Modified Wilhelmy Apparatus for Efficient Molten Salt Surface Tension Measurement

Molten salt systems are highly relevant to liquid fuel media and heat transfer fluids in advanced power generation and storage systems. Accurate measurements of molten salt thermophysical properties (density, surface tension, viscosity, etc.) are critical inputs for the modeling and engineering of next generation molten salt nuclear reactors (MSR). Such measurements are challenging due to their thermal and chemical requirements, as well as measurement precision and accuracy. Large, reliable databases of property measurements are also essential for developing and validating theoretical and computational approaches. The proposed system adapts a generalized Wilhelmy/du NoüyľPadday measurement principle to address particular challenges of working with molten salts while ensuring reliability of measured data. The proposed instrument uses a Pt measurement rod that is connected to a highly sensitive piezo force transducer mounted vertically on a motorized precision linear slide. A measurement is performed by lowering the rod into the sample of interest and recording the force acting on the rod at different depths of immersion. The surface tension and density of the sample may be determined from the measurements of force as a function of immersion depth. Use of a crucible, thermal break, and thermal and chemical management by materials selection and engineering design will traverse the technical challenges associated with molten salts. Automated control and data acquisition systems will be incorporated into the proposed measurement design to create a robust scientific instrument that can minimize variability between operators. Simultaneous measurement of surface tension and density further increases efficiency while also serving as an important means for verifying sample-to-sample consistency. Taken together, the instrument design features and operation combine to create a robust measurement platform for use in high throughput molten salt thermophysical characterization with high data reliability. The overall goal of the Phase I effort is to develop a robust platform technology for high throughput, accurate measurement of surface tension of molten salts combined with simultaneous measurement/verification of density. We will develop the full set of target technical specifications for the instrument, followed by engineering of the materials and mechanical, electronic, and basic software/data acquisition systems to demonstrate a minimum viable prototype (MVP) of the surface tension and density measurement system at the end of Phase I. The measurement and environmental control capabilities of the MVP will be verified using room temperature ionic liquids as well as high temperature fluids. Customer needs for measurement of molten salts will be established and integrated into the Phase I design process. We propose a new, high-precision system for the simultaneous measurement of surface tension and density of materials at high temperature. The instrument may be used in support of the development and operation of new clean power generation systems that use molten salts as fuel or working fluids, including molten salt reactors. The instrument can be adapted for other markets where measurements using challenging conditions and/or limited sample volume are critical, including chemical industry or biopharma.