Thermal conductivity heat flow may not be exactly the same as the direction of the thermal gradient. In metals, thermal conductivity approximately tracks electrical conductivity according to the Wiedemann–Franz law, as freely moving valence electrons transfer not only electric current but also heat energy. However, the general correlation between electrical and thermal conductance does not hold for other materials, due to the increased importance of phonon carriers for heat in non-metals. Highly electrically conductive silver is less thermally conductive than diamond, which is an electrical insulator, but due to its orderly array of atoms it is conductive of heat via phonons. The
Electrical conductivity meter develop a model to calculate concentration of the liquid. Concentration of pure liquids can be calculated when the conductivity and temperature is measured. The preset curves for various acids and bases are commercially available. For example, it is possible to measure the concentration of high purity hydrofluoric acid using conductivity based concentration measurement [Zhejiang Quhua Fluorchemical, China Valmet Concentration 3300]. Benefit of conductivity and temperature based concentration measurement is the superior speed of inline measurement compared to on-line analyzer. Conductivity based concentration measurement has limitations. The concentration-conductivity dependence of most acids and bases is not linear. Conductivity based measurement can’t