Various methods are available at the Chair for measuring thermal conductivity.

1. Hot plate method

• Hot plate apparatus based on DIN EN 12664
• Surface temperatures and heat flow are measured in steady state
• Determination of the effective thermal conductivity of homogeneous and inhomogeneous samples
• Measurement is carried out in a climatic chamber under defined conditions

Technical data

Samples: Solids plate-shaped with plane-parallel surfaces
Sample dimensions: Area depending on heat flow plates at least:
                                 - 30 mm x 100 mm
                                 - 120 mm x 120 mm
                                 - 250 mm x 250 mm
Sample thickness depending on thermal conductivity > 10 mm
Temperature range: -10 °C to 60 °C
Measuring accuracy: ±6 % for Styrodur reference (≈0.035 W m⁻¹ K⁻¹)

2. Hot wire method

• non steady state measurement with hot wire for heat supply and measurement of the temperature change
• Determination of thermal conductivity from analytical solution of the heat conduction equation assuming a line source in the infinitely volume

Technical data

Samples: powders, bulk solids, liquids, solids (after solidification around the probe)
Sample dimensions: Cylindrical measuring container - diameter 50 mm
                                                                             - Height 200 mm
Temperature range: -10 °C to 60 °C
Measuring accuracy: ±5 to ±10 %

3. Applied Precision Isomet 2114

• non steady state commercial device for measuring thermal conductivity and volumetric heat capacity
• Needle probe for powders, bulk solids, solids and surface probe for solids
• Measurement performed in a climatic chamber under defined conditions

Technical data

Samples: powders, bulk solids, solids
Sample dimensions: Insertion probe - diameter min. 40 mm
                                                     - Height min. 80 mm
                                Contact probe - diameter min. 60 mm
                                                     - Thickness min. 40 mm
Temperature range: -20 °C to 70 °C
Measuring accuracy: ±5 % in the range 0.015 to 0.70 W m⁻¹ K⁻¹
                               ±10 % in the range 0.7 to 6.0 W m⁻¹ K⁻¹