DE3818941A1 - In-line measuring cell for the measurement of the elastic and viscous behaviour of fluids - Google Patents

In-line measuring cell for the measurement of the elastic and viscous behaviour of fluids

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Publication number
DE3818941A1
DE3818941A1 DE19883818941 DE3818941A DE3818941A1 DE 3818941 A1 DE3818941 A1 DE 3818941A1 DE 19883818941 DE19883818941 DE 19883818941 DE 3818941 A DE3818941 A DE 3818941A DE 3818941 A1 DE3818941 A1 DE 3818941A1
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DE
Germany
Prior art keywords
measurement
channel
section
elastic
pressure
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
DE19883818941
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German (de)
Inventor
Erich Dr Windhab
Dietmar Kuhlmann
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
DIL Deutsches Institut fuer Lebensmitteltechnik eV
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DIL Deutsches Institut fuer Lebensmitteltechnik eV
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Priority to DE19883818941 priority Critical patent/DE3818941A1/en
Publication of DE3818941A1 publication Critical patent/DE3818941A1/en
Withdrawn legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N11/00—Investigating flow properties of materials, e.g. viscosity, plasticity; Analysing materials by determining flow properties
    • G01N11/02—Investigating flow properties of materials, e.g. viscosity, plasticity; Analysing materials by determining flow properties by measuring flow of the material

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  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Extrusion Moulding Of Plastics Or The Like (AREA)

Abstract

For the measurement of the viscous and elastic properties of fluids, a defined flow shape is generated in a flow channel. The loss of pressure in planar, parallel laminar flow (channel section having constant cross-section) is proportional to the fluid viscosity, the loss of pressure in expansion flow (channel section with defined variable cross-section) is correlated with the elastic fluid properties. The special shape of the flow channel in the subject of the invention allows the measurement of fluid viscosity and of an impirical elastic parameter by means of measurement of the static pressure at three places along the length of the flow channel. Fitting a measuring cell of this type directly into a product pipeline or into a bypass makes possible in-line measurement of the rheological fluid parameters as well as connection to a process control unit.

Description

Die Erfindung betrifft ein Gerät zur Messung der elastischen und viskosen Eigenschaften von Fluiden, wobei der als Meß­ zelle ausgeführte Erfindungsgegenstand vom zu messenden Fluid durchströmt wird. Somit kann eine kontinuierliche Messung der elastischen und viskosen Fluideigenschaften in-line (direkt in einer Produktleitung oder im Bypass) im Prozeß gemessen werden.The invention relates to a device for measuring the elastic and viscous properties of fluids, which as the measuring Cell executed object of the invention from the fluid to be measured is flowed through. A continuous measurement of the elastic and viscous fluid properties in-line (direct measured in a product line or in the bypass) in the process will.

ViskositätsmessungViscosity measurement

Die Druckdifferenz Δ p, welche beim Strömungsvorgang eines Fluids durch einen Kanal der Länge L mit definiertem konstan­ ten Querschnitt entsteht, entspricht dem Reibungsdruckverlust, sofern die Strömung laminar ist. Die Viskosität des Fluids ist proportional diesem Druckverlust Δ p. Bei Variation des Volumenstroms (z.B. im Bypass einfach möglich) kann eine Vis­ kositätsfunktion η (γ′) gemessen werden. Die zusätzliche ge­ naue Bestimmung des Volumenstroms (Volumenstrommeßgerät) er­ laubt aufgrund der in der Meßzelle gewählten Strömungskanal­ geometrie die Messung absoluter Viskositätswerte bzw. Visko­ sitätsfunktionen.The pressure difference Δ p, which arises during the flow of a fluid through a channel of length L with a defined constant cross section, corresponds to the loss of frictional pressure, provided the flow is laminar. The viscosity of the fluid is proportional to this pressure loss Δ p . When the volume flow is varied (eg easily possible in the bypass), a viscosity function η ( γ ′) can be measured. The additional precise determination of the volume flow (volume flow meter) allows the measurement of absolute viscosity values or viscosity functions based on the flow channel geometry selected in the measuring cell.

Messung der elastischen EigenschaftenMeasurement of the elastic properties

Ein Teil des "Meß-Strömungskanals" ist mit einer Verengung ausgeführt, so daß eine Beschleunigung des Fluids in dieser Verengungszone stattfindet. Die instationäre beschleunigte Strömung bewirkt eine Zugdeformation des Fluids.Part of the "measuring flow channel" is with a constriction executed so that an acceleration of the fluid in this Narrowing zone takes place. The transient accelerated Flow causes the fluid to deform.

Durch die "Zugbeanspruchung" des Fluids entsteht bei visko­ elastischen Fluiden (Zugbeanspruchung der Makromoleküle) zum Reibungsdruckverlust ein zusätzlicher elastischer Druckver­ lust durch die bei der elastischen Dehnung der Makromoleküle aufzubringende Energie. The "tensile stress" of the fluid creates at visko elastic fluids (tensile stress of the macromolecules) for Frictional pressure loss an additional elastic Druckver lust through the elastic stretching of the macromolecules energy to be applied.  

