On transient hot-wire determination of the thermal conductivity of pure, dielectric liquids

A survey is given of the theory of transient hot-wire measurement of the thermal conductivity X of pure, dielectric liquids. On the basis of the survey two possible sources of error are investigated: convection, which so far has not been studied in every detail; and a thermo-elastic error which appears in certain designs of the measuring cell, and which has not previously been mentioned in the literature. One of the purposes of the report is to serve as a foundation to which will be referred in a later report, which will deal with a modification of the method worked out by the author for measurement of A. for electrolytic solutions. It has therefore been necessary to deal rather exhaustively with some more trivial and well-known facts regarding the electric circuit analysis and the calculation method for X in sections V and VI. But the calculation method differs somewhat from the usual one because the modification mentioned made it necessary to use a hot wire of a relatively large diameter (500 urn). In the "classical" versions of the method, as thin a wire as possible is used (20 • 50 vm).