MEASUREMENT OF THERMAL CONDUCTIVITY OF AQUEOUS ORGANIC LIQUIDS USING THE RELATIVE TRANSIENT HOT-WIRE TECHNIQUE

Scope of Study. An apparatus and technique for measuring thermal conductivity of electrically non-conductive liquids was modified to allow measurement of electrically conductive liquids. Thermal conductivity measurements were made on such liquids to prove the modified apparatus and new measurement method. The results were compared to available literature data.; Findings and Conclusions. Contrary to accepted theory and practice, measurements of thermal conductivity employing the relative transient hot-wire method can be affected by thermal diffusivity when the measurement is the initial resistance change of the hot-wire. The greater the difference between the thermal diffusivities of the calibrant and test fluid, the greater the potential error of the measurement. To reduce the error caused by the difference in thermal diffusivities, the relative resistance measurement should be taken at a later time such that the error will be negligible. A tantalum hot-wire coated with oxide operated with direct current gave excellent electrical resistance for measurement of electrically conductive solutions over the range of 70 to 300 F.