DE2701774A1 - Measurement of thermal conductivity and specific heat - uses hollow sphere enclosing radiating element, with temp. sensor on outside surface monitoring temp. variation with time - Google Patents
Measurement of thermal conductivity and specific heat - uses hollow sphere enclosing radiating element, with temp. sensor on outside surface monitoring temp. variation with timeInfo
- Publication number
- DE2701774A1 DE2701774A1 DE19772701774 DE2701774A DE2701774A1 DE 2701774 A1 DE2701774 A1 DE 2701774A1 DE 19772701774 DE19772701774 DE 19772701774 DE 2701774 A DE2701774 A DE 2701774A DE 2701774 A1 DE2701774 A1 DE 2701774A1
- Authority
- DE
- Germany
- Prior art keywords
- heat
- temp
- heat capacity
- thermal conductivity
- hollow body
- 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- Withdrawn
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N25/00—Investigating or analyzing materials by the use of thermal means
- G01N25/18—Investigating or analyzing materials by the use of thermal means by investigating thermal conductivity
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K17/00—Measuring quantity of heat
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N25/00—Investigating or analyzing materials by the use of thermal means
- G01N25/005—Investigating or analyzing materials by the use of thermal means by investigating specific heat
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- Physics & Mathematics (AREA)
- Chemical & Material Sciences (AREA)
- General Physics & Mathematics (AREA)
- Life Sciences & Earth Sciences (AREA)
- Health & Medical Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Combustion & Propulsion (AREA)
- Engineering & Computer Science (AREA)
- Investigating Or Analyzing Materials Using Thermal Means (AREA)
Abstract
Description
Betrifft : PatentanmeldungSubject: patent application
Gegenstand der Erfindung Sonde zur absoluten Bestimmung der Wärmeleitfähigkeit und der spezifischen Wärme.The invention relates to a probe for the absolute determination of thermal conductivity and the specific heat.
Beschreibung Bei den in der Literatur beschriebenen Verfahren zur simultanen Bestellung der Wärmeleitfähigkeit und der spezifischen Wärme vergl. 1) ,2) ist die möglichst exakte Einhaltung oder Kenntnis der Abstände zwischen Wärmequelle und Temperaturmeßstelle erforderlich. Dies ist bei der in situ Messung in Schüttungen oder z.B. im Erdboden praktisch nicht realislerbar.Die üblichen Einsondenverfahren s.B. nach 3),bei denen Heizleiter und TemperaturfUhler direkt in Verbindung stehen liefern nur die Wärmeleitfähigkeit.Description With the procedures described in the literature for simultaneous ordering of the thermal conductivity and the specific heat see 1) , 2) is the closest possible observance or knowledge of the distances between the heat source and temperature measuring point required. This is the case with in situ measurements in bulk material or, for example, practically impossible to implement in the ground s.B. according to 3), in which the heating element and temperature sensor are directly connected only provide the thermal conductivity.
Bei zylinderförmigen Sonden mit endlicher Durchmesser 4), die die Wärmeleitfähigkeit und die spezifische Wärme liefern könnten, stellt die Wärmekapazität der Sonden und die nur ungenau bestimm= bare Wärmeübergangszahl zwischen Sonde und Medium eine praktisch nicht ausmerzbare Pehlerquelle dar,was den Einsatz solcher Sonden für Absolutmessungen ungeeignet macht.In the case of cylindrical probes with a finite diameter 4), which the Thermal conductivity and the specific heat it could deliver represents the heat capacity of the probes and the only imprecisely determinable heat transfer coefficient between probe and Medium is a practically ineradicable source of error, what the use of such Makes probes unsuitable for absolute measurements.
Erfindungsgemäß kann aus dem zeitlichen Verlauf der Oberflächen.According to the invention, from the time course of the surfaces.
temperatur einer Sonde'die in das zu untersuchende Medium eingebettet wird'die Wärmeleitfähigkeit und die spezifische Wärme des Mediums absolut bestimmt werden,wenn die Wärmekapazität der Sonde klein ist im Vergleich zur Wärmekapazität des durch die Sonde verdrängten Mediums. Dies ist zu erreichen z.B. durch eine dünnwandige Hohlkugel oder einen dünnwandigen Hohlzylinder, die (der) von innen gleichmäßig und zeitlich konstant von einer punktförmigen (linienförmigen) elektrischen Heizquelle mit Strahlungsenergie beauischlagt wird.Zur Vermeidung des ungleichmäßigen konvektiven Wärmeübergangs kann die Sonde evakuiert werden.temperature of a probe embedded in the medium to be examined is'die thermal conductivity and the specific heat of the medium absolutely determined when the heat capacity of the probe is small compared to the heat capacity of the medium displaced by the probe. This can be achieved e.g. through a thin-walled Hollow sphere or a thin-walled hollow cylinder, who (who) from within uniformly and temporally constant from a punctiform (linear) electrical Radiant energy is used to bump the heat source to avoid the uneven convective heat transfer, the probe can be evacuated.
