PUNCTIFORM HEAT SOURCE FOR MEASURING THERMAL CONDUCTIVITY AND/OR THERMAL DIFFUSIVITY

摘要

The invention relates to a method for measuring a thermal transfer variable, in particular a thermal conductivity (λ) and/or a thermal diffusivity (a), comprising the following steps: bringing a resistive element (12) in contact with a test specimen (28) so that the resistive element (12) has thermal contact with the test specimen (28) in a contact area, wherein an imaginary enveloping sphere (22) around the resistive element (12) has an enveloping sphere diameter (h), applying current through the resistive element (12) so that the resistive element (12) discharges a heat flow (Φ), measuring a resistance (R) of the resistive element (12), and calculating the thermal transfer variable (a, λ) at least also from the resistance (R), wherein the enveloping sphere diameter (h) is at most 10 millimeters and the thermal transfer variable (a, λ) is calculated at least also from the resistance (R) on the basis of a relationship that is valid under the assumption of a punctiform heat source.