Differential dielectric-to-density measurement for cryogenic fluids

Abstract

A high-speed microprocessor-based cryogenic fluid density instrumentation is developed based on the rigorous application of dielectric theory, using a dielectric susceptibility function in the application of molecular Clausius–Mossotti formula. The operating principle is formulated on a novel differential dielectric measurement approach with a new algorithm which provides for automatic adjustments for polarizability and stray capacitance changes. High-precision digital density measurement is achieved over a wide range of fluid state ranging from supercritical, through subcritical to solid formation phases. Its conceptual development is examined in view of the interplay between theoretical arguments and engineering methodology.