Unter diesen Voraussetzungen wird bereits nach kurzen Meßzeiten die Oberflächentemperatur der Sonde bis auf einen zeitlich nahezu konstanten additiven Betrag mit der Temperatur der Innenoberfläche des zu untersuchenden Mediums übereinstimmen.Under these conditions, the Surface temperature of the probe except for an additive that is almost constant over time Amount correspond to the temperature of the inner surface of the medium to be examined.
Da dieser Temperatursprung zwischen Medium und Sondenoberfläche aus dem zeitlichen Verlauf der Sondentemperatur nur ungenau zu ermitteln ist, wird der einfach und genau meßbare zeitliche Vera lauf der Sondenoberflächentemperatur nach der Zeit differenziert, wobei das konstante additive Glied zu Null wird. Aus dieser abgeleiteten Meßkurve der Sondenoberflächentemperatur können die Temperaturleitzahl und die Wärmeleitfähigkeit und (bei bekannter Dichte des zu untersuchenden Mediums ) die spezifische Wärme absolut bestimmt werden..Because of this temperature jump between the medium and the probe surface the temporal course of the probe temperature can only be determined imprecisely, the the temporal variation of the probe surface temperature can be easily and precisely measured differentiated over time, the constant additive term becoming zero. From this derived measurement curve of the probe surface temperature can be the temperature diffusivity and the thermal conductivity and (if the density of the medium to be examined is known ) the specific heat can be determined absolutely.
Für die Oberflächentemperatur eine Kugelsonde nach Abb. 1 gilt unter obigen Voraussetzungen und nach 5) - Q[1 - exp(X²) erfc(X)]/4##R + Q /4#αR² ........ 1 mit. For the surface temperature of a ball probe according to Fig. 1, under the above conditions and according to 5) - Q [1 - exp (X²) erfc (X)] / 4 ## R + Q / 4 # αR² ........ 1 with.
Pur die zeitliche ableitung erhält man T' (R,t) = Q X[Y exp(X²)erfc(X) - 1/##]/4##R ............ 2 Pur die Oberflächentemperatur einer Zylindersonde nach Abb.2 gilt unter obigen Voraussetzungen und nach 6) T(R,t) = Q([lnY+R²lnY /2xt + R²/2xt+..]/4##1 + Q/2R#α1 .....Purely the time derivative one gets T '(R, t) = Q X [Y exp (X²) erfc (X) - 1 / ##] / 4 ## R ............ 2 Purely the surface temperature of a cylinder probe Fig.2 applies under the above conditions and according to 6) T (R, t) = Q ([lnY + R²lnY / 2xt + R² / 2xt + ..] / 4 ## 1 + Q / 2R # α1 .....
mit Y = 4xt/ CR² Für die zeitliche Ableitung erhält man T' (R,t) = Q[1/t - R²lnY /2xt² + ...] /4##1 lit folgenden Bezeichnungen in 1 bis C = 1,7811 T = Temperaturerhöhung [K] R = Kugel-oder Zylinderradius [m] 1 = Heizleiterlänge in Zylindersonde [m] # = Zeit [h] Q = Ergiebigkeit der Wärmequelle [W] α = Wärmeübergangszahl zw.Sondenoberfläche und Medium [#/m²/K] x = Temperatr#urleitzahl [m²/k] # = Wärmeleitfähigkeit [W/m K] Aus 2 wie auch aus läßt. sich durch Bilden der Quotienten zweier aufeinanderfolgenden Meßwerte zunächst x und damit durch Einsetzen # ermitteln.with Y = 4xt / CR² For the time derivative we get T '(R, t) = Q [1 / t - R²lnY / 2xt² + ...] / 4 ## 1 lit the following designations in 1 to C = 1.7811 T = temperature increase [K] R = spherical or cylinder radius [m] 1 = Length of heating conductor in cylinder probe [m] # = time [h] Q = yield of the heat source [W] α = coefficient of heat transfer between probe surface and medium [# / m² / K] x = temperature guideline [m² / k] # = thermal conductivity [W / m K] From 2 as well as from leaves. through education the quotient of two successive measured values initially x and thus by insertion # determine.
