| 摘要 |
A method for measuring thermal properties of a test substance of an anisotropic material by means of a device incorporating a thin element (1) or a layer of an electrically conductive material, e.g. metal, in the form of a number ot thin strips (1a) arranged in a circular pattern is brought in heat conductive contact with said test substance, causing a temperature increase in the substance by passing an electric current through said element or layer and recording the voltage variation over the element or the layer as a function of time. The thermal properties of the test substance are assumed to be the same in two orthogonal directions but different in the third orthogonal direction. The thin element (1) is placed in parallel with the two directions of the test substance having substantially the same thermal properties and the experimental results are evaluated by an iteration process utilizing thermal conductivity equation (I), DELTA T is the temperature increase as a function of time, LAMBDA 1 and LAMBDA 3 is the thermal conductivity in the first and third direction respectively of the test substance; at which LAMBDA 1≠ LAMBDA 3; alpha is the radius of the circular element; D( tau 1) is a dimensionless time function. |
