Showing papers on "Thermal mass flow meter published in 1987"

Measuring flow in a pipe

Abstract: A gradiomanometer 1 measures the difference in pressure between points 3 and 4 to indicate density and hence proportions of two phases (e.g. liquid and gas), each of known density flowing as indicated by arrow 6. A venturi meter 2 measures the difference in pressure between points 4 and 5 to indicate flow rate, initially assumed to be that of the heavier phase only. An iterative calculation makes it possible to obtain a density measurement corrected to allow for flow friction and individual flow rates of the two components, having regard to slippage therebetween. A step discontinuity 8 may be provided downstream to create turbulence and render the flow homogenous.

Density insensitive coriolis mass flow rate meter.

Abstract: Design criteria for Coriolis mass flow rate meters with flow conduits having two modes of oscillation where the ratio of the resonant frequencies for the two modes is held constant irrespective of changes in the density of the fluid passing through the flow conduits. The design criteria embodied in the requirement that the ratio of modal mass to modal inertia for a flow conduit equal the ratio of the mass of all attachments to the flow conduit divided by the inertia of attachments to the flow conduit.

Central heating system and water system and method for controlling the tightness thereof

Abstract: In order to control the tightness of a central heating system (10, 11), the system is provided with a flow meter (8, 9) and a valve (6, 7) in the flow (3) and return pipes (4), respectively. Hereby it becomes possible to monitor the liquid flow through the flow meters (8, 9) and in a control unit (15) to compare the signals from the flow meters (8, 9). When a certain limit value is exceeded, an electric motor on the inflow flow (6) is ordered to shut off the flow of water into the system (10, 11) and a signalling device (16), if any is activated. In order to be able to control the water flow and the tightness of a water system (Fig. 3), the branch pipe (3) is connected to a motor valve (6) and a flow meter (8), before the water is led the water pipe (10) of the building. The flow meter (8) gives electrical signals to an electronic control unit (15, 18) which compares the electric signals being proportional to the water flow with the pre-determined limits, and when the flow is in excess of the upper limit and/or below the lower limit, a signal is immediately given to the motor valve (6), which will shut off the water flow in the system.

Sealant flow control for robotic applications

Abstract: A pressure profile versus flow rate is determined for a flow control system using positive displacement or a flow meter to measure flow. The profile is used as a pressure reference for closed loop pressure control of flow during the transient period following a change in commanded flow rate to reduce the time required to reach the new flow rate with compressible fluids and compliant output lines. Alternatively the pressure profile is automatically determined and updated continuously to adapt to environmental conditions affecting the accuracy of pressure controlled fluid flow.

A New Velocity Algorithm for Sing-Around-Type Flow Meters

Abstract: In many flow metering applications the fluid temperature can change rapidly during the measurements. An example is flow me- tering in district heating systems. These temperature changes will cause fast, large changes of the speed of sound in the fluid. If not recognized, this phenomenon can introduce severe errors in sing-around-type flow meters. The sing-around flow meters used today handle this problem with varying success. Therefore, the algorithm used to calculate the flow velocity from the sing-around frequencies has been modified. This new algorithm compensates for fast changes of fluid temperature dur- ing the sing-around measurement cycle. A complete derivation is given for both laminar and turbulent flow. Test measurements comparing the new algorithm and the conventional one showed a superior perfor- mance of the new algorithm, especially in the case of rapidly changing fluid temperature. \ 4

Effect of Crossflow on Flow Distribution in HTGR Core Column

Abstract: In the thermal hydraulic design of the high temperature gas-cooled reactor core consisting of prismatic fuel elements, the regulation of the coolant leakage flows is very important because these flows decrease the effective flow rate in coolant channels and are considered to be associated with the cause of the column fluctuation phenomenon. An analysis of the coolant flow distribution in the core is carried out by a one-dimensional flow network model. Since it is difficult to model leakage flow paths theoretically, the modelling of the flow network should be based on experiments. In this paper, the air flow test in a full-scale core column with one crossflow gap was carried out to study the effect of the leakage flows on the main coolant channel flows. The numerical results based on the flow network model agreed with the experimental data. Also, it is found that the effect of the leakage flow was large especially in the column with orifices.

Device for temperature compensation in a thermal mass flow meter

Abstract: not available for EP0276380Abstract of corresponding document: US4845984For temperature compensation in a thermal mass flow meter with heated and unheated electric resistors which are interlocked to a bridge, a variable temperature-independent electric resistor is connected in parallel to the bridge. The sum of the current through the bridge and of the current through the resistor connected in parallel to the bridge functions as measuring signal.

Measuring mass flow rates of fluid flows

Abstract: Apparatus for measuring the mass flow rate of a fluid flow utilises a pair of conduits (102, 104). The conduits (102, 104) are wound about a common centre line (106) to form a spiral coil having a mid cross-over point and a cross-over point on either side of the mid cross-over point. A driving mechanism (48) is connected between the conduits (102, 104), at their mid cross-over point, for applying transverse oscillations to the conduits at a selected frequency. The fluid whose mass flow rate is to be measured is divided roughly equally and supplied through the conduits (102, 104). A motion sensor (56) at the cross-over point upstream of the driving mechanism (48) and another one (58) at the cross-over point downstream of the driving mechanism (48) produce signals which have the same frequency as the driving frequency but which lead or lag the driving frequency with regard to phase. This difference in phase is a measurement of mass flow rate. The use of a spiral coil arrangement of the conduits (102, 104) provides self compensation for changes in temperature and/or thermal gradients.