Literatur 1) Jaeger J.C., Australien Jl.of Physics 12(1959) 203-217 2) Borkowetz W., Ber.Dtsch.Keram.Ges. 52(1975) 317-319 und Kunststoffe 66(1976) 434-435 3) Mittenbühler A, Ber.Dtsch.Keram.Ges. 39(1962) und 41 (1964) 4) Blackwell J.H.,Jl.of Applied Physics 25(1954) 137-145 5) Kneschke A.: Diffgl.u.Randwertprobl.Bd.2,Berlin 1960, p 290 6) Carslaw &Jaeger :Conduction of Heat ... Sec.ed.Oxford 1971, p 341Literature 1) Jaeger J.C., Australia Jl.of Physics 12 (1959) 203-217 2) Borkowetz W., Ber.Dtsch.Keram.Ges. 52 (1975) 317-319 and Kunststoffe 66 (1976) 434-435 3) Mittenbühler A, Ber.Dtsch.Keram.Ges. 39 (1962) and 41 (1964) 4) Blackwell J.H., Jl.of Applied Physics 25 (1954) 137-145 5) Kneschke A .: Diffgl.u. Randwertprobl.Bd.2, Berlin 1960, p 290 6) Carslaw & Jaeger: Conduction of Heat ... Sec.ed.Oxford 1971, p 341
Claims (3)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE19772701774 DE2701774A1 (en) | 1977-01-18 | 1977-01-18 | Measurement of thermal conductivity and specific heat - uses hollow sphere enclosing radiating element, with temp. sensor on outside surface monitoring temp. variation with time |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE19772701774 DE2701774A1 (en) | 1977-01-18 | 1977-01-18 | Measurement of thermal conductivity and specific heat - uses hollow sphere enclosing radiating element, with temp. sensor on outside surface monitoring temp. variation with time |
Publications (1)
Publication Number | Publication Date |
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DE2701774A1 true DE2701774A1 (en) | 1978-07-20 |
Family
ID=5998898
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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DE19772701774 Withdrawn DE2701774A1 (en) | 1977-01-18 | 1977-01-18 | Measurement of thermal conductivity and specific heat - uses hollow sphere enclosing radiating element, with temp. sensor on outside surface monitoring temp. variation with time |
Country Status (1)
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Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0348245A2 (en) * | 1988-06-24 | 1989-12-27 | Honeywell Inc. | Measurement of thermal conductivity and specific heat |
EP0348244A2 (en) * | 1988-06-24 | 1989-12-27 | Honeywell Inc. | Measurement of fluid density |
EP0348243A2 (en) * | 1988-06-24 | 1989-12-27 | Honeywell Inc. | Calibration of thermal conductivity and specific heat devices |
EP0439950A1 (en) * | 1989-12-28 | 1991-08-07 | Honeywell Inc. | Determination of thermal conductivity and specific heat of gases at reference conditions |
CN109916952A (en) * | 2019-04-12 | 2019-06-21 | 中国工程物理研究院化工材料研究所 | The surface convection transfer rate measuring system and measurement method of georama configuration |
-
1977
- 1977-01-18 DE DE19772701774 patent/DE2701774A1/en not_active Withdrawn
Cited By (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0348245A2 (en) * | 1988-06-24 | 1989-12-27 | Honeywell Inc. | Measurement of thermal conductivity and specific heat |
EP0348244A2 (en) * | 1988-06-24 | 1989-12-27 | Honeywell Inc. | Measurement of fluid density |
EP0348243A2 (en) * | 1988-06-24 | 1989-12-27 | Honeywell Inc. | Calibration of thermal conductivity and specific heat devices |
EP0348245A3 (en) * | 1988-06-24 | 1990-10-31 | Honeywell Inc. | Measurement of thermal conductivity and specific heat |
EP0348244A3 (en) * | 1988-06-24 | 1990-10-31 | Honeywell Inc. | Measurement of fluid density |
EP0348243A3 (en) * | 1988-06-24 | 1990-11-07 | Honeywell Inc. | Calibration of thermal conductivity and specific heat devices |
EP0439950A1 (en) * | 1989-12-28 | 1991-08-07 | Honeywell Inc. | Determination of thermal conductivity and specific heat of gases at reference conditions |
CN109916952A (en) * | 2019-04-12 | 2019-06-21 | 中国工程物理研究院化工材料研究所 | The surface convection transfer rate measuring system and measurement method of georama configuration |
CN109916952B (en) * | 2019-04-12 | 2024-01-19 | 中国工程物理研究院化工材料研究所 | System and method for measuring surface convection heat transfer coefficient of hollow sphere configuration |
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Legal Events
Date | Code | Title | Description |
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8139 | Disposal/non-payment of the annual fee | ||
8170 | Reinstatement of the former position | ||
8141 | Disposal/no request for examination |