WO2017045896A1 - Procédé de détermination d'un débit et débitmètre thermique - Google Patents

Procédé de détermination d'un débit et débitmètre thermique Download PDF

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Publication number
WO2017045896A1
WO2017045896A1 PCT/EP2016/070174 EP2016070174W WO2017045896A1 WO 2017045896 A1 WO2017045896 A1 WO 2017045896A1 EP 2016070174 W EP2016070174 W EP 2016070174W WO 2017045896 A1 WO2017045896 A1 WO 2017045896A1
Authority
WO
WIPO (PCT)
Prior art keywords
medium
mathematical model
heat transfer
thermal
determined
Prior art date
Application number
PCT/EP2016/070174
Other languages
German (de)
English (en)
Inventor
Panagiotis PAPATHANASIOU
Axel Pfau
Vivek Kumar
Tobias Baur
Original Assignee
Endress+Hauser Flowtec Ag
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Endress+Hauser Flowtec Ag filed Critical Endress+Hauser Flowtec Ag
Publication of WO2017045896A1 publication Critical patent/WO2017045896A1/fr

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P5/00—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft
    • G01P5/10—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft by measuring thermal variables
    • G01P5/12—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft by measuring thermal variables using variation of resistance of a heated conductor
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/68—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using thermal effects
    • G01F1/684—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow
    • G01F1/6842—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow with means for influencing the fluid flow
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/68—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using thermal effects
    • G01F1/684—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow
    • G01F1/688—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow using a particular type of heating, cooling or sensing element
    • G01F1/69—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow using a particular type of heating, cooling or sensing element of resistive type
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F25/00—Testing or calibration of apparatus for measuring volume, volume flow or liquid level or for metering by volume
    • G01F25/10—Testing or calibration of apparatus for measuring volume, volume flow or liquid level or for metering by volume of flowmeters

