The Thermophysical Properties Laboratory provides BIPM-traceable, high-accuracy measurements of thermophysical properties of materials such as thermal conductivity, thermal resistance, specific heat, thermal diffusivity, thermal expansion, and emissivity.
Overview
Measurements such as thermal conductivity, thermal resistance, and specific heat are necessary to understand the thermal behavior of materials and to develop more efficient, durable, and reliable systems in various applications. These measurements provide fundamental data for correct material selection and design, and are of critical importance especially in fields such as electronic devices, energy systems, automotive, aerospace, and defense.
This information is used to increase energy efficiency, optimize thermal management systems, ensure safety against rapid temperature changes, and model thermal performance. This enables the development of innovative solutions that provide advantages both in performance and cost.
The main purpose of the Thermophysical Properties Laboratory is to enable traceable measurements of the properties determined by the BIPM Thermophysical Properties Working Group. The laboratory currently performs measurements in the areas of thermal conductivity, thermal resistance, specific heat, thermal diffusivity, thermal expansion, calorimetric measurements, heat flux, emissivity, and hyperspectral measurements, among others.
The current laboratory infrastructure has been established primarily for low-level thermal conductivity measurements of thermal insulation materials. Infrastructure for measuring higher (>2 W/m*K) thermal conductivity values is being developed. A dilatometer with horizontal configuration is used for thermal expansion measurements of solid materials.
Another purpose of the laboratory consists of studies aimed at characterizing pyrometers, radiation thermometers, and IR calibrators used in calibrating thermal cameras, with the goal of measuring the temperature distribution of emissivity and radiation fields.
Research
Measurement of thermal conductivity and resistance values of thermal insulation and industrial materials with BIPM traceability.
High-accuracy measurement of specific heat capacity and thermal diffusivity of solid and liquid materials using calorimetric and laser flash methods.
Determination of linear and volumetric thermal expansion coefficients of solid materials using a dilatometer.
Determination of total and spectral emissivity values of materials; characterization of IR calibrators and thermal cameras.
Measurement and traceable calibration of heat flux density in building elements, energy systems, and industrial devices.
Measurement of spectral reflectance and transmission properties of materials in the IR spectral range using hyperspectral imaging systems.
Equipment
The laboratory performs thermophysical property measurements using a wide range of instruments, primarily including hot wire (guarded hot plate), laser flash diffusivity, differential scanning calorimetry (DSC), dilatometer, and emissivity measurement systems.
Instrument measuring the thermal conductivity of materials in accordance with ISO 22007-2 standard. Makes precise measurements in low-conductivity materials using the transient plane source method.
Method measuring the thermal diffusivity coefficient of solid materials. Measurements completed within milliseconds are also used in specific heat calculations.
Enables high-precision determination of phase transition temperatures, melting/solidification enthalpy, and specific heat capacity of materials.
Horizontal-configuration system measuring the linear thermal expansion coefficient of solid materials. Measures length changes at nanometer precision over a wide temperature range.
Fourier transform infrared spectrometry (FTIR) based system. Measures the spectral normal emissivity of material surfaces; used in IR calibrator characterization.
Infrastructure
| No | Equipment / System | Brand | Model | Range / Capacity | Purpose / Use |
|---|---|---|---|---|---|
| 1 | Hot Disk Thermal Analyzer | Hot Disk AB | TPS 2500S | 0.005 – 1000 W/m·K | Thermal conductivity and diffusivity measurement |
| 2 | Laser Flash Diffusivity (LFA) | NETZSCH | LFA 467 HyperFlash | −120 – 500 °C | Thermal diffusivity and specific heat measurement |
| 3 | Differential Scanning Calorimeter (DSC) | NETZSCH / TA Instruments | DSC 214 Polyma / Q2000 | −180 – 700 °C | Specific heat, phase transition, and enthalpy measurement |
| 4 | Dilatometer | NETZSCH | DIL 402 Expedis | −150 – 2000 °C | Thermal expansion coefficient measurement |
| 5 | FTIR Spectrometer | Bruker / Thermo Fisher | VERTEX 70 / Nicolet iS50 | 400 – 8000 cm⁻¹ | Emissivity and spectral transmittance measurement |
| 6 | IR Calibrator (Blackbody) | Fluke / Isotech | 4181 / Nu Blackbody | −20 – 200 °C | Thermal camera and pyrometer calibration |
| 7 | Heat Flux Sensor | Hukseflux / Captec | HFP01 / CP09 | 0 – 2000 W/m² | Surface heat flux measurement and calibration |
Accuracy
The expanded uncertainties (k=2) of measurements performed in the laboratory have been calculated in accordance with BIPM guidance documents and ISO/IEC 17025:2017 requirements.
| Measurand | Expanded Uncertainty (U) | Confidence Level |
|---|---|---|
| Thermal Conductivity (0.01 – 0.5 W/m·K) | < 3% | k=2 (approx. 95% confidence interval) |
| Specific Heat (DSC Method) | < 2% | k=2 (approx. 95% confidence interval) |
| Thermal Diffusivity (LFA Method) | < 5% | k=2 (approx. 95% confidence interval) |
| Thermal Expansion Coefficient | < 1% | k=2 (approx. 95% confidence interval) |
* Uncertainty values are calculated using a coverage factor k=2 and correspond to an approximately 95% confidence interval.
Calibration
Traceable calibration of thermal conductivity measurement instruments such as hot disk, hot wire, and guarded hot plate using reference materials.
Temperature and enthalpy-based calibration of differential scanning calorimeters using pure metal standards.
Emissivity and temperature distribution characterization of IR calibrators used in the calibration of thermal cameras and pyrometers.
Traceable calibration of heat flux sensors used in building energy analyses on a [W/m²] unit basis.
Services
Thermophysical property measurement and calibration services traceable to BIPM and SI units.
Thermal property testing for insulation materials, building components, electronics, and aerospace materials.
Technical training on thermophysical property measurement methods, standards, and uncertainty calculations.
Metrology support for R&D projects in new material development, energy efficiency, and thermal management.
Expert support on measurement method selection, sample preparation, and uncertainty budget.
Thermophysical property comparison measurements conducted within BIPM and European metrology networks.
Application Areas
The Thermophysical Properties Laboratory provides calibration, measurement and consultancy services to institutions and organizations in the following sectors.