THW-L1 Transient Hot Wire

The Transient Hot Wire (THW-L1) is widely used for the accurate measurement of thermal conductivity, thermal diffusivity, and specific heat capacity of liquids, pastes, and powders.

Ideal für liquids, pastes, and powders

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The THW-L1 following ASTM D7896-19, is widely used for the accurate measurement of thermal conductivity, thermal diffusivity and specific heat of liquids and pastes. This versatility is greatly expanded with the addition of Thermtest’s proprietary Temperature Platform (TP) which is appreciated by academic and commercial users alike.

The transient hot wire (THW) has been used for the testing of liquids for more than 30 years, making it one of the most published methods for measuring thermal conductivity of liquids available.

Eigenschaften

Follows international standard ASTM-D7896-19
Automated, powerful & accurate
Minimum effects of convection
Cell Pressure up to 35 bar
Integrated temperature control
Unique wire clamping for easy replacement

The Transient Hot-Wire (THW-L1) liquid thermal conductivity equipment is an advanced measurement system for testing the thermal conductivity, thermal diffusivity, and specific heat capacity of liquids, pastes and powders in accordance with ASTM D7896-19. The THW-L1 was designed with speed and operational simplicity in mind. With a single measurement of 1 second in duration, small volumes of liquids, pastes, and powders can be accurately and precisely measured for thermal conductivity, thermal diffusivity, and specific heat. The THW-L1 utilizes a non-stationary measurement approach and rapid test times to limit convective effects of samples with a wide range of viscosities.

The THW sensor consists of a thin heating wire 40 mm in length and is completely inserted into the sample to be tested. The sensor wire is heated using a constant current source (q) and the temperature rise is recorded by monitoring the change in electrical resistance of the wire. The slope (m) from the plot of temperature rise vs. logarithm of time is used in the calculation of thermal conductivity (λ). For liquid samples of high thermal conductivity, the lower the slope. For liquid samples of low thermal conductivity, the higher the slope.

Spezifikationen

Materialien	Flüssigkeiten, Pasten und Pulver
Messfähigkeiten	Flux Sensors (x2)
Wärmeleitfähigkeit	0,01 bis 2 W/m•K
Zusätzliche Eigenschaften	Temperaturleitfähigkeit, und Spezifische Wärme
Viscosity Range	0.001 to 10,000,000 cP
Messzeit	1 Sekunde \| < 5 Sekunden
Reproduzierbarkeit	± 1%
Genauigkeit^*	± 5%
Temperaturbereich^†	-150 to 300°C
Druck	Up to 35 bar
Smallest Volume	20 mL
Normen	ASTM D7896-19

^*All performance data is verified with ASTM Type II Water (IAPWS)
^†Based on THW-L1 model used

Transient Hot-Wire Models (Non-portable)

Modelle	THW-L1	THW-L1S	THW-L1E
Materialien	Flüssigkeiten, Pasten und Pulver	Flüssigkeiten, Pasten und Pulver	Flüssigkeiten, Pasten und Pulver
Messfähigkeiten	Schüttgut-Eigenschaften	Schüttgut-Eigenschaften	Schüttgut-Eigenschaften
Wärmeleitfähigkeit	0,01 bis 2 W/m•K	0,01 bis 2 W/m•K	0,01 bis 2 W/m•K
Zusätzliche Eigenschaften	Temperaturleitfähigkeit, und Spezifische Wärme	Temperaturleitfähigkeit, und Spezifische Wärme	Temperaturleitfähigkeit, und Spezifische Wärme
Viscosity Range	0.001 to 10,000,000 cP	0.001 to 10,000,000 cP	0.001 to 10,000,000 cP
Messzeit	1 Sekunde \| < 5 Sekunden	1 Sekunde \| < 5 Sekunden	1 Sekunde \| < 5 Sekunden
Reproduzierbarkeit	± 1%	± 1%	± 1%
Genauigkeit^*	± 2%	± 2%	± 2%
Temperaturbereich	10 to 200°C	-50 to 200°C	-150 to 300°C
Druck	Up to 20 bar	Up to 20 bar	Up to 35 bar
Smallest Volume	20 mL	20 mL	20 mL
Normen	ASTM D7896-19	ASTM D7896-19	ASTM D7896-19
Externes Kühlgerät erforderlich	Nein	Ja	Ja

^*All performance data is verified with ASTM Type II Water (IAPWS)

Transient Hot-Wire Models (Portable)

Modelle	THW-L2	THW-L3	THW-S
Materialien	Flüssigkeiten, Pasten und Pulver	Flüssigkeiten, Pasten und Pulver	Isolierung und weiche Materialien
Messfähigkeiten	Schüttgut-Eigenschaften	Schüttgut-Eigenschaften	Schüttgut-Eigenschaften
Wärmeleitfähigkeit	0,01 bis 2 W/m•K	0,01 bis 1 W/m•K	0,01 bis 2 W/m•K
Zusätzliche Eigenschaften	Nein	Nein	Nein
Viscosity Range	0.001 to 10,000,000 cP	0.001 to 10,000,000 cP	K.A
Messzeit	1 Sekunde \| < 5 Sekunden	1 Sekunde	1 to 5 seconds
Reproduzierbarkeit	± 2%	± 2%	± 2%
Genauigkeit^*	± 5%	± 5%	± 5%
Temperaturbereich	-50 to 100°C	10 bis 40°C	10 bis 40°C
Druck	Umgebung	Umgebung	K.A
Smallest Volume	15 mL	15 mL	Min. Sample Size: 50mm x 10 mm
Normen	ASTM D7896-19	ASTM D7896-19	K.A
Externes Kühlgerät erforderlich	Ja	Ja	K.A

Optional THW-L1 Accessories

Paste und PCM-Küvette

Special Phase Change Materials (PCM) with easy to load access. Unique spring design allows sample expansion and contraction, while ensuring sample is in constant contact with THW wire during measurement.