Definitions

  • the present invention relates to a method for determining a flow according to the preamble of claim 1 and a thermal
  • Oils have different thermal properties compared to water.
  • Transition range from the solid surface of the sensor to the measuring medium could not be detected or
  • a thermal flow meter includes a heater, that is to say a first sensor element with a heating device, and a temperature sensor, that is to say a second sensor element for determining the temperature of the medium Proper operation of the flowmeter.
  • the coefficient of performance is the measure of an expended heating capacity.
  • Measured medium was not determined in the determination of the flow rate based on mathematical models, which were created with the help of computer simulations.
  • An inventive method for determining a flow rate and / or a flow rate of a measured medium by means of a thermal flow meter carried out by the following steps:
  • the provision of the first mathematical model can take place during a calibration in a calibration medium different from the measurement medium. However, this is not absolutely necessary.
  • the calibration medium can also be of the same type as the measuring medium.
  • the second mathematical model is based on a
  • Flow simulation can be determined.
  • a heat transfer coefficient can be determined from the power coefficient with the aid of the first mathematical model for describing the internal heat transfer. Prior to the determination of the Reynolds number, it may be advantageous to provide a second mathematical model for describing the external one
  • a Reynolds number can advantageously be determined on the basis of the thermal properties of the measuring medium.
  • the first mathematical model may also be preferred based on a
  • a calibration with a calibration medium can be carried out.
  • the measuring medium may preferably be a hydrocarbon and more preferably an organic oil.
  • the calibration medium is water.
  • a thermal flow meter comprises at least one sensor and an evaluation unit, wherein the sensor at least one
  • Temperature sensor wherein the evaluation unit is configured for carrying out a method according to claim 1.
  • the first and the second mathematical model can be stored on a data memory, as well as possibly thermal properties of the Measuring medium.
  • the evaluation unit can have an arithmetic unit, which serves for the calculation of the heat transfer coefficient and the Nusselt number, as well as the Prandtiiere, the Reynolds number and the flow rate.
  • Fig. 1 is a schematic representation of a thermal flow meter in
  • Fig. 2 representation of the behavior of various media
  • FIG. 3 representation of an inner and outer heat transfer
  • Fig. 4 is a schematic representation of the sequence of steps in a variant of a
  • thermometers configured as identically as possible, which are arranged in, usually pin-shaped metal sleeves, so-called stingers, or in cylindrical metal sleeves and which are in thermal contact with the medium flowing through a measuring tube or through the pipeline.
  • both resistance thermometers are usually installed in a measuring tube;
  • the resistance thermometers can also be used directly in the
  • One of the two resistance thermometers is a so-called active sensor element, which is heated by means of a heating unit.
  • the heating unit is either an additional resistance heating provided, or the resistance thermometer itself is a
  • Resistance element z. B. an RTD (Resistance Temperature
  • the second resistance thermometer is a so-called passive sensor element: it measures the temperature of the medium.
  • thermometer in a thermal flow meter, a heatable Resistance thermometer heated so that sets a fixed temperature difference between the two resistance thermometer.
  • it has also become known to feed a constant heat output via a control / control unit.
  • the cooling of the heated resistance thermometer depends essentially on the mass flow rate of the flowing medium. Since the medium is colder than the heated resistance thermometer, heat is removed from the heated resistance thermometer by the passing medium. Thus, in order to maintain the fixed temperature between the two resistance thermometers in a flowing medium, an increased heating power is required for the heated resistance thermometer.
  • the increased heating power is a measure of the mass flow or the mass flow of the medium through the pipeline. The heating power can be controlled by a so-called
  • Performance coefficients PC are described. If, however, a constant heating power is fed in, the temperature difference between the two resistance thermometers decreases as a result of the flow of the medium. The respective temperature difference is then a measure of the mass flow of the medium through the pipeline or through the
  • Fig. 1 shows schematically the structure of a thermal
  • Sensor cap 2 is partially or completely in contact with a measuring medium.
  • the sensor cap 2 has a wall region 3 with a
  • This end face is divided into at least three sub-segments, with a central sub-segment 3b, the
  • Sub-segments 3a and 3c each have a heatable temperature sensor. 4
  • One of the temperature sensors serves as a heater or active sensor element and the second temperature sensor measures the medium temperature and serves as a passive sensor element. From the temperature sensors go signal and / or power supply cable 5, which lead to an evaluation unit 7.
  • the thermal flow meter should now be calibrated for an unknown, preferably liquid, medium.
  • an unknown, preferably liquid, medium preferably water.
  • the present invention allows for a calibration on from one medium to another medium transfer. This applies in particular to the conversion from a successful calibration with the calibration medium “water” to the measuring medium “oil”.
  • Fig. 2 shows in a comparison of different media the
  • FIG. 2 shows measuring ranges for Prandtl numbers ( ⁇ / k), which were plotted using Reynolds numbers. In addition, the transition from laminar flow to turbulent flow is shown.
  • the measurement in water is represented by measuring range with the reference symbol I.
  • the measurement in oils is represented by the measuring ranges with the reference symbols II and III. As you can see, the measuring ranges do not behave
  • Heat transfers and distributions between the sensor, respectively the sensor surface, and the sensor environment, respectively the respective media must be considered.
  • This heat transfer detects e.g. the heat transfer of the temperature sensor, e.g. a Pt1 ⁇ sensor.
  • the term heat transfer covers e.g. also the heat transfer of the bonding material to the
  • Sensor cap this may e.g. a thermal bridge, e.g. made of copper.
  • the internal heat transfer defines the entirety of the heat transfer between the heated temperature sensor 4 to the sensor cap 2.
  • the internal heat transfer is essentially due to the thermal
  • the external heat transfer describes the entirety of the heat transfers and heat distributions between the medium-contacting surface and the measuring medium.
  • This task can be enabled by a method which i.a.
  • Computer simulations for the determination of mathematical models includes. Such computer simulations are known per se and can by
  • Computer software e.g. through the commercial software Ansys.
  • the following describes a corresponding method, wherein the individual method steps do not necessarily have to be performed in the predetermined order.
  • This provision includes i.a. creating the
  • One or more calibration coefficients of the mathematical model are obtained by an iterative method in the calibration of the mathematical model
  • the calibration can be done in one of the
  • Measuring medium different calibration medium done. Typical and
  • preferred calibration medium is water.
  • Measuring medium is a hydrocarbon.
  • the heat transfer coefficient h describes the heat transfer coefficient
  • the heat coefficient is difficult to detect metrologically and therefore must be determined on the basis of the first mathematical model.
  • the power coefficient of the sensor is determined in a method step B. This can be done, for example, by calculating or measuring the medium to be measured, in particular oil.
  • the heat transfer coefficient h of the sensor can be determined on the basis of the abovementioned first mathematical model, in particular of the polynomial provided, by means of the determined
  • FIG. 3 shows in the upper figure a typical dependence of the heat transfer coefficient of
  • Fig. 3 above shows in curves IV and V correlations at different temperatures and correspondingly different Prandt numbers.
  • Curves IV and VI correspond to the data obtained from the simulation, and corresponding to V and VII are the first mathematical models generated from these data.
  • the Nusselt number can be calculated in a manner known per se in a method step D with known dimensions of the sensor and known thermal properties of the medium to be measured, in particular if the thermal conductivity is known.
  • the Nusselt number describes the convective heat transfer at the interface between the medium-contacting surface of the thermal
  • the Nusselt number can be described as a function of the Reynolds number and the Prandtl number. For this purpose, in a method step E
  • Computer simulation e.g. created by computer program Ansys, is determined, used.
  • the mathematical model describes the external one
  • a method step F it is now possible to determine the Prandtl number for the measuring medium.
  • the thermal properties can be taken from a database when specifying the measuring medium or can be determined by a previous measurement.
  • Figure 3 shows a typical dependence of the Reynolds number on the Nusselt number as correlation curves VIII and IX for different temeratures and Prandtl numbers. Curves VIII and IX correspond to the data obtained from the simulation, and correspondingly X and XI are the first mathematical models generated from these data. These are shown again in FIG. 5 as individual correlation curves for subregions of the Prandtl Reynolds numbers. For the first mathematical model also different coefficients for different Prandtl number ranges can be used. This applies alternatively or additionally also for the second mathematical model. These can preferably by
  • FIG. 5 shows several correlation curves for Nusselt numbers as a function of the Prandtl-Reynolds number. Depending on the change of the temperature of the measured medium or the Prandtl number, one of the correlation curves or the associated coefficients with which the second mathematical model determines the Reynolds number is selected , The coefficients are fixed values over a given Prandtl number range.
  • a method step G the determination of the Reynolds number for the respective measuring medium now takes place by using the abovementioned second mathematical model.
  • ⁇ is the dynamic viscosity in Pa * s
  • I is the characteristic length in m or the sensor diameter
  • p is the density of the medium in kg / m 3 ; in method step H, a flow for the measuring medium is now determined.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Engineering & Computer Science (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Measuring Volume Flow (AREA)

