Characterization of Flowing Hydrofluoroethers at Cryogenic Temperatures

Presenter: Graeme Sullivan

Faculty Sponsor: Andrea Pocar

School: UMass Amherst

Research Area: Chemical and Biomolecular Engineering

Session: Poster Session 6, 4:15 PM - 5:00 PM, Auditorium, A39

ABSTRACT

Hydrofluoroethers (HFE) are a class of high-density organics that can be produced at high purity. These properties make HFE a suitable cooling fluid for cryogenic particle detectors, such as neutrino detectors, because these instruments require extremely low levels of background radioactivity. Stationary cooling of HFE relies on free convection, which slows at temperatures where HFE is viscous, and large surface area heat exchangers which increase radioactivity. Although HFE has been used in detectors like EXO-200, previous low temperature work with HFE has occurred only in a stationary configuration. To cool the tens of tons of HFE in neutrino detectors within a reasonable time scale while limiting radiation, it is suggested to circulate HFE to external heat exchangers for cooling. To inform the design of recirculated HFE cooling systems in future particle detectors, we have developed and constructed a lab-scale HFE recirculation system capable of characterizing the flow of HFE between 25ºC and -100ºC. Recirculation of HFE at a range of temperatures inside the circuit allows for characterization of both thermal and flow behavior of HFE under conditions like those in a particle detector. The HFE system was developed using core chemical engineering principles of heat and mass transfer, fluid mechanics, process design, and process control. This study outlines the design and operating procedure for a pumped cryogenic HFE system including important design considerations and common pitfalls associated with HFE. This study informs development of future HFE systems and will allow for successful operation of the next generation of particle detectors.

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