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Thermtest THW-L1 Liquid Thermal Conductivity Instrument

THW-L1 Transient Hot Wire
Liquid Thermal Conductivity Analyzer

ASTM D7896-19

The THW-L1 following ASTM D7896-19, is widely used for the accurate measurement of thermal conductivity, thermal diffusivity, and specific heat of liquids
pastes and powders. 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.

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    Capabilities

    The THW-L1 was designed with speed and operational simplicity in mind.

    Specifications

    Read about the Transient Hot Wire THW-L1 Specifications. Click on an icon to jump to a section.

    Cells and Accessories

    Click here see the list of optional samples cells and accessories for THW-L1 equipment.

    Application

    Go more in-depth and explore applications investigating the thermal conductivity and thermal diffusivity of water and heptane.

    FEATURED TRANSIENT HOT WIRE CAPABILITIES

    THW-L1 Features
    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, 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 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.
    • 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

    THW-L1 SPECIFICATIONS

    Materials Liquids, Pastes, and Powders
    Measurement Capabilities Bulk Properties
    Thermal Conductivity 0.01 to 2 W/m•K
    Additional Properties Thermal Diffusivity and Specific Heat
    Viscosity Range 0.001 to 10,000,000 cP
    Measurement Time 1 second | < 5 seconds
    Reproducibility ± 1%
    Accuracy* ± 2%
    Temperature Range -150 to 300°C
    Pressure Up to 35 bar
    Smallest Volume 20 mL
    Standard ASTM D7896-19

    Based on THW-L1 model used
    *All performance data is verified with ASTM Type II Water (IAPWS)

    Transient Hot-Wire (THW) Models

    Models THW-L1 THW-L1S THW-L1E
    Materials Liquids, Pastes, and Powders Liquids, Pastes, and Powders Liquids, Pastes, and Powders
    Measurement Capabilities Bulk Properties Bulk Properties Bulk Properties
    Thermal Conductivity 0.01 to 2 W/m•K 0.01 to 2 W/m•K 0.01 to 2 W/m•K
    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
    Repeatability ± 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)

    Portable THW Models

    Models THW-L2 THW-L3 THW-S
    Materials Liquids, Pastes, and Powders Liquids, Pastes, and Powders Liquids, Pastes, and Powders
    Measurement Capabilities Bulk Properties Bulk Properties Bulk Properties
    Thermal Conductivity 0.01 to 2 W/m•K 0.01 to 1 W/m•K 0.01 to 2 W/m•K
    Additional Properties No No No
    Viscosity Range 0.001 to 10,000,000 cP 0.001 to 10,000,000 cP N/A
    Measurement Time 1 second | < 5 seconds 1 second 1 to 5 seconds
    Repeatability ± 2% ± 2% ± 2%
    Accuracy ± 5% ± 5% ± 5%
    Temperature Range -50 to 100°C 10 to 40°C 10 to 40°C
    Pressure Ambient Ambient N/A
    Smallest Volume 15 mL 15 mL Min. Sample Size: 50 mm x 10 mm
    Standard ASTM D7896-19 ASTM D7896-19 N/A
    External Cooling Apparatus Required Yes Yes N/A

    Optional THW-L1 Sample Cells

    THW-L1 Paste and PCM Cell

    Paste and PCM Cell

    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.

    Ambient Density Powder Cell

    Ambient Density Powder Cell

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

    THW-L1 Observation Cell

    Observation Cell

    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.

    Variable Density Powder Cell

    Variable Density Powder Cell

    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.

    Optional THW-L1 Accessories

    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.

    Vertical cell mount attached without sample
    Vertical cell mount attached without sample.
    Vertical cell mount with sample
    Vertical cell mount with sample loaded.
    THW-L1 Cooling options

    Cooling Options

    • Economy Circulator: Down to 0°C
    • THW-L1 Circulator: Down to -15 / -35 / -50°C
    • THW-L1E Only: Down to -100 / -150°C

    SAMPLE MEASUREMENT

    THW-L1 Liquid Sample

    1

    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 minute

    step 2 insert sensor

    2

    Insert Sensor

    For testing with temperature, the liquid cell is inserted into the integrated temperature platform.

    Approximate Time: < 1 minute

    Step 3 run the expirement

    3

    Run Experiment

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

    Approximate Time: < 1 minute

    thw-l1 export results

    4

    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 minute

    HFM-100 Heat Flow Meter Thermal Conductivity Steps Sample

    1

    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 minute

    step 2 insert sensor

    2

    Insert Sensor

    For testing with temperature, the liquid cell is inserted into the integrated temperature platform.

    Approximate Time: < 1 minute

    HFM-100 Heat Flow Meter Thermal Conductivity Steps Sample Clamp

    3

    Run Experiment

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

    Approximate Time: 1 minute

    HFM-100 Heat Flow Meter Thermal Conductivity Steps Sample Run

    4

    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 minute

    THW-L1 Applications

    Output results of THW-L1 are thermal conductivity, thermal diffusivity and calculated specific heat. Low back pressure was applied to the fluids, to allow measurements over their boiling point.

    Thermal Conductivity of Water

    Deviations from reference values:
    Water < 2%

    Thermal Conductivity of Heptane

    Deviations from reference values:
    Heptane < 3%

    Thermal Diffusivity of Water

    Deviations from reference values:
    Water < 2%

    Thermal Diffusivity of Heptane

    Deviations from reference values:
    Heptane < 2%

    Calculated Specific Heat Capacity

    Deviations from reference values:
    Water < 2%
    Heptane < 5%

    Low back pressure was applied to allow measurements over their boiling point.

    Thermal Conductivity of Ethylene Glycol

    Thermal Conductivity of Ethylene-Glycol

    Deviations from reference values:
    Ethylene glycol < 1%

    Thermal Diffusivity of Ethylene Glycol

    Thermal Diffusivity of Ethylene Glycol

    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.

    Download THW-L1 Brochure