Abstract

L'invention concerne un procédé de détermination d'un débit et/ou de la vitesse d'écoulement d'un fluide de mesure au moyen d'un débitmètre thermique, le procédé étant caractérisé par les étapes suivantes : I. l'élaboration d'un premier modèle mathématique pour la détermination du nombre de Nusselt qui sert à décrire le transfert de chaleur interne dans le débitmètre thermique ; II. la détermination d'un coefficient de puissance lors d'une mesure du fluide de mesure ; III. la détermination d'un nombre de Nusselt au moyen du coefficient de puissance à l'aide du premier modèle mathématique ; IV. la détermination d'un nombre de Reynolds du fluide de mesure au moyen du nombre de Nusselt à l'aide d'un second modèle mathématique qui sert à décrire le transfert de chaleur externe dans le fluide de mesure du débitmètre, le second modèle mathématique ayant été établi par une simulation informatique ; et V. la détermination d'un débit au moyen du nombre de Reynolds. L'invention concerne également un débitmètre thermique.
PCT/EP2016/070174 2015-09-18 2016-08-26 Procédé de détermination d'un débit et débitmètre thermique WO2017045896A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102015115762.4 2015-09-18
DE102015115762.4A DE102015115762B4 (de) 2015-09-18 2015-09-18 Verfahren zur Ermittlung eines Durchflusses und thermisches Durchflussmessgerät

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109916478A (zh) * 2019-03-26 2019-06-21 银川融神威自动化仪表厂(有限公司) 一种流量系数标定、流量计检定方法和标准流量装置

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112380653B (zh) * 2020-11-17 2023-04-18 潍柴动力股份有限公司 换热器性能数据确定方法、装置、设备及存储介质

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0624242A1 (fr) * 1992-01-28 1994-11-17 ENDRESS & HAUSER LIMITED Debitmetre massique pour fluides
DE102006057208A1 (de) * 2006-12-01 2008-06-05 Endress + Hauser Flowtec Ag Vorrichtung zur Bestimmung und/oder Überwachung des Massedurchflusses
DE102012106657A1 (de) * 2012-04-23 2013-10-24 Endress + Hauser Flowtec Ag Verfahren zum thermischen Bestimmen eines Massedurchflusses eines gasförmigen Mediums und thermischer Massedurchflussmesser
DE102013108099A1 (de) 2012-10-19 2014-04-24 Endress + Hauser Flowtec Ag Thermisches Durchflussmessgerät

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6450024B1 (en) 2001-03-07 2002-09-17 Delta M Corporation Flow sensing device

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0624242A1 (fr) * 1992-01-28 1994-11-17 ENDRESS & HAUSER LIMITED Debitmetre massique pour fluides
DE102006057208A1 (de) * 2006-12-01 2008-06-05 Endress + Hauser Flowtec Ag Vorrichtung zur Bestimmung und/oder Überwachung des Massedurchflusses
DE102012106657A1 (de) * 2012-04-23 2013-10-24 Endress + Hauser Flowtec Ag Verfahren zum thermischen Bestimmen eines Massedurchflusses eines gasförmigen Mediums und thermischer Massedurchflussmesser
DE102013108099A1 (de) 2012-10-19 2014-04-24 Endress + Hauser Flowtec Ag Thermisches Durchflussmessgerät

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109916478A (zh) * 2019-03-26 2019-06-21 银川融神威自动化仪表厂(有限公司) 一种流量系数标定、流量计检定方法和标准流量装置

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DE102015115762A1 (de) 2017-03-23

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