Showing papers on "Thermal mass flow meter published in 1990"

Integrated micro flow control systems

Abstract: The integration of fluid control systems on a silicon wafer allows the control of a small volume of fluid by virtue of a negligible dead volume. Microvalves driven by small piezoactuators have been fabricated on a silicon wafer by micromachining. Three types, i.e. normally open, normally closed and three-way, were developed. An integrated mass flow controller consisting of a small thermal mass flow sensor and a normally closed microvalve was fabricated for precise gas control. The small thermal capacity of the flow sensor gives high sensitivity and quick response. The response time of the mass flow controller is less than 2 ms, which is faster than that of previous ones by nearly a thousand times. The integrated system gives rise to a precise flow control for advanced deposition processes, etc.

Two and three-phase flow measurement

Abstract: A device for measuring multi-phase fluid flow includes first and second flow meters connected in series for measuring a first and second fluid flow and providing first and second signals indicative of the first and second fluid flow. The device further includes a flow restrictor located between the first and second flow meters and first and second pressure measurement means operatively connected to each of the flow meters. The device enables the measurement of multi-phase flow without the need for physically separating the different fluid flows.

Fluid flow meters

Abstract: A fluid flow meter of the fluidic oscillator type and suitable for electrically conducting liquids, for example for metering domestic water supplies, comprises a feed back oscillator with magnets (8, 9, 12, 13) creating a magnetic field across at least one of the flow paths and a pair of electrodes (10, 11, 14, 15, 16) detecting the resultant potential difference across the flow path. The frequency of the detected signal gives a measure of the flow rate and a counter of the cycles will give the total flow over a period.

Fluidic volumetric fluid flow meter

Abstract: Fluidic volumetric flow meter method and apparatus wherein undesirable dynamic interaction (ringing) which could appear in an output signal is inhibited. Electrical isolation and shielding also contribute to a high quality output signal in accordance with the invention. Particularly advantageous housing structures adapt the flow measurement device to a variety of applications as a complete flow meter.

Mass-flow meter with temperature sensors

Abstract: Mass-flow meter with temperature sensors, designed for measuring mass flow rates of liquids or gases, containing a heat conductive tube (1), through which the mass flow to be measured occurs and of which the beginning (3) and the end (4) are kept at the same temperature, as well as one or more means (56) to raise the temperature in the tube and means to measure the temperature of the mass in the tube in different places. In or on the tube one or more facilities are applied with which the zero-offset of the means to measure the temperature can be eliminated in a physical instead of an electronic way.

Mass air flow meter

Abstract: Improvements in a mass air flow meter for internal combustion engines are disclosed which comprise structure for improving the flow dynamics of the air flow through the sampling path including expansion of the dynamic range and increase of the signal to noise ratio resulting in improved engine performance, fuel efficiency, and emission control. Such structure includes a sample tube being tapered in decreasing area in the direction of air flow therethrough and a pneumatic equivalent of a low pass R C filter which decouples the high turbulence in the main flow through the venturi, averages same and provides a scaled down profiled flow through the sample tube for measurement by a transducer in the sample tube, the measurements having an accuracy of ±2% of reading.

Homogenizing and metering the flow of a multiphase mixture of fluids

Abstract: It is often desirable to meter multiphase fluid flow in pipes (e.g. bore holes). In order to obtain reliable/accurate flow rate measurements it is known to incorporate obstructions in the flow path to cause homogenization. A non-obstructive method of homogenizing the flow of a multiphase mixture of fluids in a bore hole comprises providing in the bore hole a pipe section which has an internal surface with a step discontinuity, whereby when fluid flows through the pipe section, turbulent stresses are caused by the discontinuity, leading to homogenization by turbulent mixing. There is disclosed a flow meter which comprises a pipe length with a first section having a step change in cross-section for homogenizing fluid flow therethrough, in series with a venturi flow meter in which a differential pressure can be measured in a second pipe section having a smooth change in cross-section. Non-obstructive homogenizers and flow meters do not block the passage of objects such as tools, logging devices, etc along a pipe.

Mass flow meter working on the coriolis principle

Abstract: The flow meter works on the Coriolis principle and has a measuring tube and at least two energy converters. At least one of the energy converters is an oscillation exciter for oscillating the tube to generate a wave traveling along the tube and an oscillation detector. An evaluating circuit uses the speed of travel of waves in the direction of flow of fluid through the tube and in the direction opposite the direction of flow to determine the mass flow of fluid through the tube.

Method and apparatus for determining the flow rate of a flowing fluid mass

Abstract: A method and apparatus controls the temperature of a precision resistor and, in turn, measures the flow rate of a flowing fluid mass. The precision resistor is a hot wire or hot film of an air mass meter of an internal combustion engine of a motor vehicle. Through timed current flow, the operating temperature of the precision resistor is maintained at a higher temperature than the temperature of the flowing fluid mass. The timing of the electric current for maintaining the operating temperature of the precision resistor is controlled based on the magnitude of the gating voltage supplied to heat the precision resistor.