Beobachtungsküvette

THW-L1 observation sample cell is used for liquids, powder, and paste testing. The cell has convenient glass ports for observing what is happening with your sample. Typical applications are phase separation, boiling or particle settling to name a few.

Umgebungsdichte-Pulverküvette

The THW-L1 Ambient density Powder Cell is suitable for basic powder sample testing and ambient pressure.

Puderküvette mit variabler Dichte

THW-L1 test cell with screw-type compression system for varying the density of powder samples, can also be used to ensure powders stay in contact with THW wire.

Vertical Cell Mount

Convenient THW cell mount that can be attached to your THW-L1 for vertical sample loading. Ideal for the Paste/PCM and all Powder Cells.

Cooling Options

Measurement Process

The Sample

The liquid is poured into the sample cell, the required volume is 20 ml. The THW-L1’s ability to limit convection, using short test times, allows accuracy measurements of a large range of samples, widely varying viscosities. The sample cell can then be back filled to pressures up to 35 bar, for testing liquids past their boiling points.

Approximate Time: 1 min.

Insert Sensor

For testing with temperature, the liquid cell is inserted into the integrated temperature platform.

Approximate Time: < 1 min.

Run Experiment

The THW-L1 Software automatically controls isothermal steps of temperature from -150 to 300°C.

Approximate Time: < 1 min.

Exporting Results

Smart THW-L1 Windows Software verifies quality of results and recommends changes if needed. Results report can be generated, saved, and exported to excel. For convenience results may also be emailed.

Approximate Time: 1 min.

THW-L1 Applications

Low back pressure was applied to the fluids, to allow measurements over their boiling point.

Wärmeleitfähigkeit wasser

Wärmeleitfähigkeit deviations from reference values:
Water < 2%

Thermal DIffusivity of Water

Thermische Diffusivität deviations from reference values:
Water < 2%

Thermal Conductivity of Heptane

Wärmeleitfähigkeit deviations from reference values:
Heptane < 3%

Thermal Diffusivity of Heptane

Thermische Diffusivität deviations from reference values:
Heptane < 2%

Calculated Specific Heat Capacity deviations from reference values:
Water < 2%
Heptane < 5%

Wärmeleitfähigkeit Ethylenglykol

Wärmeleitfähigkeit deviations from reference values:
Ethylene Glycol < 1%

Thermische Diffusivität

Thermische Diffusivität deviations from reference values:
Ethylene Glycol < 1%

Calculated Specific Heat Capacity deviations from reference values:
Ethylene Glycol < 2%

Citation:
Lemmon, E.W., Bell, I.H., Huber, M.L., McLinden, M.O. (2018). NIST Standard Reference Database 23: Reference Fluid Thermodynamic and Transport Properties-REFPROP, Version 10.0. National Institute of Standards and Technology, Standard Reference Data Program, Gaithersburg.

Vergleich der Modelle für den transienten heißen Draht (THW)


Modelle	MP-1 mit THW	THW-L1	THW-L2	MP-2 mit THW-L3
Materialien	Flüssigkeiten, Pasten und Pulver	Flüssigkeiten, Pasten und Pulver	Flüssigkeiten, Pasten und Pulver	Flüssigkeiten, Pasten und Pulver
Module testen	Masse	Masse	Masse	Masse
Andere Materialien	Feststoffen mit TPS	Nein	Nein	Feststoffen mit TPS, TLS
Wärmeleitfähigkeit	0,01 bis 2 W/m•K	0,01 bis 2 W/m•K	0,01 bis 2 W/m•K	0,01 bis 1 W/m•K
Stichprobengröße	20 mL	20 mL	15 mL	15 mL
Zusätzliche Eigenschaften	Temperaturleitfähigkeit, und Spezifische Wärme	Temperaturleitfähigkeit, und Spezifische Wärme	Nein	Nein
Temperaturbereich	Raumtemperatur 10 bis 200°C \| -50/-15/0 bis 200°C -160/-45/-15/0 bis 300 °C	10 bis 200°C \| -50/-15/0 bis 200°C -160/-45/-15/0 bis 300 °C	-50 bis 100 °C	Raumtemperatur 10 bis 40°C
Druck	Bis zu 35 bar*	Bis zu 35 bar*	Umgebung	Umgebung
Test Zeiten	1 Sekunde	1 Sekunde	1 Sekunde \| < 5 Sekunden	1 Sekunde
Daten-Punkte	400 Punkte/Sekunde	100 Punkte/Sekunde	60 Punkte/Sekunde	60 Punkte/Sekunde
Genauigkeit der Wärmeleitfähigkeit	2 %	2 %	5 %	5 %
Reproduzierbarkeit	1 %	1 %	2 %	2 %
Normen	ASTM D7896-19	ASTM D7896-19	ASTM D7896-19	ASTM D7896-19
Externes Kühlgerät erforderlich	Nein \| Ja*	Nein \| Ja*	Ja	Ja

*Abhängig von dem verwendeten Modell

PREISERHALTUNG.
SCHNELL, KOSTENLOS, UNVERBINDLICH.