The Transient Hot Wire (THW-L1) is widely used for the accurate measurement of thermal conductivity, thermal diffusivity, and specific heat capacity of liquids and PCMs.
Best for liquids and PCMs
Please enter your email to download the brochure.
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 PCMs. 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
The Transient Hot-Wire (THW-L1) Liquid Thermal Conductivity Meter is an advanced measurement system for primary measurements of thermal conductivity, thermal diffusivity, and specific heat instrument for measurement of liquids and PCMs 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 for 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.
Materials | Liquids and PCMs |
---|---|
Measurement Capabilities | Bulk Properties |
Thermal Conductivity | 0.01 to 2 W/m•K |
Additional Properties | Thermal Diffusivity & Specific Heat |
Viscosity Range | 0.001 to 10,000,000 cP |
Measurement Time | 1 second | < 5 seconds |
Reproducibility | ± 1% |
Accuracy* | ± 5% |
Temperature Range† | -150 to 300°C |
Pressure | Up to 35 bar |
Smallest Volume | 20 mL |
Standard | ASTM D7896-19 |
Models | THW-L1 | THW-L1S | THW-L1E |
---|---|---|---|
Materials | Liquids and PCMs | Liquids and PCMs | Liquids and PCMs |
Measurement Capabilities | Bulk Properties | Bulk Properties | Bulk Properties |
Thermal Conductivity (W/m•K) | 0.01 to 2 | 0.01 to 2 | 0.01 to 2 |
Additional Properties | Thermal Diffusivity and Specific Heat | Thermal Diffusivity and Specific Heat | Thermal Diffusivity and Specific Heat |
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 second | < 5 seconds | 1 second | < 5 seconds | 1 second | < 5 seconds |
Reproducibility | ± 1% | ± 1% | ± 1% |
Accuracy* | ± 2% | ± 2% | ± 2% |
Temperature Range | 10 to 200°C | -50 to 200°C | -150 to 300°C |
Pressure | 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 |
External Cooling Apparatus Required | No | Yes | Yes |
*All performance data is verified with ASTM Type II Water (IAPWS)
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
Low back pressure was applied to the fluids, to allow measurements over their boiling point.
Thermal Conductivity deviations from reference values:
Water < 2%
Thermal Diffusivity deviations from reference values:
Water < 2%
Thermal Conductivity deviations from reference values:
Heptane < 3%
Thermal Diffusivity deviations from reference values:
Heptane < 2%
Calculated Specific Heat Capacity deviations from reference values:
Water < 2%
Heptane < 5%
Thermal Conductivity deviations from reference values:
Ethylene Glycol < 1%
Thermal Diffusivity 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.
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 |
Simply fill in the form and submit. One of our qualified team members will reach out to you to offer a price that fits your needs.