Design and Testing of a Bubble Generator for Molten Salt Surrogate Fluid

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dc.contributor.authorBreeden, Courts Hollanden
dc.contributor.committeechairLiu, Yangen
dc.contributor.committeememberHaghighat, Alirezaen
dc.contributor.committeememberFreeman, David Wayneen
dc.contributor.departmentMechanical Engineeringen
dc.date.accessioned2025-02-14T09:01:00Zen
dc.date.available2025-02-14T09:01:00Zen
dc.date.issued2025-02-13en
dc.description.abstractThis study explores the design, testing, and modeling of a bubble injector intended for use in studying bubble dynamics in molten salt reactors using a room temperature surrogate fluid by matching the Reynolds number, Eötvös number, and Morton number defined by the properties of the helium bubbles in the pump bowl of the Molten Salt Reactor Experiment (MSRE). The injector, constructed from polydimethylsiloxane (PDMS) and acrylic, was tested to generate bubbles within a precise size range suitable for simulating conditions in molten salt reactors. Experimental data showed that the equivalent bubble diameter is directly proportional to gas flow rate and inversely proportional to liquid flow rate, with clear trends emerging when data were subdivided into constant flow rate plots. The study applied and adapted the bubble size control model proposed by Lu et al. (2014), revealing limitations in existing models under modified conditions such as an elongated two-phase channel. A novel model was developed to better predict bubble size, incorporating dependencies on both flow rate ratios and the capillary number of the microchannels. The injector's design facilitates convenient modifications in channel geometry to achieve target bubble sizes, and future improvements in pressure monitoring and imaging are recommended. This work contributes to the advancement of microfluidic bubble injection technology.en
dc.description.abstractgeneralThis study focuses on developing and testing a device that creates tiny bubbles to help us better understand bubble behavior in advanced nuclear reactors, specifically molten salt reactors. These reactors use a special type of liquid fuel, and understanding how bubbles move within them is important for improving their efficiency and safety. To simulate the conditions inside these reactors without using the actual molten salt, we used a substitute fluid that has similar properties to the molten salt and built a bubble injector made from clear, flexible materials. Our experiments showed that the size of the bubbles depends on the flow rates of the gas and liquid: larger bubbles are formed when more gas is injected, and smaller bubbles are created when the liquid flow is increased. We tested existing models that predict bubble size and found that they didn't always work well under the conditions we used, like longer channels where the gas and liquid mix. As a result, we developed a new model that better predicts bubble size by considering both flow rates and the Capillary number of the microchannels. The design of our injector allows for easy adjustments to make bubbles of different sizes, and we suggest future improvements in pressure measurement and camera equipment to enhance data accuracy.en
dc.description.degreeMaster of Scienceen
dc.format.mediumETDen
dc.identifier.othervt_gsexam:41672en
dc.identifier.urihttps://hdl.handle.net/10919/124583en
dc.language.isoenen
dc.publisherVirginia Techen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectThermal-hydraulicsen
dc.subjectMolten Salten
dc.subjectMicrofluidicsen
dc.subjectSurrogate fluiden
dc.titleDesign and Testing of a Bubble Generator for Molten Salt Surrogate Fluiden
dc.typeThesisen
thesis.degree.disciplineNuclear Engineeringen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameMaster of Scienceen

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