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
THW-L1

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

THW-L1 Features

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.

THW equation

Spezifikationen

Materialien

Flüssigkeiten, Pasten und Pulver

Measurement Capabilities

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

Measurement Time

1 sekunde | < 5 sekunden

Reproducibility

± 1%

Accuracy*

± 5%

Temperaturbereich

-150 to 300°C

Druck

Up to 35 bar

Smallest Volume

20 mL

Standard

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

Measurement Capabilities

Bulk Properties

Bulk Properties

Bulk Properties

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

Measurement Time

1 sekunde | < 5 sekunden

1 sekunde | < 5 sekunden

1 sekunde | < 5 sekunden

Reproducibility

± 1%

± 1%

± 1%

Accuracy*

± 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

Standard

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

Insulation and Soft Materials

Measurement Capabilities

Bulk Properties

Bulk Properties

Bulk Properties

Wärmeleitfähigkeit

0,01 bis 2 W/m•K

0.01 to 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

Measurement Time

1 sekunde | < 5 sekunden

1 Sekunde

1 to 5 seconds

Reproducibility

± 2%

± 2%

± 2%

Accuracy*

± 5%

± 5%

± 5%

Temperaturbereich

-50 to 100°C

10 to 40°C

10 to 40°C

Druck

Umgebung

Umgebung

K.A

Smallest Volume

15 mL

15 mL

Min. Sample Size: 50mm x 10 mm

Standard

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

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

Umgebungsdichte-Pulverküvette

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

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

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

Cooling Options

Measurement Process

The Sample

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

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.

THW-L1 Export Results

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

thermal diffusivity of water

Wärmeleitfähigkeit deviations from reference values:
Water < 2%

Thermal DIffusivity of Water

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

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

thermal diffusivity of Ethylene Glycol graph

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)


mp-1 thw

THW-L1

thw-l2

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

Solids with 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 to 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 %

Standards

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

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