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The Transient Hot-Wire (THW-L2) is a portable thermal conductivity meter for measurement of liquids.
Best For Liquids
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-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, 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 |
| Standards | ASTM D7896-19 |
The THW-L2 comes with the standard 60 mm sensor for testing of liquids and pastes. The sensor is fully inserted into an isothermal sample and measurements are made with the push of a button. In less than 2 seconds, results are displayed for thermal conductivity. Volumes as small as 15 mL can be tested. The easy to use THW software enables measurements to be controlled via computer. When used in conjunction with the optional thermoelectric dry bath, the software can even automate measurements of thermal conductivity with temperature.with temperature.
The THW-L2 is capable of testing the thermal conductivity of almost any kind of liquid including nanofluids, nanopowders, emulsions and pastes using the same sensor and measuring cell. The sensitivity of the sensor can record even the smallest thermal conductivity changes when solid particles are settling inside a liquid mixture.
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.
The optional dry bath allows for automated measurements of thermal conductivity with temperature (-10 to 90 °C or 0 to 100 °C). The THW software automatically controls the increments of temperature steps between the desired start and end temperatures to ensure isothermal conditions and test results are free of temperature drift effects. For wider temperature ranges, additional cooling/heating options are available.
Using the THW-L2, liquid samples of unlimited size can be tested. With the small volume cell insert, volumes as small as 15 mL can be measured. The instrument’s ability to control convection using short test times allows accurate measurements of a wide range of samples with varying viscosities.
Approximate Time: 1 minute
Once the liquid has been poured into the sample holder, the sensor can be vertically inserted in place. For smaller sample volumes, position the small volume cell into the sample holder, prior to the addition of the sample and sensor.
Approximate Time: < 1 minute
The instrument can be controlled through the front panel with the push of a button, or Windows-based computer software. Single temperature point measurements, as well as scheduled temperature intervals, may be performed using the easy to use THW-L2 software.
Approximate Time: < 1 minute
Using the Windows based software users can save, print, and export test results to Microsoft Excel for further processing once testing is complete.
Approximate Time: 1 minute
Physical Properties of 7-Methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (mTBD)
7-Methyl-1,5,7-triazabicyclo[4,40]dec-5-ene (mTBD) is an important industrial chemical that is commonly used as a catalyst. Prior to the research conducted by Baird et al, the only available data on this chemical pertained to its density and a single vapor pressure value that is provided on chemical safety data sheets…
Investigation of the Thermal Conductivity and the Viscosity of Carbon Black Heat Transfer Nanofluids
Seven distinct samples of nanofluids consisting of different concentrations of spherical graphitized carbon black in an ethylene glycol solution were analyzed to determine their thermal and rheological behavior. The thermal conductivity measurements were made at 20°C and 30°C with a transient hot wire instrument made by Thermtest called THW-L2…
Thermal conductivities of four commonly used solvents that have similar physical properties.
Thermal Conductivity of Deionized Ultra-filtered (DIUF) Water with the THW-L2 Transient Hot Wire
Investigating the Thermal Conductivity and Viscosity of Carbon Black Heat Transfer Nanofluids
An experiment on pure water and 6 saline water mixture samples were measured for their thermal conductivity values using THW-L2.
To cast PCM samples for the THW-L2.
Used for testing samples from -10 to 100 °C.
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