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.

El mejor para 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.

Características

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.

Especificaciones

Materiales	Líquidos, Pasta y Polvo
Capacidad de medición	Flux Sensors (x2)
Conductividad Térmica	0,01 a 2 W/m•K
Propiedades Adicionales	Difusividad Térmica y Calor Específico
Viscosity Range	0.001 to 10,000,000 cP
Tiempo de medición	1 segundo \| < 5 segundos
Reproducibilidad	± 1%
Precisión^*	± 5%
Rango de Temperatura^†	-150 to 300°C
Presión	Up to 35 bar
Smallest Volume	20 mL
Estándar	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)

Modelos	THW-L1	THW-L1S	THW-L1E
Materiales	Líquidos, Pasta y Polvo	Líquidos, Pasta y Polvo	Líquidos, Pasta y Polvo
Capacidad de medición	Propiedades de granel	Propiedades de granel	Propiedades de granel
Conductividad Térmica	0,01 a 2 W/m•K	0,01 a 2 W/m•K	0,01 a 2 W/m•K
Propiedades Adicionales	Difusividad Térmica y Calor Específico	Difusividad Térmica y Calor Específico	Difusividad Térmica y Calor Específico
Viscosity Range	0.001 to 10,000,000 cP	0.001 to 10,000,000 cP	0.001 to 10,000,000 cP
Tiempo de medición	1 segundo \| < 5 segundos	1 segundo \| < 5 segundos	1 segundo \| < 5 segundos
Reproducibilidad	± 1%	± 1%	± 1%
Precisión^*	± 2%	± 2%	± 2%
Rango de Temperatura	10 to 200°C	-50 to 200°C	-150 to 300°C
Presión	Up to 20 bar	Up to 20 bar	Up to 35 bar
Smallest Volume	20 mL	20 mL	20 mL
Estándar	ASTM D7896-19	ASTM D7896-19	ASTM D7896-19
Aparato de enfriamiento externo requerido	No	Sí	Sí

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

Transient Hot-Wire Models (Portable)

Modelos	THW-L2	THW-L3	THW-S
Materiales	Líquidos, Pasta y Polvo	Líquidos, Pasta y Polvo	Aislantes y Materiales Blandos
Capacidad de medición	Propiedades de granel	Propiedades de granel	Propiedades de granel
Conductividad Térmica	0,01 a 2 W/m•K	0,01 a 1 W/m•K	0,01 a 2 W/m•K
Propiedades Adicionales	No	No	No
Viscosity Range	0.001 to 10,000,000 cP	0.001 to 10,000,000 cP	N/A
Tiempo de medición	1 segundo \| < 5 segundos	1 segundo	1 to 5 seconds
Reproducibilidad	± 2%	± 2%	± 2%
Precisión^*	± 5%	± 5%	± 5%
Rango de Temperatura	-50 to 100°C	10 a 40 °C	10 a 40 °C
Presión	Ambiente	Ambiente	N/A
Smallest Volume	15 mL	15 mL	Min. Sample Size: 50mm x 10 mm
Estándar	ASTM D7896-19	ASTM D7896-19	N/A
Aparato de enfriamiento externo requerido	Sí	Sí	N/A

Optional THW-L1 Accessories

Celda para Pasta y PCM

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.

Celda de Observación

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.

Celda para Polvo a Densidad Ambiental

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

Celda para Polvo a Densidad Variable

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

Proceso de medición

La muestra

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.

Tiempo aproximado: < 1 min.

Run Experiment

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

Tiempo aproximado: < 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.

tc agua

Conductividad Térmica deviations from reference values:
Water < 2%

Thermal DIffusivity of Water

Difusividad Térmica deviations from reference values:
Water < 2%

Thermal Conductivity of Heptane

Conductividad Térmica deviations from reference values:
Heptane < 3%

Thermal Diffusivity of Heptane

Difusividad Térmica deviations from reference values:
Heptane < 2%

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

ethelynglycol

Conductividad Térmica deviations from reference values:
Ethylene Glycol < 1%

ethelynglycol

Difusividad Térmica 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.

Comparación de modelos de hilo caliente transitorio (THW)


Modelos	MP-1 con THW	THW-L1	THW-L2	MP-2 con THW-L3
Materiales	Líquidos, Pasta y Polvo	Líquidos, Pasta y Polvo	Líquidos, Pasta y Polvo	Líquidos, Pasta y Polvo
Módulos de prueba	A granel	A granel	A granel	A granel
Otros materiales	Sólidos con TPS	No	No	Sólidos con TPS, TLS
Conductividad Térmica	0,01 a 2 W/m•K	0,01 a 2 W/m•K	0,01 a 2 W/m•K	0,01 a 1 W/m•K
Tamaño de Muestra	20 mL	20 mL	15 mL	15 mL
Propiedades Adicionales	Difusividad Térmica y Calor Específico	Difusividad Térmica y Calor Específico	No	No
Rango de Temperatura	Temperatura ambiente de 10 a 200 °C \| -50/-15/0 a 200 °C -160/-45/-15/0 a 300 °C	10 a 200 °C \| -50/-15/0 a 200 °C -160/-45/-15/0 a 300 °C	-50 to 100 °C	Temperatura ambiente de 10 a 40°C
Presión	Hasta 35 bar*	Hasta 35 bar*	Ambiente	Ambiente
Tiempos de prueba	1 segundo	1 segundo	1 segundo \| < 5 segundos	1 segundo
Puntos de datos	400 puntos/segundo	100 puntos/segundo	60 puntos/segundo	60 puntos/segundo
Precisión de la conductividad térmica	2 %	2 %	5 %	5 %
Repetibilidad	1 %	1 %	2 %	2 %
Normas	ASTM D7896-19	ASTM D7896-19	ASTM D7896-19	ASTM D7896-19
Aparato de enfriamiento externo requerido	No \| Sí *	No \| Sí *	Sí	Sí

*Dependiendo del modelo utilizado

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THW-L1 Transient Hot Wire

Características

Especificaciones

Transient Hot-Wire Models (Non-portable)

Transient Hot-Wire Models (Portable)