Dieser Effekt wird erfindungsgemäß ausgenutzt. Mittels der Messung der Absolutdrucke an drei Stellen über der Länge des Meßkanals, wobei zwei Meßstellen (P 2, P 3) im Bereich des kon­ stanten Kanalquerschnittes, eine Meßstellen (P 1) im Bereich des veränderten Querschnitts liegen müssen, ergibt sich:This effect is used according to the invention. By measuring the absolute pressures at three points along the length of the measuring channel, two measuring points ( P 2 , P 3 ) in the area of the constant channel cross-section and one measuring point ( P 1 ) in the area of the changed cross-section result:

Für die Viskosität η:For the viscosity η :

Für den elastischen Druckverlust P E (als Maß für die elastischen Fluideigenschaften:For the elastic pressure loss P E (as a measure of the elastic fluid properties:

Δ P E = (P₁-P₃)-K₂ · (P₂-P₃) Δ P E = (P ₁- P ₃) - K ₂ · (P ₂- P ₃)

(K₁, K₂ = Geometriekonstanten; = Volumenstrom; P₁, P₂, P₃ = Meßdrucke in Strömungsrichtung) (K₁,K₂ = geometry constants;  = Volume flow;P₁,P₂,P₃ = measurement prints in flow direction)

Aufbau des ErfindungsgegenstandesStructure of the subject matter of the invention

Der grundsätzliche Aufbau der Apparatur ist in Abb. 1 darge­ stellt. Das Kernstück der Apparatur besteht aus dem Meßkanal (Teil 3). Dieser Meßkanal ist in einem Meßkanalträger (Teil 2) eingebettet. Der Meßkanal ist nach oben hin mit einer tem­ perierbaren Kopfplatte (Teil 1) verschlossen. In der Kopf­ platte sind Druckaufnehmer (Teil 5) integriert. Der Boden des Meßkanalträgers ist mit einer temperierbaren Bodenplatte (Teil 4) versehen.The basic structure of the apparatus is shown in Fig. 1 Darge. The heart of the equipment consists of the measuring channel (part 3 ). This measuring channel is embedded in a measuring channel support (part 2 ). The measuring channel is closed at the top with a tem perizable head plate (part 1 ). Pressure transducers (part 5 ) are integrated in the head plate. The bottom of the measuring channel support is provided with a temperature-adjustable bottom plate (part 4 ).

Die Apparatur dient prinzipiell dazu Druckdifferenzen in einem temperierten Meßkanal mit definierter Geometrie zu mes­ sen. Die Geometrie des Meßkanals ist durch die Abmaße c, d, e, f, R und s eindeutig definiert. Zur Messung der Druckdif­ ferenzen wird der Apparatur ein bekannter Volumenstrom des zu vermessenden Fluids zugeführt (6). Dieser Fluidstrom durchströmt den Meßkanal. Aufgrund der definierten Meßka­ nalgeometrie und des definierten Volumenstromes stellt sich über der Länge des Meßkanals eine rheometrisch definierte Strömung ein. Von dieser definierten Strömung werden die Druckverluste über die Strecken a, b und a+b gemessen. Aus diesen Druckdifferenzen und den konstanten Randbedingungen ist bei rein viskosen Fluiden eine Berechnung der Deforma­ tionsgeschwindigkeit und der Schubspannung und damit der ab­ soluten Viskosität gegeben. Für viskoelastische Fluide ist eine relative Berechnung des Grades der Elastizität gegeben.In principle, the apparatus is used to measure pressure differences in a temperature-controlled measuring channel with a defined geometry. The geometry of the measuring channel is clearly defined by the dimensions c , d , e , f , R and s . To measure the pressure differences, the apparatus is supplied with a known volume flow of the fluid to be measured ( 6 ). This fluid flow flows through the measuring channel. Due to the defined measuring channel geometry and the defined volume flow, a rheometrically defined flow is established over the length of the measuring channel. The pressure losses over the distances a , b and a + b are measured from this defined flow. From these pressure differences and the constant boundary conditions, a calculation of the deformation speed and the shear stress and thus the absolute viscosity is given for purely viscous fluids. A relative calculation of the degree of elasticity is given for viscoelastic fluids.

Claims (6)