Extended range flow meter

Abstract: This invention concerns an extended range flow meter and method of providing continuous metering of fluid flow utilizing of two or more flow meters by the more accurate flow meter or combination of flow meters at a given flow volume.

Flow meter for measuring fluid flow with multiple temperature sensors

Abstract: A part of a tube, through which a fluid passes, is cooled by means of an electronic cooling element and a flow rate of the fluid is measured on the basis of a temperature of a surface of the tube cooled. Not only can the flow rate of the liquid flowing through the tube be determined in a noncontacting manner and a very small flow rate of the liquid be determined, but also the tube is cooled so that no bubbles are generated, and thus the measurement of the liquid, which is apt to generate gases, such as low boiling point liquid, is possible. In addition, the measurement is not influenced by the gases dissolved in the liquid and merely the temperature difference resulting from the flow of the fluid, that is, the rise of the temperature of the fluid, is detected to prevent the measurement from being influenced by the installing posture of the flow meter, so that a highly accurate measurement is possible. Consequently, stable and sure controlling flow rate of liquid is possible.

Ultrasonic mass flow meter

Abstract: Methods and apparatus (1) for measuring the mass flow rate of solids suspended in a gas stream (2) flowing along a pipe (3). Two ultrasonic transducers (4, 5) are mounted in short side arms (6, 7) extending from the pipe. The transducers are arranged such that signals are transmitted from one to the other through the gas stream at an angle Υ, usually about 45°. The received signals in both transducers are received by apparatus (8) and amplified. The invention allows determination of: the mean times for the ultrasonic pulses to travel from one transducer (4) to another (5) and vice-versa; the mean peak amplitude of received pulses; and, the standard deviation or spread of these parameters. The mean times taken for the ultrasonic signals to travel between the transducers are used to determine the gas flow velocity, and the mean peak amplitudes for calculating the solids loading. From these the mass flow rate is derived. The invention is applicable to determining mass flow rates of pulverised coal contained in an air flow in a large power station.

Peculiarities of void fraction measurement applied to physical installation channels cooled by forced helium flow

Abstract: The paper presents the methods of optimizing the transducers designed for measurements of the void fraction of two-phase flows in the channels of round and annular cross section. On the basis of the analysis performed concrete solution of relatively high technical characteristics is proposed. Rated and actual characteristics of signal ranges and measurement errors are given for both sensors. Influence of the mass velocity on the void fraction of adiabatic two-phase flows is theoretically analysed. Effects of friction and of liquid-into-vapour entrainment are shown. Calculation results are compared with the obtained experimental data for helium. Special attention is given to the specific features of the processes in channels with different cross section.

Ion drag air flow meter

Abstract: An ion drag air flow meter (10) including a gas ionizer (16), an ion collector (14) and apparatus (30) for converting the collected ions into a signal providing an indication of the flow of a gas (40).

Understand two-phase flow in process piping

Abstract: Two-phase flow often presents design and operational problems not associated with liquid or gas flow. For example, several different flow patterns may exist along the pipeline. Frictional pressure losses are more difficult to estimate, and, in the case of a cross-country pipeline, a terrain profile is necessary to predict pressure drops due to elevation changes. The downstream end of the pipeline often requires a separator to separate the liquid and vapor phases, and a slug catcher may be required to remove liquid slugs. Static pressure losses in gas-liquid flow differ from those in single-phase flow because an interface can be either smooth or rough, depending on the flow pattern. Two-phase pressure losses may be up to a factor of 10 higher than those in single-phases flow; in the former, the two phases tend to separate and the liquid lags behind. Most correlations for two-phase pressure drop are empirical and, thus, limited by the range of data for which they were derived. Mathematical models for predicting the flow regime and a procedure for calculating pressure drop in process pipelines are presented.

Flow rate control system

Abstract: PURPOSE: To perform coating of high quality to constant film thickness without considering temperature variation by comparing a measured mass flow rate signal with a setting signal corresponding to a specific mass flow rate which is set previously, and controlling a control valve and spraying paint at a specific mass flow rate. CONSTITUTION: A mass flowmeter 3 responds extremely quickly because its excitation frequency is high and outputs a mass flow rate as a mass flow rate as an analog signal. A flow rate control part 12 sets a reference signal corresponding to the mass flow rate by a flow rate setting part 11 and compares said analog mass flow rate with the reference signal. An A/D converter 13 performs digital conversion so that the mass flow rate reaches the set value and the opening and closing of the control valve 4 is controlled with the digital signal to open and close the flow rate according to a coating program. Namely, the paint 2 in a tank 1 is transported by a pump 6 under fixed pressure to fill piping 9 to the constant pressure through the pressure control valve. Solenoid valves 7 and 8 are opened and closed under the command of the control part 12 and the paint is sprayed from a nozzle 5 at the set mass flow rate. COPYRIGHT: (C)1992,JPO&Japio

Measuring mass flow of gaseous media through heat exchanger - measuring gas mass flow to determine liquid cooling in vehicle from press. difference across heat exchanger

Abstract: The static press. of the gaseous medium is directly measured by cylindrical probes closed at one end arranged at the forward and reverse sides of the heat exchanger. The mass flow is determined from the press difference between the forward and reverse sides. The relationship between press. difference and mass flow is represented on a graph enabling )determination of the mass flow from several measured press. differences and the derived total press. loss. USE/ADVANTAGE - For economical measurement of gas flow through heat exchanger used as liquid cooling device in motor vehicle.