Variable area and pressure difference flowmeters

Abstract: Considers variable area flowmeters and the major types of pressure difference meter such as orifice plates, nozzles and venturi. It outlines the basic fluid mechanics relevant to both types and describes the various meters available, their range of size and common applications. The effects of installation on performance and methods of obtaining traceable calibrations of meters with liquids and gases are discussed. Recent meter developments and future needs are considered.

Designing piping systems for two-phase flow

Abstract: A wide range of industrial systems, such as thermosiphon reboilers and chemical reactors, involve two-phase gas-liquid flow in conduits. Design of these systems requires information about the flow regime, pressure drop, slug velocity and length, and heat transfer coefficient. An understanding of two-phase flow is critical for the reliable and cost-effective design of such systems. The successful design of a pipeline in two-phase flow, for example, is a two-step process. The first step is the determination of the flow regime. If an undesirable flow regime, such as slug flow, is not anticipated and adequately designed for, the resulting flow pattern can upset a tower control system or cause mechanical failures of piping components. The second step is the calculation of flow parameters such as pressure drop and density to size lines and equipment. Since the mechanism of fluid flow (and heat transfer) depends on the flow pattern, separate flow models are required for different flow patterns.

Improved parallel path coriolis mass flow meter.

Abstract: A parallel path Coriolis mass flow rate meter (10), which incorporates improved inlet and outlet manifolds (100, 100'). Each manifold includes a transition piece (110, 110') and a tube mounting block (120, 120'). The transition piece incorporates a passageway (303) to route fluid into or out of the meter and has a gradually changing cross-sectional area to reduce cavitation. Each tube mounting block has one end fixedly attached to a respective one of the transition pieces. The other end of the tube mounting blocks receives the parallel flow tubes (130, 130'). One mounting block (120) evenly divides incoming fluid whose mass flow rate is to be determined between the parallel flow tubes while the other mounting block (120') combines the fluid discharged from the flow tubes. Each of the tube mounting blocks is fabricated with an internal shoulder (707) which aligns each of the flow tubes in a parallel relationship to one another and then suitably melts upon application of heat to maintain this relationship. The mounting blocks and transition pieces also incorporate various mechanical configurations which facilitate assembly of the meter and advantageously reduce the cost of the meter.

Flow measurement arrangement.

Abstract: of EP0243294The flow measurement arrangement has a flow meter and a device arranged upstream of the latter for producing a defined inflow into the flow meter. In order, in a flow measurement arrangement of this type, to ensure that the device for producing a defined inflow operates largely without pressure losses, the device consists, according to the invention, of a tube (3) with a roughened internal surface (10).

Process and device for flow measurement

Abstract: In a process for measuring the flow of fluids that are subject to temperature changes, particularly for measuring the fuel consumption of an internalcombustion engine with fuel injection, the volumetric capacity of the supply system holding the liquid between the consuming device and the flow meter is automatically increased or decreased corresponding to the change in volume of the fluid caused by temperature. The fluid volume, which increases on heating up and decreases on cooling, no longer causes errors of measurement in the meter.

Signal processing circuit for a mass flow rate digital meter design

Abstract: This paper introduces the design of a signal processing circuit which can be used in conjunction with additional arrangement for measuring gas mass flow rate. Measurement is based on Bernoulli’s equation for subsonic flow. Voltages representing gas static pressure, static temperature, and difference pressure generated across an orifice plate are supposed to be taken from appropriate transducers. These voltages are processed with this circuit in such a way as to produce a digital number representing the mass flow rate value. The circuit shows a good accuracy result with uncertainty of about ±0.1%.

Mass flow meter using the triboelectric effect for measurement in cryogenics

Abstract: The use of triboelectric charge to measure the mass flow rate of cryogens for the Space Shuttle Main Engine was investigated. Cross correlation of the triboelectric charge signals was used to determine the transit time of the cryogen between two sensor locations in a .75-in tube. The ring electrode sensors were mounted in a removable spool piece. Three spool pieces were constructed for delivery, each with a different design. One set of electronics for implementation of the cross correlation and flow calculation was constructed for delivery. Tests were made using a laboratory flow loop using liquid freon and transformer oil. The measured flow precision was 1 percent and the response was linear. The natural frequency distribution of the triboelectric signal was approximately 1/f. The sensor electrodes should have an axial length less than approximately one/tenth pipe diameter. The electrode spacing should be less than approximately one pipe diameter. Tests using liquid nitrogen demonstrated poor tribo-signal to noise ratio. Most of the noise was microphonic and common to both electrode systems. The common noise rejection facility of the correlator was successful in compensating for this noise but the signal was too small to enable reliable demonstration of the technique in liquid nitrogen.