THB – Transient Hot Bridge
Transient Hot Bridge – Thermal Conductivity Meter
Description
On point
Knowledge of heat transport properties of solids and liquids is becoming more and more crucial. Many application fields like automotive, aviation, aerospace but also power generation / energy industries or ceramics industries, building materials and glass industry and many more need very precise information about the thermal behavior of the used materials.
Heat management is becoming very important in the building industries due to exploding energy costs (isolation) or in the semiconducting industries if we think of high charged integrated device. That’s why a lot of research & development is also done in this field.
Advantages:
- Highest Accuracy
- Absolute technique (no calibration or reference sample required)
- Fast measurement cycles
- Non destructive measurement
- Broad measuring range
- Broad temperature range
- Easy handling (no trained staff required)
- Simple sample preparation
- Applicable for solids, liquids, powders and pastes
- No influence of sensor contact pressure on measurement
- Easy measurement of porous and transparent samples
Transient Hot Bridge Method
The THB measurement method initially developed by the National Metrology Institute of Germany is an optimized hot wire technique to measure all relevant thermal transport properties (thermal conductivity, thermal diffusivity and volumetric specific heat) with the highest possible accuracy.
It preserves all advantages of the strip technique but avoids its major drawbacks using a novel multiple strip sensor. The sensors layout consists of four identical meander-shaped strips (Fig. 1) compensated for end-effects arranged in parallel and connected for an equal-ratio Wheatstone bridge (Fig. 2).
An electric current makes the unequally spaced strips establish an inhomogeneous temperature profile that turns the bridge into an unbalanced condition. From then on, the THB produces an offset-free output signal of high sensitivity as a measure of the mentioned properties of the surrounding specimen (Fig. 3).
The THB closely meets the specific requirements of industry and research institutes for an easy to handle and accurate sensor. It allows rapid thermal-conductivity measurements on solid and fluid specimens.
Measurement Set-up
Two flat surfaces of the specimens are put in contact with both sensor sides in order to assure a good thermal contact without air inclusions. Either the delivered sample holder or a weight can be used. The shapes of the faces which are not in contact with the sensor are of no importance so that sample preparation is reduced to a minimum. Minimum sample thicknesses depend on their thermal diffusivity. In most cases some mms are sufficient.
After adjusting the heating power and heating time the measurement and the evaluation run automatically. Results can be post-processed if needed. Measurements take only some seconds up to a few minutes. The sensors are automatically identified by the software (THB-100/THB-500). Multiple measurements with automatic calculation of the mean values are possible as well as the storage of measurement programs.
Measurement can be done either at room temperature (no further equipment required) or at high or low temperatures. The set-up including the sensor can be placed in a normal lab oven or climatic chamber often available in laboratories. LINSEIS offers specially adapted furnaces covering temperatures from -150 up to 700°C.
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Specifications
| Model | THB 1 |
|---|---|
| Measuring ranges | |
| Thermal conductivity: | 0,01 up to 1 W/(mK) |
| Thermal diffusivity: | 0.05 up to 10 mm2/s |
| Volumetric heat capacity: | 100 to 5000 kJ/(m3 K) |
| Measurement uncertainties: | |
| Thermal Conductivity: | better than 2 % |
| Thermal Diffusivity: | better than 5 % |
| Heat Capacity: | better than 5 % |
| Duration of the measurement: | |
| Solids: | typically 1 to 10 min |
| Liquids: | typically 1 to 120 s |
| Service temperature | |
| Sensor: | –150 °C to 200 °C |
| Sensor type: | Kapton insulated sensor |
| Sample size | |
| Smallest sample: | 40 x 20 x 3 mm |
| Maximum Sample size: | unlimited |
| Sample consistence: | solid, liquid, gel, powder, granulate |
| Sample temperature*: | -150 up to 200 °C |
* Optional climate chamber
| Model | THB 100/500/1000 |
|---|---|
| Measuring ranges | |
| Thermal conductivity: | 0.01 up to 100/500/1000 (1800) W/(mK) |
| Thermal diffusivity: | 0.05 up to 10 mm2/s |
| Volumetric heat capacity: | 100 to 5000 kJ/(m3 K) |
| Measurement uncertainties: | |
| Thermal Conductivity: | better than 2 % |
| Thermal Diffusivity: | better than 5 % |
| Heat Capacity: | better than 5 % |
| Duration of the measurement: | |
| Solids: | typically 1 to 10 min |
| Liquids: | typically 1 to 120 s |
| Service temperature: | |
| Sensor: | –150 °C to 200 °C or -150 to 700°C |
| Sensor type: | Kapton or Ceramic insulated sensor |
| Sample size | |
| Smallest sample: | 3 x 3 x 3 mm |
| Maximum Sample size: | unlimited |
| Sample consistence: | solid, liquid, gel, powder, granulate |
| Sample temperature*: | -150 up to 700 °C |
* Optional climate chamber
Sensor types
All sensor types are available as Kapton-foil-sensors and resist to temperatures from -150 up to +200°C. Ceramic sensors are available covering a temperature range up to +700°C (THB-100 and THB-500).
