A BROAD-BAND AND HIGH-SENSITIVITY DIELECTRIC-SPECTROSCOPY MEASUREMENT SYSTEM FOR QUALITY DETERMINATION OF LOW-PERMITTIVITY FLUIDS

Traditional quality measurement systems in the petroleum-related industry are complex in structure and difficult to maintain. A measurement system for high-sensitivity and accurate permittivity measurements has been built in order to investigate dielectric spectroscopy as a basis for an easier-to-maintain system, which can replace some of the traditional instrumentation systems. The permittivity measurement system has been designed and tested for]ow-permittivity and low-loss fluids in the frequency range from 1 kHz to 5 GHz. In the lower part of the frequency range impedance measurements are used, and in the higher range reflection coefficient measurements are employed. The characteristics of the measurement cells are optimized to give high sensitivity. High-accuracy permittivity measurements are obtained by calibration with several known fluids. Temperature control and careful experimental routines ensure good repeatability. Estimated overall uncertainty and presented measurement results on low-permittivity and low-loss oils and reference fluids confirm the performance of the system.