February 19
@
12:00 PM
–
1:00 PM
Thursday, February 19
12:00 – 1:00pm
106 Engineering Research Building
Please contact office@neep.wisc.edu for assistance with remote participation.
Film Dryout in Annular Flows
Annular flow boiling is a highly effective cooling strategy, with applications ranging from microelectronics to nuclear reactors. However, at sufficiently high heat fluxes, the thin liquid film characteristic of annular flows will rupture, exposing the heated surface to vapor. This phenomenon, known as dryout critical heat flux (CHF), causes a sudden drop in the heat transfer coefficient. To avoid equipment damage, is a strong incentive to delay dryout to higher heat fluxes and vapor qualities to improve system reliability and efficiency.
This presentation explores the mechanisms driving dryout CHF in low surface tension fluids and presents methods for predicting both intermittent and full dryout. We will begin by discussing our recent experimental observations, focusing on the behavior of disturbance waves in annular flows and their role in film rupture. We then will examine how flow obstructions alter film dynamics and heat transfer characteristics. Finally, we will discuss how these insights can be incorporated into four-field annular flow models to improve dryout CHF predictions across a broad range of operating conditions. Overall, this work aims to deepen our fundamental understanding of thin film flows and the influence of surface features on the limits of annular flow boiling.
Dr. Allison Mahvi is the Bluemke Assistant Professor in the Department of Mechanical Engineering at the University of Wisconsin – Madison, where she leads the Laboratory for Energy Transport and Storage (LET+S). She earned her Ph.D. in Mechanical Engineering from Georgia Institute of Technology in 2018 and her B.S. from the UW – Madison in 2012. Following her doctoral studies, Dr. Mahvi held postdoctoral research positions at the University of Illinois at Urbana-Champaign (2018–2019) and the National Renewable Energy Laboratory (2019–2022). Her research focuses on two-phase flows, surface enhancements, advanced thermal energy systems, and thermal energy storage devices. Her work has resulted in 30 peer-reviewed journal publications. During her graduate studies, she was recognized with several awards, including the ASME Graduate Teaching Fellowship, the Sam Nunn Security Program Fellowship, the Woodruff Fellowship, and the ASHRAE Grant-in-Aid.