Flow in a Rotating Straight Pipe, With a View on Coriolis Mass Flow Meters

Abstract: The fully developed flow through a straight pipe, which rotates about an axis perpendicular to its own, is considered. The perturbation of the Hagen-Poiseuille flow, produced by the pipe rotation, is computed to second order and its features are described. The force of the fluid on the rotating pipe is correlated with other parameters of the flow, among them the mass flow rate Q. Possible relevance of the flow field and of the fluid forces in the rotating pipe for Coriolis flow meters are discussed

Air flow rate meter and method for producing an air flow rate meter

Abstract: When an air flow rate meter is used in the intake tube of internal combustion engines, such a meter typically having a flat substrate with at least one resistor film disposed on it, the problem arises of dirt deposits on the substrate end face facing into the flow, which cause undesirable changes in the characteristic curve compared with the calibrated new state of the air flow rate meter. The novel embodiment of the air flow rate member is intended to enable calibration based on conditions expected in practice. To produce the effect, while the air flow rate meter is new, of long-term soiling of an air flow rate meter substrate over a period of operation, a leading body, for instance shaped as a U, is disposed on the end face of the substrate facing into the flow. The leading body simulates a soiled effect while the air flow rate meter is still new, and this effect is taken into account in the calibration. The leading body may be of electrically conductive plastic or lacquer and may be connected to a ground line (15). The air flow rate meter is quite generally suitable for measuring flowing media.

Mass flow measurement

Abstract: The Coriolis technique is now being used effectively in a variety of mass flow measurement applications.

Producing actual flow value for gaseous medium control - by drawing calibrated flow of atmospheric air into parallel flow subsequently returned to flow channel

Abstract: A method of generating an actual flow value for controlling the flow of a gas involves extracting a parallel flow (3) of the gas from the flow channel (1) and feeding it back into the channel downstream. A calibrated (6) flow (8) of atmospheric air is drawn into the parallel flow (3) and this flow is detected (9) to produce the actual value for controlling the flow of gas in the flow channel. USE/ADVANTAGE - Controlling vol. flow in air conditioning systems. Prevents degradation of, or damage to, sensor by contaminants or corrosive substances in controlled flow whilst maintaining accurate control of esp. value in laboratory.

Ultrasonic gas/liquid flow meter.

Abstract: Ultrasonic gas/liquid flow meter with a W-shaped path inside the tube. The two transducers (101, 102; 201, 202) are offset axially from the execution of known geometry with a W-shaped measurement section and/or are set at an angle such that the transducers and the W-shaped path are not situated orthogonally in relation to each other.

Radiological sensors for cross-correlation flow metering

Abstract: The most common purpose of industrial flow metering is to determine the mass flow rate of a product. Ultrasonic cross-correlation flowmeters give velocity data, and so (at best) the volumetric flow rate for the multiphase mixture is determined. Mass flow depends also on the fluid mean density which in turn depends on the void/solids fraction in the liquid. Gamma-ray attenuation is a traditional methodology for measuring density or void fraction, whereas acoustic attenuation is difficult to interpret in these terms. If gamma-ray absorptiometric sensors can also be used to derive cross-correlation velocity data, then the possibility arises of inferring mass flow rates from a single non-intrusive sensing head. The authors outline aspects of the design and evaluation of one such system.

Digital sampling of low fluid flow: application to coronary flow measurements

Abstract: A novel, simplified and inexpensive solution to the on-line monitoring of low fluid flow is reported. The method can utilise a variety of common liquid flow sampling devices (i.e. fraction collector volumeters) as a front-end, constant-volume dispenser coupled to a described sample-and-hold circuit. The latter, on triggering, samples a variably set ramp voltage which is directly proportional to liquid volume flow rate. The system is easily calibrated, has a wide dynamic range of volume flow rates, and can be configured accurately for high signal resolution of very low flow phenomena. An application to coronary flow measurement is provided as well as circuit descriptions and typical performance parameters which can be measured and adjusted for optimisation.

Sensor for determining the temperature averaged on the basis of mass flow density

Abstract: In order to create a sensor for determining the temperature averaged on the basis of the mass flow density of a medium flowing through a tube, this medium having a mass flow density gradient and a temperature gradient in the tube transverse to the direction of flow, which allows the temperature averaged on the basis of the mass flow density to be ascertained more reliably and even more exactly, it is suggested that the sensor comprise a carrier body and a resistor body held thereby, the resistor body having a measuring current flowing therethrough and a temperature-responsive variable electrical resistance which leads for its part to a correspondingly variable voltage drop, and that the resistor body be designed such that the temperature-responsive variable electrical resistance of the resistor body varies with extension of the resistor body in a transverse direction in accordance with the mass flow density.