Description
To the point
Special field of application: Nuclear materials
Since the 1950s nuclear energy is the worldwide most important energy source around the world. With their advantage of clean and cheap power supply, core reactors were undergoing a continuous global improvement during the last 50 years. Meanwhile the reactors of the 4th generation such as very high temperature reactors (VHTR) or sodium cooled fast reactors (SFR) as well as the unique molten salt reactor (MSR) are currently under development and will be the future for nuclear energy.
Due to the research that is done in that field, there is a need of analytical equipment and especially instruments for thermal analysis. Of course these special applications and safety requirements need a lot of modifications of the standard devices, that makes Linseis become the worldwide leader in thermal analysis of nuclear materials as we are the most flexible and most experienced player on that market.
Thermal analysis of nuclear materials
In case of any of the mentioned dangers, it gets tricky to operate the system and also to do service and maintenance.
To avoid such problems, the following points must be solved:
- The system must be able to be controlled from a safe place (other room, glovebox, hood)
- All critical parts that have to be accessed for maintenance must be accessible
- Samples must be placed in the system and removed from the system somehow
- All components that get in touch with corrosive substances must be able to withstand them
Laser Flash Analyzer – Measurement Principle (ASTM E 1461)
LFA – Evaluation Models
- Experiment has non-ideal conditions (e.g. heat loss to surrounding and finite pulse length)
- Models include heat loss to vicinity, finite pulse length or combine both (Dusza)
Unique Features
Wide temperature range:
-125°C to 2800°C
High precision and repeatability
of measurements
Modular design for
flexible customization
Fast measuring times thanks
to advanced IR-detector technology
User-friendly software for
comprehensive data analysis
Compatibility with different sample
geometries and materials
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Specifications
Black on white
MODEL | LFA 1000 |
|---|---|
| Temperature range: | -125 °C/ -100°C up to 500°C RT up to 1250°C RT up to 1600°C |
| Pulse source: | Nd:YAG laser, user replaceable |
| Measurement of temperature rise: | Contactless via IR (InSb or MCT) detector |
| Measuring range thermal diffusivity: | 0,01 mm2/s up to 2000 mm2/s |
| Measuring range thermal conductivity: | 0.1 W/mK up to 3500 W/mK |
| Sample size: | ∅ 6, 10, 12.7 ... 25.4 mm Square samples 10×10 or 20×20 mm |
| Sample thickness: | 0.1 mm ... 6 mm |
| Number of possible samples: | Sample robot for up to 3, 6 or 18 samples |
| Sample holder: | metal/SiC/graphite |
| Atmosphere: | inert or reducing |
| Data acquisition: | 2 MHz |
| Interface: | USB |
| Heating rate: | 0.01 - 50 °C/min* |
| *Depending on the selected furnace | |
MODEL | LFA 2000 |
|---|---|
| Temperature range: | RT up to 2800°C |
| Pulse source: | Nd:YAG laser 25 J/pulse |
| Measurement of temperature rise: | Contactless via IR (InSb or MCT) detector |
| Measuring range thermal diffusivity: | 0.01 mm2/s ... 2000 mm2/s |
| Measuring range thermal conductivity: | 0.1 W/m*K ... 4000 W/m*K |
| Sample size: | ∅ 6, 10, 12.7 ... 25.4 mm |
| Sample thickness: | 0.1 mm ... 6 mm |
| Number of possible samples: | Sample robot for up to 3 samples |
| Sample holder: | metal/SiC/graphite |
| Atmosphere: | inert or reducing (recommended) |
| Data acquisition: | 2 MHz |
| Interface: | USB |
| Heating rate: | 0.01 - 100 °C/min* |
| *Depending on the selected furnace | |
Software
Making values visible and comparable
All thermo analytical devices of LINSEIS are PC controlled, 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, just like with other thermo analytical experiments.
LFA Features
- Precise pulse length correction, pulse mapping
- Heat-loss corrections
- Analysis of 2- or 3-layers systems
- Dusza model for simultaneous finite pulse and heat loss correction
- Wizard for selection of the perfect evaluation model
- Specific heat determination
- Contact resistance determination in multi-layer systems
Evaluation Software
- Automatic or manual input of related measurement data (density, specific heat)
- Model wizard for selection of the appropriate model
- Finite pulse correction
- Heat loss correction
- Multilayer model
- Determination of contact resistance
- Cp (Specific Heat) determination by comparative method
Measurement Software
- Easy and user-friendly data input for temperature segments, gases etc.
- Controllable sample robot
- Software automatically displays corrected measurements after the energy pulse
- Fully automated measurement procedure for multi sample measurements
Applications
Application example: Thermal diffusivity measurement on Molten Salts using LFA 1000
The measurement of the thermal diffusivity of Molten Salt FLiNaK presented here was carried out in a helium atmosphere from 773 K to 973 K using a Linseis LFA1000 system.
The specially designed crucible was inserted into a sample robot that can hold up to three samples simultaneously. Before the actual test, the sample was preheated slightly above the melting temperature several times to allow degassing of the material and thus avoid bubbles in the molten salt.
The thermal conductivity of the molten salt can be calculated using the thermal diffusivity measured by the LFA and the data on specific heat capacity and density using the following relationship:
In summary, the thermal conductivity in the temperature range from 773 K to 973 K of FLiNaK liquid salt was determined to be 0.652-0.927 W/m∙K with an uncertainty of +/- 0.023 W/m∙K [1]. This shows good agreement with the previously published values.
In conclusion, it can be said that the laser flash technique in combination with the specially developed crucible and the combined model of Dusza is a reliable method for determining the thermal diffusivity of molten salts at high temperatures.
*Cf. X.-H. An et al. (2015): thermal conductivity of high temperature fluoride molten salt determined by laser flash technique, in: International Journal of Heat and Mass Transfer, pp. 872 – 877.
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