The Transient Hot-Wire (THW-L2) is widely used for the accurate measurement of thermal conductivity for liquids and pastes.
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The Transient Hot Wire (THW-L2) Liquid Thermal Conductivity Meter is a portable measurement system for direct determination of the thermal conductivity of liquids and pastes. The THW-L2 follows international standard ASTM D7896-19, and was designed with speed and operational simplicity in mind.
The Transient Hot Wire (THW-L2) Liquid Thermal Conductivity Meter is an advanced measurement system for direct determination of the thermal conductivity of liquids and pastes in accordance with ASTM D7896-19. The THW-L2 was designed with speed and operational simplicity in mind. With a single measurement of less than 2 seconds in duration, small volumes of liquids and pastes can be accurately and precisely measured for thermal conductivity.
The THW-L2 utilizes a non-stationary measurement approach and rapid test times to limit convective effects for samples with a wide range of viscosities. The THW sensor consists of a thin heating wire 60 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.
Materials | Liquids & Pastes |
---|---|
Measurement Capabilities | Bulk Properties |
Thermal Conductivity | 0.01 to 2 W/m•K |
Measurement Time | < 2 seconds |
Reproducibility | Typically better than 2% |
Accuracy | Typically better than 5% |
Temperature Range* | -50 to 100°C |
Pressure | Ambient |
Smallest Volume | 15 ml |
Largest Sample Size | Unlimited |
Standard |
Using the Thermoelectric Dry Bath, the Thermtest THW-L2 is capable of testing liquids over a wide temperature range. In this application, deionized ultra-filtered (DIUF) water was tested from 10 to 70 °C, using the THW-L2. All test results were within 5% of the literature values.
Approximate Time: < 1 min.
Approximate Time: < 1 min.
Approximate Time: 1 min.
Models | ||||
Materials | Liquids, Pastes, and Powders | Liquids, Pastes, and Powders | Liquids, Pastes, and Powders | Liquids, Pastes, and Powders |
Testing Modules | Bulk | Bulk | Bulk | Bulk |
Other Materials | Solids with TPS | No | No | Solids with TPS, TLS |
Thermal Conductivity | 0.01 to 2 W/m•K | 0.01 to 2 W/m•K | 0.01 to 2 W/m•K | 0.01 to 1 W/m•K |
Sample Size | 20 mL | 20 mL | 15 mL | 15 mL |
Additional Properties | Thermal Diffusivity and Specific Heat | Thermal Diffusivity and Specific Heat | No | No |
Temperature Range | Room Temperature 10 to 200 °C | -50/-15/0 to 200 °C -160/-45/-15/0 to 300 °C | 10 to 200 °C | -50/-15/0 to 200 °C -160/-45/-15/0 to 300 °C | -50 to 100 °C | Room Temperature 10 to 40 °C |
Pressure | Up to 35 bar* | Up to 35 bar* | Ambient | Ambient |
Test Times | 1 second | 1 second | 1 second | < 5 seconds | 1 second |
Data-Points | 400 points/second | 100 points/second | 60 points/second | 60 points/second |
Thermal Conductivity Accuracy | 2 % | 2 % | 5 % | 5 % |
Repeatability | 1 % | 1 % | 2 % | 2 % |
Standards | ASTM D7896-19 | ASTM D7896-19 | ASTM D7896-19 | ASTM D7896-19 |
External Cooling Apparatus Required | No | Yes* | No | Yes* | Yes | Yes |
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