| THB 1 | THB 100 | THB 500 | |
|---|---|---|---|
| Thermal Conductivity range | 0 to 5 W/mK | 0 to 100 W/mK | 0 to 500 W/mK |
| THB/Sensor/A | ✔ | ✔ | ✔ |
| THB/Sensor/B | ✔ | ✔ | ✔ |
| THB/Sensor/C | X | ✔ | ✔ |
| QSS-Sensor | X | ✔ | ✔ |
| Hotpoint-Sensor | X | ✔ | ✔ |
| Sensor type | Sensor size | Min. size | Temperature range | Measuring range | Suitable for |
|---|---|---|---|---|---|
| THB/Sensor/A | 82 x 42 mm | 20 x 40 x 5 mm | -150 up to 200°C | 0.01 – 1 W/m·K | liqudis, powders, gases |
| THB/Sensor/A/Metal | 105 x 42 mm | 20 x 40 x 5 mm | -150 up to 200°C | 0.01 – 1 W/m·K | liqudis, powders, gases |
| THB/Sensor/B | 42 x 22 mm | 10 x 20 x 3 mm | -150 up to 200°C | 0.01 – 1 W/m·K | liqudis, powders, gases |
| THB/Sensor/B/Metal | 54 x 22 mm | 10 x 20 x 3 mm | -150 up to 200°C | 0.01 – 1 W/m·K | liqudis, powders, gases |
| THB/Sensor/C | 300 x 3 mm | 10 x 10 x 10 mm | -150 up to 700°C | 0.01 – 1 W/m·K | liqudis, powders |
| THB/Sensor/D/QSS | 42 x 22 mm | 22 x 42 x 3 mm | -150 up to 200°C | 0.2 – 100 W/m·K | liqudis, powders, gases |
| THB/Sensor/E/QSS | 42 x 22 mm | 22 x 42 x 3 mm | -150 up to 200°C | 0.2 – 500 W/m·K | liqudis, powders, gases |
| THB/Sensor/F/QSS | 28 x 15 mm | 2.0 ml, 30 x 15 x 6 mm | -150 up to 700°C | 0.2 – 100 W/m·K | liqudis, powders; electric isolating media |
| THB/Sensor/G/HOTPOINT/ Kapton | 65 x 5 mm | 3 x 3 x 2 mm | -150 up to 200°C | 0.01 – 1 W/m·K | liqudis, powders, gases |
| Sensor THB6N | 82 x 42 mm | 20 x 40 x 5 mm | RT up to 700°C | 0.01 – 1 W/m·K | liqudis, powders, gases |
| Sensor THB6K | 42 x 22 mm | 10 x 20 x 3 mm | RT up to 700°C | 0.01 – 1 W/m·K | liqudis, powders, gases |
| Sensor QSS MC | 42 x 22 mm | 22 x 42 x 3 mm | RT up to 700°C | 0.2 – 100 W/m·K | liqudis, powders, gases |
| Sensor QSS HC | 42 x 22 mm | 22 x 42 x 3 mm | RT up to 700°C | 0.2 – 100 W/m·K | liqudis, powders, gases |
| Sensor Hotpoint HT | 300 x 3 mm | 10 x 10 x 10 mm | RT up to 700°C | 0.01 – 1 W/m·K | liqudis, powders, gases |
More on request!
Software
All thermo analytical devices of LINSEIS are PC controlled and the individual software modules exclusively run under Microsoft Windows operating systems. The complete software consists of 3 modules: temperature control, data acquisition and data evaluation. The Linseis 32 – bit software encounters all essential features for measurement preparation, execution and evaluation with a THB run, just like with other thermo analytical experiments. Due to our specialists and application experts LINSEIS was able to develop this easy understandable and highly practical software.
General Features
- Repetition measurements with minimum parameter input
- Evaluation of current measurement
- Curve comparison up to 32 curves
- Curve subtraction
- Zoom function
- Multiple smoothing functions
- Storage and export of evaluations
- Program capable of text editing
- Export and import of data ASCII
- Data export to MS Excel
- Signal-steered measuring procedures
- Zoom in function
- Undo function
Applications
Applications example: Ceramic filled Polymers
In the following diagram you can see a typical measurment of a ceramic filled polymer. All three parameters, thermal Diffusivity, thermal conductivity and specific heat have been calculated and reported simultaneously. In addition to the measurement values, the Software calculates and displays the associated measurement uncertainties in accordance with the international ISO standard.
External applications
An evaluation of the reduction of heat loss enabled by halloysite modification of oilwell cement (published Engineering Research Express – Paper on request)
Effect of Graphene Nanoplatelet Concentration on the Thermal Conductivity of Silicone Thermal Grease (published Journal of Nano- and Electronic Physics – Paper on request)
Epoxy-Thiol Systems Filled with Boron Nitride for High Thermal Conductivity Applications (published Polymers- Paper on request)