1. Gerät zur Messung der viskosen und elastischen Eigen­ schaften von Fluiden, dadurch gekennzeichnet, daß ein geo­ metrisch definierter Strömungskanal vom Fluid laminar durchströmt, und an bestimmten Stellen des Strömungskanals der statische Druck oder Druckdifferenzen gemessen werden.1. Device for measuring the viscous and elastic properties of fluids, characterized in that a geo metrically defined flow channel flows through the laminar fluid, and the static pressure or pressure differences are measured at certain points in the flow channel. 2. Gerät nach Anspruch 1, dadurch gekennzeichnet, daß der Strömungskanal für die reine Viskositätsmessung mit kon­ stantem rechteckigen oder runden Querschnitt über der Druckmeßstrecke ausgeführt ist.2. Apparatus according to claim 1, characterized in that the Flow channel for pure viscosity measurement with con Stant rectangular or round cross section over the Pressure measuring section is executed. 3. Gerät nach Anspruch 1, dadurch gekennzeichnet, daß zur Messung elastischer Fluideigenschaften im Meßkanal eine Querschnittsverengung erfolgt, wobei die Druckmessung an einer Stelle im unverengten Meßkanalabschnitt, und an min­ destens zwei Stellen im verengten Kanalquerschnitt er­ folgt.3. Device according to claim 1, characterized in that for Measurement of elastic fluid properties in the measuring channel Cross-sectional narrowing takes place, with the pressure measurement on at a point in the undiminished measuring channel section, and at min at least two places in the narrowed channel cross section follows. 4. Gerät nach Anspruch 1, dadurch gekennzeichnet, daß die Druckmeßstellen auf einer Seite des Strömungskanals in be­ stimmten Abständen angeordnet sind.4. Apparatus according to claim 1, characterized in that the Pressure measuring points on one side of the flow channel in be arranged intervals are arranged. 5. Gerät nach Anspruch 1, dadurch gekennzeichnet, daß der Meßkanal in Sandwichbauweise zwischen zwei Temperier­ platten eingebaut wird.5. Apparatus according to claim 1, characterized in that the Measuring channel in sandwich construction between two tempering devices plates is installed. 6. Gerät nach Anspruch 5, dadurch gekennzeichnet, daß die Temperierplatten mit Thermofluid, elektrisch oder mit Luft beheizt bzw. gekühlt werden.6. Apparatus according to claim 5, characterized in that the Temperature control plates with thermal fluid, electrically or with air be heated or cooled.
DE19883818941 1988-06-03 1988-06-03 In-line measuring cell for the measurement of the elastic and viscous behaviour of fluids Withdrawn DE3818941A1 (en)

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DE19883818941 DE3818941A1 (en) 1988-06-03 1988-06-03 In-line measuring cell for the measurement of the elastic and viscous behaviour of fluids

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4111295A1 (en) * 1991-04-08 1992-10-22 Fraunhofer Ges Forschung Liq. property measuring appts., esp. rheometer - e.g. for microbiological suspensions in reaction vessels
WO2012017246A3 (en) * 2010-08-03 2013-04-25 The University Of Manchester Rheometry apparatus
AT517349A4 (en) * 2015-07-22 2017-01-15 Universität Linz Measuring nozzle for determining the extensional viscosity of plastic melts

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2236572A1 (en) * 1971-07-29 1973-02-08 Wisconsin Alumni Res Found DEVICE AND METHOD FOR MEASURING PUNCH PRESSURE DIFFERENTIALS AND BUILDING PRESSURE DIFFERENTIALS IN NON-NEWTON LIQUIDS OR THE SIMILAR
US3952577A (en) * 1974-03-22 1976-04-27 Canadian Patents And Development Limited Apparatus for measuring the flow rate and/or viscous characteristics of fluids
US4118973A (en) * 1976-09-06 1978-10-10 Canadian Patents & Development Limited Apparatus for measuring the flow rate and/or viscosity of a fluid
GB2158252A (en) * 1984-04-12 1985-11-06 John Parnaby Rheometers
DE3023395C2 (en) * 1980-06-23 1987-03-19 Seismograph Service Corp., Tulsa, Okla., Us

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2236572A1 (en) * 1971-07-29 1973-02-08 Wisconsin Alumni Res Found DEVICE AND METHOD FOR MEASURING PUNCH PRESSURE DIFFERENTIALS AND BUILDING PRESSURE DIFFERENTIALS IN NON-NEWTON LIQUIDS OR THE SIMILAR
US3952577A (en) * 1974-03-22 1976-04-27 Canadian Patents And Development Limited Apparatus for measuring the flow rate and/or viscous characteristics of fluids
US4118973A (en) * 1976-09-06 1978-10-10 Canadian Patents & Development Limited Apparatus for measuring the flow rate and/or viscosity of a fluid
DE3023395C2 (en) * 1980-06-23 1987-03-19 Seismograph Service Corp., Tulsa, Okla., Us
GB2158252A (en) * 1984-04-12 1985-11-06 John Parnaby Rheometers

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4111295A1 (en) * 1991-04-08 1992-10-22 Fraunhofer Ges Forschung Liq. property measuring appts., esp. rheometer - e.g. for microbiological suspensions in reaction vessels
WO2012017246A3 (en) * 2010-08-03 2013-04-25 The University Of Manchester Rheometry apparatus
CN103154699A (en) * 2010-08-03 2013-06-12 曼彻斯特大学 Rheometry apparatus
US9354152B2 (en) 2010-08-03 2016-05-31 The University Of Manchester Rheometry apparatus
AT517349A4 (en) * 2015-07-22 2017-01-15 Universität Linz Measuring nozzle for determining the extensional viscosity of plastic melts
AT517349B1 (en) * 2015-07-22 2017-01-15 Universität Linz Measuring nozzle for determining the extensional viscosity of plastic melts

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8141 Disposal/no request for examination