good reproducibility

System for measuring liquid flow through a metering device

Abstract: A system is provided that accurately measures the quantity of liquid that is transferred through a flow meter The system is composed of a flow meter with an ultrasonic fluid (liquid) sensor mounted therein that operates to sense the presence or absence of liquid flowing through the flow meter so that air flow is not erronecously measured as liquid flow When there is substantially no liquid flow through the meter, the ultrasonic fluid (liquid) sensor interrupts the transmission of an output signal from a signal-conditioning circuit to a totalizer that operates to process the signal and total the amount of liquid so that any non-liquid material passing through the meter is not included in the total amount of removed liquid by the totalizer Also provided are methods of using the system to accurately measure the amount of liquid flowing through a flow meter, such as in a grease trap pumping operation

Improved design of a proportional flow meter

Abstract: Conventional flow meters have several drawbacks which were overcome in the improved design. Geometry of the control section of the flow meter was determined theoretically in order to maintain normal depth—discharge relation upstream. Model dimensions were computed from prototype canal with a scale of 1:30. The improved flow meter has high modular limit and nearly constant coefficient of discharge under free flow condition. Conventional expansive transition provided at the outlet of the flow meter was replaced by straight expansion. Studies were made with four different lengths of expansion governed by side splays 0:1, 1:1, 2:1 and 3:1. With level bed, the hydraulic performance of expansions defined in terms of efficiency (η0) and Coriolis coefficient (α2) were found to be extremely poor. Separation of flow occurred right from the entry of the expansions resulting in highly non-uniform velocity downstream. By providing adverse slopes to the expansion floor, performance of the flow meter was found ...

Fluid mass flow rate controller

Abstract: PROBLEM TO BE SOLVED: To provide a fluid mass flow rate controller which never causes the clogging at a flow rate detection part, has high heat resistance and can control even a large flow rate with high accuracy. SOLUTION: A fluid mass flow rate controller 1 consists of an ultrasonic flowmeter 3 which measures the flow rate of gas flowing in a gas pipe 2, a flow rate control valve 4 which controls the flow rate of gas flowing in the pipe 2 and a valve drive control circuit 5 which compares the mass flow rate measured by the flowmeter 3 with the mass flow rate of the target gas and controls the opening degree of the valve 4 to secure the coincidence between both mass flow rates. In such a constitution, the clogging is never caused at a flow rate detection part with high heat resistance, being different from the case where a thermal flow rate sensor is used. In addition, even a large flow rate can be controlled with high accuracy and the pressure loss of a gas flow is never caused at the flow rate detection part.

Predicting thermal performance of a closed-wet cooling tower for chilled ceilings:

Abstract: Computational fluid dynamics (CFD) is applied to the prediction of thermal performance of a prototype closed-wet cooling tower for chilled ceilings. The prediction involves the two-phase flow of ga...

Continuous measurement of flow speed or liquid flow involves observing flow of every bubble through flow tube using photodiode to determine flow speed or flow of liquid from path time data of bubbles

Abstract: The method involves incorporating a sequence of bubbles (5) into a liquid (4) which is made to flow through a flow tube (1). A photodiode (3) observes the flow of every bubble through the flow tube to obtain the flow of every bubble in the sequence and to continuously determine the flow speed or flow of liquid from the path time information of the bubbles.

Fluid motion in ultrasonic flowmeter cavities

Abstract: The ultrasonic flow meter is a newcomer among flow meters for measuring large quantities of natural gas. It has notable advantages compared to traditional meters. The ultrasonic flow meter is much more compact and has a wider dynamic range for flow measurements than the orifice plate meter. When manufactured, the ultrasonic sensors are often set back from the pipe wall in a cavity. When the fluid flows past the cavities, a secondary flow of vortices with characteristic size equal to the cavity width is established inside the cavities. The aim of this study has been to investigate the influence of this secondary flow on the accuracy of the ultrasonic flow meter. Both measurements and numerical simulations of the cavity flow have been conducted. It has been found from the present work, that the influence of the flow in the cavities on the measurements increases nonlinearly with the pipe flow rate.

Measurement of Water Flow in Closed Conduits by Chemical Tracer Method

Abstract: Thermal output in a nuclear power plant is verified with calorimetric heat balance on the secondary plant. The calorimetry involves the precise measurement of the feedwater flow rate. However, the correct indication of feedwater flow rate obtained by a pressure-difference measurement across a venturi can be affected by instrument errors, fouling or a poorly developed velocity profile. This can result in an inaccurate mass flow rate and consequently an inaccurate estimate of power. The purpose of this study is to develop verification methods with accuracy better than for high precision flow measurement to be used for measuring feedwater flow rate. This chemical tracer method is a testing process that uses tracers which can be applied to quantify losses in electrical output due to the incorrect measurements of feedwater flow rate. And this system has good response to the variation of the flow rate. Accuracy of better than 0.5 percent can be expected for feedwater flow measurement, providing that the system can be stabilized during the test. This methodology is applicable to other flow systems well.

Mass flow rate measuring device for IC engine air intake has surface normal to measuring surface of measuring element projecting into flow path provided with component in gravity force direction

Abstract: The mass flow rate measuring device has a measuring element (16) projecting into the flow path of the flow medium fed along the flow line for the IC engine air intake. The surface normal (F) to the measuring surface (18) of the measuring element has a component in the gravity force direction (g), the measuring surface provided by a thin-film resistance layer, extending parallel to the horizontal flow of the flow medium. An Independent claim for an IC engine air intake system with a mass flow rate measuring device is also included.

Electrodynamic flow meter

Abstract: An electrodynamic flow meter measures a flow rate of either non-conductive fluid (i.e. petrol) or conductive fluid (i.e. city water) in a pipe and, has two different configurations. One is the electrodynamic flow meter inductance model in Fig. 1 and Fig. 2 (hereafter: EDF-IM). The other is electrodynamic flow meter capacitance model in Fig. 3 and Fig. 4 (hereafter: EDF-CM). According to the principle of Lorentz transformation, the flow relative motion in an alternative magnetic field can bring out an electric signal that indicates the velocity of the flow relative motion. Both EDF-IM and EDF-CM comply with the principle of the Lorentz transformation.